A grande variedade de propriedades dos óxidos com estrutura perovskita permite sua aplicação em diversas áreas da tecnologia. Em especial, as propriedades eletroquímicas e a estabilidade térmica de alguns destes compostos faz destes materiais os mais usados em cátodos de dispositivos para geração de energia como as células a combustível de óxido sólido (SOFC). As SOFC são dispositivos que podem atingir altas eficiências na conversão de energia elétrica e são passíveis de utilização na geração de energia sustentável e distribuída. Para estas células, as perovskitas compostas de manganita de lantânio dopada com estrôncio (LSM) preenche a maioria dos requisitos para aplicação como cátodos da SOFC. Nas células a combustível de óxido sólido de temperatura intermediária (IT-SOFC) há a possibilidade de construir a célula com filmes finos dos materiais cerâmicos suportados em um interconector metálico. No entanto, para os cátodos das IT-SOFC as manganitas não possuem bom desempenho eletroquímico devido à menor temperatura de operação do dispositivo, sendo necessário o desenvolvimento de condutores mistos para aumentar os sítios reativos para reação de redução do O2. Assim, o desenvolvimento de cátodos utilizando a perovskita cobaltita de estrôncio dopada com antimônio (SCS) tem sido proposto para esta aplicação. Portanto, a execução deste trabalho visou à obtenção tanto da LSM quanto da SCS que são materiais para SOFC e IT-SOFC, respectivamente. A LSM também foi avaliada frente a condições de processamento e sinterização. Os pós de LSM foram obtidos através da síntese por combustão, variando a quantidade e tipo de combustível atentando aos aspectos morfológicos resultantes dos parâmetros selecionados. O método de sol-gel foi testado para obtenção da LSM, para fins comparativos. O método de combustão também foi utilizado para obter a SCS, observando a influência do tempo de calcinação sobre a formação das fases. Os pós das manganitas que apresentaram as características mais promissoras foram depositados sobre substratos densos de zircônia estabilizada com ítria (YSZ), na forma de filmes finos pela técnica de dip coating. A perovskita LSM pôde ser obtida de forma monofásica após calcinação e o resultado final da formação da estrutura romboédrica não foi alterado em função do excesso e do tipo de combustível ou do método de síntese utilizado. Agregados com morfologia distinta, formados por partículas nanocristalinas com tamanho médio de aproximadamente 30 nm, foram observados quando a sacarose foi utilizada como combustível e também quando misturada na solução precursora com ureia, formando cristalitos com tamanho médio próximo a 20 nm. A sacarose também promoveu a obtenção do pó de maior área superficial específica (34,9 m²/g) que apresentou taxas de sinterização mais elevadas que os outros pós. As deposições da LSM sobre a YSZ formou filmes contínuos quando os substratos utilizados possuíam rugosidade intermediária e também quando as deposições iniciais foram feitas utilizando baixas velocidades de retirada do banho. O uso de uma solução à base de água destilada com alto teor de ligantes promoveu a obtenção de um filme fino de 3 μm e com uma microestrutura porosa. A síntese por combustão também possibilitou a obtenção da perovskita SCS, no entanto após 6 horas de calcinação o pó ainda apresentou fases secundárias e maiores tempos podem ser necessários para a obtenção de um material monofásico. O alto calor da síntese do pó de SCS formou agregados densos, porém nanocristalinos. / The great variety of properties of oxides with the perovskite structure allows their application in several fields of technology. Specially, the electrochemical properties and the thermal stability of some of these compounds make these materials the most used in devices for energy generation such as the solid oxide fuel cells (SOFC). SOFC’s are devices the reach high efficiencies in the conversion of electric energy and are likely to be used in sustainable and distributed energy generation. For this cells, perovskitas composed by strontium doped lanthanum manganites (LSM) is the material that fits most of requirements for the application in SOFC’s cathodes. In the intermediate temperature solid oxide fuel cells (IT-SOFC) there is the possibility to build a cell with thin ceramic films supported in a metallic interconnector. However, for IT-SOFC’s cathodes, LSM no longer has a good electrochemical performance due to the device’s lower operating temperatures, being necessary the development of mixed conductors to increase the amount of reactive sites for the reduction of O2. In this context, the development of cathodes based on antimony doped strontium cobaltites (SCS) perovskites is being proposed to this application. This work was executed looking for the obtaining of LSM, a material for SOFC cathodes, and to evaluate its behavior against processing conditions; and for the obtaining of SCS, a material for IT-SOFC cathodes. LSM powders were obtained by combustion synthesis, varying the amount and type of fuel, and observing the resulting morphological aspect conferred by the selected parameters. For comparison, the obtaining of LSM powders was carried out via the sol-gel method. The combustion method was also used for the obtaining of SCS, watching for the calcination time. LSM powders were processed and powder with most promising characteristics was used in dispersions for dip coating of dense YSZ substrates. The LSM perovskite was obtained as a single phase powder after calcination without influence of the fuel excess, fuel type or synthesis method, in the final formation of the rhombohedral structure. Aggregates with distinct morphology, formed by nanocrystalline particles with average size around 30 nm, were observed when sucrose was used as fuel and also when mixed with urea in the precursor solution, which formed crystallites with average size near 20 nm. The use of sucrose also promoted the obtaining of the powder with the higher specific surface area (34,9 m²/g) which presented sintering rates higher than the other powders. When not too rough, the YSZ substrates had more continuous films formed in its surface and also when the first depositions were made with the substrates slowly emerging from the bath. The use of a solution based on distilled water with higher amount of binder, promoted the obtaining of films as thin as 3 μm and with a porous microstructure. Combustion synthesis also led to the obtaining of the SCS perovskite, however after 6 hours calcination the powder still presented secondary phases and longer calcination periods may be necessary for the obtaining of a single phase material. The high heat of the SCS synthesis reaction formed dense, yet nanocrystalline aggregates.

A grande variedade de propriedades dos óxidos com estrutura perovskita permite sua aplicação em diversas áreas da tecnologia. Em especial, as propriedades eletroquímicas e a estabilidade térmica de alguns destes compostos faz destes materiais os mais usados em cátodos de dispositivos para geração de energia como as células a combustível de óxido sólido (SOFC). As SOFC são dispositivos que podem atingir altas eficiências na conversão de energia elétrica e são passíveis de utilização na geração de energia sustentável e distribuída. Para estas células, as perovskitas compostas de manganita de lantânio dopada com estrôncio (LSM) preenche a maioria dos requisitos para aplicação como cátodos da SOFC. Nas células a combustível de óxido sólido de temperatura intermediária (IT-SOFC) há a possibilidade de construir a célula com filmes finos dos materiais cerâmicos suportados em um interconector metálico. No entanto, para os cátodos das IT-SOFC as manganitas não possuem bom desempenho eletroquímico devido à menor temperatura de operação do dispositivo, sendo necessário o desenvolvimento de condutores mistos para aumentar os sítios reativos para reação de redução do O2. Assim, o desenvolvimento de cátodos utilizando a perovskita cobaltita de estrôncio dopada com antimônio (SCS) tem sido proposto para esta aplicação. Portanto, a execução deste trabalho visou à obtenção tanto da LSM quanto da SCS que são materiais para SOFC e IT-SOFC, respectivamente. A LSM também foi avaliada frente a condições de processamento e sinterização. Os pós de LSM foram obtidos através da síntese por combustão, variando a quantidade e tipo de combustível atentando aos aspectos morfológicos resultantes dos parâmetros selecionados. O método de sol-gel foi testado para obtenção da LSM, para fins comparativos. O método de combustão também foi utilizado para obter a SCS, observando a influência do tempo de calcinação sobre a formação das fases. Os pós das manganitas que apresentaram as características mais promissoras foram depositados sobre substratos densos de zircônia estabilizada com ítria (YSZ), na forma de filmes finos pela técnica de dip coating. A perovskita LSM pôde ser obtida de forma monofásica após calcinação e o resultado final da formação da estrutura romboédrica não foi alterado em função do excesso e do tipo de combustível ou do método de síntese utilizado. Agregados com morfologia distinta, formados por partículas nanocristalinas com tamanho médio de aproximadamente 30 nm, foram observados quando a sacarose foi utilizada como combustível e também quando misturada na solução precursora com ureia, formando cristalitos com tamanho médio próximo a 20 nm. A sacarose também promoveu a obtenção do pó de maior área superficial específica (34,9 m²/g) que apresentou taxas de sinterização mais elevadas que os outros pós. As deposições da LSM sobre a YSZ formou filmes contínuos quando os substratos utilizados possuíam rugosidade intermediária e também quando as deposições iniciais foram feitas utilizando baixas velocidades de retirada do banho. O uso de uma solução à base de água destilada com alto teor de ligantes promoveu a obtenção de um filme fino de 3 μm e com uma microestrutura porosa. A síntese por combustão também possibilitou a obtenção da perovskita SCS, no entanto após 6 horas de calcinação o pó ainda apresentou fases secundárias e maiores tempos podem ser necessários para a obtenção de um material monofásico. O alto calor da síntese do pó de SCS formou agregados densos, porém nanocristalinos. / The great variety of properties of oxides with the perovskite structure allows their application in several fields of technology. Specially, the electrochemical properties and the thermal stability of some of these compounds make these materials the most used in devices for energy generation such as the solid oxide fuel cells (SOFC). SOFC’s are devices the reach high efficiencies in the conversion of electric energy and are likely to be used in sustainable and distributed energy generation. For this cells, perovskitas composed by strontium doped lanthanum manganites (LSM) is the material that fits most of requirements for the application in SOFC’s cathodes. In the intermediate temperature solid oxide fuel cells (IT-SOFC) there is the possibility to build a cell with thin ceramic films supported in a metallic interconnector. However, for IT-SOFC’s cathodes, LSM no longer has a good electrochemical performance due to the device’s lower operating temperatures, being necessary the development of mixed conductors to increase the amount of reactive sites for the reduction of O2. In this context, the development of cathodes based on antimony doped strontium cobaltites (SCS) perovskites is being proposed to this application. This work was executed looking for the obtaining of LSM, a material for SOFC cathodes, and to evaluate its behavior against processing conditions; and for the obtaining of SCS, a material for IT-SOFC cathodes. LSM powders were obtained by combustion synthesis, varying the amount and type of fuel, and observing the resulting morphological aspect conferred by the selected parameters. For comparison, the obtaining of LSM powders was carried out via the sol-gel method. The combustion method was also used for the obtaining of SCS, watching for the calcination time. LSM powders were processed and powder with most promising characteristics was used in dispersions for dip coating of dense YSZ substrates. The LSM perovskite was obtained as a single phase powder after calcination without influence of the fuel excess, fuel type or synthesis method, in the final formation of the rhombohedral structure. Aggregates with distinct morphology, formed by nanocrystalline particles with average size around 30 nm, were observed when sucrose was used as fuel and also when mixed with urea in the precursor solution, which formed crystallites with average size near 20 nm. The use of sucrose also promoted the obtaining of the powder with the higher specific surface area (34,9 m²/g) which presented sintering rates higher than the other powders. When not too rough, the YSZ substrates had more continuous films formed in its surface and also when the first depositions were made with the substrates slowly emerging from the bath. The use of a solution based on distilled water with higher amount of binder, promoted the obtaining of films as thin as 3 μm and with a porous microstructure. Combustion synthesis also led to the obtaining of the SCS perovskite, however after 6 hours calcination the powder still presented secondary phases and longer calcination periods may be necessary for the obtaining of a single phase material. The high heat of the SCS synthesis reaction formed dense, yet nanocrystalline aggregates.

A grande variedade de propriedades dos óxidos com estrutura perovskita permite sua aplicação em diversas áreas da tecnologia. Em especial, as propriedades eletroquímicas e a estabilidade térmica de alguns destes compostos faz destes materiais os mais usados em cátodos de dispositivos para geração de energia como as células a combustível de óxido sólido (SOFC). As SOFC são dispositivos que podem atingir altas eficiências na conversão de energia elétrica e são passíveis de utilização na geração de energia sustentável e distribuída. Para estas células, as perovskitas compostas de manganita de lantânio dopada com estrôncio (LSM) preenche a maioria dos requisitos para aplicação como cátodos da SOFC. Nas células a combustível de óxido sólido de temperatura intermediária (IT-SOFC) há a possibilidade de construir a célula com filmes finos dos materiais cerâmicos suportados em um interconector metálico. No entanto, para os cátodos das IT-SOFC as manganitas não possuem bom desempenho eletroquímico devido à menor temperatura de operação do dispositivo, sendo necessário o desenvolvimento de condutores mistos para aumentar os sítios reativos para reação de redução do O2. Assim, o desenvolvimento de cátodos utilizando a perovskita cobaltita de estrôncio dopada com antimônio (SCS) tem sido proposto para esta aplicação. Portanto, a execução deste trabalho visou à obtenção tanto da LSM quanto da SCS que são materiais para SOFC e IT-SOFC, respectivamente. A LSM também foi avaliada frente a condições de processamento e sinterização. Os pós de LSM foram obtidos através da síntese por combustão, variando a quantidade e tipo de combustível atentando aos aspectos morfológicos resultantes dos parâmetros selecionados. O método de sol-gel foi testado para obtenção da LSM, para fins comparativos. O método de combustão também foi utilizado para obter a SCS, observando a influência do tempo de calcinação sobre a formação das fases. Os pós das manganitas que apresentaram as características mais promissoras foram depositados sobre substratos densos de zircônia estabilizada com ítria (YSZ), na forma de filmes finos pela técnica de dip coating. A perovskita LSM pôde ser obtida de forma monofásica após calcinação e o resultado final da formação da estrutura romboédrica não foi alterado em função do excesso e do tipo de combustível ou do método de síntese utilizado. Agregados com morfologia distinta, formados por partículas nanocristalinas com tamanho médio de aproximadamente 30 nm, foram observados quando a sacarose foi utilizada como combustível e também quando misturada na solução precursora com ureia, formando cristalitos com tamanho médio próximo a 20 nm. A sacarose também promoveu a obtenção do pó de maior área superficial específica (34,9 m²/g) que apresentou taxas de sinterização mais elevadas que os outros pós. As deposições da LSM sobre a YSZ formou filmes contínuos quando os substratos utilizados possuíam rugosidade intermediária e também quando as deposições iniciais foram feitas utilizando baixas velocidades de retirada do banho. O uso de uma solução à base de água destilada com alto teor de ligantes promoveu a obtenção de um filme fino de 3 μm e com uma microestrutura porosa. A síntese por combustão também possibilitou a obtenção da perovskita SCS, no entanto após 6 horas de calcinação o pó ainda apresentou fases secundárias e maiores tempos podem ser necessários para a obtenção de um material monofásico. O alto calor da síntese do pó de SCS formou agregados densos, porém nanocristalinos. / The great variety of properties of oxides with the perovskite structure allows their application in several fields of technology. Specially, the electrochemical properties and the thermal stability of some of these compounds make these materials the most used in devices for energy generation such as the solid oxide fuel cells (SOFC). SOFC’s are devices the reach high efficiencies in the conversion of electric energy and are likely to be used in sustainable and distributed energy generation. For this cells, perovskitas composed by strontium doped lanthanum manganites (LSM) is the material that fits most of requirements for the application in SOFC’s cathodes. In the intermediate temperature solid oxide fuel cells (IT-SOFC) there is the possibility to build a cell with thin ceramic films supported in a metallic interconnector. However, for IT-SOFC’s cathodes, LSM no longer has a good electrochemical performance due to the device’s lower operating temperatures, being necessary the development of mixed conductors to increase the amount of reactive sites for the reduction of O2. In this context, the development of cathodes based on antimony doped strontium cobaltites (SCS) perovskites is being proposed to this application. This work was executed looking for the obtaining of LSM, a material for SOFC cathodes, and to evaluate its behavior against processing conditions; and for the obtaining of SCS, a material for IT-SOFC cathodes. LSM powders were obtained by combustion synthesis, varying the amount and type of fuel, and observing the resulting morphological aspect conferred by the selected parameters. For comparison, the obtaining of LSM powders was carried out via the sol-gel method. The combustion method was also used for the obtaining of SCS, watching for the calcination time. LSM powders were processed and powder with most promising characteristics was used in dispersions for dip coating of dense YSZ substrates. The LSM perovskite was obtained as a single phase powder after calcination without influence of the fuel excess, fuel type or synthesis method, in the final formation of the rhombohedral structure. Aggregates with distinct morphology, formed by nanocrystalline particles with average size around 30 nm, were observed when sucrose was used as fuel and also when mixed with urea in the precursor solution, which formed crystallites with average size near 20 nm. The use of sucrose also promoted the obtaining of the powder with the higher specific surface area (34,9 m²/g) which presented sintering rates higher than the other powders. When not too rough, the YSZ substrates had more continuous films formed in its surface and also when the first depositions were made with the substrates slowly emerging from the bath. The use of a solution based on distilled water with higher amount of binder, promoted the obtaining of films as thin as 3 μm and with a porous microstructure. Combustion synthesis also led to the obtaining of the SCS perovskite, however after 6 hours calcination the powder still presented secondary phases and longer calcination periods may be necessary for the obtaining of a single phase material. The high heat of the SCS synthesis reaction formed dense, yet nanocrystalline aggregates.

The ferro-, pyro- and piezoelectric properties of poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFE) have created interest with regard to its application in aqueous and ambient surroundings for sensors, functional coatings, and in the field of life sciences. P(VDF-TrFE) thin films are usually applied via spin-coating, but dip-coating will be advantageous especially for irregularly shaped substrates. The morphology of dip- and spin-coated semi-crystalline thin films is studied as a function of both the film thickness and the annealing temperature. The characterization of the films is carried out by grazing incidence wide-angle X-ray scattering (GIWAXS), X-ray reflectometry (XRR), and infrared reflection absorption spectroscopy (IRRAS). Atomic force microscopy measurements (AFM) are used to examine the resulting topography. It is found that both spin- and dip-coated thin films crystallize in the desired edge-on orientation, but the overall crystallinity after dip-coating is decreased compared to the spin-coated films of comparable thickness and the resulting roughness is increased. The higher roughness is most probably caused by the slower evaporation of the solvents and a secondary crystallization process at the air-polymer interface.

The demand for high-performance Radio Frequency (RF) passive devices has been steadily increasing due to the growing complexity and sophistication of wireless communication systems. The Quality factor (Q-factor) is a key parameter for describing the signal losses and the energy efficiency of resonators. Previous studies have been done on the spin coating technique of intermediate coating, which presented some limitations in terms of 3D resonators. In this master thesis, we investigate the development of a intermediate layer using dip coating to enhance the Q-factor, i.e., the performance of RF passive devices. The dip coating method is applied to add a nano ceramic coating to the 3D structure as the intermediate layer between the resonator ceramic substrate and the conductive silver coating. After the fabrication process, the samples are observed under Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) and tested with Vector Network Analysis (VNA). Analysis and calculations are mainly conducted with the software Matlab and Gwyddion. The proposed technique improves the smoothness of the samples by 78.95%, and the Q-factor is tested to have a 20.87% enhancement using VNA. The results demonstrate that the intermediate layer with the dip coating technique significantly improves the performance of RF passive devices by reducing the roughness of the resonator surface. These findings open up new opportunities for the design and development of high-performance RF passive devices in various applications, including wireless communication systems, radar systems, and satellite communication. Further studies can be carried out to reduce defects during fabrication and to stabilize the performance of the silver coating. / Efterfrågan på högpresterande passiva RF-enheter har stadigt ökat på grund av den växande komplexiteten och sofistikeringen hos trådlösa kommunikationssystem. Q-faktorn är en viktig parameter för att beskriva signalförluster och energieffektivitet hos resonatorer. Tidigare studier har gjorts på spin coating-tekniken för intermediära beläggningar, vilket presenterade vissa begränsningar för 3D-resonatorer. I denna masteruppsats undersöker vi utvecklingen av ett intermediärt lager med hjälp av doppbeläggning för att förbättra Q-faktorn, det vill säga prestandan hos passiva RF-enheter. Doppbeläggningstekniken tillämpas för att lägga till en nanokeramisk beläggning på 3D-strukturen som intermediärt lager mellan resonatorns keramiska substrat och den ledande silverbeläggningen. Efter tillverkningsprocessen observeras proverna med SEM och AFM och testas med VNA. Analys och beräkningar utförs främst med programvaran Matlab och Gwyddion. Den föreslagna tekniken förbättrar provernas släthet med 78.95%, och Q-faktorn testas och visar en förbättring med 20.87% med hjälp av VNA. Resultaten visar att det intermediära lagret med doppbeläggningstekniken signifikant förbättrar prestandan hos passiva RF-enheter genom att minska ojämnheten på resonatorns yta. Dessa resultat öppnar upp nya möjligheter för design och utveckling av högpresterande passiva RF-enheter inom olika tillämpningsområden, inklusive trådlösa kommunikationssystem, radarssystem och satellitkommunikation. Ytterligare studier kan genomföras för att minska defekter under tillverkningen och stabilisera prestandan hos silverbeläggningen.

Bien que ce soit un procédé industriel répandu, les films de copolymères à blocs préparés par trempage (« dip-coating ») sont moins étudiés que ceux obtenus par tournette (« spin-coating »). Pourtant, il est possible grâce à cette technique de contrôler précisément les caractéristiques de ces films. Au-delà de la méthode de fabrication, la capacité de modifier la morphologie des films trempés à l’aide d’autres facteurs externes est un enjeu primordial pour leur utilisation dans les nanotechnologies. Nous avons choisi, ici, d’étudier l’influence d’une petite molécule sur la morphologie de films supramoléculaires réalisés par « dip-coating » à partir de solutions de poly(styrène-b-4-vinyl pyridine) (PS-P4VP) dans le tétrahydrofurane (THF). En présence de 1-naphtol (NOH) et d’1-acide napthoïque (NCOOH), qui se complexent par pont hydrogène au bloc P4VP, ces films donnent, respectivement, une morphologie en nodules (sphères) et en stries (cylindres horizontaux). Des études par spectroscopie infrarouge ont permis de mesurer la quantité de petite molécule dans ces films minces, qui varie avec la vitesse de retrait mais qui s’avère être identique pour les deux petites molécules, à une vitesse de retrait donnée. Cependant, des études thermiques ont montré qu’une faible fraction de petite molécule est dispersée dans le PS (davantage de NOH que de NCOOH à cause de la plus faible liaison hydrogène du premier). La vitesse de retrait est un paramètre clé permettant de contrôler à la fois l’épaisseur et la composition du film supramoléculaire. L’évolution de l’épaisseur peut être modélisée par deux régimes récemment découverts. Aux faibles vitesses, l’épaisseur décroît (régime de capillarité), atteint un minimum, puis augmente aux vitesses plus élevées (régime de drainage). La quantité de petite molécule augmente aux faibles vitesses pour atteindre un plateau correspondant à la composition de la solution aux vitesses les plus élevées. Des changements de morphologie, à la fois liés à l’épaisseur et à la quantité de petite molécule, sont alors observés lorsque la vitesse de retrait est modifiée. Le choix du solvant est aussi primordial dans le procédé de « dip-coating » et a été étudié en utilisant le chloroforme, qui est un bon solvant pour les deux blocs. Il s’avère qu’à la fois la composition ainsi que la morphologie des films de PS-P4VP complexés sont différentes par rapport aux expériences réalisées dans le THF. Premièrement, la quantité de petite molécule reste constante avec la vitesse de retrait mais les films sont plus riches en NCOOH qu’en NOH. Deuxièmement, la morphologie des films contenant du NOH présente des stries ainsi que des lamelles à plat, tandis que seules ces dernières sont observables pour le NCOOH. Ce comportement est essentiellement dû à la quantité différente de petite molécule modulée par leur force de complexation différente avec le P4VP dans le chloroforme. Enfin, ces films ont été utilisés pour l’adsorption contrôlée de nanoparticules d’or afin de guider leur organisation sur des surfaces recouvertes de PS-P4VP. Avant de servir comme gabarits, un recuit en vapeurs de solvant permet soit d’améliorer l’ordre à longue distance des nodules de P4VP, soit de modifier la morphologie des films selon le solvant utilisé (THF ou chloroforme). Ils peuvent être ensuite exposés à une solution de nanoparticules d’or de 15 nm de diamètre qui permet leur adsorption sélective sur les nodules (ou stries) de P4VP. / Although it is an important industrial process, block copolymer thin films obtained by dip-coating have been far less studied than those obtained by spin-coating. However, this technique allows precise control of film properties and morphologies without the need for subsequent annealing. Besides the process itself, the ability to modify the morphology of block copolymer thin films is of interest for their use in nanotechnology applications. Here, we investigated supramolecular thin films of poly(styrene-b-4-vinyl pyridine) (PS-P4VP) dip-coated from tetrahydrofuran (THF) solutions containing small molecules that hydrogen bond to P4VP. In the initial dip-coating conditions, films complexed with 1-naphthol (NOH) show a dot morphology (spheres), whereas those containing 1-naphthoic acid (NCOOH) show a stripe morphology (horizontal cylinders). It was discovered that the amount of small molecule in the film, measured by infrared spectroscopy, varies with dip-coating rate, but is the same for both small molecules at any given rate. A thermal study showed that a small fraction of the small molecule, more NOH than NCOOH due to the weaker H-bond of the former, is dispersed in the PS phase, thus rationalizing the difference in their morphology evolution with rate. Thus, the dip-coating rate is a key parameter for controlling both the average film thickness and, for supramolecular polymers, the film composition. We observed that the evolution of the thickness with rate can be modeled by two regimes, in accordance with a recent literature study on dip-coated sol-gel films. At low rates, the thickness first decreases (capillarity regime), reaches a minimum and, at higher rates, increases (draining regime), resulting in a V-shaped film thickness/dip-coating rate curve. In parallel, the amount of small molecule in the film increases with rate in the capillarity regime before reaching a plateau corresponding to the solution composition in the draining regime. Morphology changes, related to the film thickness and the small molecule content, are therefore observed by modifying the dip-coating rate. We further show that the dip-coating solvent also influences the composition and morphology of the film, by comparing the use of chloroform (CHCl3), which is a good solvent for both blocks, with THF, which is a non-solvent for P4VP. With CHCl3, the small molecule content remains constant with the dip-coating rate, although it is higher for NCOOH than for NOH. Furthermore, the morphology of NOH-containing PS-P4VP thin films shows stripes and flat-on lamellae, whereas those containing NCOOH show only flat-on lamellae. This is attributed to the difference in their small molecule content, possibly modulated by the reduction in solubility of the P4VP block in CHCl3 when complexed with the small molecule. Finally, dip-coated films were used as templates for the controlled adsorption of gold nanoparticles. Prior to adsorption, solvent annealing was applied to the films either to improve the long-range order of the P4VP dots or to change the film morphology, which is dependent on the solvent used (THF or chloroform). They were then exposed to a 15-nm gold nanoparticles solution, which allows the selective adsorption on the P4VP dots (or stripes). It was possible to adsorb one nanoparticle per P4VP dot by matching their diameters.

No description available.

Pour les applications aéronautiques, les fibres en céramique piézoélectrique à âme métallique permettent d'imaginer des solutions pour avoir des dispositifs actifs et des capteurs complétement intégrés dans des structures, telles que les composites renforcés par des fibres.La démarche de cette étude est d'élaborer et de caractériser de telles fibres qui présentent de nombreux avantages : l'activation en mode radial permet d'utiliser de faibles tensions de commandes, l'utilisation d'un cœur et d'une matrice conducteurs permet de s'affranchir du dépôt d'électrodes et de garantir leur continuité, la présence d'un coeur métallique améliore la résistance mécanique de la fibre, l'utilisation sous forme de fibres fines et longues permet de l'intégrer à des profils de formes complexes sur de grandes longueurs. Dans un premier temps, le procédé d'enduction est utilisé pour la réalisation de ces fibres en déposant des particules céramiques à base de titano-zirconate de plomb (PZT) sur des fils de platine. Le développement et l'optimisation d'un procédé multicouche permet de réaliser des fibres avec des épaisseurs parfaitement contrôlées pour obtenir les capacités de déformations optimales en alternant des cycles dépôt/traitement thermique avant une opération de frittage finale. La caractérisation d'échantillons massifs traités dans les mêmes conditions permet de s'assurer des propriétés piézoélectriques atteintes pendant les différents traitements thermiques. Les caractérisations électromécaniques réalisées sur les fibres permettent de vérifier le comportement en tant qu'actionneur et que capteur, bien qu'il s'avère difficile de remonter aux caractéristiques intrinsèques des fibres.Dans un second temps, une réflexion est menée sur les moyens à mettre en oeuvre pour envisager un développement à grande échelle de ce type de fibre. Dans ce sens, des expérimentations sur la mise en place du procédé continu de coextrusion avec un polymère chargé sont menées, de même que sur la réduction de la température de frittage à l'aide d'additifs pour substituer les fils en platine, mais aussi sur la réduction du temps de frittage à l'aide de techniques non conventionnelles comme le frittage laser et le frittage micro-ondes. Ces investigations ouvrent des pistes sérieuses pour imaginer une production continue de fibres piézoélectriques à âme métallique.Enfin, des travaux de modélisation par éléments finis du comportement de ces fibres, intégrées ou non dans une structure, permettent de mettre en évidence l'influence du dimensionnement des fibres sur les déformations résultantes, en fonction notamment de l'épaisseur du matériau actif déposée et des propriétés élastiques des différents éléments. Différentes configurations sont imaginées pour utiliser ces fibres dans des structures en tant qu'actionneur et capteur. / Metal core piezoelectric fibres are suitable for active devices and sensors fully embedded in structuresas fibres reinforced polymers for aeronautic applications.The aim of this study is to develop and characterize such fibres that have many advantages: radial mode activation allows the use of low voltage control, the use of a core and a conductive matrix eliminates the deposition of electrodes and the necessity to maintain their continuity, the presence of a metal core improves the mechanical strength of the fibre, the use of thin and long fibres permits their integration in profiles with complex shapes over long distances.In a first step, a dip-coating process is used to realize such fibres by depositing ceramic particles based on lead zirconium titanate (PZT) on platinum wire. The development and optimization of a multilayer process, by alternating deposition cycles / heat treatment prior to the final sintering step, lead to the production of fibres with perfectly controlled thickness in order to obtain optimal strain capability. Characterization of bulk samples under the same thermal conditions allows to measure equivalent piezoelectric properties as fibres submitted to the same heat treatments. Electromechanical characterizations performed on the fibres confirm their behaviour as actuator and sensor, although it is still difficult to determine the effective piezoelectric properties of the fibres.In a second step, the possibility to develop a large-scale production of this type of fibre is investigated.In this regard, experiments are carried on coextrusion process with a PZT loaded polymer, as well as the reduction of the sintering temperature by using additives to replace the platinum core. In addition, reducing the sintering time using unconventional techniques such as laser sintering and microwave sintering are investigated. It is then open serious leads to imagine a continuous production of metal core piezoelectric fibres.Finally, a finite element modelling approach of the behaviour of these fibres, integrated or not in a structure, allows to highlight the influence of fibre sizing on the resulting strains, in particular according to the thickness of the active deposited material and elastic properties of the individual elements (metal core, matrix). Different configurations are analysed to use these fibres in structures as actuator and sensor.

Les travaux présentés dans ce manuscrit traitent des mécanismes de croissance associés au dépôt de nanofils d’oxyde de zinc (ZnO) en bain chimique. Cette technique de croissance, attractive de par sa facilité de mise en œuvre et son coût limité, consiste à immerger un substrat dans une solution de précurseurs portée à basse température (typiquement 90°) pendant quelques heures. Le dépôt préalable d’une fine couche de ZnO fortement texturée est nécessaire à l’obtention de la morphologie nanofils et il est donc nécessaire de maîtriser le processus de croissance associé. Dans un souci de cohérence, la méthode sol-gel dite de trempage consistant à immerger le substrat dans une solution de précurseurs avant de recuire la couche ainsi déposée est ici adoptée. Le ZnO, sous sa morphologie nanofils, est actuellement fortement étudié du fait de son fort potentiel applicatif. Typiquement, il peut être utilisé en tant que brique de basse dans la réalisation de cellules solaires de types Grätzel ou à absorbeur extrêmement fin. Dans ce contexte, il est nécessaire que les nanostructures élaborées présentent des propriétés physiques attractives et ces dernières doivent donc être finement caractérisées. Dans un premier temps, l’influence des paramètres expérimentaux associés au processus de trempage sur les propriétés morphologiques et structurales de films minces de ZnO déposés via ce processus est quantifiée. Il est montré à cette occasion que dans des conditions extrêmes de recuits, les couches évoluent vers une morphologie de type fil. Fort des conclusions obtenues, les mécanismes régissant la croissance de nanofils de ZnO en bain chimique, et plus particulièrement l’influence de la surface de nucléation sur ces derniers, sont étudiés. La possibilité d’obtenir des nanofils localisés et parfaitement alignés à travers la réalisation de masques est démontrée. L’ensemble des nanostructures élaborées (couches et nanofils) sont caractérisées par photoluminescence afin de pouvoir estimer leur qualité structurelle et d’étudier les défauts en présence. Pour finir, une étude plus fondamentale consistant à suivre in situ l’évolution des nanofils au cours de la croissance par rayonnement synchrotron est proposée avec une attention toute particulière aux phénomènes de polarité. / ZnO nanowires are of strong interest in the realization of solar cells based on type-II band alignment. They can be grown by chemical bath deposition, a technique in which the substrate is seeded with ZnO nanoparticles by dip-coating and then placed in a precursor solution heated at 90°C for a couple of hours. In this document, we will discuss the nucleation and growth mechanisms associated with this low cost technique. In particular, we will see how the seed layer morphology can drive the one of the nanowires. Also, advanced characterization by photoluminescence and synchrotron radiation will be performed on the grown nanostructures.

L'oxyde de nickel est l'un des matériaux électrochromes les plus utilisés dans le domainedes fenêtres intelligentes qui contrôlent la lumière et la chaleur provenant de l'extérieur versl'intérieur des bâtiments. Il est important de mentionner que l’oxyde de nickelstoechiométrique est un isolant à température ambiante. Les propriétés microstructurales,chimiques, optiques et électrochromes des couches minces dépendent fortement du procédéde préparation et traitement final. En outre, l’un des principaux défis consiste à fabriquer lescouches minces sur des substrats souples afin de fabriquer des fenêtres électrochromes degrande taille ce qui demande un traitement à T ambiante. A cet égard peu d’étudesbibliographiques ont évalué l’effet du traitement par les rayonnements UV sur les propriétésdes couches électrochromes. Dans ce travail, des couches minces d'oxyde de nickel (NiO) ontété préparées par la méthode Sol-Gel associée aux techniques de dépôts par centrifugation(spin-coating) et par trempage-retrait (dip-coating). L’ajustement des paramètresexpérimentaux relatifs à ce procédé (la concentration du précurseur, la nature du solvant et dustabilisant, le nombre de couches déposées et le type des traitement final (calcinationà 300 °C ou traitements UV) a permis d’optimiser les conditions de préparation des couchesminces et par la suite de contrôler les caractéristiques chimiques, microstructurales et optiquesdes couches développées. Cette étude a montré qu'une concentration de 0,3 M d'acétate denickel, le méthanol comme solvant et le triton X-100 en tant que stabilisant conduisent à unecouche mince NiO avec les meilleures performances optiques. Les caractérisations par lestechniques (DRX, ATG, FT-IR, XPS et GDOES) ont particulièrement mis en évidence le rôledes conditions de traitement final sur la composition et la morphologie des couches d’oxydede nickel élaborées. La DRX a montré qu’elles sont faiblement cristallisées et que la structuredevient plus amorphe avec le traitement UV. La spectrométrie UV-visible et les CV ont révéléque les couches traitées par UV en utilisant une lampe de 30 W pendant 5 h (UV-30W-5h)possèdent le contraste optique le plus élevé et la meilleure stabilité électrochimique. L'analysemorphologique a montré que les couches minces déposées par la technique de spin coatingsouffrent de la formation de fissures et d’une hétérogénéisation de la surface. Pour résoudre ceproblème, le procédé de spin-coating a été remplacé par la technique dip-coating tout enconservant les paramètres optimisés précédemment. Cette technique a permis de produire descouches minces plus homogènes et moins fissurées. D'autre part, pour continuer à améliorerles propriétés électrochromes, ces couches ont été dopées par le lithium. Les résultats obtenusont montré l’importance de l’addition de Li sur l’amélioration des propriétés électrochromesde Li : NiO cyclé dans KOH comme électrolyte. En effet, une variation de la transmittanceΔT de 70% (à 450 nm) a été obtenue dans les couches minces 8 % Li: NiO. Le résultat quiressort des caractérisations FT-IR et ATG, porte sur le fait que les couches calcinéescontiennent moins de composés organiques, à l’inverse de celles traitées par UV riches enmatière organique. L'analyse XPS a montré que la teneur en Ni2+ est plus élevée dans lescouches dopées. L’analyse GDOES a montré une distribution homogène de Li dans toutel’épaisseur de la couche. Toutefois, les couches minces de 8% de Li: NiO traitées par UV-30W-5h souffrent d’une dégradation de leurs performances électrochromes dans le KOHaprès quelques cycles, pour cette raison, elles ont été cyclées dans d’autres électrolytesliquides ioniques, tels que le LiTFSI-EMITFSI, le NaTFSI-EMITFSI et le KTFSI-EMITFSI.Les meilleures propriétés électrochromiques ont été obtenues avec l'électrolyte KTFSIEMITFSI.Ce résultat important représente une bonne perspective pour l'avenir. / Nickel oxide is one of the most widely used electrochromic materials in the field of smartwindows that control light and heat from the outside to the inside of buildings. It is importantto mention that stoichiometric nickel oxide is an insulator at room temperature. Themicrostructural, chemical, optical and electrochromic properties of the films are highlydependent on the process of preparation and final treatment. In addition, one of the mainchallenges is the elaboration of thin films on flexible substrates suitable for electrochromicapplications which requires treatment at ambient T. In this respect, in literature, few studieshave reported the effect of UV treatment on the properties of electrochromic layers. In thiswork, thin films of nickel oxide (NiO) were prepared by the Sol-Gel method associated withspin-coating and dip-coating techniques. The adjustment of the experimental parametersrelating to this process (the concentration of the precursor, the nature of the solvent and thestabilizer, the number of deposited layers and the type of final treatment (calcination at300 °C or UV treatments) made it possible to optimize conditions for the preparation of thinlayers and subsequently to control their chemical, microstructural and optical characteristics.This study showed that a concentration of 0.3 M nickel acetate, methanol as solvent and triton100-X as a stabilizer lead to NiO thin film with the highest optical properties. The techniquesof characterizations (DRX, ATG, FT-IR, XPS and GDEOS) have particularly highlighted therole of the final treatment conditions on the composition and the morphology of the preparednickel oxide thin films. The XRD results showed that they are weakly crystallized and thestructure becomes even more amorphous for UV treated samples. UV-visible spectrometryand cyclic voltammetry revealed that UV-treated thin films using a lamp of 30 W for 5 h(UV-30W-5h) have the highest optical contrast and the highest electrochemical stability.Morphological analysis (SEM) indicated that the thin films deposited by the spin-coatingtechnique suffer from crack formation and surface heterogenization. To solve this issue, thespin-coating process has been replaced by the dip-coating technique while retaining thepreviously optimized parameters. This technique has made it possible to produce thin filmsthat are more homogeneous and less cracked. On the other hand, to continue to improve theelectrochromic properties, these thin films were doped with lithium. The results showed theimportance of the addition of Li on the improvement of the electrochromic properties ofLi : NiO cycled in KOH as electrolyte. Indeed, a variation of the ΔT transmittance of 70 %was reached for the thin films 8 % Li : NiO. The result of the FT-IR and ATGcharacterizations showed that the calcined thin films contain lesser amount of organiccompounds compared to those treated by UV which still contains large amount of organicmatter. XPS analysis has shown that the Ni2+ content is higher in the doped layers. GDOESanalysis showed a homogeneous distribution of Li along the thickness of the thin film.However, 8% Li: NiO thin films treated with UV-30W-5h suffer from a degradation of theirelectrochromic performances in KOH after a few cycles. For this reason, their cyclingproperties have been investigated in a large range of electrolytes, based on ionic liquidincluding LiTFSI-EMITFSI, NaTFSI-EMITFSI and KTFSI-EMITFSI. The highestelectrochromic properties were obtained with KTFSI-EMITFSI as an electrolyte. Thisimportant result presents a good prospect for the future.