Quantum Dots Sensitized TiO 2 Photoanode for PEC Solar Hydrogen Production

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1 Quantum Dots Sensitized TiO 2 Photoanode for PEC Solar Hydrogen Production Rajesh Adhikari, Lei Jin, Yufang Zhou, Haiguang Zhao, Alberto Vomiero, Federico Rosei Institute National da la Research Scientific (INRS-EMT), 1650 Boul. Lionel Boulet, J3X 1S2 Varennes (QC), Canada Abstract Here, we present the fabrication of quantum dots (CdSe, CdSe/ 3CdS and CdSe/13CdS) sensitized TiO 2 photoanode aiming to utilize in the photoelectrochemical (PEC) solar hydrogen production. The deposition of Quantum dots on TiO 2 film were performed by the Electrophoretic deposition (EPD) process and the photophysical properties were investigated. Photoluminescence (PL) and corresponding life time measurement of the luminescence decay reveal the as fabricated photoanodes could be a promising material for the PEC solar hydrogen production. Key Words: Quantum Dots, Photoanode, Solar hydrogen production 1

2 Electrocatalytic Behaviour of Nickel Coated Electrodes Formed by Atmospheric and Suspension Plasma Spraying Maniya Aghasibeig, Ali Dolatabadi, Rolf Wuthrich, Christian Moreau Concordia University, Department of Mechanical and Industrial engineering, 1455 De Maisonneuve Blv. W., Montreal, Quebec, Canada Alkaline water electrolysis can be used as a promising method to produce hydrogen as a green and renewable energy resource. To increase the energy efficiency of the electrolysis process, hydrogen production overpotential needs to be reduced by using electrodes with large and porous surface areas. A larger electrode surface area adds to the reaction area by increasing the electrode-electrolyte interface, which reduces the operating current density and contributes to a higher electrocatalytic activity. These surface properties depend strongly on the technique used to prepare the electrodes. Plasma spraying could be effectively used to deposit electrocatalytically active electrode coatings with controlled morphologies by interplay of the process parameters. In the present study, porous nickel electrode coatings were fabricated using atmospheric plasma spray (APS), suspension plasma spray (SPS) and combination of both methods. The morphology of the coated electrodes was studied by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Steady-state polarization curves were used to study the electrocatalytic activity of the electrodes for hydrogen evolution reaction (HER). The electrode fabricated by a combination of APS and SPS techniques demonstrated the highest electrocatalytic activity for the HER. The increased activity of the APS-SPS coated electrode was related to its enhanced surface area with a good accessible triple phase boundaries formed by a combination of micron and nanosized features. 2

3 Size Distribution Measurement Techniques of In-flight Particles in Suspension Plasma Spray Process A. Akbarnozari, S. Amiri, A. Dolatabadi, C. Moreau Mechanical and Industrial engineering, Concordia University, Montreal, Quebec, Canada Suspension plasma spray (SPS) is an emerging coating technique mainly applicable in the energy, aerospace, and automotive industries. In SPS, a suspension of sub-micron coating particles in water or organic liquid is injected into a hot and high speed plasma gas flow. The suspension is atomized by the plasma jet and particles are then melted and accelerated toward a substrate to make a thin coating layer. The size distribution of the in-flight particles, which has a great impact on the thermal and mechanical properties of the coating, is strongly dependent on the plasma and suspension characteristics. These characteristics are controlled by a number of parameters such as the plasma gas composition and flow rate, arc current as well as suspension composition, flow rate and injection speed. In this study, the measurement of particle size distribution of in-flight particles is investigated mainly by optical methods such as light diffraction, phase Doppler particle analysis (PDPA), and imaging. For this purpose, a suspension of sub-micron yttria stabilized zirconia (YSZ) particles in ethanol is radially injected into the plasma plume. The primary plasma gas is argon and the secondary plasma gases are hydrogen and helium. The high intensity of scattered light of plasma, small size of the particles, the high temperature gradient and turbulence in the plasma jet are main challenges for the measurement. In this condition, the different methods of sizing and their measurement capability in the plasma condition are evaluated. At the end, the advantages and limitations of measurement with these techniques in the plasma spray are summarized. 3

4 Laser-induced photodetachment in a magnetically confined lowpressure argon-acetylene plasma destined for nanoparticles formation Georges Al Makdessi 1, Ahmad Hamdan 1, Joëlle Margot 1 and Richard Clergereaux 2 1 Groupe de physique des plasmas, Université de Montréal, Canada 2 Université de Toulouse-LAPLACE-CNRS, France In this work, we present a diagnostic study of negative species present in a Ar-C 2 H 2 plasma using laser photodetachment technique. The plasma was created in different gas mixtures and different gas pressures ranging from 2 to 10 mtorr. A magnetic field (mirror configuration) has been applied to the discharge and its intensity B was changed continuously from 0 to 140 G. Its effect on the negative species density (n ) is the main parameter studied in this work. n has shown an increase with B and a slight decrease with C 2 H 2 percentage. This increase as function of B is reported to be the result of the confinement of electrons in the plasma inducing a change in the plasma kinetics. The effect of the gas pressure was studied in the range mentioned before and it was observed that n decreases with the pressure due to the increase of collisions frequency leading to a loss in the negative species density. Moreover, the photodetachment cross section has been deduced and it was found two orders of magnitude higher than that of typical negative ions usually present in Ar-C 2 H 2 plasmas. This difference pushes us to assume that the dominant photodetached species are the negatively charged nanoparticles synthesized and confined in the plasma. 4

5 Particle accelerators: From particles to light......from light to particles Patrizio Antici INRS-Énergie Matériaux et Télécommunications, Varennes, Québec The acceleration of particles is a continuing challenge that has been interesting scientists and engineers since the end of the 19 th century, in particular for the manifold applications particle accelerator can be used for: medicine (tumor treatment, PET, radiography), environment (spallation and transmutation), material science (material transformation), fundamental physics, etc. The advent of lasers, which can produce compact bunches of coherent photons, has opened up possibilities of laser-based particle acceleration thanks to it s very high accelerating gradient, almost 1000 times stronger than for conventional accelerators. A stronger accelerating gradient reduces potentially the size and hence the costs of big accelerator facilities (e.g the LHC accelerator ring at CERN-Geneva, where the electron storage ring is around 27 km long). Besides reducing costs, laser-based particles open up many innovative applications. I will present some new generation accelerators and applications. 5

6 Structures des arcs produits dans un four à arc électrique utilisant deux cathodes jumelles. F. Aristizabal 1, F.P. Sainct 1, M.D.G. Evans 1 and S. Coulombe 1 1 Department of Chemical Engineering, McGill University, Montréal, Québec, Canada Keywords: electric arc furnace, twin-cathode, arc interaction Industrial applications of DC and AC electric arc furnaces (EAF) range from steelmaking and smelting processes to municipal waste treatment. In a typical twoelectrodes arrangement, the powered electrodes are mounted above the load to be treated. Two configurations are commonly used for DC EAF: 1) dual- electrode, where one electrode is the cathode while the other acts as the anode; or 2) twin-cathode, where both electrodes act as cathodes and the load acts as the anode. The first configuration offers the possibility to operate with non-conductive or poorly conductive loads, while the second leads to more stable arcs and higher heat transfer rates to the loads. An interesting difference between these two configurations is that, due to the arcs interaction via the Lorentz force, the arcs repel each other in the dual-electrode configuration, while they attract each other in the twin-cathode configuration. This difference gives the twincathode configuration a significant advantage for industrial applications, i.e. reduced arcing to the walls of the EAF and better arc stability. This study reports on our first findings on the arcs interaction dynamics with a twincathode EAF configuration. The main objective is to characterize the types of structures the interacting arcs form depending on the electrode gap (cathode-to-anode distance) and other operating parameters. A preliminary study of arc structures formed in a laboratoryscale twin-cathode DC EAF was performed. The V-I curves obtained while varying the cathode-to-anode distances revealed the characteristic arc behavior, with a continuous merging of the data obtained at various electrode distances. Three characteristic structures were observed: two separated arcs (II), merged arcs with a single anode attachment point (Y), and merged arcs with two separate anode attachment points (X). Structure II tends to prevail at cathode-to-anode distance smaller than the spacing between the twin cathodes, while structure Y tends to be more frequently observed at larger spacing. Cycling the cathode-to-anode spacing revealed a memory effect where a given structure persists longer depending on the cycling direction. 6

7 Influence of Plasma Radiation Scattered by Inflight Particles on Temperature Measurement in Suspension Plasma Spraying Bishoy Aziz, Christian Moreau Conncordia University The temperature of in-flight particles in plasma spraying is one of the main parameters affecting the coating microstructure. Temperature measurement has been carried out before for in-flight particles in air plasma spray (APS) and other thermal spraying processes. Suspension plasma spray (SPS) is an emerging coating deposition technology that permits the deposition of nanostructured coatings with unique structural characteristics. The aim of this work is to evaluate the influence of radiation emitted by the plasma and metallic vapors on temperature measurement of SPS particles performed by two-color pyrometry. To do so, spectroscopic analysis in the visible to near-infrared range is carried out on the jet stream when suspension of 20wt% YSZ particles in ethanol is sprayed. The analysis takes into account the radiation scattered by the particles (Mie scattering) as well as the radiation directly detected from the jet stream, and it was found that the effect of the scattered radiation by the particles on temperature measurement is 1 degree at its melting point (2700 C) and 16 degrees at 2500 C. 7

8 Plasma Deposited Functional Organic Coatings with Tunable Surface Charge for Selective Cell Adhesion Sara Babaei, Pierre-Luc Girard-Lauriault Plasma Processing Lab, Department of Chemical Engineering, McGill University, Montréal, H3A 2B2, Canada Synthetic polymers play an important role in disease management and health care. However, most of these polymers suffer from limited interaction capabilities with cells and biomolecules due to their intrinsically low surface energy. In particular, they lack the ability to trigger selective interactions towards particular groups of cells and biomolecules. In this regard, the performance of devices made of synthetic polymers can be greatly improved by the use of a surface engineering approach, such as the plasma deposition of functional organic coatings, commonly referred to as plasma polymers. It has been shown that physico-chemical properties of these coatings have an important effect on their interaction with biological environments. Among different kinds of plasma polymers, oxygen rich and nitrogen-rich plasma polymers have been found to promote cell adhesion, through interactions mediated by functional groups, mainly carboxylic acid and primary amines. This effect can be rendered to be selective to certain cell types and therefore be exploited for selective cell adhesion applications. In this contribution, low-pressure plasma co-polymerization of binary gas mixtures of ethylene/ammonia, butadiene/ammonia, ethylene/carbon dioxide and butadiene/carbon dioxide were produced in order to deposit either nitrogen rich or oxygen rich coatings. Deposition kinetics, surface characterization, surface charge and stability of the coatings were investigated by use of profilometer, x-ray photon spectroscopy (XPS), infrared reflection absorption spectroscopy (IRRAS), ultraviolet-visible spectroscopy (UV-vis) and electro kinetic analyser (EKA). The results show that increasing the flow ratio of heteroatom source gas (ammonia or carbon dioxide) to hydrocarbon gases increased the concentration of bonded nitrogen or oxygen functional groups in the coatings. The concentration of functional groups was found to be directly correlated to the absolute value of the surface charge at physiological ph, which was positive for nitrogen based coatings and negative for their oxygen based couterparts. 8

9 Comportement thermochimique de nanoparticules de ferrite de nickel produites par plasma inductif Samuel Bastien, Laura Paradis Fortin, Nicolas Dumaresq, Nadi Braidy Département de génie chimique et biotechnologique, Université de Sherbrooke, Sherbrooke, Qc, Canada J1K2R1 La ferrite de nickel (NiFe 2 O 4 ) est un matériau de type spinel avec des propriétés catalytiques prometteuses, notamment pour des réactions de reformage. Des nanoparticules de NiFe 2 O 4 ont été synthétisées en injectant une solution de nitrate de fer et de nickel dans un plasma inductif. En contrôlant la quantité relative de fer et de nickel dans la solution mère, nous pouvons contrôler la quantité relative de Ni et Fe de la ferrite de nickel (Ni x Fe 3-x O 4, x = 0, 0.25, 0.5, 1.0), en accord avec le diagramme de phase Ni/Fe/O [1,2]. Ces nanoparticules sont ensuite analysées in situ par diffraction des rayons X (DRX) et par analyse thermogravimétrique (ATG) lors d'opérations de réduction et d'oxydation. L'activité catalytique du NiFe 2 O 4 provient de sa capacité à accommoder un certain degré de lacunes en oxygène (NiFe 2 O 4-δ ), tout en assurant une stabilité dans la maille cristalline. Ces lacunes sont créées par l'application d'un agent réducteur (H 2, CH 4, etc.), et sont par la suite comblées par l exposition à un agent oxydant (O 2, CO 2, etc.). Par contre, un degré de réduction trop élevé de la ferrite de nickel entraine sa transformation potentiellement irréversible en d'autres phases cristallographiques. Ainsi, une connaissance de la limite de réductibilité du NiFe 2 O 4 (δ max ) et de sa cinétique de réduction et d'oxydation est cruciale pour opérer un procédé catalytique à des conditions optimales. Nous démontrons que le Ni x Fe 3-x O 4 est capable d'accommoder une plus grande quantité de lacunes pour x=0.25 et 0.5, et que ces lacunes se forment plus rapidement comparativement à x = 0 et x = 1. De plus une réduction complète de la ferrite de nickel entraine la formation de (Ni,Fe) dans la phase BCC ou FCC, selon les conditions de réduction. Les résultats de DRX démontrent en outre que la phase BCC est plus facilement régénérable vers la phase spinel lors d'une réoxydation comparée à la phase FCC. [1] S. Bastien and N. Braidy. J. Appl. Phys. 114 (2013), p [2] M.A. Rhamdhani et al., Metall. Mater. Trans. B. 39 B (2008), p

10 Engineered SnO 2 Photoanodes for Dye Sensitized Solar Cells Kaustubh Basu 1, Daniele Benetti 1, Haiguang Zhao 1,2, Alberto Vomiero 1,2,3 Vetrone 1 and Federico Rosei 1,4 Fiorenzo 1 Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, Varennes, Quebec, Canada 2 CNR IDASC SENSOR Lab, Università degli Studi di Brescia, Brescia, Italy 3 Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden 4 Centre for Self-Assembled Chemical Structures, McGill University, Montreal, Quebec, Canada Over the last two decades, Dye Sensitized Solar Cell (DSSC) has been emerging as an alternative to conventional silicon photovoltaic devices because of its low cost, abundant raw material, facile fabrication process, efficient photovoltaic performance and stability [1,2]. For becoming a potential candidate to replace traditional solar cells, DSSC has to undergo a lot of challenges in enhancing the device performance, one of the key role, for which, is being played by the photoanode material.tio 2 (Titanium dioxide) nanoparticle films have been used widely for DSSC since the electron injection rates from the excited dye into the TiO 2 nanoparticles are ultra-fast, in the order of femto seconds, but due to low electron mobility, the electron recombination rates are high [3]. SnO 2 (Tin dioxide) on the other hand is a promising oxide material because of its higher electronic mobility and large band gap (3.8 ev). Mobility reported in both single crystal SnO 2 [4] as well as nanostructures [5] are orders of magnitude higher than in both single crystal TiO 2 [3]. Furthermore, SnO 2 has a low sensitivity to UV degradation due to its larger band gap and hence has better long term stability [6]. We prepare photoanodes made from self-prepared paste using commercial nanoparticles of APS~20nm.We investigate the performance of DSSC fabricated with pre-treatment with TiCl 4 and TiO x precursor solution separately to form a blocking layer between the FTO layer and electrolyte to inhibit electron recombination from FTO to the elctrolyte and post treat our SnO 2 photoanodes with both TiCl 4 and TiO x precursor solution separately so as to passivate the SnO 2 anode layer with titania layer and reduce recombination from the photoanode to the electrolyte. The pre-treatment and post treatment of SnO 2 as a photoanode can improve the V oc, which is necessary since the conduction band minima of SnO 2 is located below that of TiO 2 and in turn decides a low V oc in SnO 2 anode DSSC. We also study the performance of the cells with the introduction of graphene and Multi Walled Carbon NanoTubes (MWCNT) which provide a directed path for electron transport within the photoanode. The crystallinity of the nanoparticles, pre and post treatment of photoanode and the presence of graphene and MWCNT influence the functional properties of the solar cells, and call for optimization of the photoanode to maximize the photo conversion efficiency. [1] M. Gratzel, Nature, 2001, 414, 338. [2] A. Hagfeldt, G. Boschloo, L. C. Sun, L. Kloo and H. Pettersson,Chem. Rev., 2010, 110, [3] E. Hendry, M. Koeberg, B. O Regan, M. Bonn,Nano Lett.2006,6, 755 [4] Z. M. Jarzebski, J. P. Marton, J. Electrochem. Soc. 1976, 123, 299C. [5] M. S. Arnold, P. Avouris, Z. W. Pan, Z. L. Wang, J. Phys. Chem.B 2003, 107, 659. [6] N. G. Park, M. G. Kang, K. S. Ryu, K. M. Kim, S. H. Chang, J. Photochem. Photobiol. A 2004, 161,

11 Aminated Surfaces for Synthetic Vascular Grafts: Processes and Characterization. Boespflug, Gaël 1,3,4 ; de Crescenzo, Gregory 2 ; Lerouge, Sophie 4,5 ; Wertheimer, Michel R. 1, 3. École Polytechnique de Montréal, Montreal, QC, Canada ( 1 Institute of Biomedical Engineering, 2 Department of Chemical Engineering, 3 Department of Engineering Physics); 4 Laboratory of Endovascular Biomaterials (LBeV), Research Centre, Centre Hospitalier de l Université de Montreal (CRCHUM), Montreal, QC, Canada; 5 Department of Mechanical Engineering, École de technologie supérieure, Montreal, QC, Canada Primary amine-rich [C-NH 2 ] surfaces have shown great interest to foster cell adhesion and growth, or efficient covalent immobilization of bioactive molecules to induce specific interactions with cells. In this study, plasma processes involving both surface functionalization and plasma polymerization are compared with conventional chemical processes (using polyallylamine), in regard to their efficacy in grafting amine groups and immobilizing bioactive molecules. Moreover, since surfaces combining both oxygen- and nitrogen-bearing functional groups, such as Primaria (plasma-modified medicalgrade polystyrene), have shown interesting cell binding properties, N- and O-functionalized plasmagenerated surfaces have been included in the study. Plasma-polymer coatings have been prepared on poly(ethylene terephthalate) (PET) films at low pressure, with gas mixtures of C 2 H 4 and NH 3 ( L-PPE:N ), or C 2 H 4 and N 2 O ( L-PPE:O,N ), while surface modification (functionalization) was also carried out on PET with NH 3 plasma only ( PETf ). Commercial Primaria tissue culture plates were used for comparison. The conventional chemical process mentioned above consists of aminolysis of a PET surface by polyallylamine (PAAm), whereby the PET samples were immersed in an alkaline PAAm solution at various ph, after adding dioxane. The elemental chemical compositions and chemical bond types of these various surfaces were determined by X-ray photoelectron spectroscopy (XPS). Derivatization by TFBA (4- trifluoromethybenzaldehyde) was also performed, along with XPS analyses, to determine [C-NH 2 ], the concentration of primary amines. In addition, surface densities of amines (pmol/mm²) were measured by the Orange II colorimetric method. CS (Chondroitin Sulfate) grafting was performed on the various surfaces using EDC/NHS chemistry, and the amount of immobilized CS was evaluated by the Toluidine blue O (TBO) colorimetric method. Divergent results have been observed between chemical derivatization and colorimetric approaches; these can be explained by the diffusion of dye molecules into the bulk of thin coatings. Therefore, we acknowledged that the latter approach is not suited to the comparison of coatings of different thickness or nature. All examined surfaces were found to be [C-NH 2 ]-rich, most specifically PETf and L-PPE:N. PAAmmodified PET displayed more ambiguous results, depending on the quantification method. The Orange II method revealed a drastic rise in [C-NH 2 ] at high ph; we believe it is linked to increased surface area arising from greatly-enhanced surface roughness that accompanies aminolysis. Further work is in progress to evaluate the various amine-rich underlayers' influence regarding cell behavior on grafted CS. Acknowledgements This work was supported by CIHR and NSERC. The authors also thank the Fondation Pierre Arbour for a scholarship to G.B, Dr. Benoît Liberelle and Samantha Noel for their help in aminolysis and dying, and Drs. Josianne Lefebvre and Bernard Nisol for their expertise in XPS analysis. 11

12 Efficient Optical Energy Harvesting in Self-Accelerating Beams Domenico Bongiovanni 1, Yi Hu 1,2, B. Wetzel 1, A. Tomasino 1, R. Amaury Robles 3, G. Mendoza Gonzalez 3, Erwin A. Martí-Panameño 3, Zhigang Chen 2,4 and Roberto Morandotti 1 1 INRS-EMT, 1650 Blvd. Lionel-Boulet, Varennes, Québec J3X 1S2, Canada 2 The MOE Key Laboratory of Weak-Light Nonlinear Photonics, TEDA Applied Physics Institute and School of Physics, Nankai University, Tianjin , China 3 Benemérita Universidad Autónoma de Puebla, Puebla 72000, Mexico 4 Department of Physics & Astronomy, San Francisco State University, San Francisco, CA 94132, USA In the last few years, self-accelerating optical beams propagating along a curved trajectory have attracted a lot of attentions. Since Airy beams were the first to be introduced into optics, they have been employed in a variety of applications, such as the generation of curved plasma channels, optical trapping and manipulation, and micro-fabrication. It has been shown that accelerating beams can be designed to propagate along arbitrary convex trajectories through engineering the phase of a light wave in either real or Fourier space. However, most of the work thus far focused on one-dimensional configurations only, with the emphasis on the engineering of beam trajectories. The dynamics of two-dimensional (2D) accelerating beams, a useful knowledge for practical applications, has not been investigated in a general way. In this work, we study analytically and experimentally the dynamics of two dimensional accelerating beams generated from the Fourierspace phase modulation of a light. We demonstrate that the trajectory of a 2D accelerating beam can be designed from a direct mapping between the spatial spectrum and the propagation distance. In addition, the main lobe of the beam can be approximately described by an analytical solution in a generalized way. Moreover, we also propose a method to optimize the accelerating beam generation, aiming at obtaining enhanced peak intensities. Our theoretical analyses are in good agreement with the experimental results. Our findings may be relevant to many applications as mentioned in the introduction. 12

13 Résolution numérique de l équation de Fokker-Planck isotrope dépendante du temps C.Boukandou Mombo, 1, F. Vidal, 1 and J-P. Matte 1 1 Institut National de la Recherche Scientifique-Centre Énergie, Matériaux et Télécommunications, 1650 boul. Lionel Boulet, Varennes, Québec, Canada J3X 1S2 Dans les plasmas collisionnels, l équation de Fokker-Planck (EFP) décrit l effet des collisions coulombiennes entre particules de même espèce. La résolution numérique de cette équation requiert un schéma stable et rapide d une part, et d autre part les solutions obtenues doivent vérifier les principales propriétés de l EFP à savoir: la positivité de la fonction de distribution, l équilibre maxwellien, la conservation de la densité de particules, de la densité d énergie, et l augmentation de l entropie [1]. Dans ce contexte, nous développons une méthode de résolution numérique basée sur la méthode des différences finies dans laquelle le schéma numérique se présente comme un système d équations tridiagonal nonlinéaire pouvant être résolu par itérations. La variante purement implicite de l approche proposée conserve toutes les propriétés de l EFP continue. Cela a été rendu possible par la discrétisation appropriée du terme de collision dans l EFP. La méthode proposée a été utilisée pour l étude d une distribution initiale gaussienne et celle d une distribution initiale Maxwellienne quasi-tronquée qui est un exemple pertinent aux simulations de plasmas froids. Les résultats obtenus démontrent la stabilité inconditionnelle du schéma totalement implicite. En outre, en comparaison avec le temps CPU pour la méthode totalement explicite qui varie comme O(N 3 ) dans la limite de stabilité, nous obtenons pour le schéma totalement implicite un temps CPU de l ordre de O(N). Ce qui se traduit par un gain considérable en temps de calcul [3]. Ce traitement numérique des collisions électron-électron est en cours d intégration dans un code décrivant un plasma d hélium [3] avec une variation temporelle. [1] C. Buet and S. Cordier, Numerical Analysis of the Isotropic Fokker Planck Landau Equation, 179, 43 (2002). [2] L.L Alvest, G. Gousset, and C.M. Ferreira, A collisional-radiative model for microwave discharges in Helium at low and intermediate pressures 25, 1713 (1992). [3] C. Boukandou-Mombo, H. Bakrim, J. P. Matte and F. Vidal Fast conservative scheme for solving numerically the time-dependent isotropic Fokker-Planck equation, to be submitted to the Journal of Computational Physics. charlotte.boukandou@emt.inrs.ca 13

14 Spin-orbit coupling effects on the magnetization and polarization in the multiferroic Bi2FeCrO6 plasma-synthesized epitaxial thin films Liliana Braescu 1,2,3, François Vidal 1, Alain Pignolet 1 1 Institut National de la Recherche Scientifique Centre Énergie, Matériaux et Télécommunications, 1650 Boulevard Lionel-Boulet, Varennes, J3X 1S2, Québec, Canada 2 Department of Mathematics and Computer Science, Alfaisal University, P. O. Box 50927, Riyadh 11533, KSA 3 Radiological Technologies University-VT, 100 E. Wayne St., South Bend, IN 46601, USA Magnetic ferroelectrics possessing both spontaneous magnetization and spontaneous polarization simultaneously are rare in nature since transition metal ions with unpaired magnetically active d-electrons often tend to reduce the off-centre distortion necessary for ferroelectricity to exist [1]. Recently, there has been an increased research interest in multiferroic systems due to the observation of good multiferroic properties and magnetoelectric coupling in thin films of some of these materials, enabling potential applications in many magneto-electric devices. An example of multiferroic material having the potential to revolutionize electronic industry is the rhombohedral double-perovskite Bi2FeCrO6 (BFCO) because good magnetic properties at room temperature were demonstrated in epitaxial thin films synthesized by the plasma technique of pulsed laser deposition (PLD) [2]. To complement our understanding of BFCO, theoretical investigations have been performed for the first time on the spin-orbit coupling (SOC) effect on the magnetic and ferroelectric properties of the material. Using first-principles density functional theory (DFT) calculations within the VASP package, investigations were performed for both collinear and noncollinear spin structures, respectively. Exchange and correlation effects were treated using the local density approximation plus Hubbard potential total-energy functional (LSDA+U) on the high spin (HS) and low spin (LS) states of the ferromagnetic (FM) and ferrimagnetic (FiM) spin arrangements. In the case of collinear spin calculations without SOC, the existence of four competing phases (FMHS, FMLS, FiMHS and FiMLS) with distinct electronic and magnetic properties was found, in agreement with recent published theoretical results [3]. The FiMHS state was found to be the most stable, with a total magnetic moment MBFCO ~2 µb per unit cell, and a computed spontaneous polarization of Ps=79.1 µc/cm 2 in agreement with reported data [4]. When SOC was considered, the calculations also showed the existence of the above four stable states, FiMHS remaining the most stable state. Also, the obtained magnetizations do not have a preferred direction in the HS states, but they do show a preferred axis along the direction (1 1 1) in the LS states. Spontaneous polarization computed for optimized structures with Berry-phase method, was found to be slightly higher when SOC is considered, namely Ps~81.5 µc/cm 2 for FiMHS. Finally, the calculated bandgap increased by about 25% when SOC was considered, which is in better agreement with recent experiments [5]. [1] H. Schmid, Ferroelectrics 162, 317 (1994). [2] R. Nechache, C. Harnagea and A. Pignolet, J. Phys.: Condensed Matter 24, (2012). [3] M. Goffinet, J. Iniguez and P. Ghosez, Phys. Rev. B 86, (2012). [4] P. Baettig, C. Ederer and N. A. Spaldin, Phys. Rev. B 72, (2005). [5] R. Nechache et al. Nature Photonics 19, 61 (2015). 14

15 Formes d ondes en dent de scie : un nouveau degré de liberté pour les plasmas capacitivement couplés Bastien Bruneau 1, Trevor Lafleur 2, Timo Gans 3, Deborah O Connel 3, Arthur Greb 3, Erik Johnson 1, Jean-Paul Booth 2 1 LPICM-CNRS, Ecole Polytechnique, route de Saclay, Palaiseau, France 2 LPP-CNRS, Ecole Polytechnique, route de Saclay, Palaiseau, France 3 York Plasma Institute, Department of Physics, University of York, York, United Kingdom Les formes d onde arbitraires (en anglais «tailored voltage waveforms»), où une fréquence fondamentale radio-fréquence ainsi que ces premières harmoniques sont utilisées pour construire la forme d onde désirée, ont permis de découpler efficacement énergie et flux d ions dans le domaine des plasmas capacitivement couplés. Ainsi, l énergie des ions peut être contrôlée par la forme d onde appliquée, le flux d ions étant constant. Ce découplage s appuie sur l asymétrie d amplitude de la forme d onde. En utilisant des formes d ondes présentant une asymétrie temporelle, ressemblant à des ondes en dent de scie, nous montrons qu une asymétrie du mouvement des gaines du plasma peut être obtenue dans un plasma d argon. Une gaine s étend rapidement et se contracte lentement, alors que l autre gaine s étend lentement et se contracte rapidement. En conséquence, le chauffage des électrons présente lui aussi une asymétrie spatiale. Les électrons chauds, présents en quantités différentes à proximité de chaque électrode, vont alors ioniser le gaz, principalement là où ils sont les plus chauds. Cette asymétrie du taux d ionisation va alors se traduire par une asymétrie du flux d ions. Ces résultats, obtenus par simulations PIC (particle-in-cell), sont comparés avec des données expérimentales. Des mesures de spectroscopie d émission optique résolues spatialement et temporellement, permettant d avoir accès au taux d excitation de l état Ar 2p 1, montrent notamment l accord excellent des simulations avec l expérience. Les résultats obtenus pour différentes chimies seront montrés, et la dépendance de l effet par rapport au mécanisme de chauffage des électrons sera discutée. Ces formes d ondes, de par leur effet sur les plasmas, peuvent avoir un intérêt conséquent pour les processus utilisant un plasma capacitivement couplé. En effet, en utilisant une forme d onde en dent de scie dans un processus de dépôt ou de gravure, on peut imaginer augmenter la vitesse de dépôt, ou de gravure, en déposant, ou gravant, peu l électrode opposée, ce qui permettrait de réduire significativement le temps de maintenance des réacteurs. 15

16 Deposition of Amine-Rich Stable Organic Coatings by Plasma Co- Polymerization of Ethylene, 1,3-Butadiene and Ammonia Mixtures Madhuwanthi Buddhadasa, Pierre-Luc Girard-Lauriault Plasma Processing Laboratory, Department of Chemical Engineering, McGill University Plasma polymerisation is a widely studied technique for various biomedical applications such as protein immobilisation, tissue engineering and cell culture. For these applications, plasma polymerised coatings with certain physico-chemical properties can be useful to bring about the desired interaction between the coating and the surrounding biological environment. For example, surface chemical functional groups, surface charge and roughness of the deposited coatings can be tuned in order to gain some control over the cell processes occurring at the surface. In this work, we focus on amine-rich plasma polymer films, an important class of functional coatings which have found to promote cell adhesion and also to influence differentiation of mesenchymal stem cells. These effects have been attributed to amine groups that, being positively charged in aqueous environments at physiological ph values, attract negatively charged biomolecules such as proteins and DNA, and living cells. Amine groups can also be used for covalent coupling of proteins in aqueous environments and to enable imine or enamine coupling. While high density of amine groups can improve the interaction between the coating and surrounding biomolecules and cells, it is found that amine-rich coatings are not physically stable in aqueous media. This is attributed to the polarity of amine groups which results in high affinity towards polar solvents which in turn leads to the dissolution of the film if it is not sufficiently cross-linked. In order to obtain plasma polymer coatings with optimised film stability and amine content, we add 1,3-butadiene to the precursor gas mixture. This molecule contains two C-C double bonds and is expected to facilitate the formation of a highly crosslinked, stable macromolecule. A series of plasma co-polymerised coatings prepared from mixtures of ethylene, 1,3-butadiene and ammonia has been deposited by varying the plasma power, ammonia to total hydrocarbon gas flow ratio and butadiene to ethylene gas flow ratio. The effect of these plasma parameters on the surface amine content and water stability of these coatings has been investigated. Surface amine content was determined by chemical derivatisation with 4-trifluromethyl benzaldehyde, followed by XPS analysis. Water stability was evaluated by immersing the coating in DI water for 24 hours and measuring the change in film thickness using a Dektak Profilometer. Results indicate that coatings deposited from 1,3-butadiene show a clear improvement in performance as compared to the ethylene based films. 16

17 How to design catalytic materials for PEMFC by plasma sputtering deposition? A. Caillard 1, C. Cuynet 1, T. Lecas 1, C. Charles 2, R. Boswell 2, S. Baranton 3, C. Coutanceau 3, A.-L. Thomann 1, P. Brault 1 (1) Groupe de Recherches sur l Energétique des Milieux Ionisés (GREMI), UMR7344 CNRS/Université d Orléans, BP6744, 14 rue d Issoudun, Orléans, France. (2) Institue de Chimie des Milieux et Matériaux de Poitiers, UMR 7285 CNRS/Université de Poitiers, 40 avenue du Recteur Pineau, Poitiers, France (3) Space Plasma, Power and Propulsion group (SP3), Research School of Physical Sciences and Engineering, The Australian National University, Canberra, ACT 0200, Australia Improving the core of a Proton Exchange Membrane Fuel Cell is a very challenging task which requires new materials and new related synthesis processes. Among many methods, plasma deposition is a promising technique for manufacturing these fuel cell materials. In the past ten years, various catalytic materials have been designed at a sub-micrometric level using plasma deposition techniques in order to optimise the geometry of the thin catalytic layer. Pt-C nanowire composites [1,2] have been synthesized by using different plasma deposition technique (plasma enhanced chemical vapor deposition or high pressure plasma sputtering deposition techniques). Moreover, High Power Impulse Magnetron Sputtering (HiPIMS) has been used to produce Pt nanoclusters on and inside a commercial microporous carbon support used as fuel cell electrode [3]. Even if the platinum is the most efficient catalytic material, its amount must be reduced because of its cost. More recently, plasma techniques were employed to design nanoclusters to the atomic level. Efficient fuel cell electrode containing monoatomic, bimetallic and trimetallic Pt-based nanoclusters has been synthesized by magnetron co-deposition and a gascondensation technique. In the best conditions, that allows a Pt utilization of 20 kw g Pt -1 and a power density of 0.7 W cm -2. ANR is acknowledged for partial support under grant #ANR-2010-EMMA-037. CNRS (GdR PACS) is acknowledged for support. Part of this work is benefiting of a grant from European Commission under agreement FP JTI-FCH for the SMARTCat project. [1] A. Caillard, C. Charles, R. Boswell and P. Brault, Nanotechnology 18, (2007) [2] P. Brault; A. Caillard, S. Baranton et al, CHEMSUSCHEM 6, (2013) [3] S. Cuynet, A. Caillard, T. Lecas, J. Bigarré, P. Buvat and P. Brault, J. Phys. D: Appl. Phys. 47 (2014)

18 Enhanced Light to Electrical Power Conversion Efficiency in Bilayer Multiferroic thin films J. P. Chakrabartty 1, R. Nechache 1, C. Harnagea 1, S. Li 1, and F. Rosei 1,2 1 Centre Énergie, Matériaux et Télécommunications, Institut national de la recherche scientifique (INRS), 1650 boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada. 2 Center for Self-Assembled Chemical Structures, McGill University, H3A 2K6 Montreal, Quebec, Canada. Corresponding chakrabartty@emt.inrs.ca Abstract The mechanism of the generation of the driving force behind photo carrier generation i.e. internal electric field in ferroelectric photovoltaic (FEPV) materials is completely different than that occurring at the p-n interface. Usually, the non-centrosymmetry of ferroelectric crystals implies the presence of a spontaneous polarization accompanied by a depolarizing field in opposite direction. However the polarization induced photovoltaic power conversion efficiency in FEPV materials is still poor because of low mobility of charge carriers at conduction band. However, the proper selection of low band gap FE materials ( ev) and the engineering of their physical properties might lead to enhance PCE. Here in this work, we show an external solar power conversion efficiency of ~1.43% with fill factor (FF) of ~0.72 in a bilayer BiFeO 3 (BFO)/BiMnO 3 (BMO) thin film heterostructure both epitaxially grown onto (111) oriented Niobium doped SrTiO3 (NSTO) single crystal substrate by pulse laser deposition. Sn doped Indium oxide (ITO) has been used as top electrodes because of its light transparency (~90%). The ITO/BFO/BMO/NSTO heterostructured devices exhibit 14.3 times higher PCE than individual BMO films (~0.1%) under 1 Sun. In comparison, the PCE of BFO films is even lower than BMO films under 1 Sun. The measured FF in our case is higher than among ever reported in FE based PV devices. The results demonstrate that photocurrent density and photovoltage are tunable by polarization direction. This effect is described in terms of a more favorable energy band alignment of the electrode/bilayer/nsto heterostructure junction, which controls photo carrier separation. 18

19 Gas film stability during Spark Assisted Chemical Engraving (SACE) F. Charbonneau, L.A. Hof, J.D. Abou Ziki Departement of Mecanical & Industrial Engineeering, Concordia University, 1455 de Maisonneuve Blvd. West, Montréal H3G 1M8, Canada The development of Microfluidics and MEMS devices becomes increasingly important for several applications. In fact, several novel non-traditional microfabrication technologies are being developed. Among others, Spark Assisted Chemical Engraving (SACE) is a promising technology for micromachining dielectric materials, such as glass (figure 1.A). This novel machining technique relies on an electrochemical process that heats up the tool electrode, hence promoting local surface etching [1]. To machine by SACE, two electrodes are dipped in an alkaline solution (typically 30 wt.% NaOH) where the cathode (tool-electrode) is much smaller (< 10 times) than the anode. When a voltage higher than a critical value is applied, a gas film is formed around the tool-electrode by coalescence of gas bubbles created by electrolysis (figure 1.B). Discharges are then generated causing thermal-assisted local etching of the glass surface. A key element of the SACE machining quality is the gas film stability. New parameters are investigated to stabilize the gas film such as voltage level, pulsed voltage, duty cycle and tool-electrode side-insulation [2]. Although better machining quality could be obtained, the effect of these parameters is not well understood yet. Controlling these parameters will allow to predict the machining quality, control the surface formed texture [3] and increase the machining speed whenever required. Therefore, new elements are investigated to understand the discharge process such as spectroscopic emission analysis of discharges, modelling the gas film formation [4] and its thickness [5] and varying the electrolyte flow. This presentation summarizes key parameters that can improve the gas film stability and it introduces the potential of novel parameters in promoting the understanding of the gas film stability. Figure 1.A Example of a microhole, drilled by SACE machining (3D optical microscope image). B. Schematic presentation of the gas film formation. Acknowledgements This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC). The authors would like to thank Prof. L. Stafford and Dr. R. Gangwar for their support while conducting the OES experiments. They would also like to thank Posalux S.A. and Prof. R. Wüthrich for their support and fruitful discussions. References [1] R. Wüthrich and V. Fascio, Machining of non-conducting materials using electrochemical discharge phenomenon an overview, Int. J. Mach. Tools Manuf., vol. 45, no. 9, pp , Jul [2] C.-P. Cheng, K.-L. Wu, C.-C. Mai, C.-K. Yang, Y.-S. Hsu, and B.-H. Yan, Study of gas film quality in electrochemical discharge machining, Int. J. Mach. Tools Manuf., vol. 50, no. 8, pp , Aug [3] J. D. Abou Ziki, T. Fatanat Didar, and R. Wüthrich, Micro-texturing channel surfaces on glass with spark assisted chemical engraving, Int. J. Mach. Tools Manuf., vol. 57, pp , Jun [4] B. Jiang, S. Lan, K. Wilt, and J. Ni, Modeling and experimental investigation of gas film in micro-electrochemical discharge machining process, Int. J. Mach. Tools Manuf., vol. 90, pp. 8 15, [5] M.-S. Han, B.-K. Min, and S. J. Lee, Modeling gas film formation in electrochemical discharge machining processes using a sideinsulated electrode, J. Micromechanics Microengineering, vol. 18, no. 4, p , Apr

20 3D Model Of Low Latitude Ionosphere - Application To The Atmospheric Gravity Waves J. Claustre 1 and F. Deluzet 2 1 INRS - Energie, Materiaux et Telecommunications, Varennes QC, Canada 2 Universite de Toulouse; UPS, IMT, F Toulouse, France. We developped a 3D low latitude ionospheric model to treat the dynamic and the chemical evolution of the plasma composed by electrons and seven ions species (O +, H +, H + e, O + 2, NO+, N +, N + 2 ). This 3D fluid model is based on a system of coupled Euler equations for ions and electrons species with the Maxwell equations for the evolution of electromagnetic field. The ion continuity and the momentum equations are solved for all ions species and the energy balance equations are solved for two ion species (O + and H + ). The temperature of the molecular ions (O + 2, NO+ ) and atomic ions (N +, H + ) is taken to be that of the ion O +. The altitudes of the ionospheric plasma at low latitude range from 85 km to 2000 km and the terrestrial magnetic field is generalized by a classical approach of a dipolar axisymmetric magnetic field. The Euler potential techniques permit us to define new coordinates whereby the geomagnetic field tube can be seen as a rectangular domain [1]. In our considered altitude ranges, the Hall parameter h (ratio of the cyclotron angular frequency to the collision frequency, h = ω c /ν) decrease significantly between 90 km to 180 km where collisions with neutrals become considerably small and the charged particles are magnetized and strongly constrained to move along the magnetic field lines. As the magnetic field affects the charged particles motion, it makes the plasma an anisotropic medium. The numerical treatment of the three-dimensional transport equations with strong anisotropic mobilities (i.e. Pedersen, Hall and field-aligned mobilities) lead to a degenerated solution in the computation of elliptic equation for the electric potential and require the use of more refined grid to compensate the anisotropy [2]. We propose a new model of ionosphere using an adapted three-dimensional geometry coordinates based on the Euler Potentials. The computation of the self-consistent electrostatic field is performed using the asymptoting preserving scheme [2] permitting the choice of coarse grids discretization. On the basis of the 3D ionosphere model results, we describe the plasma properties and show the propagation of medium-scale traveling ionospheric disturbances (MSTIDs) along the magnetic field tubes [3]. [1] C. Besse, J. Claudel, P. Degond, F. Deluzet, G. Gallice and C. Tessieras. Computer Physics Communications, 176 (2), (2007) [2] C. Besse, F. Deluzet, C. Negulescu and C. Yang. J. of Sci. Comput., 55 (1), (2013) [3] T. Onishi, T. Tsugawa, Y. Otsuka, J.J. Berthelier and J.P. Lebreton. Geophysical Research Letters 36 (11), 808 (2009) 20

21 Richard Clergereaux LAPLACE, Université de Toulouse, France Plasmas poussiéreux et poussières cosmiques : Processus de croissance Le milieu interstellaire est un mélange de gaz (ionisés, atomiques et moléculaires) et de poussières. Ces dernières ont été révélées par des mesures d absorption, de diffusion et d émission dans le domaine infrarouge, millimétrique ou submillimétrique. Aujourd hui, le nombre de données sur ces poussières augmente fortement avec la mise en place des télescopes terrestres ou spatiaux comme Alma au Chili ou Hubble. Par ailleurs, les satellites Spitzer, Herschel et Planck ainsi que les missions Stardust, Rosetta et Philae sont à la recherche de poussières pour déterminer leurs structures et leurs propriétés. Ainsi, l ensemble de ces données permet de décrire le rôle que ces poussières jouent dans l évolution du milieu interstellaire et dans la formation d objets astronomiques comme par exemple les météorites, les protoplanètes et les planètes. Les poussières cosmiques sont majoritairement formées dans les géantes rouges à partir de carbone et d'hydrocarbures aromatiques polycycliques (PAH) ou de glace et de silicate selon qu elles soient produites dans un environnement riche en carbone ou en oxygène. Dans le cas des environnements riches en carbone, elles seraient formées par nucléation à partir de neutres tels que C 2 H 2 et de radicaux tels que C 2, C 3, CN ou CH puis par croissance de PAH de tailles différentes. Toutefois, il est difficile de décrire finement les processus de formation. Bien que les distances et les cinétiques soient très différentes, les plasmas poussiéreux représentent des objets pertinents pour remonter aux mécanismes de croissance de poussières cosmiques. En particulier, la comparaison des signatures spectrales mesurées dans les réacteurs plasmas avec les signaux spatiaux permettrait d identifier les processus de croissance mis en jeu. Les travaux que je détaillerai seront focalisés sur des plasmas poussiéreux obtenus dans des décharges très basse pression (mtorr) magnétisées. En effet, dans ces conditions, du fait de leur faible quantité, le plasma n est que faiblement modifié par la présence de poussières permettant ainsi d étudier les processus de croissance et d interaction plasma-poussières. D autre part, dans ce type de décharge, il est possible de confiner efficacement les poussières dans le volume du plasma et ainsi de déterminer in-situ leurs signatures optiques dans le visible et l infra-rouge. Enfin, les poussières collectées dans les réacteurs plasmas sont des analogues aux poussières cosmiques pertinents à analyser ex-situ. 21

22 Epitaxial Thin Films of ε-fe 2 O 3 and ε-al x Fe 2-x O 3 grown by PLD. L. Corbellini 1, C. Harnagea 1, C. Lacroix 2, A. Morin 3, X. Ropagnol 1, T. Ozaki 1, D. Menard 3 and A. Pignolet 1 1 Institut National de la Recherche Scientifique, Université du Québec Varennes, Québec, Canada J3X 1S2 2 Department of Electrical Engineering, Polytechnique Montréal, Montréal, Québec, Canada H3C 3A7 3 Department of Engineering Physics, Polytechnique Montréal, Montréal, Québec, Canada H3C 3A7 ε-fe 2 O 3 is a metastable intermediate phase of iron (III) oxide, between maghemite (γ-fe 2 O 3 ) and hematite (α-fe 2 O 3 ). Epsilon ferrite has been investigated essentially because of its ferrimagnetic ordering with a Curie temperature of circa 500 K [1]. However, given its orthorhombic crystal structure that belongs to the non-centrosymmetric space group Pna2 1, it should exhibit at least piezoelectric and magnetoelectric, and potentially even multiferroic, properties [2,3]. Moreover, the material is characterized by strong magnetic anisotropy, resulting in a ferromagnetic resonance (FMR) frequency in the THz range in the absence of magnetic field and at room temperature. This is of particular interest given its potential use in short-range wireless communications (e.g. 60GHz WiFi) and ultrafast computer non-volatile memories [4-6]. Due to its metastable nature, ε-fe 2 O 3 needs to undergo size confinement in order to be stabilized: that is the reason why it has been mainly synthesized by sol-gel as nanoparticles embedded inside a SiO 2 matrix. Recently however, deposition of epitaxial thin films of ε-fe 2 O 3 on SrTiO 3 (111) was demonstrated [7] ; in this case the stabilization is thought to be due to both epitaxial strain and interface interaction between the substrate and the film. We report the growth by Pulsed Laser Deposition of epitaxial thin films of ε-fe 2 O 3 and ε-al x Fe 2-x O 3 on different single crystal substrates, and the study of the influence of aluminum doping on the structural, magnetic and dielectric properties. In particular, given the ferroelectric nature of isostructural AlFeO 3, we focused our attention on the effect of Al inclusion inside the ε-fe 2 O 3 lattice, which should result in an improvement of the electric properties and should lower the FMR frequency due to non-magnetic nature of Al. Electric and magnetic properties were probed both macroscopically and locally through ferroelectric measurements/vibrating sample magnetometer and piezoelectric/magnetic force microscopy (PFM MFM), while measurements of the ferromagnetic resonance were conducted by direct FMR probing and through THz light absorption. [1] S. Ohkoshi et al., Angew. Chem. Int. Ed. 46, 8392 (2007); [2] E. Tronc et al., J. Solid State Chem. 139, 93 (1998); [3] M. Gich et al., Nanotechnology 17, 687 (2007); [4] M. Nakajima, A. Namai, S. Ohkoshi, T. Suemoto, Optics Express 18, (2010); [5] H.C. Siegmann et al., J. Magn. Magn. Mater. 151, L8 (1995); [6] C.H. Back et al., Science 285, 864 (1999); [7] M. Gich et al., Appl. Phys. Lett. 96, (2012). 22

23 Synthesis of the ITO/CdS/Calix[4]arene Films system and the study of its Morphological, Optical and Electrical Properties for the Sensing of Copper J. Crespo-Villegas 1, M. A. Hernandez-Perez 1, C. Gómez-Yañez 1, A. Ruediger 2. 1 Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, Zacatenco, Mexico City, 07738, Mexico 2 Nanoelectronics-Nanophotonics, INRS-Énergie Matériaux et Télécommunications, 1650 Lionel-Boulet, Varennes, Québec, J3X1S2, Canada joseffina.crespo@gmail.com, The increasing necessity of having efficient chemical detection systems that exhibit high sensitivity, rapid detection and easy portability has driven the development of the chemical sensors area. Extensive studies in the development of analytical technology have required the development of novel materials and new methods of fabrication. Diverse kind of material array of semiconductor nanostructures, quantum dots systems, functionalized structures, etc. have been synthesized in order of satisfy the growing expectation of environmental, clinical and industrial sectors. Due to the functioning of a sensor strongly depends on the transduction mechanism and on the nature of the receptor element, the selection of the materials that will form a sensor must consider both. The effectiveness of the calix[n]arenes in the process of complexation with metal ions in aqueous solution has been reported in quantum dots systems; nevertheless, currently thin film systems compatible with the emerging micro-technologies are required. The incorporation of organic molecules in thin films obtained through different deposition techniques that nowadays are available arise many possibilities for Chemical detection systems to provide analytical information at an affordable price and with relatively few instrumentation. Amongst the semiconductors employed in the identification of ions in quantum dots systems, CdS has been outstanding due to its electric and optical properties, as well as its wide range of applications in electronic and optoelectronic devices. In this work we report the synthesis of ITO/CdS bilayer synthetized by Chemical Bath Deposition and its functionalization with Calix[4]arene by Thermal Evaporation technique. The structural and microstructural characterization included X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). X-Ray Diffraction shows the effect of the temperature on the increase in the crystallinity of the thin films, while Transmittance UV-Vis reveals the influence of the experimental conditions on the optical properties (Band Gap). The response of the films system to different concentrations of Copper (Cu) ions was evaluated using conductivity and Raman measurements. With the objective of establishing the best parameters to obtaining a sensitive ITO/CdS/TBC4A system for chemical sensor of Copper, the morphologic, electric and optical characteristics based on experimental conditions are analyzed. 23

24 Modeling of electromagnetic near field interactions with anisotropic materials in Tip- Enhanced Raman Spectroscopy C. Dab 1, G. Kolhatkar 1, J. Plathier 1, and A. Ruediger 1 1 Institut National de la Recherche Scientifique Centre Énergie, Matériaux, Télécommunications, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X 1S2, Canada Contact author: chahinez.dab@emt.inrs.ca Abstract Tip-Enhanced Raman Spectroscopy (TERS) is a very promising field of research that has attracted increasing attention over the last few years [1]. This technology combines the strengths of scanning probe microscopy with those of optical spectroscopy to achieve a high spatial resolution and signal amplification. TERS consists in externally focusing a laser beam on a metallic tip generating an amplified optical near field [2]. The structural and chemical properties of Raman-active nanomaterials can then be studied in depth. The aim of this work is to study the electric field enhancement in order to optimise the tip parameters. Indeed, the electric field is sensitive to the wavelength of the laser, the radius and material of the tip, and the permittivity and geometry of the surrounding environment. We excite a dielectric thin film with a nm laser beam propagating at an incident angle of 65. The thin film layer consists of 30 nm thick of ferroelectric lead titanate (PbTiO 3 ) islands grown on a Platinum (Pt) substrate of 100 nm thickness. A silver and gold nano-antenna tip with a radius varying between 10 nm to 25 nm was used. The tip-to-substrate distance was varied from 2 nm to 10 nm in order to evaluate its influence on the electric field enhancement. The simulation were performed by analysing and numerically solving Maxwell s equations using the finite element method with COMSOL Multiphysics software. Mie scattering theory was also used to study the absorption cross section on the tip [3]. We show that the electric field amplification increases when the distance nano-antenna tip-substrate decreased. Moreover, the absorption is strongly affected by the radius of nano-antenna tip; with increasing size of the nano-antenna tip, the absorption maximum is shifted to longer wavelength and the bandwidth increases. We also show the influence of the incident angle on the polarisation of the electric field. Keywords: Tip-Enhanced Raman Spectroscopy (TERS), Mie scattering theory, Maxwell s equations, absorption cross section, field enhancement, and polarisation. [1] Norihiko Hayazawa, Yasushi Inouye, Zouheir Sekkat, Satoshi Kawata, Metallized tip amplification of near-field Raman scattering, Optics communications, 183, , (2000) [2] A. Campion, and P. Kambhampati, 'Surface-enhanced Raman scattering', Chemical SocietyReviews, 27, , (1998). [3] Sergei Yushanov, Jeffrey S. Crompton*, and Kyle C. Koppenhoefer, Mie Scattering of Electromagnetic Waves, AltaSim Technologies. 24

25 Inactivation de spores de B. atrophaeus dans un système de post-décharge en flux d un mélange N 2 -O 2 : effet de la température sur la vitesse d inactivation, avec et sans emballage. J. H. C. de Souza, P. Levif et M. Moisan Groupe de Physique des Plasmas, Département de Physique, Université de Montréal La littérature scientifique montre qu'il y a synergie entre la température et l'inactivation des spores de B. atrophaeus lorsqu exposées dans un système de postdécharge en flux d un mélange N 2 -O 2. Les calculs réactionnels prédisent, en plus du rayonnement UV, la présence de molécules singulets d oxygène O 2 ( 1 Δ g ) dans la région de post-décharge. Cette molécule métastable jouerait un rôle important dans la stérilisation, car elle peut éroder et interférer dans les processus biochimiques des microorganismes. La longueur d'onde caractéristique (tête-de-bande) pour la détection du singulet O 2 ( 1 Δ g ) est à 1268 nm, dans le domaine spectral de l'infrarouge. Ce travail vise à évaluer la synergie entre la température et l inactivation des spores de B. atrophaeus, le rôle des espèces réactives dans la stérilisation, et à détecter le singulet O 2 ( 1 Δ g ). Notre système est constitué d'une source de plasma micro-ondes, une chambre de stérilisation parallélépipédique et une pompe à vide liée à l enceinte. La source et la chambre sont réunies par un long tube de silice, et la décharge est maintenue dans le tube par ondes de surface électromagnétiques de fréquence 2450 MHz, émises par un surfaguide. Pour évaluer l effet de la température des spores sur l inactivation, nous avons installé un porte-substrat en aluminium dans la chambre, connecté à un échangeur de chaleur. Les meilleurs paramètres obtenus (rayonnement UV intense et uniforme dans la chambre de stérilisation) pour exposer les indicateurs biologiques (dépôts de 10 7 spores de B. atrophaeus dans des boîtes de Petri) sont: 4.0 Torr, 260 W de puissance absorbé par le plasma, et débits de 1800 sccm N 2 et 8.0 sccm O 2 (0,442% O 2 ). Nous avons exposé les spores en triplicata pendant 15, 30 minutes, 1h, 2h, et 4h. Pour chaque temps d exposition, les spores ont été maintenues à 15 o C, 25 o C, 35 o C, 45 o C et 55 o C. Nous avons exposé les spores sans emballage et dans l emballage Baglight. Sans système de chauffage, le nombre de spores viables décroît lorsque le temps d exposition augmente; nous avons ainsi obtenu la stérilisation après 4h d exposition. Quand le système de chauffage fonctionne, le nombre de spores viables décroît également lorsque le temps d exposition augmente pour toutes les températures. De plus, les résultats suggèrent que, quand la température est augmentée, la vitesse d inactivation augmente. Nous avons obtenu la stérilisation après 4h d exposition à 45 o C mais après 2h seulement à 55 o C. Mots-clés : stérilisation, plasma, spectroscopie, B. atrophaeus. 25

26 Comparaison de couches minces de TiO 2, TiO 2 :N et TiO 2 :W,N dopés à l azote, et co-dopés déposées par plasma de pulvérisation magnétron réactive pour des applications électro-photocatalytiques N. Delegan 1, R.Pandiyan 1, A. Dirany 2, P. Drogui 2, et M. A. El Khakani 1, * 1 Institut National de la Recherche Scientifique, INRS-Énergie, Matériaux et Télécommunications, 1650 Lionel-Boulet, Varennes, Canada, J3X 1S2 2 Institut National de la Recherche Scientifique, Centre-ETE, 490 Rue de la Couronne, Québec, Canada, G1K 9A9 * elkhakani@emt.inrs.ca Nous avons développé un procédé de pulvérisation magnétron utilisant une décharge RF à MHz pour la synthèse et le dopage in-situ de films de TiO 2. Nous avons ainsi pu obtenir des films de TiO 2 :W,N avec différents niveaux de dopage d azote (entre 0 et 8 at.%.) et de tungstène (entre 0 et 4 at.%). Les propriétés physico-chimiques des films de TiO 2, TiO 2 :N, et TiO 2 :W,N ont été étudiées et comparés systématiquement en fonction de leur teneur en N et W par différentes techniques, incluant la diffraction à rayons X (DRX), la spectroscopie des photoélectrons (XPS), l absorption UV-Vis, et la microscopie électronique à balayage (MEB). Nous avons pu suivre la structure cristalline qui dépend fortement des ratios des deux dopants mais demeure généralement de type anatase. La morphologie des films est plutôt dense et généralement colonnaire, jusqu à l ajout de W qui densifier davantage la structure. Enfin, les mesures d absorption optique, de changement de bande de valence (XPS), et de la fonction de travail (UPS) ont tous clairement confirmés un rétrécissement de la bande interdite des films de TiO 2 :W,N au fur et à mesure que leur teneur en N et W augmente, en passant de 3.2 ev pour le TiO 2 pur à 2.35 ev pour le TiO 2 :N (à ~5 at.% de N), et finalement à 2.2 ev pour les teneurs optimales de W et N de 1.6 at.% et 4.2 at.%, respectivement. Ces résultats montrent clairement le décalage vers le rouge de nos films étendant ainsi leur plage de photosensibilité de l UV vers le pic de l irradiance solaire. Finalement, les propriétés photocatalytiques des films ont été évaluées pour la décomposition électro-photocatalytique de polluants émergeants, sous illumination solaire standard de AM-1.5. Nous avons ainsi obtenu une efficacité de décomposition de l atrazine d au-delà de 90% en 30min dans les eaux synthétiques après 2h de traitement. Les résultats obtenus ont non seulement confirmer l effet bénéfique du codopage pour la passivation des pièges de photocharges, mais surtout de corréler directement les propriétés optoélectroniques des films de TiO 2 :W,N et leur performance électro-photocatalytique. 26

27 Low resistivity W x V 1-x O 2 -based multilayer structure with enhanced temperature coefficient of resistance features for microbolometer applications N. Émond 1, A. Hendaoui 1, E. Haddad 2 and M. Chaker 1 1 INRS Centre Énergie, Matériaux, Télécommunications, Varennes (Canada) 2 MPB Communications Inc., Pointe-Claire (Canada) The fabrication of highly-sensitive uncooled microbolometers requires the development of low resistivity sensing materials with a high thermal coefficient of resistance (TCR). In addition, two factors need to be achieved for the sensing material in order to have easier and more reliable signal readout from the microbolometer over its whole operating range of temperatures; first, the TCR value of the sensing material needs to remain unchanged over a wide range of temperatures close to room temperature, second, the hysteresis behaviour of the resistivity as a function of the temperature needs to be ideally suppressed. In this work, the semiconductor-to-metal phase transition (SMT) features of undoped and tungsten-doped vanadium dioxide thin films synthesized on LAO substrates by reactive pulsed laser deposition (RPLD) were first studied and further exploited to produce a W x V 1-x O 2 multilayer structure with a bottom-up gradient in tungsten content. This structure combines high TCR value which remains constant around room temperature, low resistivity values across the SMT as well as a small hysteresis width between heating and cooling segments of the temperature dependent resistivity curves. With a proper choice of its tungsten gradient, we anticipate that this W x V 1-x O 2 multilayer structure could be used as a sensing material in highlysensitive and highly-reliable uncooled infrared microbolometers. 27

28 Titre : Caractérisation physico-chimique et mécanique de revêtements d'hydroxyapatite élaborés par projection de suspension dans un plasma inductif Auteurs : Frederic Faivre 1-2, François Gitzhofer 1, Ghislaine Bertrand 2, David Grossin 2, Joël Alexis 3, Jade Pécune 3 Affiliation : 1 Université de Sherbrooke, Laboratoire de génie des plasmas Sherbrooke, Qc, Canada 2 Centre Interuniversitaire de Recherche et d Ingénierie des Matériaux (CIRIMAT UMR 5085, Institut Carnot), Toulouse, France 3 Université de Toulouse, INPT-ENIT, Laboratoire Génie de Production, Tarbes, France Résumé : Les revêtements d'hydroxyapatite (HA), Ca 10 (PO 4 ) 6 (OH) 2, réalisés par projection plasma atmosphérique conventionnelle, sont largement utilisés pour améliorer l intégration des prothèses osseuses grâce à leur biocompatibilité. Cependant, des propriétés telles que la composition chimique, la cristallinité, les phases, les tailles de cristallites, la rugosité, la porosité et l épaisseur ont notamment été identifiées comme ayant une forte influence sur la durée de vie de ce type de revêtement. L objectif des travaux est donc de proposer un nouveau revêtement dont la composition s approche de celle du minéral osseux et la microstructure est maîtrisée afin d'améliorer sa bioactivité tout en maintenant ses propriétés mécaniques. La projection de suspension dans un plasma à couplage inductif, développée à l'université de Sherbrooke, nous a permis d'obtenir des dépôts composés majoritairement de phase HA (91%) avec des traces (9%) de tricalcium de phosphate(-tcp), d'oxyde de calcium (CaO) et de tetracalcium de phosphate, nanocristallisés (10 à 20 nm) comme ont pu le prouver les caractérisations par diffraction des rayons X, spectroscopies infrarouge et Raman. De plus, ces revêtements égalent voire dépassent les propriétés des dépôts obtenus par plasma atmosphérique conventionnel(fc=100 à 160N, Lc=0.5 à 2N, E=10GPa, H=1.5 à 3GPa) en terme de tenue mécanique lors de leurs caractérisations en flexion (charge critique Fc=140N), dureté (E=7±2GPa, H=2.5±1GPa) et scratch test (Lc=6±1N). 28

29 Abstract of poster presentation : Polymeric Encapsulation of TiO2 Powder via PICVD Authors: Donya Farhanain, Gregory De Crescenzo, Jason R. Tavares* Affiliation: École Polytechnique de Montréal, Québec, Canada TiO 2 particles can be used for either air or water purification, self-cleaning surfaces, composites, and painting due to their photocatalytic properties. However, these particles have a strong tendency to agglomorate, which results in their non-uniform distribution in desired applications. We thus present a functional encapsulation process for such particles, using photo-initiated chemical vapor deposition (PICVD). This scalable process allows us to overcome the agregation problem while adding desired functionalities to the particle surfaces. TiO 2 powders, with a μm particle size distribution, were treated in a quartz tube reactor illuminated by two 254 nm UVC lamps. Syngas (CO and H 2 ) was applied as a gaseous precursors for the deposition of functional polymeric thin films. In some cases, hydrogen peroxide was added as a photoinitiator reagent to accelerate reaction kinetics, and small quantities of liquid co-monomers (such as acetic acid) could be added to further tailor the surfaces functionality. Powder analysis with attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) demonstrated the formation of a polymeric film with chemical functionalities such as hydroxyl, carboxylic, ketonic and alkyne groups. The encapsulation method we developed in this work is quite new both in the case of precursors and the deposition technique and it has great potential in surface treatment of powders. *Corresponding Author : Jason R. Tavares, École Polytechnique de Montréal, C.P. 6079, Succ. Centre-Ville, Montréal, Québec, Canada, H3C 3A7, Tel.: , Ext 2326, Fax: , jason.tavares@polymtl.ca 29

30 Ambient Air Processed Near Infrared PbS/CdS Core-shell Quantum Dots/ TiO 2 Nanorod Arrays Bulk Heterojunction Solar Cells Belete Atomsa Gonfa 1, My Ali El Khakani 1, Dongling Ma 1 1 Institut National de la Recherche Scientifique (INRS), Énergie, Matériaux et Télécommunications 1650 Boulevard Lionel-Boulet, Varennes, QC, Canada J3X 1S2 Abstract Colloidal quantum dots (QDs) based solar cells have recently attracted significant research interest due to their low cost solution processability and potential to achieve high efficiency [1]. So far the highest efficiency QD solar cells reported are based on the near infrared PbS QDs [2]. Meanwhile PbS/CdS core-shell QDs are more stable and better surface passivated than the PbS QDs and therefore it is quite interesting to investigate them in solar cells [3]. Indeed it has been demonstrated that PbS/CdS core-shell QDs can offer easier processability in ambient air and yield better performance than PbS QDs processed in glovebox [4]. However, the efficiency achieved is still low and needs to be improved by further optimization. In this work, we report on high efficiency air-processed bulk heterojunction solar cell devices involving wet chemically synthesized NIR PbS/CdS core-shell QDs and TiO 2 nanorod arrays. After optimization of several parameters of the device architecture an AM 1.5 power conversion efficiency of 4.43 % have been achieved with the photoresponse extended to wavelengths of about 1200 nm [5]. This efficiency was achieved by device involving thin, uniform, sputter-deposited TiO 2 seed layer on FTO glass substrate for the growth of TiO 2 nanorod arrays, optimum TiO 2 nanorod arrays length of about 450 nm and mild thermally annealed QDs film under inert atmosphere after deposition on TiO 2 nanorod arrays and prior to thermal evaporation of the back electrode. The seed layer is beneficial in improving the performance especially when the TiO 2 nanorods are longer. Although short circuit current did not change much with the length of TiO 2 nanorod arrays, both open circuit voltage and fill factor clearly changed, which is due to the variation of charge transport and recombination processes. Thermal annealing of the QD film in inert atmosphere after QD deposition further improved the efficiency by about 18 % attributed to improved charge carrier transport in the QD film. Our results demonstrate the high potential of PbS/CdS core-shell QDs for the development of high efficiency, easy solution processable, NIR responsive QD solar cells. Key Words: Bulk heterojunction solar cells, Quantum dots, PbS/CdS core-shell quantum dots, TiO 2 nanorods, Thermal annealing References 1. I.J. Kramer, E.H. Sargent, Chem. Rev. 114 (2014) C.H.M. Chuang, P.R. Brown, V. Bulovic, M.G. Bawendi, Nat. Mater. 13 (2014) H. Zhao, M. Chaker, N.Q. Wu, D. Ma, J. Mater. Chem. 21 (2011) B.A. Gonfa, H. Zhao, J.T. Li, J.X. Qiu, M. Saidani, S.Q. Zhang, R. Izquierdo, N.Q. Wu, M.A. El Khakani, D. Ma, Sol. Energ. Mat. Sol. Cells 124 (2014) B. A. Gonfa, M. R. Kim, N. Delegan, A. C. Tavares, R. Izquierdo, N. Wu, M. A. E. Khakani, D. Ma, submitted,

31 Ferroelectric thin films of lanthanides-doped tetragonal tungsten bronze Ba 2 LnFeNb 4 O 15 grown by pulsed laser deposition T. Hajlaoui 1, M. Josse 2, and A. Pignolet 1 1 Institut National de la Recherche Scientifique Centre Énergie, Matériaux, Télécommunications, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X 1S2, Canada 2 CNRS, Université de Bordeaux, ICMCB, 87 Avenue du Dr. A. Schweitzer, Pessac F-33608, France Abstract: Contact author: thameur.hajlaoui@emt.inrs.ca (Thameur Hajlaoui) The study of Ba 2 LnFeNb 4 O 15 bulk ceramics revealed that they have a tetragonal tungsten bronze (TTB) crystal structure, are ferroelectric, and that a magnetic phase of barium hexaferrite spontaneously forms within the TTB phase during the ceramic processing, resulting in a novel composite material that exhibit multiferroic properties at room temperature [1]. Our objective is to study the physical properties of thin films of Ba 2 LnFeNb 4 O 15 (TTB-Ln) grown by pulsed laser deposition (PLD) and to establish under which conditions their behavior is similar to that of bulk ceramics of the same composition. We have thus investigated the structural, ferroelectric and magnetic properties of c-oriented thin films of Ba 2 LnFeNb 4 O 15 (Ln = Eu and Sm) successfully grown on Nb-doped STO (100) and MgO (100) single crystalline substrates by PLD. The optimum deposition conditions established are Ts 750 C and PO mtorr for TTB-Ln films on NSTO substrates and Ts 750 C and PO 2 1 mtorr for TTB-Ln films on MgO substrates. The thickness of all thin films was estimated to be about 380 nm, and a structure of grains with diameters around 100 nm was observed. The XRD analysis reveals that the thin films of TTB-Ln are c-axis oriented with c Å and an estimated in-plane lattice parameters a Å. These values are slightly smaller than those observed in the bulk [1], indicative of a compressive stress buildup in the films during the deposition. Further structural analysis reveals two kinds of azimuthal orientations of the c-axis oriented grains of TTB-Ln onto the (100) surface of the cubic NSTO and MgO substrates, with the a and b axes of Ba 2 LnFeNb 4 O 15 aligned at ±18 with respect to the a-axis of the cubic substrates. Ferroelectric macroscopic P-E hysteresis loops have demonstrated the existence of a switching polarization at room temperature in the PLD-grown c-oriented TTB-Ln thin films. The measured remnant polarization in the Ba 2 LnFeNb 4 O 15 (Ln = Eu and Sm) thin films is 0.4 μc/cm 2 and 0.2 μc/cm 2 respectively, only slightly smaller than the remnant polarization in the bulk reported to be 0.6 μc/cm 2 for Ln = Eu and 1.5 μc/cm 2 for Ln = Sm [1]. An investigation of the microscopic electromechanical properties of the studied thin films by piezoresponse force microscopy showed the existence of a piezoelectric signal and of piezoelectric hysteresis loops, which confirm the ferroelectric behavior of the prepared thin films. A magnetic signal was also detected, which confirms the multiferroic/magnetoelectric behavior of the prepared TTB-Ln thin films. This magnetic signal can be enhanced by using targets enriched in barium hexaferrite, the magnetic phase in these TTB-Ln multiferroic composites, and/or by modifying the conditions of deposition in order to form more barium hexaferrite with the ferroelectric TTB-Ln films. Key words: thin film, pulsed laser deposition, multiferroic. [1] M. Josse, O. Bidault, F. Roulland, E. Castel, A. Simon, D. Michau, R. Von der Muhll, O. Nguyen, M. Maglione, Solid State Sciences 11 (2009)

32 Glass micromachining by Spark Assisted Chemical Engraving (SACE) L. A. Hof, F. Charbonneau, J.D. Abou Ziki Department of Mechanical & Industrial Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal H3G 1M8, Canada With the great technological advancement that we are witnessing in the micro-technology field, micro-machining of various materials has become a vital task. Glass is, after silicon, the mostly used material in MEMS devices and microfluidics. In fact, due to its unique properties including its chemical durability, mechanical strength, and its optical and thermal properties there is a growing trend to replace silicon with glass. Nowadays, a number of glass micro-machining technologies such as wet etching, laser, ultrasonic and mechanical machining is available. However, drilling high-aspect ratio micro-holes is still challenging due to long machining times, high machining costs, or poor resulting surface quality. Spark assisted chemical engraving (SACE) is one of the non-traditional glass micromachining technologies and is based on electrochemical discharges. When a voltage, higher than a critical value, is applied between the two electrodes, the bubbles formed around the tool-electrode coalesce into a gas film through which discharges are generated [1] [3]. Due to the advancements accomplished recently regarding the SACE process understanding, it has been transferred the last year and for the first time to industry, where SACE machines are available today on the market (figure 1.B.). One of the most intriguing establishments is the understanding of the SACE machining process which was proved to be due to thermal-assisted local etching of the surface due to the discharges generated beside the tool tip. Furthermore, important aspects in SACE drilling process were understood and reported recently. In fact, a novel approach was used to extract information about local variables in the machining zone by the measurement of the force exerted on the tool-electrode. These variables include the tool workpiece gap average values and origin of its formation, the nature of the locally formed surface layer and texture, the machining temperature and the nature of the drilling forces [1]. In addition, the gas film propriety and the discharges generated around the tool-electrode are better controlled [4]. This is obtained by tuning the electrical propriety of the input voltage signal and the geometry of the tool. The advancement in the knowledge about SACE allowed this process to drill high-aspect-ratio holes during few seconds using tiny tools and results in high machining quality and control of the desired structures in glass (figure 1.C.). Also, SACE proved to be able to modify the local machined surface properties, such as hardness and texture. Currently, research is ongoing on whether it is possible to control the surface composition and chemistry locally. This talk summarizes the stateof-art-knowledge about SACE, its advantages and limitations compared to other processes. Figure 1. A. Current-voltage characteristic of SACE process. B. Industrial SACE machine by Posalux S.A. C. SACE machined microhole (Ø=378µm) in glass. Acknowledgements This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC). L.A.H. and J.D.A.Z would like to thank the Ministère de l Education, de l Enseignement superieur et de la Recherche (MEESR) for the bourse d excellence pour étudiants étrangers (V1). The authors would like to acknowledge Posalux S.A. and Prof. R. Wüthrich for their support and fruitful discussions. References [1] R. Wüthrich and J. D. Abou Ziki, Micromachining Using Electrochemical Discharge Phenomenon. Elsevier, [2] R. Wüthrich and L. A. Hof, The gas film in spark assisted chemical engraving (SACE) - A key element for micro-machining applications, Int. J. Mach. Tools Manuf., vol. 46, no. 7 8, pp , [3] B. Jiang, S. Lan, K. Wilt, and J. Ni, Modeling and experimental investigation of gas film in micro-electrochemical discharge machining process, Int. J. Mach. Tools Manuf., vol. 90, pp. 8 15, [4] C.-P. Cheng, K.-L. Wu, C.-C. Mai, C.-K. Yang, Y.-S. Hsu, and B.-H. Yan, Study of gas film quality in electrochemical discharge machining, Int. J. Mach. Tools Manuf., vol. 50, no. 8, pp , Aug

33 Functionalization of Single-Wall Carbon Nanotubes by Photo-Initiated Chemical Vapor Deposition Authors: S.Hosseininasab 1, N. Faucheux 2, G. Soucy 2, J.R. Tavares 1 * 1 Department of Chemical Engineering, Polytechnique Montreal, Quebec (Canada) 2 Department of Chemical Engineering and Biotechnological Engineering, Université de Sherbrooke, Quebec (Canada) Carbon nanotubes (CNTs) have various properties such as high mechanical and electrical conductivity, remarkable thermal stability (up to 2800 C under vacuum) [1, 2], high optical properties and the highest Young s modulus among all different types of composites and nano-materials [1, 3]. These individual properties make them promising candidates for a wide range of applications such as biotechnology, aerospace, biomedicine, tissue engineering, etc. Despite all these individual properties, their inherent hydrophobicity and insolubility are the most challenging features, which needed to be modified for certain applications. Various techniques have been reported to solve these problems such as surfactants, oxidation, sonication and functionalization, etc. [1]. Here, we propose an affordable and novel method to functionalize single wall carbon nanotubes (SWCNTs) developed at Polytechnique Montreal s Photochemical Surface Engineering Laboratory group (PhotoSEL). A PICVD (photo-initiated chemical vapor deposition) reactor utilizing two UVC lamps with a peak emission wavelength at 254 nm was used in this investigation. Purified SWCNT deposited on a glass substrate were treated by PICVD using a mixture of CO and H 2 (syngas), along with small quantities of hydrogen peroxide (radical photo-initiator). Processing pressure is slightly below atmospheric (-20 kpa). Surface wetting was assessed through sessile drop contact angle measurements (tensiometer ODG 20AMP) for raw SWCNT (R-SWCNT), purified SWCNT (P-SWCNT) and treated SWCNT (T-SWCNT) (Figure 1). The average contact angle of R-SWCNT and P-SWCNT samples was 144±1.2 and 79±2.8, respectively while this value for T-SWCNTs was less than 5, proving the capability of PICVD to make SWCNT surfaces superhydrophilic. This modification was achieved by adding oxygen-containing groups such as hydroxyl and carboxyl groups. In addition, the contact angle of T-SWCNT was measured after 1, 2 and 3 weeks in order to investigate the stability of functionalization: all measurements remained below 21. Full surveys for all samples including R-SWCNT and P-SWCNT and T-SWCNT by PICVD obtained by X- ray photoelectron spectroscopy (XPS). The XPS results showed that ratio of oxygen to carbon of P-SWCNT increased compared to R-SWCNT. This increase was because of oxidation of SWCNTs by acid used for their purification. Another increase in this ratio for T-SWCNT compared to P-SWCNT revealed successful deposition of oxygen-containing groups on the SWCNT surface by PICVD method. Figure.1. Contact Angle measurement obtained by goniometer A) R-SWCNTs, B) P-SWCNT, C) T- SWCNT by PICVD method and Syngas monomer. Reference: [1] M. C. Serrano, C. Gutiérrez and F. del Monte, Prog Poly Sci, 39, , [2] E.T. Thostenson, Z. Ren and T.W. Chou, Compos Sci Technol, 61, , [3] P. Bradford and A. Bogdanovich, J Compos Mater, 42, ,

34 The uptake dynamics of semiconducting nanocrystals into mesoporous TiO 2 thick films using electrophoretic deposition and its application in solar energy Lei Jin, Haiguang Zhao, Dongling Ma, Alberto Vomiero and Federico Rosei INRS-Énergie Matériaux et Télécommunications, 1650 Lionel-Boulet, Varennes, Québec An intense effort is boosting the development quantum dot (QD)-based solar cells due to their unique optical properties, tunable bandgap, high extinction coefficient and stability. This interest has been reinforced by near infrared (NIR) QDs with photoconversion efficiency (PCE) boosted above 8.5%. Electrophoretic deposition (EPD) has been demonstrated for preparation of high efficiency photo-anodes for QD solar cells, [1] in which QDs are grafted to a mesoporous TiO 2 thick film, but a complete analysis of EPD process is missing. Here, for the first time, we report a systematic investigation of the dynamics of NIR QDs loaded into TiO 2 mesoporous film via EPD. [2] We used PbS@CdS core@shell QDs and investigated the influence of EPD time, QD s concentration and voltage on the QD uptake process via Rutherford backscattering for Pb depth profiling. The optical density of the obtained film is strongly dependent on the applied voltage, the deposition time and the concentration of solution containing the QDs. We modeled the deposition process using Fick s diffusion law and explained the observed trends as a fast (and depth-independent) QD uptake induced by the presence of the electric field, followed by a diffusion-induced QD migration from outside the film, due to the fast creation of a QD concentration gradient. In addition, we demonstrated the increased stability of the core@shell structure compared to PbS QDs in terms of structure and optical property, based on X-ray photoelectron spectrometry and photoluminescence measurements. Based on our previous studies that confirmed a fast charge transfer from PbS@CdS to TiO 2, QD sensitized TiO 2 can be strong candidates for the development of highly efficient and stable photoanodes in PV devices and photoelectrochemistry H 2 generation. [1] Nima Parsi Benehkohal, Victoria González-Pedro, Pablo P. Boix, Sudam Chavhan, Ramón Tena-Zaera, George P. Demopoulos, and Iván Mora-Seró, J. Phys. Chem. C, 2012, 116 (31), [2] Lei Jin, Haiguang Zhao, Dongling Ma, Alberto Vomiero and Federico Rosei, J. Mater. Chem. A, 2015, 3,

35 Nanofluides à base de nanotubes de carbone fonctionnalisés par plasma pour l absorption de CO 2 L. Jorge, P.-L. Girard-Lauriault et S. Coulombe Laboratoire des procédés plasmas (LPP), Département de génie chimique, Université McGill, Montréal (QC), Canada En concentration élevée dans l atmosphère, le CO 2 a plusieurs effets néfastes sur l environnement tels que le réchauffement climatique et les pluies acides. Afin de diminuer les émissions de CO 2, de nouveaux matériaux capables de capturer, entreposer ou même réutiliser le CO 2 à la source sont nécessaires. Les nanofluides (NF), qui consistent en des dispersions de nanoparticules (NPs) dans une variété de fluides, sont des nouveaux matériaux absorbants où les NPs améliorent le transfert de masse de la phase gazeuse à la phase liquide. De plus, la surface des NPs peut être adaptée chimiquement au gaz désiré, dans le cas présent avec des fonctions nucléophiles qui interagissent favorablement avec le CO 2. Nous développons des NFs à base de nanotubes de carbone (NTCs) fonctionnalisés par plasma radio-fréquentiel (RF, MHz) à basse pression. Lors de l exposition au plasma opérant à 35 W sous une atmosphère contrôlée de NH 3 (10 cm 3 standard/min) et C 2 H 4 (10 cm 3 standard/min) à une pression de 80 Pa pendant 5 min, la surface des NTCs est recouverte d une couche polymérique d environ 10 nm d épaisseur telle qu observée par microscopie électronique à transmission (MET). Les analyses par spectroscopie de photoélectrons induits par rayons X (XPS) indiquent que cette couche contient 19 N at% et 12 % de ces atomes d azote forment des sites nucléophiles. Des analyses par spectroscopie de la structure près du front d'absorption par rayons X (NEXAFS), qui sont plus sensibles aux groupes insaturés, ont aussi mis en évidence certains des groupes fonctionnels possibles sur la surface des NTCs tels que C=N et C N. L ajout de cette couche polymérique rend les NTCs hydrophiles et donc en suspension stable dans l eau. Lorsque testé dans une colonne à bulles de gaz, la capacité d absorption de CO 2 du NF était supérieure de 36% à celle de l eau. Des cycles d absorption et de désorption ont aussi indiqué que la capacité d absorption de CO 2 par le NF demeurait constante. 35

36 Synthesis of CBN Thin Film Materials for Electro-Optic Device Applications S. M. H. Kabir 1, N. Hossain 1, S. Vigne 1, F. Fesharaki 2, K. Wu 2, J. Margot 3 and M. Chaker 1 1 INRS Centre Énergie, Matériaux, Télécommunications, Varennes (Canada) 2 Poly-Grames Research Center, École Polytechnique de Montréal, Montréal (Canada) 3 Département de Physique, Université de Montréal, Montréal (Canada) Calcium-barium niobate (Ca x Ba 1-x Nb 2 O 6, CBN) in the form of thin films is a very promising electro-optic (EO) material for the development of high performance EO modulators thanks to its high EO coefficient of 130 pm/v. We have successfully synthesized such epitaxial thin films on various substrates including MgO, Nb:SrTiO 3, as well as polycrystalline thin films on Si. However, epitaxial CBN films have to be achieved on Si substrates before they can be integrated in high-performance devices. In this work, we report on the synthesis of CBN thin films on Si using MgO as a buffer layer to grow highly oriented CBN. Growth of epitaxial MgO on Si was performed by Pulsed Laser Deposition (PLD) at 400 C under an oxygen pressure of 3.6x10-5 Torr. CBN was further grown on the MgO / Si stack layer by PLD at 800 C and 1mTorr O 2 pressure. The CBN thin film is highly textured in the (001) orientation, which represents a significant improvement of the crystalline quality of CBN directly deposited on Si. We therefore expect a much higher EO coefficient. Waveguides were fabricated using inductively coupled plasma etching. An original etching method using Cl 2 plasma at 1 mtorr with a power of 1000 W at a substrate temperature of 275 C and a nickel hard mask was employed. Waveguides with smooth and nearly vertical side walls were fabricated. These waveguides were characterized using the Metricon prism coupler (Model 2010/M) system. They exhibit single mode propagation and low losses. Based on the high quality of the deposited CBN thin films and on the high degree of optimization achieved for the fabrication of the waveguide structures, there is a great potential towards the conception of high performance EO modulators. 36

37 Vacuum Ultraviolet Deposition of Organic Coatings Evelyne Kasparek 1, Pierre-Luc Girard-Lauriault 1, Jason R. Tavares 2, Michael R. Wertheimer 3 1 Plasma Processing Lab, Department of Chemical Engineering, McGill University, Montréal, H3A 2B2, Canada 2 Department of Chemical Engineering, Ecole Polytechnique de Montreal, H3C 3A7, Canada 3 Department of Engineering Physics, Ecole Polytechnique de Montreal, H3C 3A7, Canada The performance of many applications of synthetic polymers, including those in biomedical fields, can be improved by modifying their surface properties. Polymer surfaces are generally of low chemical reactivity, not willing to form adhesive bonds, and non-wetting. Several methods exist to modify surfaces, many based on cold plasma treatments. In this work, a novel approach is used for modifying surfaces, namely photochemistry involving exposure of surfaces to short-wavelength, vacuum ultraviolet radiation in reactive gases at low pressure. This approach yields a more targeted surface chemistry when compared to plasma-based methods. The changes in surface composition, surface energy, and morphology can improve the surface wettability, adhesion of coatings, and biocompatibility. Among different kinds of functionalized surfaces, oxygen and nitrogen-rich surfaces have been found to be capable on influencing cell processes (i.e. cell adhesion and differentiation). In this project copolymerization of a hydrocarbon backbone gas and a functional gas are used to deposit functional polymer-like films using VUV photochemistry. Aminerich films were created using mixtures of ethylene/ammonia and butadiene/ammonia. First results showed that films deposited with butadiene/ammonia mixtures were more stable than the films deposited with ethylene/ammonia mixtures. Furthermore, the deposition rate of the butadiene/ammonia films was high at gas ratios up to R =!!!! = 10 in contrast to the!!!!! ethylene/ammonia films, which showed an etching effect rather than a deposition at R>2. Next, we are planning to investigate a new functionalized surface, namely a thiol-terminated surface. We aim at producing surfaces containing a high density of thiol groups and that are stable in air and aqueous media. Chemical characterization will be performed using X-ray photon spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy. 37

38 Amélie Lachapelle Sujet : Accélération d électrons par champ direct à haute intensité laser Auteurs : A. Lachapelle a, K. Otani a, S. Fourmaux a, S. Payeur a, M.Glesser a, S. MacLean a,b, J.C. Kieffer a a INRS-EMT, 1650 Blvd Lionel Boulet, J3X1S2, Varennes, Qc, Canada b Institute for Quantum Computing, U. of Waterloo, Waterloo, On, Canada Les faisceaux d électrons de courte durée d impulsion sont utilisés dans des expériences de type pompesonde pour sonder la dynamique d évènement ultrarapide. De là provient l intérêt de produire des faisceaux d électrons de durée de plus en plus courte. Une nouvelle technique d accélération par champ laser a été proposée pour produire des faisceaux d électrons d une durée de quelques attosecondes. Dans cette présentation, le processus d accélération d électrons par champ direct est exploré de façon expérimentale à haute intensité laser. L accélération par champ direct nécessite l utilisation d un mode laser exotique qui est le mode TM01 (polarisation radiale). Lorsque l on focalise un faisceau laser de courte durée d impulsion (femtoseconde), de puissance élevée (Terawatts) et de polarisation radiale, un fort champ électrique longitudinal est obtenu. Nous avons démontré expérimentalement que cette technique permet d accélérer des électrons à des énergies élevées (MeV). Les résultats expérimentaux obtenus en mode TM01 (présence d un champ longitudinal) sont comparés au signal électronique produit avec un mode TE01 (polarisation azimutale) pour lequel il n y a pas de champ longitudinal d accélération. Nous avons observé une accélération d électrons par champ direct pour les électrons les plus énergétiques. Cependant, à très haute intensité nous avons observé une compétition entre différents mécanismes d accélération. 38

39 Synthèse et caractérisation de Spinelles MFe 20 4 (M=Mn,Co) par plasma inductif Les spinelles de structures MFe2O4 (M=Mn,Co) sont des matériaux à fort potentiel. Ils permettent une application dans les domaines de la catalyse des gaz ou encore comme capteurs magnétiques. En inspectant le diagramme de phase de Fe3O4-MO, il est intéressant de noter que la phase spinelle se forme à haute température sur toute la plage de composition du diagramme. Bien que plusieurs voies de synthèse soient possibles, comme la co-précipitation de précurseurs ou la voie sol-gel, la méthode des plasmas inductifs offre plusieurs avantages, dont une grande capacité de production, un contrôle sur la stoechiométrie, etc. Ces matériaux ont été produits en injectant les nitrates de Fe et de Co dans un plasma inductif dans des conditions oxydantes. En se condensant dans une atmosphère contrôlée du réacteur, nous parvenons à contrôler la formation des différentes phases prévues par le diagramme de phase pseudo binaire FeO-CoO. Les matériaux sont caractérisés par plusieurs techniques : diffraction des rayons X pour déterminer la présence des phases, microscope électronique à balayage pour leur morphologie. La distribution en taille des nanoparticules produites sera sondée par microscopie électronique à transmission. Afin pour vérifier la stoechiométrie des échantillons, une analyse de spectroscopie à fluorescence X permettra de mesurer précisément la composition afin de comparer sa structure à celle prévue par le diagramme de phase. L analyse mettra en perspective la correspondance des phases prévues par le diagramme de phase à l équilibre avec les résultats obtenus. Enfin, nous discuterons de la taille des particules, la présence de phase(s) ou les paramètres de synthèse par plasma pour contrôler et définir au mieux les conditions de synthèse de nanoparticules de spinelle. Nadi Braidy, Jocelyn Veilleux, Maxime Lagny 39

40 Phase coexistence in Bi 2 FeCrO 6 thin film Jonathan Laverdiere, Alex Gélinas, Riad Nechache, Federico Rosei, Mohamed Chaker INRS Centre Énergie, Matériaux, Télécommunications, Varennes (Canada) Pulse laser ablation deposition (PLD) is a largely used technique for the deposition of highquality thin films. Thanks to both its capacity to transfer the stoichiometry of a given target directly to the substrate and the high kinetic energy of the species in the plasma plume, PLD excels in the deposition of materials with complex stoichiometry like multiferroic Bi 2 FeCrO 6 (BFCO). Controlling the growth of BFCO is an essential issue in the pursuit of high efficiency photovoltaic (PV) applications. As a ferroelectric material, BFCO has a considerably low band gap. Recent studies show that both band gap and light absorption of this material can be tuned with deposition conditions toward increasing its PV efficiency. The BFCO gap tunability has been explained by the Fe and Co cationic ordering and with the size of the ordered clusters. In this presentation, we will draw the general picture of recent developments around BFCO. Then we will present surface and structural analysis of BFCO films grown under many deposition conditions. We will show a continual change of the surface with deposition rate and oxygen pressure and that a hexagonal phase competes against the rhombohedral one. At a fixed temperature and pressure, growth rate alone is enough to discriminate what will be the dominant phase in the deposited film. For morphological reason, the hexagonal phase can be invisible in the X-ray diffraction measurements, suggesting that phases of BFCO could actually coexists in most films, hence shedding an additional light on the BFCO gap tunability. 40

41 Synthèse par plasma thermique à couplage inductif de dioxyde d étain nanostructuré Julien Lavie Université de Sherbrooke Jocelyn Veilleux Université de Sherbrooke jocelyn.veilleux@usherbrooke.ca Résumé Grace à leur grande capacité de stockage et à leur grande énergie spécifique, les batteries au lithium jouent un rôle important dans notre société, notamment pour les applications mobiles. Ceci étant dit, les matériaux constituant les électrodes des batteries au lithium peuvent encore être améliorés, notamment en ce qui a trait à l anode. En effet, les anodes conventionnelles, constituées de graphite, ont une capacité théorique relativement peu élevée de 370 mah/g comparativement à l étain qui possède une capacité de 990 mah/g. Les anodes d étain sont souvent formées d oxydes (SnO 2 ) et l intercalation du lithium à l intérieur de celles-ci s accompagne d une augmentation de volume de l ordre de 200%. Cela entraîne une perte partielle de contact électronique, voire un bris mécanique de la batterie, et donc décroissance de sa capacité. Pour remédier à cette problématique, il est essentiel de travailler sur la mise en forme des matériaux d anode à base de SnO 2, notamment en formant des nanostructures pour permettre une meilleure relaxation des contraintes. Dans cette étude, nous proposons d utiliser les plasmas thermiques à couplage inductif pour produire des nanostructures de SnO 2. Deux voies de synthèse par plasma sont explorées : i) l injection d une poudre micrométrique d étain métallique dans un plasma Ar-O 2 et ii) l injection de précurseurs (SnCl 4 5H 2 O) en solution aqueuse, aussi dans un plasma Ar-O 2. Les résultats préliminaires obtenus à partir de l étain métallique montrent qu il est possible d obtenir des nanostructures diverses (cubes, bâtonnets, sphères, etc.) ayant des tailles variant entre 5 et 200 nm. Or, l injection de SnCl 4 5H 2 O devrait permettre un meilleur contrôle de la morphologie et de la taille des nanostructures. L influence des paramètres d opération du plasma (puissance, gaz plasmagène, pression, etc.) et du recuit des nanostructures sur la morphologie et la taille sera discutée. 41

42 Fonctionnalisation des Nanoflocons de Graphène par Plasma Thermique et Applications. U. Legrand, P.-A. Pascone, J.-L. Meunier, D. Berk Département de génie chimique, Bâtiment Wong, Université McGill. Les nanoflocons de graphène (NFG) sont des nanoparticules constituées d une multicouche de feuillets de graphène, typiquement entre 5 et 20, pour des dimensions approximatives de 100 par 100 nm. Les NFG sont synthétises par nucléation homogène, suite à la décomposition d un précurseur de carbone, ici du méthane, dans un plasma thermique d argon généré par une torche ICP. Tels quels les NFG présentent plusieurs qualités, comme une grande pureté, une homogénéité dans la distribution de taille, peu de défauts cristallins et une grande surface spécifique. Les avantages cités précédemment font des NFG des candidats intéressants pour des applications dans différents domaines (Energie, Matériaux, Biomédical ). La principale application des NFG a été le développement de catalyseurs non nobles pour piles à combustible. Inspirés par les performances intéressantes de la molécule de phtalocyanine de fer dans la réaction de réduction de l oxygène, l idée est de disperser des atomes de fer à l échelle atomique, lies aux NFG par des atomes d azote. En premier lieu, de l azote (N 2 ) peut être introduit en même temps que le précurseur de carbone, conduisant à une faible fonctionnalisation des NFG par l azote (~2 % at.). L azote peut aussi être introduit après la synthèse des NFG, en modifiant les conditions du plasma, et en générant un plasma d azote a la place d un plasma d argon, ce qui conduit à un fort taux d azote dans les NFG (~20 % at.). La fonctionnalisation au fer peut être réalisée par voie humide, après récolte des NFG dans le réacteur, ou in-situ, par introduction de poudre micrométrique de fer dans le plasma d argon. Une fois fonctionnalisés au fer, le catalyseur à base de NFG montre une certaine stabilité de l activité dans la réaction de réduction de l oxygène, sur plus de 100h. Récemment, de nouvelles conditions de fonctionnalisation ont été testées, par introduction d oxygène dans le plasma d argon comme étape post-synthèse. Le but de cette fonctionnalisation est d introduire des groupes hydrophiles à la surface des NFG, et créer une suspension stable dans des solvants tels que l eau ou l éthanol. Cette étape devrait potentiellement aider la fonctionnalisation des NFG par voie humide, ainsi qu accéder à de nouvelles applications, telle que la dispersion des NFG dans un polymère, pour modifier ses propriétés électriques et mécaniques. 42

43 Désinfection/stérilisation de matériel informatique par une post-décharge N 2 -O 2 à pression réduite. P. Levif 1, S. Larocque 2, M. Moisan 1, J. Barbeau 2 1 Groupe de Physique des Plasmas, 2 Laboratoire Contrôle des Infections Université de Montréal, Montréal, H3C 3J7 Québec Les objets technologiques tels que téléphone cellulaire intelligent, tablette et ordinateur portable font aujourd hui partie intégrante de notre vie de tous les jours. Des microorganismes tels que des bactéries, spores bactériennes, moisissures voire virus peuvent se retrouver sur ces dispositifs informatiques. Les sources de cette contamination sont l environnement (spores bactériennes, moisissures) et l humain (bactéries, virus). Certains de ces microorganismes sont pathogènes et peuvent donc présenter un problème de santé publique (exemples : épidémie de gastro-entérite, C.difficile, etc.) Nous disposons actuellement d un système de stérilisation, basé sur une post-décharge de N 2 -O 2 à pression réduite, dont l efficacité a été démontrée sur des spores bactériennes déposées sur des boîtes de Petri de polystyrène et des protéines prions pathogènes [1]. Notre travail de recherche montre qu il est possible de stériliser des claviers d ordinateurs suite à une exposition de 2h à notre post-décharge N 2 -O 2. Nous évaluerons également l effet de la présence de ce dispositif informatique sur la réduction de l intensité du rayonnement UV par le biais de la spectroscopie optique en émission. Pour finir, nous discuterons du devenir de la charge naturelle de microorganismes présente sur cet objet après son traitement avec notre système de stérilisation. [1] Sterilization/disinfection of medical devices using plasma: the flowing afterglow of the reduced-pressure N 2 -O 2 discharge as the inactivating medium Michel Moisan et al. Eur. Phys. J. Appl. Phys. (2013) 63:

44 Synthèse de matériau de cathode par plasma thermique pour des applications dans les batteries au lithium Karine Major, Jocelyn Veilleux et Gessie Brisard Dans le quotidien ou pour la fabrication de produits de consommation, l énergie est au cœur de l activité humaine. Le développement de la batterie au lithium a été une des nombreuses solutions apportées aux problèmes énergétiques. Les batteries au lithium-ion ont aujourd hui une importance indéniable puisqu elles se retrouvent dans de nombreux appareils électroniques tels que les cellulaires et les ordinateurs portables. Cette technologie offre aussi une alternative à l utilisation des combustibles fossiles dans le domaine des transports. Toutefois, la capacité et la sécurité de ces batteries peuvent encore être améliorées. En ce sens, la recherche actuelle vise l amélioration de l efficacité des différentes composantes des batteries au lithium-ion, à savoir l anode, la cathode et/ou l électrolyte. Nos recherches visent principalement l amélioration des matériaux de cathodes de type lithium fer phosphate (LiFePO 4 ou LFP) par l utilisation d une nouvelle méthode synthèse. Cette méthode consiste à injecter une solution sol-gel dans des plasmas thermiques RF. À l aide d un réacteur de synthèse de poudre, une poudre nanométrique et de morphologie sphérique a été obtenue. Un réacteur de projection a permis d obtenir un dépôt sur un substrat conducteur sans l utilisation de liant polymérique. Les premiers résultats démontrent que la synthèse de poudre de LiFePO 4 et les dépôts par plasma ont une bonne réversibilité électrochimique, ce qui permettrait aux batteries d avoir un bon rendement énergétique ainsi qu une meilleure cyclabilité (durée de vie plus longue). Par ailleurs, la déposition par plasma permet d obtenir un revêtement résistant ayant une structure olivine stable. Les résultats de caractérisation physique et électrochimique seront aussi présentés. 44

45 Terahertz Field Induced Second Harmonic Coherent Detection Scheme based on a Biased Nonlinear Micro-slit Anna Mazhorova 1, Sze-Ping Ho 1,2, Matteo Clerici 1,3, Marco Peccianti 4, Alessia Pasquazi 4, Luca Razzari 1, Jalil Ali 2 and Roberto Morandotti 1 1 INRS-EMT, University of Quebec, 1650, Blvd. Lionel-Boulet, Varennes, Quebec JSX 1S2, Canada 2 Nanophotonics Research Alliance, Universiti Teknologi Malaysia, UTM Skudai, Johor, Malaysia 3 School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, United Kingdom 4 Department of Physics and Astronomy Pevensey Building II, 3A8, University of Sussex, United Kingdom It is well known that static fields can break the symmetry of a centrosymmetric medium (like SiO 2 ), which can hence show a quadratic nonlinear behavior, e.g. Electric Field Induced Second Harmonic (EFISH). Terahertz radiation can be regarded to as a static field compared to an optical field and can hence also induces quadratic behavior in Kerr media (Terahertz Field Induced Second Harmonic TFISH). It has been shown that coherent (field-sensitive) detection schemes can be obtained exploiting TFISH in air by adding an external, oscillating bias field to the interaction. This technique is largely employed as a broadband THz detection scheme and is named Air Biased Coherent Detection (ABCD). The ABCD, due to the low dispersion of air, can record THz fields with extremely large bandwidth (>20 THz), yet require bulk setups and cannot be easily miniaturized. Furthermore, it typically requires kv sources, since the detection signal to noise ratio depends on the amplitude of the bias field and it is limited by the air breakdown voltage. We demonstrated coherent THz characterization based on TFISH effect in few microns thick Silica (SiO 2 ) samples that can be easily operated with V sources. Our sample is an infinitely long 30 μm slit written in gold. The underlying idea of our work is that of exploiting the large breakdown voltage and the high nonlinearity of glass to achieve a large signal to noise ratio detection with a very weak optical probe at moderate bias fields, thus drastically reducing the electrodes gap. Our results pave the way to a novel approach towards broadband THz detection. Fig. 1. (a) Basic scheme of the sample with the biased micro-slit. PMT is a photo-multiplier tube. (b) Electric field trace recorded via the proposed technique with 250 V applied on the electrodes. In the inset the THz electric field trace recorded with standard EO sampling with ZnTe crystal is shown. Trace (c) shows the measurement obtained for the same situation of (b) but without bias field. (d) Numerical simulation of a section of the electric field map inside the fabricated sample for an applied 250 V potential between the electrodes. 45

46 Évolution structurale 2D de nano flocons de graphène produits dans un réacteur à plasma thermique N. Y. Mendoza-González, U. Legrand, P. Pascone, J.-L. Meunier et D. Berk. Département de Génie Chimique, Université McGill, Montréal H3A 2B2, Québec-Canada La synthèse des nanostructures 2D à base de graphène dans un réacteur à plasma thermique pour des applications catalytiques est présentement en développement au laboratoire PPL [1,2]. Des travaux de modélisation dans le groupe [3] ont été faits pour améliorer la compréhension du procédé de synthèse et avoir un contrôle sur les caractéristiques finales de ces produits appellés ici nano-flocons de graphène (GNF). Les derniers résultats de modélisation [4] fournissent de l information sur l épaisseur de la structure du graphène (nombre de plans atomiques) et les longueurs de feuilles en fonction de la géométrie du réacteur et les paramètres d opération. Ces données sont calculées dans une étape postérieure au modèle fluide. Le modèle implique le calcul couplé des champs de l'écoulement, de la température du gaz plasma et de la dynamique de nucléation des nanoparticules. La méthode des moments est utilisée pour résoudre l'équation de la dynamique des particules qui inclue la formation de nanoparticules par nucléation homogène et la croissance principalement due à la condensation. Le transport des nanoparticules se produit par convection, thermophorèse et diffusion Brownienne. À ce jour, nous avons considéré le taux de condensation des particules sphériques comme étant le même que pour les flocons de graphène en forme de disque; cependant, la surface extérieure d'un flocon est différente de celle d une particule sphérique de la même masse, et donc les taux de condensation sont différents. Ce travail présente la modification du modèle de croissance de particules en ajoutant un facteur de correction dans le terme de condensation qui tient compte de la relation des flocons et de la particule sphérique. Le calcul du nouveau terme de condensation est inclus dans chaque itération affectant ainsi l équation de la population d aérosols in-situ. Ce calcul ajoute une précision et une évolution plus près de la structure réelle des GNF. Les résultats démontrent qu une fois la création de particules primaires, le taux de croissance 2D par condensation est effectivement fortement lié à la surface. Cette évolution structurelle obtenue grâce à la modélisation est déjà un grand pas vers la compréhension et le contrôle du mécanisme de croissance des structures 2D. Références: [1] D. Binny, J.-L. Meunier, D. Berk (2012). IEEE Nano 2012, Birmingham (UK), [2] P.A. Pascone, D. Berk, J.-L. Meunier (2013). Catalysis Today, 211, [3] R. Pristavita, N. Mendoza-Gonzalez, J.-L. Meunier, D. Berk, (2011). Plasma Chem. Plasma Process, 31, 6, [4] J. -L., Meunier, N. -Y., Mendoza-Gonzalez, R., Pristavita, D., Binny, & D. Berk (2014). Plasma chem. plasma process., 34,

47 Synthesis of Gallium Orthophosphate thin films by pulsed laser deposition Mohammadhossein Mirhaj 1, Gaston Dubé 2 and Mohamed Chaker 2 1 INRS Centre Énergie, Matériaux, Télécommunications, Varennes (Canada) 2 Alsense Electronic Sensors Inc., Ste-Anne-des-Monts (Canada) Gallium Orthophosphate (GaPO 4 ) is a piezoelectric material that presents a unique combination of a relatively large piezoelectric coefficient (up to 5 times larger than that of the common alphaquartz) and a high thermal stability (remains piezoelectric up to 970 C). This makes GaPO 4 an excellent candidate for high temperature sensors and actuators applications. GaPO 4, that exhibit an alpha-quartz structure, was recently synthetized as a bulk crystal and is commercially available at very high price due to the very low growth rate of the material. The production of this material in the form of thin films could be a good option not only to decrease the related cost, but also to integrate this material in multifunctional devices. To date, only one paper reported the deposition of this material as a thin film without giving much detail on the material properties [1]. In this work, we report the deposition of Gallium Phosphide as a thin film by reactive pulsed laser deposition. In order to obtain Gallium Phosphate thin films on Z-cut quartz, a GaP target is ablated by KrF laser in presence of oxygen background pressure. First, various deposition conditions were explored to study their influence on the thin film composition. For example, it is found that the Ga/P ratio, analyzed by X-ray photoelectron spectroscopy (XPS), present two different regimes as a function of the deposition pressure; the Ga/P ratio increases from 1 mtorr to 50 mtorr and decreased from 50 mtorr to 150 mtorr. Hence, for the different regimes of pressure, the amorphous films composition can be changed from phosphorous-rich to galliumrich, with Ga/P ratio going from 0.66 to Second, the crystallization of Gallium Phosphate films occurring at temperatures higher than 700 C, it was found that the best way to obtain alpha-cristobalite phase of GaPO 4 on quartz (the one presenting piezoelectric properties) was to use ex-situ crystallization of amorphous films obtained by PLD at room temperature. Different annealing methods, temperatures, heating ramp and annealing time were explored in order to study their influence on the material crystallization. Alpha-cristabalite films with a thickness of 2µm are obtained using Rapid Thermal Annealing at 940 C in an Oxygen atmosphere starting from P-rich films. Finally, stoichiometric GaPO 4 films with a preferential (111) orientation were analyzed by Second Harmonic Generation technique (SHG) which confirm the presence of a piezoelectric effect in the films. [1] J. D. Pedarnig, S. Roither, and M. Peruzzi, Applied Physics Letters, 89, (2006). 47

48 High-order Harmonic Generation from Laser-ablated Graphite Waveguides M. A. Fareed, S. Mondal, M. Boudreau, Y. Pertot and T. Ozaki Institut national de la recherche scientifique Centre Energie, Matériaux et Telécommunications, 1650 Lionel-Boulet, Varennes, Québec J3X 1S2, Canada Author address: High-order harmonic generation (HHG) from laser-ablated plumes (LAP) has been demonstrated to be an efficient technique to generate ultrashort pulses of extreme ultraviolet radiations (XUV) with high photon flux [1,2]. In this technique, a heating pulse (called prepulse) is used to ablate plasma from the surface of a solid material. Then this plasma is cooled down for few tens of nanoseconds to produce the neutrals in the plasma. Finally, an ultrashort laser pulse (called main pulse) irradiates this plume to generate high-order harmonics [3]. In LAP technique, a prepulse with peak intensity ~10 10 Wcm -2 is focused on the target surface and a plume of ~ µm diameter, with expansion length ~1 mm (distance from the target surface), is ablated. It shows that the interaction volume of the main pulse with the nonlinear medium is small. So if we increase the diameter of the LAP, main pulse can interact with the large volume of LAP and efficiency of the harmonics should increase. However, it is observed that by using LAP with the large diameters harmonics efficiency is reduced. This reduction in efficiency mainly occurs due to phase mismatch and self-absorption by the medium itself. However, this phase mismatch and self-absorption can be controlled by using nonlinear medium inside waveguides [5]. It is observed that by using special geometry of the waveguides, the phase-matching of the harmonics can be improved and photon flux of high-order harmonics can be improved about two to three orders of magnitude. This waveguide technique is successfully applied to harmonic generation with gaseous mediums, which is another technique of HHG [6]. In this work, we introduce a plasma waveguides to improve the efficiency of the high-order harmonics, generated from solid materials. It is observed that by using a plasma waveguide of appropriate dimensions, the efficiency of the high-order harmonics can be improved. Graphite waveguide is selected for the experiment, as graphite plumes are observed as an efficient nonlinear medium for intense harmonic generation [4]. We have used a 3 mm long plasma waveguide, with input diameter of ~200 µm, for harmonics generation and then compared the harmonics yield with the harmonics generated with LAP. It is observed that using 3 mm long waveguide, the efficiency of the harmonics can be improved about 2.8 times than the harmonics generated from LAP. We believe that this flux can be improved further by using laser waveguides of longer lengths. References [1] R. A. Ganeev, L. B. Elouga Bom, J. Abdul-Hadi et al, Phys. Rev. Lett. 102, (2009). [2] T. Ozaki, R. A. Ganeev, M. Suzuki, and H. Kuroda, in (In Tech, 2010). [3] R. A. Ganeev, M. Suzuki, M. Baba et al, Opt. Lett. 30, 768 (2005). [4] L. B. Elouga Bom, Y. Pertot, V. R. Bhardwaj and T. Ozaki, Opt. Express 19, 3077 (2011). [5] A. Rundquist, C. G. Durfee, Z. Chang et al, Science 280, 1412 (1998). [6] C. Winterfeldt, C. Spielmann, and G. Gerber, Rev. Mod. Phys. 80, 117 (2008). 48

49 Intense broadband THz pulse generation via laser-plasma interaction at relativistic intensity S. Mondal, Q. Wei, H. A. Hafez, M. A. Fareed, A. Laramée, S. Sun, T. Ozaki INRS-Énergie Matériaux Télécommunications,1650, boulevard Lionel-Boulet, Varennes, QC, J3X 1S2, Canada THz radiation is very useful for imaging because they can pass through many materials that are opaque in the visible range without ionizing them. Also it provide better resolution compared to microwave radiation. 1,2 It also has strong interaction with many materials hence very useful in probing physical, chemical and biological systems 3 5. Intense broadband THz pulses can open up new scientific areas to explore, such as nonlinear optics in the THz domain, single-shot THz spectroscopy and single-shot THz imaging 6. Intense THz pulses are also useful in developing the THz streak camera for the temporal measurement of femtosecond bunches of high energy electrons generated in high-intensity femtosecond laser plasma interaction or any other techniques 7. High intensity laser plasma interaction is reach in physics and numerous physical processes are involved during and immediately after the interaction 8. This interaction is also considered as an excellent tabletop source of high energy photons, electrons, protons and ions 9. Development of a tabletop sources of high energy charged particles and photons are of scientific interest 10. Recently, it has been found that intense laser-plasma interaction can also generate intense broadband terahertz (THz) pulses and can be a promising source of intense THz pulses We have developed a tabletop source of intense THz pulses at INRS-ALLS based on the interaction of high intensity femtosecond laser plasma interaction on a solid surface. 240mJ, 40fs 800nm pulses from 10TW, 10 Hz beam line of ALLS are focused on a solid Cu target, mounted inside a vacuum chamber, by using an off-axis parabolic mirror. Intensity at focus can reach maximum up to W/cm 2. Intense THz pulses are generated as a result of laser plasma interaction. THz pulses are then collimated by using thick gold coated off-axis parabolic mirror and guided outside the vacuum chamber by using a low pass window made of ultrahigh molecular weight polyethylene with a cutoff at 20THz and then refocused on a pyroelectric detector to measure the THz pulse energy by using another parabolic mirror. In this experiment we have characterized generated THz pulses (peak electric filed and band width, refocussing ability). We are also able to enhance the THz pulse energy by using aligned Cu nanorod targets by maximum upto13.8 times in the spectral band 20THz and 28 times in the spectral range 20THz to 200THz. Aligned Cu nanorod targets are prepared electrochemically by using Whatman Anodisc template in collaboration with Prof. Sun s group at INRS. We also have studied effect of preplasma on THz pulse generation and optimized preplasma conditions favorable for THz pulse generation. References: 1 X.-C. Zhang, Physics in Medicine and Biology 47, 3667 (2002). 2 J.F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, Semiconductor Science and Technology 20, S266 (2005). 3 B.M. Fischer, M. Walther, and P.U. Jepsen, Physics in Medicine and Biology 47, 3807 (2002). 4 M. Walther, P. Plochocka, B. Fischer, H. Helm, and P. Uhd Jepsen, Biopolymers 67, 310 (2002). 5 H.A. Hafez, I. Al-Naib, M.M. Dignam, Y. Sekine, K. Oguri, F. Blanchard, D.G. Cooke, S. Tanaka, F. Komori, H. Hibino, and T. Ozaki, Physical Review B 91, (2015). 6 Já. Hebling, K.-L. Yeh, M.C. Hoffmann, and K.A. Nelson, IEEE Journal of Selected Topics in Quantum Electronics 14, 345 (2008). 7 U. Frühling, M. Wieland, and M. Gensch, Nature Photonics 3, 523 (2009). 8 P. Gibbon, Short Pulse Laser Interactions with Matter (Imperial College Press London, 2005). 9 D. Umstadter, Journal of Physics D: Applied Physics 36, R151 (2003). 10 T. Donnelly, M. Rust, and I. Weiner, Journal of Physics B: 313, (2001). 11 H. Hamster, A. Sullivan, S. Gordon, W. White, and R.W. Falcone, Phys. Rev. Lett. 71, 2725 (1993). 12 X. Dong, Z. Sheng, H. Wu, W. Wang, and J. Zhang, Physical Review E 79, (2009). 13 A. Gopal, S. Herzer, A. Schmidt, P. Singh, A. Reinhard, W. Ziegler, D. Brömmel, A. Karmakar, P. Gibbon, U. Dillner, T. May, H.-G. Meyer, and G.G. Paulus, Physical Review Letters 111, (2013). 14 A. Gopal, T. May, S. Herzer, A. Reinhard, S. Minardi, M. Schubert, U. Dillner, B. Pradarutti, J. Polz, T. Gaumnitz, M.C. Kaluza, O. Jäckel, S. Riehemann, W. Ziegler, H.-P. Gemuend, H.-G. Meyer, and G.G. Paulus, New Journal of Physics 14, (2012). 15 M. Singh and R.P. Sharma, Contributions to Plasma Physics 53, 540 (2013). 49

50 Nanofiber/net structured polymer films coated with TiO2 nanoparticles F. Navarro-Pardo 1, H. Zhao 1, A. Vomiero 2, and F. Rosei Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, J3X 1S2, Québec, Canada 2. Luleå University of Technology, Luleå, Sweden. Abstract Electrospinning of polyamide 6 has been used in order to obtain films composed of spider-net-like sub-nanofibers with diameters of nm among the main nanofibers with diameters of nm. This approach was made in order obtain structured films with enhanced interconnectivity and high surface area for additional anchoring of the TiO2 nanoparticles. The coating of the TiO2 nanoparticles was tailored as a function of temperature and time by using the hydrothermal method. The treated films showed that TiO2 nanoparticles were uniformly deposited on the nanofiber/nets and variation of the parameters before mentioned lead to either the decoration or coating of the fibers by the nanoparticles. A heat treatment was applied to the coated films in order to remove the polymer and sinter the TiO2 nanoparticles. The morphology of the main fibers remained after polymer removal and the particles anchored in the netting regions filled the micropores of the electrospun films. These nanofiber/net structured films can be employed as the scattering layer in the photonoade of dye sensitized solar cells. Figure 1. Micrographs of the nanofiber/nets polymer films (a), TiO 2 coated films (b) and TiO 2 nanofibers after polymer removal. 50

51 Precise Energy and Temperature Measurements in Dielectric Barrier Discharges (DBD) at Atmospheric Pressure Bernard Nisol 1, Mylène Archambault-Caron 1, Hervé Gagnon 1, Sophie Lerouge 2, Michael R. Wertheimer 1 * 1 Groupe des Couches Minces (GCM) et Département de Génie Physique, Polytechnique Montréal, Box 6079, Station Centre-Ville, Montréal, QC, H3C 3A7, Canada 2 Centre de Recherche du Centre Hospitalier de l Université de Montréal (CRCHUM), et Département de Génie Mécanique, École de technologie supérieure (ÉTS), Montréal, QC, H2X 0A9, Canada *Corresponding author; michel.wertheimer@polymtl.ca Abstract A specially designed dielectric barrier discharge (DBD) cell and associated equipment has been used to carry out precise measurements of electrical energy, E g, dissipated per discharge cycle of the applied a.c. voltage, V a, over the frequency range 5 f 50 khz. Twin pairs of several different dielectric materials (2.54 cm diameter discs, thicknesses = 2.0 or ca. 0.1 mm) with relative permit 2015tivities between 2.1 K' 9.5 were used as dielectric barriers in DBDs of four different gases: He, Ne, Ar and N 2. Much of the work relates to the study of atmospheric pressure glow discharge (APGD) plasma in flowing He gas; five separate thermometers (including fiberoptic probes immune to high voltage and high-frequency electromagnetic fields) have enabled us to perform a detailed calorimetric (heat balance) investigation in He APGD, believed to be the first of its kind. Fair agreement in the overall energy balance, which includes vacuum ultraviolet (VUV) light emission, lends strong support to the validity of both measurements and methodology. The latter includes refined algorithms that permit rapid data acquisition and processing. The present results are compared with literature, allowing several important conclusions / recommendations to emerge. Next, we turn to the particular case of DBD in Ar in a pilot-scale reactor dedicated to deposition of thin organic films (PECVD) for biomedical applications. We have found that transfer of data from the small to the large (near 50-fold greater surface area) apparatus has been very successful, and that we can now precisely measure the amount of energy (ΔE g ) consumed in a particular PECVD process. We finish by presenting specific example reactions and link energy measurements with physico-chemical characteristics of deposits. 51

52 ABSTRACT Synthèse de films de carbone amorphe par plasma de pulvérisation-magnétron, et caractérisations de leur microstructure et de leur capacité de production électrochimique de H 2 O 2 pour des applications de décontamination des eaux. R. Pandiyan 1, N. Delegan 1, A. Dirany 2, P. Drogui 2 and M. A. El Khakani 1 1 Institut National de la Recherche Scientifique, Centre-Énergie, Matériaux et Télécommunications, 1650 Blvd. Lionel Boulet, C.P. 1020, Varennes, Qc, Canada J3X-1S2 2 Institut National de la Recherche Scientifique, Centre Eau, Terre et Environnement, 490 Rue de la Couronne, Québec, Qc, Canada G1K-9A9 rajesh.pandiyan@emt.inrs.ca Des couches minces de carbone amorphe (a-c) ont été déposées sur divers substrats (Si(100) Ti, et quartz) avec la pulvérisation magnétron utilisant une décharge RF à 13.56M Mhz à des températures de dépôt (T d ) contrôlés et variés entre 20 (RT) et 750 C. Les propriétés physiques, chimiques, et optiques des couches minces ont été étudiées en fonction de la T d. La nature des liaisons atomiques de carbone a été systématiquement étudiée à l aide des spectroscopies Raman et des photoélectrons (XPS). Les résultats Raman indiquent un changement microstructural significatif, d un état mixte des liens sp 2 /sp 3 à RT vers une microstructure à tendance quasi-graphitique (sp 2 ) à T d 450 C. De façon plus quantitative, les analyses XPS des niveaux énergétiques du C 1s confirme que l augmentation de T d induit directement une augmentation du rapport de liens sp 2 /sp 3 dans les films de a-c. En effet, la proportion relative des liens C-C sp 3 diminue de 44% à T d = RT pour atteindre une valeur minimale de 16% à T d =450 C, et pour ensuite tendre à se stabiliser autour de ~26% à T d =750 C. Par ailleurs, nous avons integré ces couches de a-c en cathode dans une cellule électrochimique pour étudier leur capacité de production de H 2 O 2, en fonction de leur T d, et apr conséquent en fonction de leur rapport sp 2 /sp 3. Nous avons ainsi pu montrer un maximum de production de e H 2 O 2 aussi élevé que μg/l/cm 2 à la T d =450 C (température à laquelle le maximum des liaisons sp 2 a été obtenu dans les films de a-c). En élargissant la gamme des cathodes à base de carbone contenant des C=C sp 2 (de 0 à 84%), nous avons pu établir une corrélation directe entre la production de H 2 O 2 des films a-c et leur teneur relative en liens de carbone hybridé sp 2. Ces résultats démontrent clairement la pertinence des films d a-c avec un caractère graphitique prédominant pour la production d H 2 O 2 dans des montages électrochimiques de décontamination de polluants organiques persistents dans l eau. 52

53 Projection par plasma thermique à couplage inductif de précurseurs de titanate de bismuth Laurent Provençal Université de Sherbrooke Baptiste Le Roux Université de Sherbrooke Jocelyn Veilleux Université de Sherbrooke Résumé Les matériaux piézoélectriques sans plomb attirent l attention de nombreux chercheurs depuis que l Agence européenne des produits chimiques a ajouté le titano-zirconate de plomb (PZT) à sa «Liste des substances extrêmement préoccupantes» pour cause de toxicité. Une alternative intéressante au PZT pour la transduction ultrasonore dans des environnements à température élevée est le titanate de bismuth (Bi 4 Ti 3 O 12 ou BIT). Grâce à une température de Curie élevée, la piézoélectricité du BIT peut être utilisée par les industries nucléaire et pétrochimique pour détecter l épaisseur des parois et monitorer la corrosion des conduites. Dans cette étude, des précurseurs de BIT en solution (nitrate de bismuth pentahydraté et isopropoxyde de titane) et en suspension (nitrate de bismuth pentahydraté et dioxyde de titane) sont projetés par plasma thermique à couplage inductif pour former des revêtements sur des substrats d acier inoxydable. La structure cristalline et la morphologie des revêtements déposés sont étudiées en fonction des paramètres d opération du plasma tels que les gaz plasmagènes, la puissance, la pression et la distance de projection. Les résultats montrent que la phase Bi 4 Ti 3 O 12 peut être obtenue tant par la projection de précurseurs en solution que de suspensions dans une atmosphère oxydante. Tel qu attendu, la projection de suspensions permet d obtenir des revêtements plus épais, compatibles avec les épaisseurs requises pour une utilisation en transduction ultrasonore. Le dépôt par plasma du BIT est donc une alternative novatrice, efficace et avantageuse comparativement aux méthodes classiques de dépôt de sols-gels comme la pulvérisation pyrolytique et le dépôt par trempage. 53

54 Multiplexed high purity photon-pair source on a chip Christian Reimer, 1 Lucia Caspani, 1,2 Matteo Clerici, 1,2 Marcello Ferrera, 1,2 Michael Kues, 1,* Marco Peccianti, 1,3 Alessia Pasquazi, 1,3 Luca Razzari, 1 David Duchesne, 1 Brent E. Little, 4 Sai T. Chu, 5 David J. Moss, 1,6 and R. Morandotti 1 1 INRS-EMT, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada 2 School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK 3 Department of Physics and Astronomy, University of Sussex, Falmer, Brighton BN1 9QH, UK 4 HiQ Photonics, Upper Brookville, New York, USA 5 City University of Hong Kong, Department of Physics and Material Science, Tat Chee Avenue, Hong Kong, China 6 School of Electrical and Computer Engineering, RMIT University, Melbourne, VIC, 3001 Australia *kues@emt.inrs.ca Abstract We report an integrated, CMOS-compatible source of multiplexed photon-pairs, distributed over a frequency comb [1], centered on standard fiber communication wavelengths. Our source is pumped in a stable, self-locked configuration without the use of an external pump laser, resulting in stable pump operations over several days without significant fluctuations in pump power. Furthermore, due to very narrow photon bandwidths and long coherence times, our source is compatible with quantum memories as well as standard telecom filters. We report photon coincidence measurements on five individual channel pairs with coincidence to accidential ratios (CAR) exceeding 10 on each channel, as required by many quantum key distribution (QKD) protocolls. Our source furthermore exhibits close to single mode operation with and a heralding efficiency above 10%, underlining the quality of our source and usability for QKD applications, as well as a heralded single photon source. The integrated microring resonator (140 MHz bandwidth and 200 GHz free spectral range, FSR), fabricated in a CMOS compatible high refractive index glass, is embedded in an external active cavity, in a scheme we recently introduced in the context of a classical optical parametric oscillator (OPO) [2]. Lasing is initiated by the amplified spontaneous emission from the erbium doped fiber amplifier that acts as the gain medium for the pump laser, which is then sustained by reinjecting one ring resonance into the amplifier. With this scheme the pump is automatically self-locked to the ring resonance without the need of any external tuning or feedback loop [2,3], thereby eliminating the otherwise large issue of thermal resonacnec shifts and a resulting unstable pump condition [4]. When pumped below threshold, the OPO generated individual photon pairs on a frequency comb determined by the FSR of the ring resonator. At the detection stage the pump is eliminated by means of a notch filter and the comb is de-multiplexed using standard dense wavelength division multiplexing (DWDM) filters. Each output of the DWDM is then connected to single photon detectors for coincidence measurements. Clear coincidence peaks are visible on all the five symmetric channel pairs (Fig. 1), while no coincidences are measured between non-diagonal elements of the frequency matrix. For a pump power of 30 mw at the ring input we obtained CAR values between 10 and 14, and pair generation rates between 26 and 48 Hz per channel simultaneously, resulting in a pair generation probability per channel between 2.4 and 2.9x The signal-idler coherence time is determined from the coincidence peaks, resulting in a measured value of 110 MHz, consistent with the linewidth of the ring resonator (considering the time jitter of the detectors). Fig. 1. Measured coincidence matrix, showing clear photon coincidences between symmetric signal (s1-s5) and idler (i1-i5) channels, while no photon coincidences are meased at non-diagonal elements. In order to estimate the quality of the multiplexed photon pair source, a 3dB beamsplitter is added in the signal arm of the detection setup. From the signal-signal correlation measurmenet, we extract 1.8 effective modes of the channel, underlining the high purity of the source. Finally, a heralded correlation measurements is performed with a beam-splitter in the idler arm and three single photon detectors, resulting in a (2) antibunching dip as deep as g H < << 0.5 with a heralding efficiency above 10%, underlining the quantum characterisitc of our course. Taken together, the stable multi channel operation, narrow linewidths and heralding efficiency makes our source a unique integrated source of quantum correlated photon pairs, compatible with standard telecommunication technologies as well as quantum repeaters. References [1] C. Reimer et al., Opt. Express 22, (2014) [2] A. Pasquazi et al., Opt. Express 21, (2013). [3] M. Peccianti et al., Nat. Commun. 3, 765 (2012). [4] T. Carmon et al., Opt. Express 12, (200 54

55 SYNTHÈSE DE COUCHES MINCES ET DE NANOPARTICULES PAR PLASMAS ATMOSPHERIQUES FROIDS - UNE NOUVELLE CHIMIE VERTE, ET SES DÉFIS François Reniers Université Libre de Bruxelles, Faculté des Sciences, Chimie Analytique et des Interfaces, cp , avenue F.D. Roosevelt, 1050 Bruxelles, Belgique freniers@ulb.ac.be Les plasmas atmosphériques froids sont des plasmas non thermiques dans lesquels des espèces énergétiques fortement réactives, générées principalement par des collisions électroniques ou avec des métastables, peuvent exister à température ambiante. Ces espèces peuvent être utilisées pour traiter des surfaces, synthétiser des couches minces, décomposer des contaminants toxiques, ou pour initier une nouvelle chimie en phase gazeuse. L exposé présentera, après un bref rappel des spécificités des plasmas froids à pression atmosphériques, quelques applications spécifiques représentatives des possibilités de ces plasmas, comme : - Synthèse de couches minces organiques: effet de la chimie du précurseur et de la puissance plasma sur la chimie de la couche résultante. - Etude du mécanisme de synthèse de couche par une étude combinée de la phase plasma par spectrométrie de masse atmosphérique et de la chimie de la couche déposée par XPS - Effet du mode d injection du précurseur sur les propriétés de biocompatibilité de couches de polyéthylène glycol (PEG). - Obtention de surfaces superhydrophobes par la texturation de PTFE à l aide de la chimie particulière d une post-décharge plasma atmosphérique. - Effet du gaz plasmagène sur la chimie de couches fluorées, - synthèse de nanoparticules métalliques par microplasmas atmosphériques. 55

56 Anelastic Behavior of Suspension Plasma Sprayed Ceramic Coatings Omid Rezania a, Andrew Vackel b, Fadhel Ben Ettouil a, Sanjay Sampath b and Christian Moreau a a Concordia University, Montreal, QC, Canada b Center for Thermal Spray Research, Stony Brook University, Stony Brook, New York, USA Suspension plasma spraying (SPS) is a rising coating technology producing fine nanostructured coatings with promising mechanical and physical properties while taking advantages of the well-established Atmospheric Plasma Spray (APS) process. Anelastic behavior of the coatings can be a specific identifier of their mechanical behavior which is related to the residual stresses and defect architecture. To better understand the relationship between SPS conditions and anelastic responses, post-deposition characterization technique under low temperature thermal cycles using ex situ curvature and temperature measurements is applied. This technique makes it possible to determine the elastic modulus, non-linear degree and hysteresis degree of the spray coatings in a dependable and repeatable way. In this work, suspension plasma-sprayed ceramic coatings are produced under different spray conditions and their anelastic characteristics are compared. These results make it possible to better understand the relationship between sprayed coating microstructures and mechanical properties in SPS coatings. Keywords: Suspension Plasma spray; Nanostructured coating; Ceramic coatings; Curvature measurement; Anelastic responses; 56

57 Spectroscopie du plasma produit par laser (LIBS) pour l analyse de l or dans des échantillons miniers K. Rifai, M. Laflamme, M. Constantin, M. Sabsabi, A. Blouin, F. Vidal, P. Bouchard Le Québec compte 17 mines produisant pour environ 1.5 milliard de dollars d or annuellement, en plus de créer plus de 4500 emploi directs. Par contre, l industrie minière est confrontée à des défis importants tels que la baisse des teneurs des gisements et la complexité de minéralisation avec des niveaux d impureté plus élevées. Tous ces facteurs augmentent les coûts d exploration et de production. La fluorescence des rayons x, qui a été utilisée avec succès pour un certain nombre de métaux de base tels que le cuivre, le zinc et le nickel, est cependant inadéquate pour l application désirée, qui nécessite une limite de détection de 50 à 100 fois plus basse. Dans ce travail nous proposons l utilisation de la technique LIBS pour l analyse des teneurs en or in-situ et en temps réel. Dans ce travail préliminaire nous avons testé avec succès la faisabilité de la technique sur une panoplie d échantillons synthétiques simulant différents types de matrices minéralogiques contenant de l or (quartz, pyrite, etc.). La technique LIBS standard nous a permis d obtenir une limite de détection de ~ 0.8 ppm sur tous les types d échantillons, ce qui est adéquat pour l application désirée (~ 1 ppm). Différentes stratégies ont été mises à l essai afin de s affranchir des effets de la matrice. En particulier : (1) la normalisation du signal de l or par l intensité d un signal particulier du spectre d émission du plasma (continuum, raie d émission du Si et/ou du Fe, etc.), et (2) la classification préalable de la matrice au moyen de calculs de chimiométrie effectués à partir du spectre d émission du plasma laser sur une grande plage de longueurs d onde. Finalement, la cartographie de la surface de carottes de forage a été réalisée afin de définir une stratégie efficace d analyse des échantillons miniers sur le terrain. 57

58 Study of plasma kinetics for the deposition of hydrogenated carbon films by Atmospheric Pressure Dielectric Barrier Discharge R.Rincón 1, P. Brunet 1,2, A. Hendaoui 1, J. Matos 1, F. Massines 2 and M. Chaker 1 1 INRS Centre Énergie, Matériaux, Télécommunications, Varennes (Canada) 2 Laboratoire PROcédés Matériaux et Energie Solaire, Perpignan (France) Atmospheric-pressure dielectric barrier discharge (AP-DBD) is emerging as a versatile, scalable and eco-friendly process for the deposition of functional thin films on heat-sensitive materials [1]. However, the production of functional films based on AP-DBD requires correlating plasma regimes (homogeneous/filamentary) as well as the density of the precursor species to the films composition and morphology. In this presentation, plasma characteristics and chemistry of AP-DBD discharges working with different argon and methane mixtures is studied to produce amorphous hydrogenated carbon (a- C:H) films [2]. First, current-voltage analysis is conducted to determine plasma regimes as function of methane concentration in Ar/CH 4 mixtures. Second, a deep analysis of the plasma kinetics and chemistry is done by means of Optical Emission Spectroscopy technique. Third, the study of the films characteristics in terms of surface roughness, composition and chemical bonds is carried out by means of AFM (Atomic Force microscopy), XPS (X-ray Photoelectron Spectroscopy) and FTIR (Fourier Transform Infrared Spectroscopy), respectively. Combining the aforementioned techniques, a direct correlation between the CH species density in the plasma and the carbon content in the a-c:h films is reported. Furthermore, we demonstrate that the overall deposition process is carried at moderate plasma (gas) temperature. This work provides insights to the deposition of a-c:h films with controlled properties over heat-sensitive materials. [1] F. Massines, C. Sarra-Bournet, F. Fanelli, N. Naude, N. Gherardi, Plasma Process. Polym. 9 (2012) [2] M.A. Bratescu, Y. Yoshizaki, Y. Suda, Y. Sakai, H, sugawara, O. Takai, Thin Solid Films , 145 (2006) 58

59 Formation et transport de poudres en plasma basse pression magnétisé. 1,2,3 M. RojoP P, US. DapUP1,2, X. Glad 1,2, J-L. Briançon 4, R. ClergereauxP 1,2P, J. Margot 3 P 1 Univ Toulouse, UPS, INPT, LAPLACE, F Toulouse 9, France 2 CNRS, LAPLACE, F Toulouse, France 3 Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada 4 Institut Jean Lamour, Departement CP2S UMR 7198 CNRS, Universite de Lorraine, BP 70239, Vandoeuvreles-Nancy Cedex, France Dans cette étude, nous nous sommes intéressés à la formation et au transport de particules carbonées dans un plasma d'acétylène excité par Résonance Cyclotronique Électronique (RCE). Dans ces plasmas, des particules rayonnantes (voir figure) se déplaçant dans le volume du plasma sont observées. Dans un premier temps, nous avons étudié le transport de ces poussières. Grâce à la lumière émise par celles-ci, nous avons pu les suivre à l aide d une caméra rapide filmant à images par seconde. À l aide d un code Matlab développé à Nancy, nous avons reconstruit leurs trajectoires puis déterminé une distribution de leurs vitesses et accélérations, cela permettant de remonter à la force qu elles subissent. Il a été mis en évidence que ces particules se déplacent principalement en ligne droite et dans des directions privilégiées. Suggérant un rôle clé d un champ électrique sur leur transport, nous nous sommes intéressés aux profils spatiaux du potentiel plasma. Ceux-ci ont été mesurés dans les trois dimensions de l espace à l aide d une sonde de Langmuir. À l aide de ces profils, un modèle simple, de type OML a été mis en place pour estimer l ordre de grandeur du rapport charge sur masse des poussières. Enfin il semblerait qu une minorité de poussières de charges positives soient observées dans le plasma. Dans le but d étudier la formation des poussières, nous avons effectué des analyses ex-situ sur des échantillons qui ont stratégiquement été placés dans le réacteur pour collecter des particules. Les substrats ont ensuite été étudiés au Microscope Électronique à Balayage (MEB). Les images MEB obtenues révèlent deux types de poussières. D une part des particules sphériques qui suggèrent une croissance en volume du plasma. D autre part des particules sous forme de «pétales» qui semblent être originaires du dépôt carboné. Certaines photographies MEB semblerait montrer un phénomène d agglomération de particules sphériques formant de gros agrégats à des endroits bien localisés dans le réacteur. Enfin des films à hautes cadences viennent confirmer une forte interaction plasma-surface (remobilisation de poussières, explosion du dépôt, etc.). Figure ci-contre: poussières rayonnantes photographiées dans un plasma d Acétylène généré par RCE dans un réacteur linéaire. À chaque photographie correspond une position différente dans le réacteur. 59

60 Non-linear Terahertz spectroscopy on the Bi 2 Se 3 on Topological Insulator FF. GGGGGGGGGGGGGGGGGGGG 1, EE. CChiiiiiiiiiiiiii 2, AA. RRRRRRRRRRRR 1,3 and SS. LLLLLLLL 1, 1 - INFN and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, Roma, Italy 2 - LNF-INFN, Via E. Fermi 40, Frascati (Rome) Italy 3 INRS, Énergie, Matériaux et Télécommunications, 1650 Blvd Lionel Boulet, J3X 1S2 Varennes, Québec, Canada The Topological Insulators (TIs) are a new quantum phase of matter, with very interesting features. Their name is due to the fact that in these system the electronic properties are closely related to their topology: in fact, the bulk and the surfaces of the same material show, respectively, an electrically insulating and conducting nature. Moreover, together with graphene, the TIs are one of the few cases in nature in which the electronic transport takes place via Dirac mass-less electrons on their surface states. Since the Dirac electrons exhibit chirality and are also protected by back-scattering by time-reversal symmetry, these materials promise applications ranging from spintronics to quantum computing and for use as sources and detectors of terahertz radiation. A further predicted property of the TIs, due to the presence of the Dirac surface states, concerns their nonlinear optical response when a radiation sufficiently intense (i.e. with an amplitude of the associated electric field associated on the order of hundreds of kv/cm) and with a frequency which falls in the Terahertz region of the electromagnetic spectrum (THz, 1 THz = Hz = 33 cm 1 = 4 mev) is sent to the system. This property could open the use of these materials for the development of new THz devices and ultrafast THz tabletop source. In order to observe this non-linear phenomena, several thin films of TI Bi 2 Se 3 has been measured, using Fourier Transform Infrared Spectroscopy and THz time-domain Spectroscopy, to feature the samples in the regime of linear response, while transmission measurements in non-linear regime have been realized through the high energy single-cycle THz source, produced in SPARC_LAB, at the National Laboratories of Frascati (Rome, Italy). The non-linear measurements show a strong increase of transparency of the system vs the THz electric field amplitude. Furthermore, we developed a theoretical model describing the response of the system vs. the amplitude of the incident THz electric field, achieving a good agreement between measurements and theory. 60

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