Dissertations / Theses on the topic 'Transparent solids'

La finalité de cette étude était de mettre au point un rouge à lèvre transparent. Le screening des agents gélifiants a permis de déceler la capacité du lanosterol à gélifier certains liquides lipophiles en préservant la transparence du mélange. La formule dépend de deux contraintes opposées qui sont d'avoir un point de rupture assez haut -ce qui pousse à augmenter la cire (lanosterol)-, tout en évitant la formation de cristaux dans le temps -ce qui pousse au contraire, à diminuer le lanosterol-. La formulation consiste donc à trouver le juste milieu et à jouer sur les autres matières premières du rouge à lèvres pour obtenir un compromis acceptable. Les alcanes se comportent très bien avec le lanosterol et donnent un mélange solide, transparent, homogène. La présence d'une double liaison retarde la solidification du mélange ainsi que la présence d'électrons délocalisés des cycles aromatiques. Un fort encombrement stérique accroît la vitesse de gélification. .
@The aim of this study is to create a transparent lipstick. We carried out a wide range of investigations in the field of oils solidifying agents such as waxes, gums, resins and powders. This screening has revealed the capacity of lanosterol to gelify some lipophilic liquids, preserving transparency. The formula always has to take in account two constraints : -Having a high enough breakage value. This has led us to increase the wax, lanosterol. -Avoiding formation of crystals when aging. This has led us to decrease the wax content, The formula thus has to be a compromise varying the raw materials to obtain the required properties. The raw materials selection criteria are restrictive. They include visible spectroscopic measurements to quantify transparency of the formulated product. The stick solidify is validated drop point and breakage measurements. After several investigations, a mixture of oils and solidifying agents is selected. Alkanes work well with lanosterol and give a homogenous, transparent solid mixture. Regarding the esters, the presence of a double bond as well as delocalised electrons from aromatic wrings delays the solidification of the medium. .

Ce travail de thèse présente une méthode de synthèse par le procédé sol-gel pour la préparation de matériaux hybrides organiques-inorganiques (OIH) basés sur le mélange de deux polyéthers différents, le poly (oxyde d´éthylène) (PEO) et le poly (oxyde de propylène) (PPO) liées de façon covalente avec l´agent de réticulation ureasil (U). Dû aux différents sites actifs présents dans la structure du matériau OIH, plusieurs cations métalliques peuvent être introduits dans la matrice hybride par complexation soit avec l´oxygène de type éther, soit avec l´oxygène du type carbonyle. Suite à ce constat, différentes matrices hybrides ont été synthétisées en introduisant des ions Eu3+ ou Li+ afin de conférer aux matériaux des propriétés optiques ou électriques. La compréhension des propriétés structurales et thermiques des différents polymères, l´ajout de différents cations Eu3+/Li+, et l'effet du plastifiant (PPO2000) dans la mélange hybride U-xPEO1900:/U-1-xPPO2000 (ratio de PPO2000 dans la mélange, x = 0.2, 0.5 et 0.8), ont été étudiés par DSC et SAXS. Les résultats de DSC ont révélé une unique température de transition vitreuse (Tg) pour tous les matériaux étudiés. L´ajout des ions Eu3+ dans le matrice n´a pas causé de variations dans les valeurs de Tg tandis que l´insertion de cations Li+ a provoqué une augmentation dans les valeurs de Tg, indiquant l´existence d’interactions entre les cations Li+ et la phase polymérique du matériau OIH. Les courbes de calorimètrie de l´U-PEO1900 ont aussi révélé la présence d´une pic endothermique à 25 °C, associé à la fusion des domaines cristallins du PEO1900. La présence d´un deuxième maximum dans les courbes de diffusion des rayons X à petits angles (SAXS) a confirmé l’existence de la structure semi-cristalline du PEO1900 dans une région de température entre -100 °C < T < Tf. Tous les échantillons, non-dopés et dopés avec les ions Li+ et Eu3+, ont montré un pic de corrélation indiquant que la nano-structure de la matrice hybride n´est pas affecté par le dopage avec les cations métalliques. Les études par Spectroscopie Infrarouge à Transformée de Fourier (FTIR) et par spectroscopie Raman ont confirmé l´interaction des ions Eu3+ avec l´oxygène du type carbonyle présent dans les groupes urées de la matrice hybride, et des ions Li+ avec l´oxygène du type éther. La photodégradation accélérée a révélé une perte des performances de la photo-luminescence (PL) associée à des changements dans la coordination des ions Eu3+ avec la matrice hybride. La photodégradation induit la formation de photo-produits venant de la β-scission du macroradical formé dans la portion organique de la matrice hybride. La β-scission peut-être responsable pour la diminution de la PL du matériau dû la perte de l´efficacité de l´effet antenne du ligand organique pour le centre luminescent. La transition dans la région visible du rouge vers le bleu avec la photodégradation qualifie ces matériaux de bons candidats pour l'application comme capteurs et marqueurs optiques. La conduction ionique des matrices hybrides dopés avec Li+ a été évaluée par Spectroscopie d´Impédance en fonction de la température et les résultats ont révélé des corrélations entre la superstructure lamellaire du PEO1900 et le mécanisme de conduction. L´addition d´un plastifiant, le PPO2000, a permis l´augmentation de la conductivité ionique dans une région de température entre -100 °C < T < 10 °C dû à l´augmentation de la portion amorphe utilisée comme chemin de transport ionique efficace dans le mélange polymère hybride U-xPEO1900/U-1-xPPO2000
In this PhD thesis a greener synthesis route via sol-gel reactions aiming to prepare multifunctional organic-inorganic hybrid (OIH) materials based on blending of two polyether amine end chains (i.e., Jeffamine® compounds) Poly(ethylene oxide) (PEO) and Poly(propylene oxide) (PPO) covalently bonded with an ureasil cross-linking agent (U) is reported. Due to the different polar oxygen sites present in this OIH material, several metallic cations can to be introduced into the OIH matrix via ether- or carbonyl-type oxygen. So, different OIH matrices containing Eu3+ or Li+ cations were synthetized to evaluate their potential as photoluminescent or ionic conductor material, respectively. The thermal and structural characteristics of the Eu3+ or Li+ – loaded OIH materials, as well as the plasticizer effect of PPO2000 at the U-xPPO2000:/U-1-xPEO1900, (PPO2000 fraction x = 0.2, 0.5 and 0.8) blends, were carried out by DSC and SAXS. DSC results revealed a unique glass transition temperature (Tg) for all the studied OIH materials. The addition of Eu3+ cations do not change the Tg values while the Li+ cations caused an increase in the values of Tg, due to the Li+ interaction with the polymeric phase of the material. The U-PEO1900 calorimetric curves also showed the presence of an endothermic peak at 25 °C associated to the fusion of the crystalline domains of PEO1900. The second maxima observed in the curves of small angle X-ray scattering (SAXS) confirmed the presence of the crystalline structure of PEO1900 in a temperature range of -100 < T < Tf. All the samples, undoped and Li+ or Eu3+ doped ones, showed a correlation peak indicating that the OIH nano-structure is not affected by the metallic cations doping. Analysis carried out by Fourier Transform InfraRed (FTIR) and Raman Spectroscopy confirmed the Eu3+ cations interaction via the oxygen carbonyl-type present in the urea groups of the hybrid matrix, and that of Li+ cations with the oxygen ether-type. The accelerate photo-degradation revealed a loss of the photo-luminescence (PL) efficiency due to the changes in the Eu3+ cations coordination with the hybrid matrix. The photo-degradation induces the formation of photo-products from the macro-radical β-scission formed in the organic fraction of the hybrid matrix. The β-scission can be responsible for the material PL decrease due to the drop in the antenna effect from organic ligand to luminescent center. The visible emission transition from red → blue with the photo-degradation qualify these materials as good candidates to be applied as sensors and optical markers. The ionic conduction of the Li+-loaded hybrid matrices was investigated by Impedance Spectroscopy as a function of the temperature. Results showed a correlation between the lamellar superstructure of the PEO1900 and the conducting process. The plasticizers addition (PPO2000) alloyed to improve the value of the ionic conductivity in the low temperature range, -100 °C < T < 10 °C due to the increase of the amorphous fraction used as effective ionic transport pathway in the U-xPEO1900/U-1-xPPO2000 polymeric hybrid blend

xix, 142 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
Transparent amorphous oxide semiconductors are a relatively new class of materials which show significant promise for electronic device applications. The electron mobility in these materials is at least ten times greater than that of the current dominant material for thin-film transistors: amorphous silicon. The density of states within the gap of a semiconductor largely determines the characteristics of a device fabricated from it. Thus, a fundamental understanding of the electronic structure within the mobility gap of amorphous oxides is crucial to fully developing technologies based around them. Amorphous zinc tin oxide (ZTO) and indium gallium zinc oxide (IGZO) were investigated in order to determine this sub-gap structure. Junction-capacitance based methods including admittance spectroscopy and drive level capacitance profiling (DLCP) were used to find the free carrier and deep defect densities. Defects located near insulator-semiconductor interfaces were commonly observed and strongly depended on fabrication conditions. Transient photocapacitance spectroscopy (TPC) indicated broad valence band-tails for both the ZTO and IGZO samples, characterized by Urbach energies of 110±20 meV. These large band-tail widths imply that significant structural disorder exists in the atomic lattice of these materials. While such broad band-tails generally correlate with poor electronic transport properties, the density of states near the conduction band is more important for devices such as transistors. The TPC spectra also revealed an optically active defect located at the insulator-semiconductor junction. Space-charge-limited current (SCLC) measurements were attempted in order to deduce the density of states near the conduction band. While the SCLC results were promising, their interpretation was too ambiguous to obtain a detailed picture of the electronic state distribution. Another technique, modulated photocurrent spectroscopy (MPC), was then employed for this purpose. Using this method narrow conduction band-tails were determined for the ZTO samples with Urbach energies near 10 meV. Thus, by combining the results of the DLCP, TPC and MPC measurements, a quite complete picture of the density of states within the mobility gap of these amorphous oxides has emerged. The relationship of this state distribution to transistor performance is discussed as well as to the future development of device applications of these materials.
Committee in charge: Stephen Kevan, Chairperson, Physics; J David Cohen, Member, Physics; David Strom, Member, Physics; Jens Noeckel, Member, Physics; David Johnson, Outside Member, Chemistry

L'objet de cette étude est l'élaboration de matériaux polymères nanocomposites transparents à matrice polycarbonate, pour des applications dans des domaines tels que la lunetterie ou le vitrage automobile. L'incorporation de nanoparticules au sein du polycarbonate a été envisagée afin de lui conférer certaines propriétés mécaniques telles qu'une plus grande rigidité, une meilleure stabilité dimensionnelle, une résistance à la rayure plus importante, tout en conservant sa transparence. Le maintien de la transparence du matériau passe d'une part par l'utilisation de particules nanométriques présentant un indice de réfraction proche de celui de la matrice et d'autre part par une trés bonne dispersion de ces particules au sein de la matrice polymère. Ainsi différents types de nanoparticules minérales ont d'abord été sélectionnés puis incorporés dans la matrice polycarbonate. L'évaluation des performances de ces nanocomposites en termes de transparence et de propriétés mécaniques a non seulement permis d'affiner la sélection des charges, mais aussi mis en évidence la difficulté de limiter la dégradation de la matrice polycarbonate en présence des nanocharges. Afin d'optimiser les performances des matériaux considérés, une étude approfondie des mécanismes de dégradation de la matrice polycarbonate a été réalisée, et des modifications du procédé d'élaboration ont été envisagées afin de limiter la dégradation de la matrice au cours de l'élaboration des nanocomposites. Enfin, dans le cadre d'une réflexion plus générale sur les mécanismes de renforcement des nanocomposites, une étude a mis en évidence les relations structure/propriétés existant au sein des matériaux élaborés, soulignant l'influence des nanoparticules sur la mobilité moléculaire de la matrice polycarbonate
This study deals with the preparation of transparent polycarbonate nanocomposites for industrial applications such as optical lenses or automotive glazing. Incorporating nanoparticles to polycarbonate matrix aimed to improve some of its properties such as stiffness, dimensional stability, or scratch resistance, while maintaining intrinsic properties such as its transparency. Polycarbonate nanocomposites transparency depends on one hand on mineral partic/es diameter and refractive index, and on the other hand on the good dispersion of particles in polymer matrix. Therefore, different types of mineral fillers were selected and incorporated in polycarbonate matrix. The evaluation of mechanical and optical properties of these nanocomposites permitted not only to refine particles selection, but also to highlight polycarbonate degradation during compounding with nanofillers. ln order to optimize materials performances, a thorough study of degradation mechanisms was carried out, and the nanocomposites preparation process was modified so as to Iimit polycarbonate degradation in presence of mineral fillers. Lastly, in a more general framework, the reinforcement mechanisms involved in nanocomposite materials were investigated, and showed the existence of correlations between materials structure and properties, and the effect of mineral fi/lers on polycarbonate molecular dynamics

L'ojet de cette these est la mise en uvre d'une methode de detection interferometrique des ondes acoustiques guidees se propageant dans les milieux solides et transparents. Cette methode exploite l'interaction acousto-optique entre un faisceau laser issu d'un interferometre et le champ acoustique. La description de l'interaction dans le cas d'un faisceau laser polarise traversant orthogonalement une onde acoustique guidee permet de montrer que la methode interferometrique fournit une information complete (amplitude et phase) sur le champ de dilatation a l'interieur du solide. Les resultats experimentaux dans le cas d'une onde de surface (onde de rayleigh) ou des ondes de lamb confirment ces proprietes. La detection interferometrique est ensuite appliquee a l'etude de deux types de propagation guidee. Les modes acoustiques guides par une couche fluide entre deux substrats semi-infinis font l'objet d'une etude experimentale qui conduit a la determination des vitesses de groupe des premiers modes. Les ondes acoustiques guidees a l'interface entre deux solides (de type stoneley ou rayonnantes) ont ete detectees pour plusieurs combinaisons de materiaux et deux types de conditions limites. La mesure interferometrique a permis de mettre en evidence la presence simultanee de deux modes d'interface rayonnant dans le cas de l'interface silice-plexiglas. Les proprietes mesurees de ces modes (vitesse, attenuation, evanescence) sont en accord avec les predictions theoriques

L’objectif de cette thèse est l’étude de matériaux oxydes pour le développement de lasers solides, émettant en particulier dans le domaine visible. Nous nous sommes intéressés à des matériaux monocristallins et à des céramiques transparentes. Des ions Pr3+ ont été envisagés comme dopants en raison de leurs niveaux d’énergie adaptés pour des émissions directes (bleu, vert, orange, rouge et rouge foncé). En outre, des ions Nd3+ émettant dans le proche infrarouge, autour de 0.9 μm, ont été utilisés comme dopants afin de générer un laser bleu par un processus de conversion de fréquence. Nous avons ainsi préparé des matrices oxydes sous forme polycristalline pour des mesures de spectroscopie optique permettant de sélectionner les meilleurs matériaux. Des matrices d’oxyde à fusion congruente étudiées correspondent aux différentes familles comme suit : hexa-aluminate, mélilite, germanate, tungstate et sesquioxide. Les cristaux ont été élaborés par la méthode de Czochralski. En plus, certains matériaux cubiques a haut point de fusion comme Nd:Y2O3 et Nd:Y3Al5O12 ont été étudiés sous forme de céramiques transparentes de type classique ou composite. Nous avons ensuite caractérisé les propriétés physiques, optiques et spectroscopiques. Finalement, des émissions lasers dans le visible ont été démontrées en régime continu dans une cavité résonante de type plan-concave ou déplié (V). Pour les matériaux dopés Nd3+ et dopés Pr3+, nous avons obtenu l’effet lasers dans le visible avec les efficacités satisfaisantes. Les matériaux monocristallins: Pr:Sr1-xLaxAl12-xO19 et céramique composite Nd:Y3Al5O12 présentent un potentiel important pour le développement de lasers dans le domaine visible
This thesis is aimed to find efficient oxide based solid-state materials for the development of lasers, particularly in visible spectral regions. We focused on Pr3+ and Nd3+ luminescent ions, doped in oxide-based hosts. Pr3+ ions are suitable for direct visible emissions in various regions, whereas the emission of Nd3+ ions in near infrared around 0.9 μm can be converted into blue laser by Second Harmonic Generation. A large-covered visible region could be expected in the range of 450 nm – 750 nm. First, we selected appropriate oxide hosts by using optical spectroscopy tools. All selected materials with congruent melting behavior were grown as single crystal. On the other hand, cubic materials with very high melting point, Nd:Y2O3 and Nd:Y3Al5O12, were prepared as standard and micro-core composite transparent ceramics, respectively. Next, all samples were thoroughly investigated in terms of physical, optical and spectroscopic properties. In the meantime, Judd-Ofelt analysis were computationally performed by using ground state absorption data to calculate radiative properties of studied solid-state materials, including radiative lifetime and branching ratio. Finally, laser operations were carried out within a plane-concave or V-type resonant cavity under blue and near infrared pumping for Pr3+ and Nd3+ solid-state materials, respectively. We achieved visible lasers in the relevant range with satisfying efficiencies with Pr:Sr1-xLaxAl12-xO19 single crystal and Nd:Y3Al5O12 micro-core transparent ceramic. Both present a real potential for the development of laser emissions in visible spectral regions

The objective of the present work is to provide a better understanding of magnetron sputtered transparent conducting oxides based on ZnO in order to use them as electrodes in thin film silicon solar cells at the Grup d'Energia Solar of the Universitat de Barcelona. This thesis presents the properties of magnetron sputtered aluminium and gallium doped ZnO as well as the properties of multi-compound materials deposited by the co-sputtering of zinc oxide and indium tin oxide. The application of ZnO based transparent conducting oxides to the back reflector of pin amorphous solar cells is also discussed. A set of aluminium doped zinc oxide layers were deposited under different substrate temperature and discharge power. The structural, electrical and optical properties were characterised and discussed. The higher substrate temperatures and discharge powers used during deposition led to highly transparent layers in the visible range with lower resistivities. The polycrystalline layers were oriented with the c-axis perpendicular to the substrate surface and the crystalline quality of the layers improved at higher temperatures and powers. A remarkable increase in mobility was found for temperatures above 300°C and the carrier concentration also rose with temperature reaching 3.71x1020 cm-3 at 420°C. The most remarkable feature found at higher deposition power was the increase in deposition rate (from 0.9 to 9 nm/min). By means of a high temperature (650°C) annealing process under a capping layer of silicon or alumina, the mobility of aluminium doped zinc oxide layers was considerably raised achieving 68.5 cm2V-1s-1. This process led also to more transparent layers in the near infrared as well as in the ultraviolet part of the spectrum. Gallium doped zinc oxide films were deposited in order to investigate the suitability of gallium as a dopant in zinc oxide layers. Highly transparent layers with higher carrier concentrations but lower mobilities compared to aluminium doped zinc oxide were obtained. The dependence of the layer properties on the pressure, doping concentration, substrate temperature and oxygen volume concentration during deposition were studied in order to find the adequate layer to be applied as electrode in thin film solar cells. 4 wt.% Ga2O3 doping concentration was found to be optimal for the production of highly conductive ZnO:Ga layers with a high band gap energy. The incorporation of oxygen gas during the sputter deposition led to more transparent layers at wavelengths longer than 1100 nm, but was found to be detrimental for the electrical properties of the studied layers. By means of co-sputtering, a set of multi-compound layers formed by Zn-In-Sn-O were deposited and carefully characterised. The resulting layers were studied as a function of the Zn content ratio, which varied between 17.1 to 67.3%. The layers were amorphous in nature but presented embedded nanometric crystals. The incorporation of Zn cations into an indium tin oxide matrix favoured the transmittance but did not modify the mobility. The carrier concentration was found to decrease resulting in an increase in resistivity. The electronic band structure was investigated by means of photoelectron spectroscopy. The measurements showed that, with an increase in Zn concentration, the oxygen vacancy concentration of the surface increased resulting in a degenerately n-doped surface layer. The work function of the material was determined by low intensity X-ray photoelectron spectroscopy and the values varied between 4.7 and 4.3 eV with the variation of Zn content. The final experiments were focussed on the application of ZnO layers in the back reflectors of pin amorphous silicon solar cells. Trials were performed onto pin structures deposited at T-Solar Global SA and the Universitat de Barcelona. The cells deposited at T-Solar were long exposed to air before a back reflector could be deposited and evidence for the formation of a thin silicon oxide layer at the interface was obtained. The oxide layer was removed using acid etching in dilute HF, but an analysis by X-ray photoelectron spectroscopy showed that the cleaning step resulted in an important amount of carbon contamination on the surface. Both, the silicon oxide and the carbon layer led to devices with S-shaped J-V curves. Later, the n-type interface was protected by a thin ZnO:Al layer at T-Solar to avoid oxidation during transportation. However, the existence of this thin ZnO:Al protective layer determined the growth of the subsequently deposited layers. Thus, the deposition of ZnO layers under different conditions led to similar results. Finally, different back reflectors were tried over the solar cells fabricated at UB. Aluminium and gallium doped zinc oxide layers were deposited on amorphous silicon pin structures, and a clear improvement in performance with respect to devices with only a metal layer as back reflector was observed. Similar performances were observed when Ga doped ZnO or Al doped ZnO was used in the back reflector. It showed that both gallium and aluminium were suitable dopants for the ZnO to be applied in the back reflector.
L'objectiu d'aquest treball rau en l'estudi i optimització dels òxids conductors transparents basats en l'òxid de zinc. Aquests materials, que s'han dipositat mitjançant polvorització catòdica magnetró, es van estudiar amb la finalitat d'emprar-los com elèctrodes en cèl•lules solars de silici en capa prima al Grup d'Energia Solar de la Universitat de Barcelona. En aquesta tesi es presenten les propietats de l'òxid de zinc dopat amb alumini o amb gal•li, així com les propietats de multi-compostos dipositats a partir de la co-polvorització catòdica d'òxid de zinc i d'òxid d'indi dopat amb estany. També es discuteix l'aplicació d'òxids conductors transparents basats en l'òxid de zinc al reflector posterior de cèl•lules solars de silici amorf amb estructura tipus pin. S’ha trobat que l’òxid de zinc dopat amb alumini, a altes temperatures de substrat i altes potències, presenta una elevada transmitància òptica i una baixa resistivitat. La mobilitat de les capes augmentà considerablement fins assolir 68.5 cm2V-1s-1 mitjançant l'aplicació de tractaments tèrmics a alta temperatura previ dipòsit d'una capa protectora de silici amorf o d'alúmina. Pel cas de l'òxid de zinc dopat amb gal•li s'han obtingut una sèrie de capes altament transparents i amb concentracions de portadors superiors, però amb mobilitats inferiors que les de capes dopades amb alumini. Mitjançant co-polvorització d’òxid de zinc i òxid d’indi dopat amb estany s’han obtingut capes amorfes del multi-compost Zn-In-Sn-O amb un contingut de zinc que varia entre el 17.1 i el 67.3%. La incorporació del zinc a l'òxid d'indi dopat amb estany afavoreix l'increment de la transmitància, sense que la mobilitat de les capes es vegi afectada. En canvi, la concentració de portadors disminueix amb la incorporació de Zn. Comparant l'ús del gal•li i de l'alumini com a dopants de l'òxid de zinc del reflector posterior de cèl•lules de silici amorf tipus pin, s'ha observat una gran similitud en el comportament dels dispositius. Això ens ha portat a la conclusió que ambdós materials són adients per ser emprats com a reflectors posteriors.

Recentemente, grande interesse tem sido demonstrado por cerâmicas transparentes dopadas com íons terras raras trivalentes, como meios ativos para lasers na região espectral do infravermelho próximo. Em particular, cerâmicas dopadas com altas concentrações de Nd3+ e Yb3+ são muito estudadas pela possibilidade de gerar emissão laser de alta potência em torno de 1,0 mm. Embora a cerâmica transparente de titanato zirconato de chumbo e lantânio (PLZT), com composição La/ Zr/Ti = 9/65/35, seja originalmente reconhecida por suas propriedades ferroelétricas e eletro-ópticas, a mesma também apresenta características interessantes como matriz hospedeira de íons oticamente ativos. Recentemente, de Camargo et al. realizaram vários estudos espectroscópicos que comprovam a potencialidade laser de amostras dopadas com Yb3+, Er3+, Tm3+ e em especial Nd3+. Apesar de a cerâmica PLZT:Nd ser a mais promissora, se comparada a líder de mercado YAG:Nd (sistema ítrio-alumínio garnet dopado com neodímio), ainda não foi possível obter ação laser da primeira, devido à presença de fases espúrias (imperceptíveis a olho nu), que comprometem a qualidade óptica do material, especialmente para concentrações de dopagem maiores que 1,0% peso de Nd2O3. Uma vez que a qualidade estrutural tem implicação direta na qualidade óptica/espectroscópica de materiais ópticos, faz-se necessário estender os estudos visando otimizar a obtenção de amostras transparentes com mais altos níveis de dopagem. Neste trabalho apresenta-se um método alternativo para a dopagem da matriz PLZT com os íons TR = Nd3+ e Yb3+, e utiliza-se de várias técnicas (DR-X, DTA-TG, FT-IR, Raman, RMN e Luminescência), para caracterizar os compostos precursores e/ou produtos. O novo método baseia-se na obtenção prévia de óxidos precursores dopados, seguida da utilização destes para o preparo das cerâmicas PLZT:TR. As caracterizações foram conduzidas em função da concentração de dopantes (0,1 4,0% peso TR2O3), comparativamente ao método de dopagem convencional utilizado nos trabalhos anteriores. A espectroscopia de ressonância magnética nuclear em sólidos em 207Pb, mostrou-se uma ferramenta bastante útil na elucidação de questões estruturais desses sistemas tão complexos. Como os íons paramagnéticos Nd3+ e Yb3+ não podem ser diretamente acessados por RMN, a estratégia para caracterizar suas distribuições espaciais foi investigar suas respectivas mímicas diamagnéticas Y3+ e Sc3+ (núcleos 45Sc e 89Y). Resultados de DR-X apresentam menor formação de fase secundária nas amostras preparadas via método alternativo, sendo identificado as fases secundárias como (La,Nd)2(Zr,Ti)2O7 (estrutura do tipo pirocloro), ZrO2 em fase parcialmente monoclínica e cúbica e ZrO2 em fase cúbica, das amostras dopadas com Nd3+, Y3+ e Yb3+, respectivamente. De acordo com os resultados de DR-X, experimentos de RMN permitiram melhor avaliação quanto a inserção do íon dopante a medida que há formação de fase secundária e mostraram que a inserção dos íons dopantes é homogênea, bem como resultados de luminescência, com o limite de solubilidade do íon dopante sempre menor do que o necessário para que seja observado supressão da luminescência dos íons emissores.
In recent years, there has been a great interest for rare-earth (RE) doped transparent ceramics as near-infrared laser active media. Particularly, Nd3+ and Yb3+-doped ceramics are of special interest due to the possibility of generating high power emissions at around 1.0 mm. Even though lead lanthanum zirconate titanate (PLZT) ceramics, with composition La/Zr/Ti = 9/65/35, are mostly known by their ferroelectric and electro-optic properties, recent works by de Camargo et al. have also indicated their potentiality as laser active media. In this regard, the most promising system is PLZT:Nd (as compared to YAG:Nd - neodymium-doped yttrium aluminium garnet), however, laser action of the former has not yet been possible, the reason lying in the presence of secondary phases (invisible to the naked eye) that compromise the optical quality of the ceramics, especially for samples with concentration higher than 1.0 wt% Nd2O3. Since the structural quality of samples has a direct implication on their spectroscopic and optical qualities, the goals pursued in this work are to present means to obtain highly transparent samples with higher incorporation of dopants, as well as to understand some fundamental questions regarding the microstructure of PLZT:RE ceramics. Thus, an alternative method, based on the obtainment of RE-doped precursor oxides, is presented for the synthesis of PLZT:RE and several techniques (XRD, DTA-TG, FT-IR, Raman, NMR and Luminescence) are used to characterize the samples, as a function of doping concentration (0,1 4,0 wt% RE2O3). These studies are done in comparison to the conventional method used in previous works. Solid state NMR spectroscopy of 207Pb proved to be a very useful tool for the understanding of these complex systems. Because Nd3+ and Yb3+ are paramagnetic and thus inaccessible by NMR, the strategy used for the characterization of their spatial distribution was to study samples doped with their respective diamagnetic mimics Sc3+ and Y3+ (45Sc and 89Y nuclei). XRD results have shown formation of less secondary phase for samples prepared by alternative method, being identified as secondary phase pyrochlore structure (La,Nd)2(Zr,Ti)2O7, partially monoclinic/cubic ZrO2 and cubic ZrO2 of the samples doped with Nd3+, Y3+ and Yb3+ respectively. NMR measurements allowed to make proposals about dopant ion insertion while secondary phase is formed and showed homogeneous distribution of dopant into the matrix, aswell luminescence measurements with maximum dopant solubility being less than enough to show any suppression of luminescence.

The objective of this work was to study two different light management approaches to enhance the efficiency of thin film Si solar cells and these were the manipulation of the light path (light trapping) and changing the incoming photon energy (upconversion). In the first approach the light path was manipulated by creating either periodic or random textured interfaces. Periodic patterns were created at the front AZO by means of direct laser ablation. Amongst all the patterns assessed, the best result was achieved with a linear pattern of 10 lam of pitch and 360 nm of groove depth, that yielded to an Rs of 11 SI/sq and a haze of 12.7% at 600 nm. However structures in the sub-micrometer range cannot be created because the minimum period is limited by the laser spot. By means of the Aluminum Induced Texturing method (AIT) random textures were performed on glass substrates. In this method, a thin Al film is deposited onto a glass substrate and a redox reaction between the Al and the SiO2 of the glass is induced by high temperature annealing. The reaction products are wet-etched and the result is a uniform and rough glass surface. The process parameters were varied in order to control the resultant glass roughness and it was found that the most critical was the Al deposition method. By using evaporation smooth U-shaped craters morphology and roughness up to 90 nm were created, whereas the sputtered films resulted in rough and porous textures with roughness until 145 nm. AZO grown over the U-shape crater morphology led to a double texture with haze values above 10% at 600 nm, transparency above 84%, and Rs-7 SI/sq whereas AZO over very rough glass resulted in a cauliflower-like surface with haze values >32% at 600 nm, Rs around 9.5 SI/sq and transmittance of 74%. A-Si:H solar cells were deposited on different AIT textures and an improvement of the short circuit current, as well as a reduction of the device reflectivity was achieved in all cases in comparison to the cells deposited on smooth glass textures. The second approach was to create a transparent and conducting upconverter to be used on top of the rear reflector of a thin film Si solar cell. For that purpose, ZnO was doped with Er and Yb ions and was post-annealed under different treatments. The unique spectral properties of rare earth (RE) elements due to their electronic configuration occur as a result of their intra 4f-4f shell transitions. In the case of Er, its excitation takes places at 1500 nm and 980 nm and the upconverted photons are emitted within the Si absorption range. Moreover, codoping with Yb can enhance the Er visible emission because they cooperate together due to the matching of their energy levels for k=980 nm. As deposited ZnO doped with rare earths (RE) was found to be transparent and conducting but not luminescent. RE ions need to be surrounded by 6 oxygen in a distorted octahedron to be optically active and REs replacing zinc in the ZnO lattice do not present this symmetry; hence, a post deposition treatment is needed. When the films were post-annealed in air, visible upconversion (UC) was seen at 660 nm under 980 nm laser excitation, however, the films become almost insulating. When the films were annealed in vacuum, lower UC luminescence was achieved, and the resistivity increased 1 order of magnitude. By using CW laser radiation, the electrical properties were maintained and high UC was observed. UC came from clusters of RE06 as well as from RE203 inside or outside the matrix. When annealing in air, in vacuum or by laser radiation, oxygen from the atmosphere bound to the RE to form RE oxides and/or RE06 complexes but just laser annealing was able to preserve the conductivity while producing optically active centers.
L'objectiu d'aquesta tesi és la millora de l'eficiència de les cèl•lules solars de silici en capa prima mitjançant l'estudi de nous mètodes per a l'aprofitament de la llum solar al dispositiu. El primer mètode consisteix en texturar el substrat de vidre per dispersar la llum incident i així incrementar l'absorció en la capa activa. El mètode emprat es la texturització induïda per alumini (AIT); que es basa en una reacció de reducció no uniforme entre el vidre i una capa prima d'alumini gràcies a un tractament tèrmic. Posteriorment els productes de la reacció s'eliminen mitjançant una solució basada en àcid i el resultat és un vidre transparent i texturat. S'ha fet un estudi de la rugositat en funció dels paràmetres del procés i s'ha aconseguit obtenir rugositats controlades i uniformes en superfícies de fins a 10x 10 cm2. Diferents textures s'han provat en cèl.lules solars de silici amorf i s'ha demostrat l'eficàcia d'aquestes en la millora del corrent respecte a les mateixes cèl•lules dipositades sobre vidre pla. El segon mètode estudiat és el fenomen de l'up-conversion que consisteix en la conversió de fotons de baixa energia (EEg) que podran ser absorbits en la zona activa; així doncs s'ha intentat fer una capa conductora, transparent i amb propietats d'up-conversion per utilitzar com a contacte per a cèl• lules solars. Per aquest propòsit s'han estudiat capes conductores i transparents d'òxid de zinc dopat amb erbi i iterbi dipositades per polvorització catòdica sobre vidre. Com que les terres rares han d'estar envoltades d'oxigen per actuar com a centres òptics actius, i en les capes de ZnO:Er:Yb no es dóna aquesta configuració, les capes s'han hagut de sotmetre a diferents tractaments tèrmics, com escalfament en aire, en buit o escalfament amb làser. Escalfant en aire o en buit s'aconsegueix obtenir up-conversion però la conductivitat disminueix notablement, en canvi, escalfant amb radiació làser es possible de mantenir les propietats elèctriques i a més, activar òpticament les terres rares.

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The construction of reservoirs for hydroelectric generates various environmental impacts, for instance, changes in the displacement and the concentration of suspended solids, thus causing changes in the fauna and flora of the water. The survey of suspended solids in a determined watershed is important to make correct decisions regarding the planning for a bowl, because the amount of solids is directly related to the land use. The problems caused by suspended solids include erosion, transport, deposition and compaction, in addition the suspended solids impair the quality of water for human consumption. This study aimed to analyze the spatial and temporal distribution of the concentration of suspended solids (CSS) in the main source of the lake in Barra dos Coqueiros and its influence on the life cycle of the reservoir from March 2011 to August 2011. To achieve the proposed goals, it was used methods such as calculating the concentration of suspended solids according to the proposal of Wetzel and Likens (1991), checking the levels of turbidity and water clarity in accordance with the proposal to Esteves (1998) and Tundisi (2008), calculating the flow of the sources of water by the method of floats as proposed by Ramos and Oliveira (2003), Palhares (2007), and calculating the total solid discharge of the main sources of water (of the) using simplified method of Colby (1964) that takes into consideration: liquid discharge, average speed, average depth, width and cross section measured concentration of suspended solids. According to the data, we reached the following conclusion: the concentration of suspended solids is well related to the data turbidity and water transparency. In the data collection reservoir of the rainy season, the concentration of suspended solids ranged from 7,5 to 30,5 mgL-1 and greater than the collection of the dry period, which ranged from 0,25 to 7,5 mgL-1. The same thing happens to the water transparency using a Secchi disk that ranged from 0,16 to 0,30 meters in the rainy season and 1,40 to 3,50 meters in the dry season. As for turbidity, the indices found shows that the reflectance of light in a rainy period ranged from 51 to 72 NTU, whereas the dry period ranged from 0 to 3,7 NTU. According to the evaluation of the spatial and temporal distribution of suspended solids concentration of the main sources of water in the reservoir of Barra dos Coqueiros, the main lake stands out among the sources analyzed, due to the higher concentration of suspended solids, ranging from 2,5 mgL-1 in the dry season to 14,5 mgL-1 in the rainy season.
A construção de reservatórios para usinas hidrelétricas geram impactos ambientais diversos, como, por exemplo, mudanças no deslocamento e concentração de sólidos em suspensão, ocasionando assim mudanças na fauna e flora aquáticas. O estudo dos sólidos em suspensão de uma determinada bacia hidrográfica é importante para que se possam tomar decisões corretas quanto ao planejamento de atividades de uma bacia, pois a quantidade de sólidos está diretamente associada ao uso da terra. Os problemas gerados pelos sólidos em suspensão vão desde a erosão, transporte, deposição e compactação, além de que os sólidos em suspensão prejudicam a qualidade da água para o consumo humano. O presente trabalho teve por objetivo analisar a distribuição espacial e temporal da concentração de sólidos em suspensão (CSS) nos principais afluentes e lago da UHE Barra dos Coqueiros, e sua influência na vida útil do reservatório no período de março a agosto de 2011. Os métodos utilizados para alcançar os objetivos propostos foram: calcular a concentração de sólidos em suspensão de acordo com a proposta de WETZEL E LIKENS (1991), verificar os níveis de turbidez e transparência da água de acordo com a proposta de ESTEVES (1998) e TUNDISI (2008), calcular a vazão dos afluentes pelo método de flutuadores, de acordo com a proposta de RAMOS e OLIVEIRA (2003), PALHARES (2007), e calcular a descarga sólida total dos principais afluentes pelo método simplificado de COLBY (1964) que leva em consideração: descarga líquida, velocidade média, profundidade média, largura da seção transversal e concentração medida de sólidos em suspensão. De acordo com os dados obtidos, chegou-se à seguinte conclusão: que a concentração de sólidos em suspensão tem boa relação com os dados de turbidez e transparência da água. Na coleta de dados do reservatório do período chuvoso, a concentração de sólidos em suspensão variou de 7,5 a 30,5 mgL-1, sendo maior que na coleta do período seco, que variou de 0,25 a 7,5 mgL-1. O mesmo acontece com transparência de água utilizando o disco de Secchi que variou de 0,16 a 0,30 metros no período chuvoso e de 1,40 a 3,50 metros no período seco. Quanto à turbidez, os índices encontrados mostram que a refletância da luz no período chuvoso variou de 51 a 72 NTU, enquanto no período seco variou de 0 a 3,7 NTU. Quanto à avaliação da distribuição espacial e temporal da concentração de sólidos em suspensão dos principais afluentes do reservatório da UHE Barra dos Coqueiros o Córrego Matriz se destaca entre os afluentes analisados, por apresentar maiores concentrações de sólidos em suspensão, variando de 2,5 mgL-1 no período seco a 14,5 mgL-1 no período chuvoso.

Dans cette thèse CIFRE nous avons élaboré une solution originale d’assemblage de cristaux optiques pour applications lasers avec les sociétés Cristal Laser et Oxxius. Nous avons ensuite optimisé notre composition de colle ainsi que le procédé d’encollage des cristaux avec la réalisation d’un robot par nos partenaires industriels. De nombreux tests d’assemblage ont été effectués avec des homo-assemblages de paires de cristaux de SiO2, Quartz, YAG, KTP, LBO, BBO et RTP. Ces homo-assemblages sont ensuite traités thermiquement pour stabiliser notre interface de colle et nos résultats sont satisfaisants. Nous avons également réalisé des hétéro-assemblages avec des paires de cristaux de nature différente parmi les cristaux précédemment étudiés comme YAG/Quartz ou SiO2/KTP. Les résultats que nous obtenons avec ces hétéro-composites semblent indiquer que le différentiel de CTE entre les pièces assemblée limite fortement le bon déroulement des traitements thermiques. Nous avons donc étudié le CTE ainsi que le comportement de notre interface de colle en fonction de la température afin de proposer une composition et un traitement adapté à la réalisation de ces hétéro-composites
In this CIFRE thesis we elaborate a bonding solution, with Cristal Laser and Oxxius companies, for non-linear optical crystals for laser applications. We had to optimize solution’s composition and the bonding process, this resulted in the creation of a bonding robot by our industrial partners. Numerous homo-assemblies bonding tests has been realized with the following crystal pairs of SiO2, Quartz, YAG, KTP, LBO, BBO and RTP. Those homo-assemblies have been thermally treated to stabilize our bonding solution interface and we obtained relatively good results. We also bonded hetero-assemblies with different crystal pairs like YAG/Quartz or SiO2/KTP. The results we get with these hetero-composites suggest that the difference in CTE between the assembled parts greatly limits the smooth heat treatments. We therefore investigated the CTE and the behavior of our adhesive interface depending on the temperature to provide adapted composition and treatment to the realization of these hetero-composites

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The solar energy that arrives at the Earth surface is an essential phenomenon for the life maintenance and the knowledge of its dynamics contributes to the understanding of complex processes, like the water spectral behavior. Among the main properties that interact with electromagnetic radiation are chlorophyll "a" and suspended solids. In this sense, this study aims to analyze the influence of the Active Optical Components on the water spectral behavior of reservoirs of the Barra dos Coqueiros hydroelectric power plant (GO) at 40 data collection sites. To obtain the data, four field campaigns were carried out on February 10, 2016 and January 28, 2017 (higher precipitation) and 04 / August 4, 2016 and July 7, 2017 (lower precipitation). The spectral data were obtained using a portable spectroradiometer, FieldSpec® Hand Held model in spectral bands of 400 nm to 900 nm. The analysis of chlorophyll "a" followed the proposal of Mackinney (1941), suspended solid data followed Wetzel and Likens (1991; 2000) and APHA (1998; 2005) and the water transparency was according to Esteves (1998) and Peixoto et al. (2015). The analysis of the main information of the water bi-directional reflectance spectra occurred with the application of techniques: continuous removal, 1st and 2nd derivative, cluster analysis, surface reflectance extraction from the Landsat 8-OLI satellite image. Based on the results, there were several factors of performance in the spectral behavior of waters in Barra dos Coqueiros HPP reservoir, such as the climatic seasonality (rainy and dry periods) and the types of land use and occupation, due to the different agricultural production. These aspects favor higher values of suspended solids and chlorophyll a and lower water transparency in fields work of February/2016 and January 2017, resulting in higher reflectance in green (500 nm to 600 nm ) and red (600 nm at 700 nm) spectral ranges. In the field studies conducted in August/2016 and July/2017, reflectance influenced by suspended solids and chlorophyll a was low and the water transparency showed higher depth due to the higher levels of absorption of electromagnetic radiation in the water in the spectral bands of blue (400 nm to 500 nm) and infrared (700 nm to 900 nm). Thus, the geotechnologies applied in this study evidenced several possibilities for interpretation of water spectral information.
A energia solar que chega à superfície da Terra representa um fenômeno essencial para a manutenção da vida e o conhecimento de sua dinâmica contribui para a compreensão de processos complexos, como o comportamento espectral da água. Dentre as principais propriedades que interagem com radiação eletromagnética encontram-se a clorofila-a os sólidos em suspensão. Nessa perspectiva, o presente estudo tem por objetivo analisar em 40 pontos de coleta de dados, a influência dos Componentes Opticamentes Ativos no comportamento espectral das águas, do reservatório da Usina hidrelétrica Barra dos Coqueiros (GO). Para obtenção dos dados, foram realizadas quatro campanhas de campo, as quais ocorreram em 10/fevereiro/2016 e 28/janeiro/2017 (maiores precipitações) e 04/agosto/2016 e 07/julho/2017 (menores precipitação). Os dados espectrais, foram obtidos por meio de espectrorradiômetro portátil, modelo FieldSpec® Hand Held. A análise de clorofila-aseguiu a proposta de Mackinney (1941), os dados de sólidos em suspensão a metodologia de Wetzel e Likens (1991; 2000) e APHA (1998; 2005) e a transparência da água realizada conforme Esteves (1998) e Peixoto et al. (2015). O diagnóstico das principais informações dos espectros de reflectância da água ocorreu com aplicação de técnicas: remoção do contínuo, derivada, análise cluster, extração da reflectância de superfície da imagem do satélite Landsat 8-OLI. Com base nos resultados, verificou-se diversos fatores de atuação no comportamento espectral das águas do reservatório da UHE Barra dos Coqueiros (GO), como a sazonalidade climática (período chuvoso e seco) e as formas do uso e ocupação da terra, distintas pelas produções agrícolas, aspectos esses, que favorecem nos campos de fevereiro/2016 e janeiro/2017, valores mais elevados de sólidos em suspensão e clorofila-a menores transparência da água, resultando em maiores reflectância nas faixas espectrais do verde (500 nm a 600 nm) e vermelho (600 nm a 700 nm). Nos campos realizados em agosto/2016 e julho/2017, os níveis da reflectância influenciados por sólidos em suspensão e clorofila-asão baixas e as transparências da água apresentou maiores profundidade, devido a maior absorção da radiação eletromagnética na água nas bandas espectrais do azul (400 nm a 500 nm) e infravermelho (700 nm a 900 nm). Desse modo, as geotecnologias aplicadas neste estudo, evidenciaram diversas possiblidades para interpretação da informação espectral da água.

Transparent conducting oxides (TCOs) combine optical transparency in the visible region with a high electrical conductivity. In2O3 doped with Sn (widely, but somewhat misleadingly, known as indium tin oxide or ITO) is at present the most important TCO, with applications in liquid crystal displays, touch screen displays, organic photovoltaics and other optoelectronic devices. Surprisingly, many of its fundamental properties have been the subject of controversy or have until recently remained unknown, including even the nature and magnitude of the bandgap. The technological importance of the material and the renewed interest in its basic physics prompted the research described in this thesis. This thesis aims (i) to establish conditions for the growth of high-quality In2O3 nanostructures and thin films by oxygen plasma assisted molecular beam epitaxy and (ii) to conduct comprehensive investigations on both the surface physics of this material and its structural and electronic properties. It was demonstrated that highly ordered In2O3 nanoislands, nanorods and thin films can be grown epitaxially on (100), (110) and (111) oriented Y-stabilized ZrO2 substrates respectively. The mismatch with this substrate is -1.7%, with the epilayer under tensile strain. On the basis of ab initio density functional theory calculations, it was concluded that the striking influence of substrate orientation on the distinctive growth modes was linked to the fact that the surface energy for the (111) surface is much lower than for either polar (100) or non-polar (110) surfaces. The growth of In2O3(111) thin films was further explored on Y-ZrO2(111) substrates by optimizing the growth temperature and film thickness. Very thin In2O3 epilayers (35 nm) grew pseudomorphically under high tensile strain, caused by the 1.7% lattice mismatch with the substrate. The strain was gradually relaxed with increasing film thickness. High-quality films with a low carrier concentration (5.0  1017 cm-3) and high mobility (73 cm2V-1s-1) were obtained in the thickest films (420 nm) after strain relaxation. The bandgap of the thinnest In2O3 films was around 0.1 eV smaller than that of the bulk material, due to reduction of bonding-antibonding interactions associated with lattice expansion. The high-quality surfaces of the (111) films allowed us to investigate various aspects of the surface structural and electronic properties. The atomic structure of In2O3 (111) surface was determined using a combination of scanning tunnelling microscopy, analysis of intensity/voltage curves in low energy electron diffraction and first-principles ab initio calculations. The (111) termination has an essentially bulk terminated (1 × 1) surface structure, with minor relaxations normal to the surface. Good agreement was found between the experimental surface structure and that derived from ab initio density functional theory calculations. This work emphasises the benefits of a multi-technique approach to determination of surface structure. The electronic properties of In2O3(111) surfaces were probed by synchrotron-based photoemission spectroscopy using photons with energies ranging from the ultraviolet (6 eV) to the hard X-ray regime (6000 eV) to excite the spectra. It has been shown that In2O3 is a highly covalent material, with significant hybridization between O and In orbitals in both the valence and the conduction bands. A pronounced electron accumulation layer presents itself at the surfaces of undoped In2O3 films with very low carrier concentrations, which results from the fact the charge neutrality level of In2O3 lies well above the conduction band minimum. The pronounced electron accumulation associated with a downward band bending in the near surface region creates a confining potential well, which causes the electrons in the conduction band become quantized into two subband states, as observed by angle resolved photoemission spectra (ARPES) Fermi surface mapping. The accumulation of high density of electrons near to the surface region was found to shrink the surface band gap through many body interactions. Finally epitaxial growth of In2O3 thin films on α-Al2O3(0001) substrates was investigated. Both the stable body centred cubic phase and the metastable hexagonal corundum In2O3 phase can be stabilized as epitaxial thin films, despite large mismatches with the substrate. The growth mode involves matching small but different integral multiples of lattice planes of the In2O3 and the substrate in a domain matching epitaxial growth mode.

La rééducation neuromotrice est un des nouveaux champs d'application de la robotique en interaction physique. Dans ce domaine, on cherche à concevoir des machines pouvant assister les mouvements de patients atteints de troubles neuromoteurs dans la réalisation d'exercices physiques. Un des enjeux importants est de pouvoir proposer des machines capables de maîtriser des efforts mécaniques distribués le long des membres du patient durant les mouvements. Ceci a conduit la communauté à travailler au développement de structure exosquelettiques. L'essentiel des recherches en cours est focalisé sur les aspects cinématiques plus que sur le problème des transmissions d'efforts. C'est au contraire à ces aspects cruciaux qu'est consacrée la présente thèse. Pour améliorer la qualité du contrôle des efforts dans la mise en oeuvre des exosquelettes robotiques, les principales contributions se situent dans les domaines de la conception et de la commande. S'agissant de la conception, nous avons exploité des résultats existants dans la littérature pour la structure mécanique et la mécatronique d'actionnement, en utilisant l'exosquelette réversible ABLE conçu au CEA LIST. Partant de ce modèle, représentatif de l'existant, nous avons travaillé sur le problème du couplage mécanique entre le robot et le bras. Ce travail a permis de proposer une méthode générale pour synthétiser des mécanismes de fixation articulés passifs entre un exosquelette et un membre humain. Les fixations ainsi conçues garantissent l'isostaticité globale de l'ensemble. L'étude théorique générale est appliquée à ABLE, montrant une amélioration nette de la qualité de l'interaction. S'agissant de la commande, nous avons déployé une commande en efforts multi-contacts, ce qui constitue en soit une originalité, puis proposé de faciliter l'accompagnement des mouvements du sujet en exploitant une anticipation de trajectoire, grâce à un contrôleur mixte force/position. Là encore, l'apport expérimental évalué sur l'exosquelette ABLE est probant. Un dernier résultat important de la thèse concerne l'évaluation de la qualité de l'interaction homme-exosquelette dans des tâches de comanipulation. En effet, pour pouvoir quantifier l'apport des différentes propositions dans le domaine de la conception et de la commande, nous avons dû établir une méthode permettant d'étudier de manière reproductible l'interaction physique homme-robot, en analysant simultanément les efforts et la cinématique des gestes.

Metal oxides are of immense technological importance. Their wide variety of structural and electronic characteristics leads to a flexibility unrivalled by other groups of materials. However, there is still much debate about the fundamental properties of some of the most widely used oxides, including TiO₂ and In₂O₃. This work presents high quality, in-depth characterisation of these two oxides in pure and doped form, including soft and hard X-ray photoelectron spectroscopy and X-ray diffraction. Bulk samples as well as thin film samples were prepared analysed. For the preparation of thin films a high quality sol-gel dip-coating method was developed, which resulted in epitaxial films. In more detail the organisation of the thesis is as follows: Chapter 1 provides an introduction to key ideas related to metal oxides and presents the metal oxides investigated in this thesis, In₂O₃, Ga₂O₃, Tl₂O₃, TiO₂, and SnO₂. Chapter 2 presents background information and Chapter 3 gives the practical details of the experimental techniques employed. Chapters 4 presents reciprocal space maps of MBE-grown In₂O₃ thin films and nanorods on YSZ substrates. Chapters 5 and 6 investigate the doping of In₂O₃ bulk samples with gallium and thallium and introduce a range of solid state characterisation techniques. Chapter 7 describes the development of a dip-coating sol-gel method for the growth of thin films of TiO₂ and shows 3D reciprocal space maps of the resulting films. Chapter 8 concerns hard x-ray photoelectron spectroscopy of undoped and Sn-doped TiO₂. Chapter 9 interconnects previous chapters by presenting 2D reciprocal space maps of nano structured epitaxial samples of In₂O₃ grown by the newly developed sol-gel based method. Chapter 10 concludes this thesis with a summary of the results.

Optically-transparent solids have a significant role in many emerging topics of fundamental and applied research, in areas related to Applied Optics and Photonics. In the functional devices based on them, the presence of ‘time-varying temperature fields’ critically limit their achievable performance, when used particularly for high power laser-related tasks such as light-generation, light-amplification, nonlinear-harmonic conversion etc. For optimization of these devices, accurate knowledge of the material thermal parameters is essential. Many optical and non-optical methods are currently in use, for the reliable estimation of the thermal parameters. The thermal diffusivity is a key parameter for dealing with ‘transient heat transport’ related problems. Although its importance in practical design for thermal management is well understood, its physical meaning however continues to be esoteric. The present effort concerns with a few investigations on the “Optical interrogation of ‘transient thermal conduction’ in dielectric solids”. In dielectric solids, the current understanding is that the conductive heat transport occurs only through phonons relevant to microscopic lattice vibrations. Introducing for the first time, a virtual linear translator motion as the basis for heat conduction in dielectric materials, the present investigation discusses an alternative physical mechanism and a new analytical model for the transient heat conduction in dielectric solids. The model brings into limelight a ‘new law of motion’ and a ‘new quantity’ which can be defined at every point in the material, through which time-varying heat flows resulting in time-varying temperature. Physically, this quantity is a measure for the linear translatory motion resulting from transient heat conduction. For step-temperature excitation it bears a simple algebraic relation to the thermal diffusivity of the material. This relationship helps to define the thermal diffusivity of a dielectric solid as the “translatory motion speed” measured at unit distance from the heat source. A novel two-beam interferometric technique is proposed and corroborated the proposed concept with significant advantages. Two new approaches are introduced to estimate thermal diffusivity of optically transparent dielectric solid; first of them involves measurement of the position dependent velocity of isothermal surface and second one depend on the measurement of position dependent instantaneous velocity of normalized moving intensity points. A ‘new mechanism’ is proposed and demonstrated to visualize, monitor and interrogate optically, the ‘linear translatory motion’ resulting from the transient heat flow due to step- temperature excitation. Two new approaches are introduced, first one is ‘mark’ and ‘track’ approach, it involves a new interaction between sample supporting unsteady heat flow with its ambient and produces optical mark. Thermal diffusivity is estimated by tracking the optical mark. Second one involves measurement of instantaneous velocity of optical mark for different step-temperature at a fixed location to estimate thermal diffusivity. A new inverse method is proposed to estimate thermal diffusivity and thermal conductivity from the volumetric specific heat capacity alone through thought experiment. A new method is proposed to predict volumetric specific heat capacity more accurately from thermal diffusivity.

Optically-transparent solids have a significant role in many emerging topics of fundamental and applied research, in areas related to Applied Optics and Photonics. In the functional devices based on them, the presence of ‘time-varying temperature fields’ critically limit their achievable performance, when used particularly for high power laser-related tasks such as light-generation, light-amplification, nonlinear-harmonic conversion etc. For optimization of these devices, accurate knowledge of the material thermal parameters is essential. Many optical and non-optical methods are currently in use, for the reliable estimation of the thermal parameters. The thermal diffusivity is a key parameter for dealing with ‘transient heat transport’ related problems. Although its importance in practical design for thermal management is well understood, its physical meaning however continues to be esoteric. The present effort concerns with a few investigations on the “Optical interrogation of ‘transient thermal conduction’ in dielectric solids”. In dielectric solids, the current understanding is that the conductive heat transport occurs only through phonons relevant to microscopic lattice vibrations. Introducing for the first time, a virtual linear translator motion as the basis for heat conduction in dielectric materials, the present investigation discusses an alternative physical mechanism and a new analytical model for the transient heat conduction in dielectric solids. The model brings into limelight a ‘new law of motion’ and a ‘new quantity’ which can be defined at every point in the material, through which time-varying heat flows resulting in time-varying temperature. Physically, this quantity is a measure for the linear translatory motion resulting from transient heat conduction. For step-temperature excitation it bears a simple algebraic relation to the thermal diffusivity of the material. This relationship helps to define the thermal diffusivity of a dielectric solid as the “translatory motion speed” measured at unit distance from the heat source. A novel two-beam interferometric technique is proposed and corroborated the proposed concept with significant advantages. Two new approaches are introduced to estimate thermal diffusivity of optically transparent dielectric solid; first of them involves measurement of the position dependent velocity of isothermal surface and second one depend on the measurement of position dependent instantaneous velocity of normalized moving intensity points. A ‘new mechanism’ is proposed and demonstrated to visualize, monitor and interrogate optically, the ‘linear translatory motion’ resulting from the transient heat flow due to step- temperature excitation. Two new approaches are introduced, first one is ‘mark’ and ‘track’ approach, it involves a new interaction between sample supporting unsteady heat flow with its ambient and produces optical mark. Thermal diffusivity is estimated by tracking the optical mark. Second one involves measurement of instantaneous velocity of optical mark for different step-temperature at a fixed location to estimate thermal diffusivity. A new inverse method is proposed to estimate thermal diffusivity and thermal conductivity from the volumetric specific heat capacity alone through thought experiment. A new method is proposed to predict volumetric specific heat capacity more accurately from thermal diffusivity.

New transparent p- and n-type semiconductors and luminescent materials have been prepared and characterized. Synthesis, structures, optical and electrical properties of new chalcogenide fluoride p-type transparent semiconductors MCuQF (M=Ba, Sr; Q=S, Se, Te) are described. Band-gap tuning and improvement in conductivity through p-type doping are demonstrated in the family. The new Ag sulfide fluoride BaAgSF has been prepared, and its optical and electrical properties have been examined. Phase stabilization as well as optical and electrical properties of the p-type conductors BaCu₂S₂ and BaCu₂Se₂ are considered. New n-type transparent conducting films of W-doped In₂O₃ and W-doped zinc indium oxide (ZIO) have been prepared by pulsed laser deposition, and their electrical properties have been examined. Results on new transparent thin-film transistors containing SnO₂ or ZIO are also presented. Strong near-infrared luminescence of BaSnO3 is described, and the emission brightness is correlated to the crystallite size of assembled nanoparticles. Syntheses, structures, and optical properties of (La,Y)Sc₃(BO₃)₄:Eu³⁺, (Ba,Sr)Sc₂(BO₃)₄:Eu²⁺, and LuAl₃(BO₃)₄:Ln³⁺ (Ln=Eu, Tb, Ce) have been considered with emphasis on relations between structures and optical properties. Finally, the synthesis and luminescence properties of new potential X-ray phosphors Lu₂O₂S:Ln³⁺ (Ln=Eu, Tb) are summarized.
Graduation date: 2005

碩士
大同大學
材料工程研究所
89
Abstract MgO-ZnO-Al2O3-SiO2 glass-ceramics is a kind of transparent glass-ceramics. After suitable nucleation and crystallized processes, the fine grain of spinel crystallization and residual glass can be obtained . The study discuss the different nucleation agent (TiO2 and ZrO2) ratio (R) , discuss the effect on the glass-ceramics crystallization and properties of different nucleation agent ratio; change the ratio (N) of MgO and ZnO, discuss the variation of the ratio between the initial glasses and the spinel crystal. The nucleation temperature and softening point were increased by increasing ratio of Zirconia Oxide ; The main phase is (Mg,Zn)Al2O4 between the crystallization temperature, 950 to 1100℃, and its grain size is about 20 nm. Coefficient of thermal expansion(CTE) had no substantial variety in the range 20~40×10-7 K-1. The transparency of glass-ceramics was decreased by the increment of crystallization temperature and time. Changing the ratio of MgO and ZnO, nucleation and softening temperature was increased by the increment of MgO ratio. The main crystalline phase is (Mg,Zn)Al2O4 at its DTA exothermic peak after crystalline treatment for 1 to 4 hours. The ratios of MgO/(MgO+ZnO) were zero at N=0, and they were 8 to 15% at N=0.25; they was decreased 10 to 17% compared with the ones of initial glass. The ratios of MgO/(MgO+ZnO) in the crystal were 38 to 43% at N=0.5, and they were decreased 7 to 12% compared with the ones of initial glass, 50%. The coefficient of thermal expansion had increasing tendency to the increase of crystallization temperature, and its varied range is 29~40×10-7 K-1 . The transparency of glass-ceramics was decreased by the increment of crystallization time.

abstract: New sol-gel routes were developed to fabricate transparent conducting oxide coatings for energy applications. Sol-gel synthesis was chosen because the metal oxide products have high surface area and porosity. Titanium sol-gel chemistry was the main focus of the studies, and the synthesis of macroporous antimony-doped tin oxide was also explored. The surface chemistry and band characteristics of anatase TiO2 show promise for solar energy purposes as photoelectrodes in DSSCs and as photocatalysts to degrade organic dyes and to split water. Modifying the band structure by increasing the conduction band edge energy is specifically of interest for reducing protons in water. To this end, a new sol-gel method was developed for incorporating Zr-dopant in nanoporous anatase TiO2. The products follow Vegard’s law up to 20 atom%, exhibiting surface area of 79 m2/g and pore volume of 0.20 cm3/g with average pore diameter of 10.3 nm; the conduction band edge energy increased by 0.22 eV and the band gap increased by 0.1 eV. In pursuit of a greener sol-gel route for TiO2 materials, a solution of TiOSO4 in water was explored. Success in obtaining a gel came by utilizing hydrogen peroxide as a ligand that suppressed precipitation reactions. Through modifying this sol-gel chemistry to obtain a solid acid, the new material hydrogen titanium phosphate sulfate, H1-xTi2(PO4)3-x(SO4)x, (0 < x < 0.5) was synthesized and characterized for the first time. From the reported synthetic route, this compound took the form of macroscopic agglomerates of nanoporous aggregates of nanoparticles around 20 nm and the product calcined at 600 °C exhibited surface area of 78 m2/g, pore volume of 0.22 cm3/g and an average pore width of 11 nm. This solid acid exhibits complete selectivity for the non-oxidative dehydrogenation of methanol to formaldehyde and hydrogen gas, with >50% conversion at 300 °C. Finally, hierarchically meso-macroporous antimony doped tin oxide was synthesized with regular macropore size around 210 nm, determined by statistical dye trajectory tracking, and also with larger pores up to micrometers in size. The structure consisted of nanoparticles around 4 nm in size, with textural mesopores around 20 nm in diameter.
Dissertation/Thesis
Doctoral Dissertation Chemistry 2016

碩士
國立成功大學
化學工程學系
104
This thesis concerns the developments of flexible transparent conductive electrodes and supercapacitors using carbon nanotube (CNT), reduced graphene oxide, and their hybrids with conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). At first, the CNT and rGO-based thin films were fabricated as flexible transparent conductive electrodes by the blade-coating of CNT or graphene oxide (GO) dispersion on polyethylene terephthalate (PET) and the followed GO reduction with hydroiodic acid for the case of GO. The decreases of transmittance and sheet resistance with the increase of layer numbers have been described. Secondly, CNT or GO (0~0.1wt%) was added to the equal volume mixture of PEDOT:PSS and dimethyl sulfoxide (DMSO) to yield homogeneous dispersions. For the case of GO, the dispersion was further microwave-treated to obtain the rGO dispersion. Then, the CNT or rGO dispersion was blade-coated on PET to form the CNT/PEDOT:PSS or rGO/PEDOT:PSS hybrid thin films as flexible transparent conductive electrodes. It was found that the appropriate addition of CNT or rGO indeed could effectively enhance the conductivity via the formation of conductive network. The lowest sheet resistance around 1000 Ω with a transmittance above 80% was obtained for both the hybrid thin films. Finally, it was demonstrated that both the CNT/PEDOT:PSS and rGO/PEDOT:PSS hybrid thin films also could be used as the electrodes for supercapacitors. The capacitance could be raised by appropriately increasing the thickness of hybrid thin films. Furthermore, the flexible transparent all-solid-state supercapacitors were fabricated with polyvinyl alcohol/sulfuric acid (PVA/H2SO4) gel electrolyte between two CNT/PEDOT:PSS or rGO/PEDOT:PSS hybrid thin film-based electrodes. It was found that both the resulting supercapacitors had transmittances above 56% and could be quickly charged and discharged. Also, their electrochemical performance could be retained while bending. All the results revealed that both the CNT/PEDOT:PSS and rGO/PEDOT:PSS hybrid thin films could be developed as good electrode materials for flexible transparent supercapacitors.

碩士
國立清華大學
奈米工程與微系統研究所
99
New p-type transparent conductive oxide materials, MoO3:In single crystal nanowires and amorphous films, were synthesized in this work. Both nanowires and amorphous films exhibit high optical transmittance, 80–88% for 80 nm thick films at 400–800 nm wavelength, and low resistivity (down to 5.98 × 10-4 Ω-cm) suitable for photovoltaic device applications. The amorphous films were also deposited on flexible polyimide substrates and exhibit excellent electrical properties even after bending. Besides, p-MoO3:In/i-ZnO/n-AZO devices were fabricated to demonstrate the potential for all-transparent flexible electronic applications. MoO3:In nanowires were also used as hole transport layers for solid-state dye-sensitized solar cells (SS-DSSCs). The MoO3:In nanowires were used to increase the surface contact with dyed titanium dioxide nanoparticles so as to enhance the short circuit current of SS-DSSCs. Various methods of solution-processing were also used to fill titanium dioxide nanoparticles in MoO3:In nanowires. Besides, indium doping in MoO3 nanowires was utilized to improve the hole concentration and enhance the open voltage of SS-DSSCs.