La simulation haute-fidélité des coeurs de réacteurs nucléaires nécessite une évaluation précise du flux neutronique dans le coeur du réacteur. Ce flux est modélisé par l’équation de Boltzmann ou équation du transport neutronique. Dans cette thèse, on s’intéresse à la résolution de cette équation par la méthode des ordonnées discrètes (SN) sur des géométries cartésiennes. Cette méthode fait intervenir un schéma d’itérations à source, incluant un algorithme de balayage sur le domaine spatial qui regroupe l’essentiel des calculs effectués. Compte tenu du très grand volume de calcul requis par la résolution de l’équation de Boltzmann, de nombreux travaux antérieurs ont été consacrés à l’utilisation du calcul parallèle pour la résolution de cette équation. Jusqu’ici, ces algorithmes de résolution parallèles de l’équation du transport neutronique ont été conçus en considérant la machine cible comme une collection de processeurs mono-coeurs indépendants, et ne tirent donc pas explicitement profit de la hiérarchie mémoire et du parallélisme multi-niveaux présents sur les super-calculateurs modernes. Ainsi, la première contribution de cette thèse concerne l’étude et la mise en oeuvre de l’algorithme de balayage sur les super-calculateurs massivement parallèles modernes. Notre approche combine à la fois la vectorisation par des techniques de la programmation générique en C++, et la programmation hybride par l’utilisation d’un support d’exécution à base de tâches: PaRSEC. Nous avons démontré l’intérêt de cette approche grâce à des modèles de performances théoriques, permettant également de prédire le partitionnement optimal. Par ailleurs, dans le cas de la simulation des milieux très diffusifs tels que le coeur d’un REP, la convergence du schéma d’itérations à source est très lente. Afin d’accélérer sa convergence, nous avons implémenté un nouvel algorithme (PDSA), adapté à notre implémentation hybride. La combinaison de ces techniques nous a permis de concevoir une version massivement parallèle du solveur SN Domino. Les performances de la partie Sweep du solveur atteignent 33.9% de la performance crête théorique d’un super-calculateur à 768 cores. De plus, un calcul critique d’un réacteur de type REP 900MW à 26 groupes d’énergie mettant en jeu 1012 DDLs a été résolu en 46 minutes sur 1536 coeurs. / High-fidelity nuclear reactor core simulations require a precise knowledge of the neutron flux inside the reactor core. This flux is modeled by the linear Boltzmann equation also called neutron transport equation. In this thesis, we focus on solving this equation using the discrete ordinates method (SN) on Cartesian mesh. This method involves a source iteration scheme including a sweep over the spatial mesh and gathering the vast majority of computations in the SN method. Due to the large amount of computations performed in the resolution of the Boltzmann equation, numerous research works were focused on the optimization of the time to solution by developing parallel algorithms for solving the transport equation. However, these algorithms were designed by considering a super-computer as a collection of independent cores, and therefore do not explicitly take into account the memory hierarchy and multi-level parallelism available inside modern super-computers. Therefore, we first proposed a strategy for designing an efficient parallel implementation of the sweep operation on modern architectures by combining the use of the SIMD paradigm thanks to C++ generic programming techniques and an emerging task-based runtime system: PaRSEC. We demonstrated the need for such an approach using theoretical performance models predicting optimal partitionings. Then we studied the challenge of converging the source iterations scheme in highly diffusive media such as the PWR cores. We have implemented and studied the convergence of a new acceleration scheme (PDSA) that naturally suits our Hybrid parallel implementation. The combination of all these techniques have enabled us to develop a massively parallel version of the SN Domino solver. It is capable of tackling the challenges posed by the neutron transport simulations and compares favorably with state-of-the-art solvers such as Denovo. The performance of the PaRSEC implementation of the sweep operation reaches 6.1 Tflop/s on 768 cores corresponding to 33.9% of the theoretical peak performance of this set of computational resources. For a typical 26-group PWR calculations involving 1.02×1012 DoFs, the time to solution required by the Domino solver is 46 min using 1536 cores.

Materiais magnetostrictivos exibem deformação elástica na presença de um campo magnético aplicado e por isso são de grande interesse para aplicação em sensores e atuadores. Trabalhos publicados no ano 2000 mostraram que a adição de Ga e Al ao Fe resulta em ligas com elevada magnetostricção em campos baixos. A partir daí os esforços foram direcionados para a descoberta de novas ligas magnetostrictivas à base de Fe com propriedades similares às encontradas nas ligas Fe-Ga e Fe-Al. No presente trabalho foram adicionados o Sn e o V ao Fe com o objetivo de avaliar a magnetostricção e a microestrutura das ligas formadas. Para isso, foram produzidas por fusão a arco as ligas Fe-9%at.Sn, Fe-20%at.Sn e as ligas Fex% at.V para x = 20, 25 e 30. As ligas Fe-Sn foram submetidas a tratamentos térmicos em 550 e 750°C por 24 h e em 880°C por 6 h e depois resfriadas rapidamente para a retenção das fases (Fe?,Sn), FeSn, Fe3Sn2 e Fe5Sn3. Já as ligas Fe-V foram tratadas em 1100°C por 6 h para homogeneização da fase única (Fe?,V). A caracterização microestrutural e análise quantitativa das fases foram feitas por microscopia óptica e eletrônica de varredura, microanálise por energia dispersiva (EDS) e difratometria de raios X. Também foi medida a microdureza Vickers das amostras. A magnetostricção foi medida por dilatometria de capacitância usando um dilatômetro de placa inclinada inserido no equipamento Maglab da Oxford Instruments, em campos na faixa de -1,5 a 1,5 T e temperaturas próximas de 203 K. A magnetização de saturação das amostras foi obtida em 77, 203 e 300 K utilizando o PPMS 6000 da Quantum Design. A magnetostricção de saturação (?S) das amostras da liga Fe-9Sn foi negativa e o comportamento das curvas similar ao do Fe puro. As amostras da liga Fe- 20Sn apresentaram ?S positiva devido à presença das fases ferromagnéticas Fe3Sn2 e Fe5Sn3. A ?S das ligas Fe-V foi positiva e maior em módulo do que a das ligas Fe-Sn. Concluiu-se que a substituição do Fe por Sn e V de modo geral melhorou a magnetostricção do Fe, porém a melhora não foi tão relevante quanto a observada pela substituição por Ga. / Magnetostrictive materials exhibit elastic strain in the presence of an applied magnetic field and therefore are of great interest for use in sensors and actuators. Works published in 2000 showed that the addition of Ga and Al in Fe results in alloys with high magnetostriction at low fields. Since then efforts have been directed to the discovery of new magnetostrictive Fe based alloys with similar properties to those found in Fe-Ga and Fe-Al alloys. In the present work Sn and V were added to Fe with the purpose of evaluating the magnetostriction and microstructure of these alloys. Therefore, Fe-9at.%Sn, Fe-20at.%Sn alloys and Fexat.% V alloys for x = 20, 25 and 30 were produced by arc melting. The Fe-Sn alloys were heat-treated at the temperatures of 550 and 750°C for 24 h and 880°C for 6 h and then rapidly cooled to the retention of the (?Fe,Sn), FeSn, Fe3Sn2 and Fe5Sn3 phases. Fe-V alloys were heat-treated at the temperature of 1100°C for 6 h to homogenize the (?Fe,Sn) single phase. Microstructural characterization and quantitative analysis of the phases were made by optical and scanning electron microscopy, microanalysis by energy dispersive spectroscopy (EDS) and X-ray powder diffraction. The Vickers microhardness of the samples was also measured. The magnetostriction was measured by capacitance dilatometry using a tilted plate dilatometer inserted into the Maglab platform by Oxford Instruments, using applied field in the range from -1.5 to 1.5 T and at temperatures close to 203 K. The samples saturation magnetization was obtained at 77, 203 and 300 K using the Quantum Design PPMS 6000. The saturation magnetostriction (?S) of the Fe-9Sn alloy samples was negative and the ?S vs. H curves behavior are similar to the pure Fe. Fe-20Sn alloy samples had positive ?S due to the presence of Fe3Sn2 and Fe5Sn3 ferromagnetic phases. The Fe-V alloys ?S was positive and larger in module than the Fe-Sn alloys ?S. We concluded that the substitution of Fe by Sn and V in a general way improved the magnetostriction of Fe, but the improvement was not as significant as observed with the substitution by Ga.

Materiais magnetostrictivos exibem deformação elástica na presença de um campo magnético aplicado e por isso são de grande interesse para aplicação em sensores e atuadores. Trabalhos publicados no ano 2000 mostraram que a adição de Ga e Al ao Fe resulta em ligas com elevada magnetostricção em campos baixos. A partir daí os esforços foram direcionados para a descoberta de novas ligas magnetostrictivas à base de Fe com propriedades similares às encontradas nas ligas Fe-Ga e Fe-Al. No presente trabalho foram adicionados o Sn e o V ao Fe com o objetivo de avaliar a magnetostricção e a microestrutura das ligas formadas. Para isso, foram produzidas por fusão a arco as ligas Fe-9%at.Sn, Fe-20%at.Sn e as ligas Fex% at.V para x = 20, 25 e 30. As ligas Fe-Sn foram submetidas a tratamentos térmicos em 550 e 750°C por 24 h e em 880°C por 6 h e depois resfriadas rapidamente para a retenção das fases (Fe?,Sn), FeSn, Fe3Sn2 e Fe5Sn3. Já as ligas Fe-V foram tratadas em 1100°C por 6 h para homogeneização da fase única (Fe?,V). A caracterização microestrutural e análise quantitativa das fases foram feitas por microscopia óptica e eletrônica de varredura, microanálise por energia dispersiva (EDS) e difratometria de raios X. Também foi medida a microdureza Vickers das amostras. A magnetostricção foi medida por dilatometria de capacitância usando um dilatômetro de placa inclinada inserido no equipamento Maglab da Oxford Instruments, em campos na faixa de -1,5 a 1,5 T e temperaturas próximas de 203 K. A magnetização de saturação das amostras foi obtida em 77, 203 e 300 K utilizando o PPMS 6000 da Quantum Design. A magnetostricção de saturação (?S) das amostras da liga Fe-9Sn foi negativa e o comportamento das curvas similar ao do Fe puro. As amostras da liga Fe- 20Sn apresentaram ?S positiva devido à presença das fases ferromagnéticas Fe3Sn2 e Fe5Sn3. A ?S das ligas Fe-V foi positiva e maior em módulo do que a das ligas Fe-Sn. Concluiu-se que a substituição do Fe por Sn e V de modo geral melhorou a magnetostricção do Fe, porém a melhora não foi tão relevante quanto a observada pela substituição por Ga. / Magnetostrictive materials exhibit elastic strain in the presence of an applied magnetic field and therefore are of great interest for use in sensors and actuators. Works published in 2000 showed that the addition of Ga and Al in Fe results in alloys with high magnetostriction at low fields. Since then efforts have been directed to the discovery of new magnetostrictive Fe based alloys with similar properties to those found in Fe-Ga and Fe-Al alloys. In the present work Sn and V were added to Fe with the purpose of evaluating the magnetostriction and microstructure of these alloys. Therefore, Fe-9at.%Sn, Fe-20at.%Sn alloys and Fexat.% V alloys for x = 20, 25 and 30 were produced by arc melting. The Fe-Sn alloys were heat-treated at the temperatures of 550 and 750°C for 24 h and 880°C for 6 h and then rapidly cooled to the retention of the (?Fe,Sn), FeSn, Fe3Sn2 and Fe5Sn3 phases. Fe-V alloys were heat-treated at the temperature of 1100°C for 6 h to homogenize the (?Fe,Sn) single phase. Microstructural characterization and quantitative analysis of the phases were made by optical and scanning electron microscopy, microanalysis by energy dispersive spectroscopy (EDS) and X-ray powder diffraction. The Vickers microhardness of the samples was also measured. The magnetostriction was measured by capacitance dilatometry using a tilted plate dilatometer inserted into the Maglab platform by Oxford Instruments, using applied field in the range from -1.5 to 1.5 T and at temperatures close to 203 K. The samples saturation magnetization was obtained at 77, 203 and 300 K using the Quantum Design PPMS 6000. The saturation magnetostriction (?S) of the Fe-9Sn alloy samples was negative and the ?S vs. H curves behavior are similar to the pure Fe. Fe-20Sn alloy samples had positive ?S due to the presence of Fe3Sn2 and Fe5Sn3 ferromagnetic phases. The Fe-V alloys ?S was positive and larger in module than the Fe-Sn alloys ?S. We concluded that the substitution of Fe by Sn and V in a general way improved the magnetostriction of Fe, but the improvement was not as significant as observed with the substitution by Ga.

Made available in DSpace on 2016-06-02T20:36:27Z (GMT). No. of bitstreams: 1 3249.pdf: 11024185 bytes, checksum: 80826ca263ef595b53e77d333e4a12a8 (MD5) Previous issue date: 2009-05-27 / Financiadora de Estudos e Projetos / This study evaluated the electrodeposition processes of Sn, Zn and Sn-Zn alloy in the absence and presence of tartaric acid as complexing agent. Initially all the systems studied were evaluated by Cyclic Voltammetry to determine the deposition potentials of the pure metals and alloy. The results showed that the presence of the complexant shifts the deposition process of both Sn and Zn to more negative potential values. The metals codeposition can be determined by the variation in the shape and potentials of the peaks of deposition in the voltammograms obtained for the alloy when compared to those for individual metals. The potential-step technique (Chronoamperometry) was used to characterize the initial stages of electrocrystallization. It was found that the nucleation processes of Sn (in the absence and presence of the complexant) and Sn-Zn alloy (in complexed medium) are governed by progressive nucleation, while for Zn in both media and for the Sn-Zn alloy in non-complexed medium were ill-defined. Thus, these can be characterized as mixed processes. Films obtained at different deposition potentials were characterized by Scanning Electron Microscopy (SEM), Energy-Dispersive X-Ray Spectroscopy (EDX). It was observed that using the tartaric acid it was possible to obtain more uniform and homogeneous deposits and, apparently, favouring the reduction process and achieving a more protective coating. The morphology, composition and X-Ray Diffraction (XRD) of films galvanostatically deposited varying the complexing agent (potassium sodium tartrate or sodium gluconate) and the deposition current (5,0 mA cm-2 and 30,0 mA cm-2) were also analyzed. It was found that at a lower current density the films obtained showed a better uniformity, while those obtained at a higher current density showed a finer grain structure due to an increased nucleation rate in this last instance. Moreover, we can say that the tartrate favours the deposition of Zn when compared to the gluconate. By the XRD analysis it was possible to observe that the alloys consist of separated phases of Sn and Zn crystals and they do not form any intermetallic compound. / Neste trabalho foram avaliados os processos de eletrodeposição do Sn, do Zn e da liga de Sn-Zn na ausência e na presença de ácido tartárico como agente complexante. Inicialmente todos os sistemas foram avaliados por Voltametria Cíclica para determinação dos potenciais de deposição dos metais puros e da liga. Os resultados obtidos mostraram que a presença do complexante desloca o processo de deposição, tanto do Sn como do Zn, para potenciais mais negativos. A codeposição dos metais pode ser verificada pela variação nas formas e potenciais dos picos de deposição obtidos nos voltamogramas da liga quando comparados com os dos metais individuais. A técnica de saltos potenciostáticos (Cronoamperometria) foi utilizada para caracterizar os estágios iniciais de eletrocristalização. Foi constatado que os processos de nucleação do Sn (na ausência e na presença do complexante) e da liga de Sn-Zn, em meio complexado, são governados por nucleação progressiva, enquanto para o Zn em ambos os meios e para a liga de Sn-Zn, em meio não complexado, não foram bem definidos, podendo ser caracterizados como processos mistos. Filmes obtidos em diferentes potenciais de deposição foram caracterizados por voltametria de dissolução anódica, Microscopia Eletrônica de Varredura (MEV), Espectroscopia por Energia Dispersiva de Raios-X (EDX). Foi observado que com a utilização do ácido tartárico era possível obter depósitos mais uniformes e homogêneos e, aparentemente, houve favorecimento do processo de redução e obtenção de um revestimento mais protetor. Também foram realizadas análises de morfologia, composição e Difração de Raios-X (DRX) de ligas de Sn-Zn eletrodepositadas galvanostaticamente variando o complexante (tartarato duplo de potássio e sódio ou gluconato de sódio) e a corrente de deposição (5,0 mA cm-2 e 30,0 mA cm-2). Verificou-se que, com a utilização de uma densidade de corrente menor, os filmes obtidos apresentaram maior uniformidade, enquanto os obtidos com uma densidade de corrente maior apresentaram cristais menores devido a uma maior velocidade de nucleação neste último caso. Além disso, pode-se dizer que o tartarato favoreceu a deposição de Zn em relação ao gluconato. Com a análise por DRX foi possível observar que as ligas são constituídas de fase separadas de cristais de Sn e de Zn, não formando qualquer composto intermetálico.

Lorsqu'un champ magnétique est appliqué au cours de la solidification directionnelle, une convection dans la phase liquide peut être induite par l'effet thermoélectrique. En effet la présence d'un gradient de température le long du front de solidification peut provoquer la circulation du courant thermoélectrique, qui interagit avec le champ magnétique appliqué pour créer un écoulement (convection thermo électromagnétique-TEMC). Les conditions de transport de soluté et de l'énergie sont affectées par cette convection, donc il y a influence sur l'espacement des dendrites et la macro-ségrégation des composants de l'alliage. Dans ce travail, l'influence du champ magnétique sur la solidification directionnelle d'alliages métalliques est étudiée. Des travaux expérimentaux de la solidification directionnelle de Sn-Pb et Sn-Bi alliages sont réalisés. La solidification directionnelle dans la configuration Bridgman est effectuée avec ou sans champ magnétique appliqué. L'influence, sur la solidification, du champ magnétique et d'un courant électrique (AC et DC) appliqués est étudiée. Les mouvements du liquide provoquent de fortes macro-ségrégations ainsi qu'un modification des espacements interdendritiques. Les résultats expérimentaux sont interprétés à la lumière d'une modélisation heuristique. Le cas d'un champ magnétique tournant a été aussi étudié. Ainsi, la valeur de la rotation du champ est choisie pour ralentir assez brassage électromagnétique sans pour autant supprimer les effets de TEMC. À faible vitesse de tirage et faible vitesse de rotation faible champ une macro-ségrégation en forme de spirale a pu être obtenue. / If magnetic field is applied during directional solidification, liquid phase convection can be induced by means of thermoelectromagnetic effect. Temperature gradient at the solidification front can cause thermoelectric current circulation, which then interacts with field and creates convection (Thermoelectromagnetic convection-TEMC). Solute and energy transport conditions are affected by this convection, thus it influences dendrite spacing and macrosegregation of the alloys. In this work magnetic field influence on the directional solidification of metallic alloys is studied. Experimental work of directional solidification of Sn-Pb and Sn-Bi alloys is done. Alloys are directionally solidified in Bridgman setup without or with applied magnetic field. Influence on the structure by magnetic field and applied electric current (AC and DC) is studied in this work. Analytical and experimental results are compared and interpreted. Bridgman solidification under rotating transverse magnetic field is studied as well, field rotation value is chosen to be slow enough that electromagnetic stirring does not fully suppress effects of TEMC. At low pulling velocity and low field rotation velocity spiral shaped component macrosegregation can be achieved.

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-05-12T13:11:00Z No. of bitstreams: 1 arquivo total.pdf: 5933598 bytes, checksum: f90080e0529915a4c5c37308259bee89 (MD5) / Made available in DSpace on 2016-05-12T13:11:01Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 5933598 bytes, checksum: f90080e0529915a4c5c37308259bee89 (MD5) Previous issue date: 2015-03-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Zinc stannate (Zn2SnO4) and zinc titanate (Zn2TiO4) are inverse spineltype oxides and stand out due to their optical, electrical, magnetic, semiconductor and photocatalytic properties. In this work, the two materials were combined in order to obtain a solid solution, Zn2Sn1-xTixO4 (x= 0; 0.25; 0.50; 0.75; 1.0), using the modified-Pechini method, in order to evaluate the influence of the Sn4+ ions substitution by Ti4+ ones in the spinel lattice for application as catalysts in the photodiscoloration of the golden yellow remazol. Catalysts were characterized by the X-ray diffraction (XRD), infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy and surface area measurements (BET). XRD results showed that the materials presented a high long range order when heat treated at 700 °C, using zinc acetate and pH = 1. IR and Raman spectra confirmed the presence of the [TiO6] and [SnO6] octahedra and (ZnO4) tetrahedron. The parameters used in the dye discoloration were: catalyst mass and irradiation times. The results showed that a higher irradiation time provided a better efficiency. Zn2SnO4 presented the best result, with 81 % of discoloration after 4 h of irradiation. As tin was replaced by titanium in the spinel structure, the catalyst efficiency decreased, achieving 37 % for the Zn2TiO4. / O estanato (Zn2SnO4) e o titanato de zinco (Zn2TiO4) são óxidos do tipo espinélio inverso, destacam-se devido a suas propriedades óticas, elétricas, magnéticas, semicondutoras e fotocatalíticas. Nesse trabalho, os dois materiais foram combinados com a finalidade de obter uma solução sólida, Zn2Sn1-xTixO4, (x= 0; 0,25; 0,50; 0,75; 1,0), utilizando o método Pechini modificado, de modo a investigar a influência da substituição dos íons Sn4+ por íons Ti4+ na rede do espinélio para aplicação como catalisadores na fotodescoloração do corante amarelo remazol ouro. Os catalisadores foram caracterizados pelas técnicas de difração de raios-X (DRX), espectroscopia na região do infravermelho (IV), espectroscopia na região do ultravioleta visível (UV-Vis), espectroscopia Raman e medida de área superficial por BET. Os resultados de DRX mostraram que os materiais apresentaram alta organização a longo alcance, quando calcinados a 700 °C, utilizando acetato de zinco e pH 1. Os espectros de IV e Raman confirmaram a presença dos octaedros [ZnO6], [TiO6],[SnO6] e tetraedro (ZnO4). Os parâmetros utilizados na descoloração do corante foram: massa fixa de catalisador e tempos de radiação. Os resultados mostraram que um maior tempo de radiação proporcionou maior eficiência. O Zn2SnO4 apresentou o melhor resultado, com descoloração de 81% após 4 h de radiação. À medida que o estanho foi substituído pelo titânio na estrutura do espinélio, a eficiência do catalisador foi decrescendo, chegando a 37% para o Zn2TiO4.

Einleitung/ Zielstellung Zusätzlich zur Gammastrahlung emittiert 99mTc ca. 5 niederenergetische Auger-Elektronen mit Reichweiten von wenigen Nanometern im Gewebe. Diese haben für die nuklear-medizinische Diagnostik keine Bedeutung. Es wird jedoch über eine therapeutische Nutzung diskutiert, wofür eine Anreicherung der Auger-Elektronen-Emitter in einem strahlensensitiven Zellkompartiment erforderlich ist. Ziel der Arbeit war es, verschiedene [99mTc]Tc-Radiopharmaka hinsichtlich ihres Uptakeverhaltens, der subzellulärer Verteilung und des Retentionsverhaltens in vitro zu untersuchen, sowie die mutmaßlich durch den Auger-Effekt hervorgerufene Radiotoxizität der [99mTc]Tc-markierten Radiopharmaka zu vergleichen und die gewonnenen Ergebnisse in Hinblick auf potentielle extranukleäre strahlensensitive Targets zu interpretieren. Material und Methode Durchgeführt wurden die Versuche im ersten Abschnitt der Arbeit an Natrium-Iodid-Symporter (NIS)-positiven FRTL-5-Schilddrüsenzellen. Von [99mTc] Pertechnetat ([99mTc]TcO4-), [99mTc]TcO4- nach Vorinkubation von Perchlorat ([99mTc]TcO4-/ ClO4-), [99mTc]Tc-Hexakis-2-Methoxyisobutylisonitril ([99mTc]Tc-MIBI), [99mTc]Tc-Hexamethyl-Propylenaminoxim ([99mTc]Tc-HMPAO) und [99mTc]TcO4- nach Vorinkubation von Zinn-Pyrophosphat (Sn- PYP/ [99mTc]TcO4-) wurden die intrazelluläre Radio¬nuklid¬aufnahme und die subzelluläre Verteilung untersucht. Basierend auf den Ergebnissen dieser Versuche wurde die mittlere absorbierte Zellkerndosis kalkuliert. Zur Beurteilung der strahlenbiologischen Wirkung wurde das klonogene Zellüberleben mit der Anzahl residualer gH2AX-Foci (DNA-Schaden) verglichen und die Wirkung der [99mTc]Tc Tracer auf den Zellzyklus von FRTL-5-Zellen untersucht. Im zweiten Abschnitt der Arbeit wurde an EGFR-positiven A431-Zellen die radiotoxische Wirkung in Abhängigkeit von der intra¬zellulären Lokalisation von [99mTc]Alexa(488)-C225-Cyclooctin-Dpa-Tc(CO)3 ([99mTc]Tc-C225), [99mTc]Tc-HMPAO und [99mTc]TcO4- auf das klonogene Zellüberleben untersucht. Ergebnisse und Diskussion Aufgrund verschiedener Uptakemechanismen zeigte jedes der untersuchten [99mTc]Tc-Radiopharmaka Unterschiede im zeitlichen Verlauf der Uptakekinetik. Durch Blockierung des NIS durch ClO4- konnte eine intrazelluläre Aufnahme von [99mTc]TcO4- verhindert werden, wogegen durch Vorinkubation mit Sn-PYP die zelluläre Aufnahme von [99mTc]TcO4- um das 22-fache gesteigert wurde. [99mTc]Tc-MIBI und [99mTc]Tc-HMPAO wurden aufgrund ihrer lipophilen Eigenschaften unabhängig vom NIS passiv in die Zelle transportiert. Die Untersuchung der intrazellulären Verteilung ergab für [99mTc]Tc-HMPAO und Sn-PYP/ [99mTc]TcO4- eine vergleichbar hohe Anreicherung in der Membran/Organellen-Fraktion sowie in der Zellkernfraktion. Von [99mTc]TcO4- und [99mTc]Tc-MIBI wurde die Hauptaktivität in der Zytosol-Fraktion und nur geringe Anteile in der Membran/Organellen-Fraktion sowie in der Zellkernfraktion nachgewiesen. In guter Übereinstimmung zur subzellulären Verteilung zeigten Sn-PYP/ [99mTc]TcO4- und [99mTc]Tc-HMPAO eine fast vollständige, hingegen [99mTc]Tc-MIBI und [99mTc]TcO4- nur eine geringe Retention. Aufgrund der genannten Unterschiede wurde bei gleicher inkubierter Aktivitätskonzentration folgende Reihenfolge der resultierenden Zellkerndosis ermittelt: [99mTc]TcO4- < [99mTc]Tc-MIBI < [99mTc]Tc-HMPAO < Sn-PYP/ [99mTc]TcO4-. [99mTc]TcO4- und [99mTc]Tc-HMPAO zeigten eine ähnliche Wirkung auf das klonogene Zellüberleben und auf den Zellzyklus. Jedoch bewirken sie eine wesentlich stärkere Reduzierung des Überlebens und einen stärkeren G2-Arrest als [99mTc]Tc-MIBI und Sn-PYP/ [99mTc]TcO4-, wobei [99mTc]Tc-MIBI bei allen drei untersuchten biologischen Endpunkten die geringste Wirkung zeigte. Bei einer vergleichbaren Reduktion des Zellüberlebens von [99mTc]TcO4- und [99mTc]Tc-HMPAO induzierte [99mTc]Tc-HMPAO lediglich die Hälfte der gH2AX-Foci im Vergleich zu [99mTc]TcO4-. Die trotz geringerem DNA-Schaden vergleichbare radiotoxische Wirkung zeigte, dass das klonogene Zellüberleben nicht allein vom DNA-Schaden abhängt. Daraus folgt, dass es außer der Kern-DNA noch weitere strahlensensitive Kompartimente gibt, die durch [99mTc]Tc-HMPAO stärker geschädigt wurden als von den anderen untersuchten [99mTc]Tc Tracern. Ein mögliches extranukleäres strahlensensitives Target ist die Zellmembran, so dass im zweiten Teil der Arbeit zur Überprüfung der Radiosensitivität der Zellmembran die radiotoxische Wirkung von [99mTc]Tc-C225 an EGFR-positiven A431-Zellen untersucht wurde. [99mTc]Tc-C225 wurde über den EGFR und [99mTc]Tc-HMPAO aufgrund seiner Lipophilie durch Diffusion intrazellulär aufgenommen. [99mTc]TcO4- dagegen zeigte keine intrazelluläre Aufnahme in die NIS-negativen Zellen und wurde als Referenz für eine extrazelluläre Bestrahlung verwendet. [99mTc]Tc-C225 wies nach einstündiger Inkubation eine Membranbindung von lediglich 10 % auf, die im Laufe von 24 h auf 1,9 % absank. Dies zeigte, dass [99mTc]Tc-C225 rasch in den A431-Zellen internalisiert wurde und dass nur bei sehr kurzen Inkubationszeiten von einer spezifischen Zellmembranmarkierung gesprochen werden kann. [99mTc]Tc-HMPAO ging keine Bindung an die Zellmembran ein. Weiterhin wurde bei der Inkubation steigender Aktivitäts- und Antikörperkonzentrationen von [99mTc]Tc C225 eine Sättigung des EGFR beobachtet, woraus eine wesentlich geringere Zellkerndosis als bei Inkubation von [99mTc]Tc-HMPAO resultierte. Im Vergleich des klonogenen Zellüberlebens zeigten [99mTc]Tc-C225 und [99mTc]Tc-HMPAO bei gleicher Zellkerndosis keine Unterschiede in der radiobiologischen Wirkung. Somit konnte lediglich eine Verstärkung der radiotoxischen Effekte von [99mTc]Tc-C225 an A431-Zellen im Vergleich zur ausschließlich extrazellulären Verteilung von [99mTc]TcO4- gezeigt werden. Schlussfolgerung Die Untersuchung der radiotoxischen Wirkung von [99mTc]Tc-C225 ermöglichte bei den angewendeten Versuchsbedingungen keine Rückschlüsse auf die Strahlensensitivität der Zellmembran. Weiterführende Arbeiten zur Entwicklung eines 99mTc-markierbaren spezifischen Membranmarkers wären notwendig, um klären zu können, ob die Zellmembran ein ähnlich strahlensensitives Target wie die nukleäre DNA ist. Dosimetrische Betrachtungen an den als Modellsystemen dienenden FRTL-5- und A431-Zellen deuten darauf hin, dass aufgrund ungenügender Anreicherung eine therapeutische Wirkung der Auger-Elektronen im Tumorgewebe eher unrealistisch ist. Damit sollte aus gegenwärtiger Sicht die klinische Anwendung von 99mTc auf den diagnostischen Einsatz beschränkt bleiben. Jedoch könnte 99mTc als Auger-Elektronen-Emitter bei spezifischer Anreicherung in definierten Zellkompartimenten als Nano-Tool zur Erforschung der Strahlensensitivität einzelner Zellbestandteile eingesetzt werden. / Introduction In addition to gamma radiation, 99mTc emits approximately 5 low energy Auger and internal conversion electrons per decay, resulting in high ionization density proximal to the radionuclide’s decay position. Low-energy Auger electrons with path lengths of only nanometers cannot be utilized for diagnostic procedures; however, they have frequently been discussed for therapeutic applications. To achieve a radiobiological effect, an intracellular accumulation and distribution in relevant cell compartments of the Auger electron emitter is required. Aim The aim of the thesis was the comparison of different [99mTc]Tc-labeled compounds concerning their intracellular uptake, subcellular distribution and retention in vitro. Furthermore the radiotoxicity caused by the Auger effect has to be investigated. Material and Methods The intracellular radionuclide uptake, subcellular distribution (ProteoExtract®-Kit) and retention of [99mTc] pertechnetate ([99mTc]TcO4-), [99mTc]TcO4- after pre-incubation of perchlorate ([99mTc]TcO4-/ClO4-), [99mTc]TcO4- after pre-incubation of stannous pyrophosphate ([99mTc]TcO4-/Sn-PYP), [99mTc]Tc-hexamethyl-propylene-aminoxime ([99mTc]Tc-HMPAO) and [99mTc]Tc-hexakis-2-methoxyisobutylisonitrile ([99mTc]Tc-MIBI) were quantified in sodium-iodide symporter (NIS)-positive rat thyroid FRTL-5 cells. Basing on these results the mean absorbed nucleus dose was calculated. Radiotoxicity was investigated using phosphorylated histone H2AX (gH2AX foci), clonogenic cell survival and cell cycle analyzes. Additionally the radiotoxicity of [99mTc]Alexa(488)-C225-Cyclooctin-Dpa-Tc(CO)3 ([99mTc]Tc-C225) was compared with the one of [99mTc]TcO4- and [99mTc]Tc -HMPAO depending on the subcellular distribution in EGFR-positive A431 cells. Results and Discussion For the analyzed [99mTc]Tc-labeled compounds we detected differences in the time courses of the uptake kinetics caused by different uptake mechanisms into the FRTL-5 cells. The radionuclide uptake of [99mTc]TcO4- was blocked in the presence of perchlorate and increased by a factor of approximately 22 after pre-incubation of Sn-PYP. The lipophilic complexes [99mTc]Tc-MIBI and [99mTc]Tc-HMPAO crossed the cell membrane through passive transport via diffusion. The compartmental analysis indicated that [99mTc]Tc-HMPAO and [99mTc]TcO4-/Sn-PYP revealed a comparable high uptake in the nucleus and in the membrane/organelle fraction. [99mTc]TcO4- and [99mTc]Tc-MIBI were preferentially distributed in the cytosol, with lower amounts of the accumulated activity in both the membranes/organelles and the nucleus compared with the other compounds. In good agreement with the subcellular distribution [99mTc]Tc-HMPAO, [99mTc]TcO4-/Sn-PYP showed a nearly complete retention and [99mTc]TcO4-, [99mTc]Tc-MIBI a low retention. Due to the differences mentioned above the following sequence of the calculated mean nucleus dose for identical activity concentrations was determined: [99mTc]TcO4- < [99mTc]Tc-MIBI < [99mTc]Tc-HMPAO < Sn PYP/ [99mTc]TcO4-. [99mTc]TcO4- and [99mTc]Tc-HMPAO caused a similar reduction of the cell survival and a dose dependent G2-arrest. [99mTc]Tc-MIBI and Sn-PYP/ [99mTc]TcO4- are both less radiotoxic in terms of the estimated nucleus dose compared with [99mTc]TcO4- and [99mTc]Tc-HMPAO. Despite the similar effect on the cell survival [99mTc]Tc-HMPAO induced only half of the residual gH2AX foci than [99mTc]TcO4-. These findings reveal that clonogenic cellular survival is not solely determined by the DNA-DSB response, which may suggest the involvement of extra-nuclear radiosensitive targets in cell inactivation. A possible extra-nuclear radiosensitive target is the cell membrane. That’s why the aim of the second part of the thesis is the investigation of the radiosensitivity of the cell membrane. Therefore the radiotoxic influence of [99mTc]Tc-C225 was analyzed at EGFR-positive A431 cells. [99mTc]Tc-C225 was taken up over the EGFR and the lipophilic [99mTc]Tc-HMPAO was transported via diffusion over the cell membrane. In contrast, [99mTc]TcO4- did not show any intracellular uptake into the NIS-negative cells and therefore was used as extracellular reference. An incubation of [99mTc]Tc-C225 for one hour resulted to a membrane binding of only 10 %, which was reduced to 1.9 % after 24 hours. This demonstrated a fast internalization into A431-cell. Therefore only in the case of a very short incubation time [99mTc]Tc-C225 leads to a specific targeting of the cell membrane. [99mTc]Tc-HMPAO did not bind to the cell membrane. Furthermore the incubation of increasing concentrations of activity and antibody resulted in a saturation of the EGFR, leading to a significant lower nucleus dose in comparison to the incubation of [99mTc]Tc-HMPAO. Concerning the clonogenic cell survival no differences in the radiotoxicity of [99mTc]Tc-C225 and [99mTc]Tc-HMPAO were observed for equal nucleus dose. Thus only an amplification of the radiotoxic effects of [99mTc]Tc-C225 in comparison to the extracellular distribution in A431 cells of 99mTc-pertechnetate was observed. Conclusion The investigation of the radiotoxic effect of [99mTc]Tc-C225 did not allow any conclusions about the radiosensitivity of the cell membrane under the given experimental conditions. For clarifying if the radiosensitivity of the cell membrane is comparable to the one of the nucleus DNA further experiments for the development of a [99mTc]Tc-labeled specific target for the cell membrane are necessary. On the basis of the dosimetric considerations of the FRTL-5 cells and A431 cells used as model systems it can be concluded that because of an insufficient accumulation a therapeutic radiotoxic effect of the Auger electrons is not realistic. Therefore the clinical use of 99mTc should be limited to the diagnostics. Nevertheless specific accumulated Auger electrons of 99mTc could be applied in the field of investigation as nano-tools for the subcellular analysis of radiotoxicity.

En Europe, l’utilisation en agriculture de grandes quantités d’engrais chimiques est la principale cause de contamination des eaux. Les concentrations en nitrate dans l’eau deviennent nuisibles pour les personnes lorsqu’elles dépassent certaines limites car elles sont la cause de méthémoglobinémie, de cancers et agissent comme perturbateurs endocriniens. L’hydrogénation catalytique hétérogène des nitrates est la méthode de dénitration la plus connue et la plus efficace due à la grande sélectivité pour les produits non toxiques, azote et eau. La photocatalyse hétérogène a émergé comme une voie très prometteuse de dénitration du fait de la possibilité d’utiliser la lumière solaire ce qui la rend commercialement compétitive et compatible avec la protection de l’environnement. Les procédés catalytiques conduisent fréquemment à l’obtention des sous-produits toxiques nitrite et ion ammonium, ainsi qu’à des oxydes d’azote gazeux NOx. Dans ce travail ont été utilisés des catalyseurs monométalliques supportés (Ag/P25, Pt/P25), leur mélange physique, et des catalyseurs bimétalliques supportés (Ag-Pt/P25 et Pd-Sn/P25). Le support oxyde de titane (TiO2) P25 est choisi pour développer un catalyseur performant pour la dénitration à la fois catalytique et photocatalytique permettant d’atteindre les normes requises par l’UE dans l’eau potable (50 mg/L NO3-, 0.5 mg/L NO2-, 0.3 mg/L NH4+). L’influence des teneurs en métaux (Ag: 0.5 – 4 pds.%; Pt: 2 et 4 pds.%), du précurseur Pt (H2PtCl6 (H)/K2PtCl6 (K)), de l’ordre d’imprégnation de Ag et Pt et de la morphologie des particules bimétalliques Pd-Sn (nanoparticules et nanobâtonnets) ont été étudiés. Les conditions expérimentales (présence/absence de H2 ; λ = 254 ou 365 nm; 4W; 45.4 mW/cm2) ont été également variées et les réactions effectuées dans un réacteur batch en PTFE sous atmosphère inerte et dans des conditions standard (catalyseur : 0.7 mg/L ; 100 mg/L NO3- ; 500 r.p.m). Contrairement à la plupart des études précédentes aucun «piégeur de trous» (expl. acides formique ou oxalique) n’a été utilisé dans nos conditions de réaction, Les analyses ont été effectuées par chromatographie ionique ou photométrie. Les propriétés physico-chimiques des catalyseurs ont été déterminées par DRX, Physisorption de N2, MET, DRUV-Vis, XPS, TPR et chimisorption de H2. Le support TiO2 P25 est inactif dans les deux procèdés non photocatalytique et photocatalyique. Le mélange physique Ag/P25+Pt/P25 conduit à une conversion (~ 56%) et sélectivité en N2 (~ 76%) plus élevées dans les conditions non photocatalytiques que chacun des homologues monométalliques, cependant NO2- and NH4+ sont obtenus. Les catalyseurs bimétalliques Ag-Pt(Pt-Ag)/P25 se montrent polyvalents étant actifs dans les procédés non-photocatalytiques et photocatalytiques. Les meilleurs résultats photocatalytiques ont été obtenus sous irradiation ultraviolette de 365 nm et en présence de H2 dû à la synergie entre les électrons générés par irradiation et l’hydrogène dissocié sut Pt. Le Pt imprégné en premier conduit à une conversion plus élevée en raison de l'amélioration de l'accessibilité de NO3- aux sites actifs Ag0 recouvrant partiellement Pt. Toutefois la sélectivité en NO2- est élevée du fait de la faible accessibilité de Pt. Pt imprégné en second décore les ensembles Ag et diminue de ce fait le nombre de sites actifs et la conversion. Le catalyseur bimétallique Pt(4)-Ag(2)/P25(K) conduit au meilleur compromis entre conversion (ca. 45%) et sélectivité en N2 (ca. 80%) dans les conditions photocatalytiques. Ceci est attribué au transfert électronique élevé entre Ag et Pt en forte interaction mis en évidence par XPS. Néanmoins, NO2- et NH4+ sont aussi obtenus. Des travaux sont encore nécessaires pour améliorer le rendement en N2. / In Europe, the agricultural use of nitrates in chemical fertilizers has been a main source of water contamination. High level of soluble nitrate in water becomes harmful pollutant for people when it exceeds the limit causing methemoglobinemia (blue baby syndrome), cancer or act as endocrine disruptor. Conventional catalytic nitrate reduction processes into N2 and H2O lead to some toxic products (NO2-, NH4+, and NOx gases). Alternatively, photocatalytic nitrate removal using solar irradiation and heterogeneous catalysts is a very promising and ecofriendly route, which has been scarcely performed. In this work monometallic supported catalysts (Ag/P25, Pt/P25), their physical mixture, and bimetallic supported catalysts (Ag-Pt(Pt-Ag)/P25 and Pd-Sn/P25) have been used. The support TiO2 P25 was chosen to develop both efficient non-photocatalytic and photocatalytic processes able to reach the EU legislation in drinking water (50 mg/L NO3-, 0.5 mg/L NO2-, 0.3 mg/L NH4+). Different compositions of catalyst including, various metal loadings (Ag: 0.5 – 4 wt%; Pt: 2 and 4 wt%), Pt precursor (H2PtCl6 (H)/K2PtCl6 (K)), Ag and Pt impregnation order, and morphology of Pd-Sn nanoparticles (spherical and nanorods) have been studied. Different experimental conditions (presence/absence of H2; λ = 254 or 365 nm; 4W; 45.4 mW/cm2) have been also evaluated and the experiments performed in a PTFE batch reactor under inert standard operational conditions (0.7 mg/L catalyst ; 100 mg/L NO3- ; 500 r.p.m). Contrary to most previous studies, any hole scavenger (e.g. formic or oxalic acid) was used in the reaction . Analyses were performed by ionic chromatography or photometry. Physico-chemical characterizations of the catalysts were done by XRD, N2-physisorption, TEM, DRUV-Vis, XPS, TPR and H2-Chemisorption in order to explain both the catalytic and photocatalytic performances.The support TiO2 P25 was inactive in both processes. The physical mixture Ag(2)/P25+Pt(4)/P25(H) showed better conversion (ca. 56 %) and N2 selectivity (ca. 76%) under non-photocatalytic conditions than each monometallic catalyst, however NO2- and NH4+ were obtained. Bimetallic Ag-Pt(Pt-Ag)/P25 catalysts exhibit a versatile behavior being active both in the non-photocatalytic and photocatalytic processes. The best photocatalytic conditions were interestingly obtained under the ultraviolet irradiation of 365 nm and in presence of hydrogen. Photocatalytic activity was enhanced in presence of H2 due to synergetic effect induced by light between photogenerated electrons and dissociation of hydrogen on Pt. Therefore, all bimetallic catalysts based on Ag and Pt were tested under these conditions. Pt impregnated first leads to higher conversion due to improved accessibility of NO3- to active Ag0 sites partially covering Pt than the opposite impregnation order where the Pt decorates Ag and reduces the number of active sites. However, high NO2- selectivity at the expense of N2 is obtained in the former case due to low Pt accessibility. The bimetallic catalyst Pt(4)-Ag(2)/P25(K) led to the most interesting conversion (ca. 45%) with the highest selectivity to N2 (ca. 80%) under photocatalytic conditions. This was assigned to the highest electronic transfer between Ag et Pt particles in close contact revealed by XPS. Nevertheless, NO2- and NH4+ are obtained too. Further studies must be done to enhance the catalytic and photocatalytic activity towards desired N2.

Lithium-Ionen-Batterien besitzen ein ausgezeichnetes Potential für die Energiespeicherung. Das derzeit dominierende Anodenmaterial in Lithium-Ionen-Batterien mit einer Energiespeicherkapazität von 339 mAh/g ist Graphit. Als Alternative hierfür bieten sich Lithiumsilicide und Lithiumstannide an. Diese Materialien zeichnen sich durch eine viel größere Speicherkapazität und geringere Selbstentladungspotentiale aus. Für die kommerzielle Anwendung dieser beiden Systeme in Lithium-Ionen-Batterien werden grundlegende und verlässliche thermodynamische Daten benötigt. Derzeit ist die Existenz von sieben Lithiumsiliciden sicher nachgewiesen. Dazu zählen die sechs stabilen Phasen Li17Si4, Li16.42Si4, Li13Si4, Li7Si3, Li12Si7, die Hochdruckphase LiSi und die metastabile Phase Li15Si4. Für die ersten fünf genannten Phasen wurden in der ersten Förderperiode des Schwerpunktprogrammes 1473 Wärmekapazitäten und Standardentropien bestimmt. Bei den Lithiumstanniden sind derzeit sieben Phasen gesichert belegt. Allerdings existiert für keine Phase der Lithiumstannide ein verlässlicher thermodynamischer Basisdatensatz. Aus diesem Grund wurden für die beiden zuletzt genannten Lithiumsilicide (Li15Si4 und LiSi), sowie für die Lithiumstannide Li17Sn4, Li7Sn2, Li13Sn5 und Li7Sn3 die fehlenden thermodynamischen Daten experimentell bestimmt. Die hergestellten Phasen wurden zunächst mittels Röntgenbeugung, thermischer und chemischer Analyse charakterisiert. Ein Schwerpunkt dieser Arbeit lag auf der experimentellen Bestimmung der Wärmekapazitäten in einem Temperaturbereich von 2 K bis zur jeweiligen Zersetzungstemperatur der untersuchten Verbindungen. Hierfür wurden zwei unterschiedliche Kalorimeter verwendet: ein Physical Property Measurement System (Quantum Design) von 2 K bis 300 K und eine DSC 111 (Setaram), beginnend ab 300 K. Die experimentellen Daten konnten mit Messunsicherheiten von 1 % bis 2 % über 20 K und bis zu 20 % unterhalb von 20 K angegeben werden. Die Messungen bei niedrigen Temperaturen erlauben zudem die Berechnung der Standardentropien, sowie die Bestimmung von elektronischen Beiträgen und Gitterschwingungsbeiträgen zur Wärmekapazität. Weiterhin ist Fokus dieser Arbeit die Bestimmung der Standardbildungsenthalpien der Lithiumsilicide und Lithiumstannide auf Basis von Wasserstoffsorptionsmessungen mittels einer Sieverts-Apparatur. Hierfür wurden erstmals Messungen an den Lithiumsiliciden ausgehend von Li17Si4, LiH:Si (Li:Si = 17:4), Li16.42Si4 und LiSi durchgeführt. Für die Lithiumstannide dienten als Ausgangsmaterial Li17Sn4, LiH:Sn (Li:Sn =17:4), sowie Li7Sn2 und LiH:Sn (Li:Sn = 7:2). Die Anwendung des van´t-Hoff-Plots resultierte in Messunsicherheiten von mindestens 10 %. Aus diesem Grund wurde eine alternative Auswertemethode gewählt, bei der die ermittelten Wärmekapazitäten und Standardentropien mit den Gleichgewichtsdrücken aus den Wasserstoffsorptionsmessungen miteinander verknüpft werden. Auf diese Weise konnten Standardbildungsenthalpien für die untersuchten Phasen mit Fehlern kleiner 1 % ermittelt werden. Aus den Ergebnissen dieser Arbeit resultierte ein vollständiger, gesicherter thermodynamischer Datensatz für das System Li-Si. Das berechnete Li-Si-Phasendiagramm ist im sehr guten Einklang mit experimentellen literaturbekannten Daten. Für die Lithiumstannide erfolgte eine Validierung der ermittelten thermodynamischen Werte. Die in dieser Arbeit erzielten Ergebnisse liefern einen wesentlichen Beitrag zur Verbesserung der Datenbasis für thermodynamische Berechnungen und für das Verständnis von Phasensequenzen und Gleichgewichten beim Einsatz von Lithiumsiliciden bzw. Lithiumstanniden als Anodenmaterialien in Lithium-Ionen-Batterien.

Dans le domaine du photovoltaïque, le composé Cu2ZnSnS4 (CZTS) serait une solution alternative aux composés classiques en couches minces qui sont à base d'éléments chers ou toxiques. Mise à part un gap de 1.5 eV et un coefficient d'absorption de 10-4 cm-1, il est constitué d'éléments bénins et abondants, ce qui réduira le coût de revient de la cellule finale. Il connaît un intérêt particulier et bien qu'il ait atteint un rendement de 12.6%, il demeure méconnu quant à l'effet de ses propriétés intrinsèques sur ses performances photovoltaïques. En raison de la volatilité du soufre, des déviations à la stoechiométrie peuvent être enregistrées rendant la synthèse d'un monophasé très difficile. Les phases secondaires sont difficilement inévitables, elles constituent une barrière à la formation de la phase CZTS, ce qui rend difficile la fixation du gap et augmente le taux de recombinaison des porteurs de charges. Dans le cadre de cette thèse, une série de composés CZTS a été synthétisée par réaction à l'état solide et liquide avec des excès en soufre pour compenser les pertes liées à la décomposition chimique et l'évolution de la composition dans le diagramme de phase Cu-Zn-Sn-S. L'effet du souffre sur la cristallinité, la pureté et l'ordre dans la maille a été mis en évidence. Le domaine monophasé a été déterminé et il a été montré qu'il est possible d'obtenir des composés de grande pureté. La morphologie par microscopie optique a révélé des polycristaux granulaires avec rejet des phases secondaires dans les joints de grains. Le composé Cu2ZnGeS4 (CZGS) pourrait trouver des applications dans le photovoltaïque et l'optoélectronique. L'ajout de l'étain pourrait sensiblement améliorer la cinétique réactionnelle et la cristallinité d'où l'intérêt d'étudier le composé Cu2ZnGexSn(1-x)S4 ( x=0 à 1). L'analyse cristallographique par DRX a montré une transition structurale d'une kesterite pour CZTS vers une orthorhombique pour CZGS. Le composé Cu2Zn(Ge,Sn)S4 est une solution solide avec gap de miscibilité entre 0 et 20% de germanium / In the photovoltaic field, Cu2ZnSnS4 (CZTS) compound is an alternative solution to substitute solar thin film based on toxically and expensive conventional materials. The gap of this material is around 1.5eV and absorption coefficient 10-4 cm-1, in addition this material is composed of abundant and harmless elements which will strongly decrease the price of the final cell. This material present a particular interest and in spite of the efficiency which reached 12.6%, till now this material is not well known especially the effect of its intrinsic properties on its photovoltaic performances. Because of the sulfur volatility, it is difficult to prepare single phase compound. Also, it is difficult to surmount the formation of secondary phases which are a barrier to CZTS complete reaction allowing difficulties to fix the gap and increase the recombination of carrier. In the frame of this PhD thesis, a serial of CZTS compounds has been synthetized from solid and liquid state using an excess of sulfur to compensate its volatility and the composition change in the Cu-Zn-Sn-S equilibrium diagram. We have determined the monophased field and we have shown that it is possible to obtain a compound with high purity. By optical microscopy we have observed a granular morphology composed of polycrystalline grains and the secondary phases were rejected in the grains boundary. The Cu2ZnGeS4 (CZGS) compound can be used for photovoltaic and optoelectronic applications. The addition of tin can be a good way to improve the kinetic reaction and the crystallinity of this materials, So, it is interesting to study Cu2ZnGexSn(1-x)S4 ( x=0 to 1) compound . By X ray diffraction we have shown a structure transition from Kesterite (CZTS) to orthorhombic (CZGS). The Cu2Zn(Ge,Sn)S4 compound is a solid solution with a gap miscibility between 0 and 20% of germanium