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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

La skutterudite PrOs4Sb12: supraconductivité et corrélations

Méasson, Marie-Aude 08 December 2005 (has links) (PDF)
La skutterudite PrOs4Sb12 est le premier composé à fermion lourd supraconducteur à base de Praséodyme. Cette thèse s'attache à répondre à plusieurs questions le concernant comme la détermination de l'intensité de la renormalisation <br />de la masse des quasi-particules, la nature et le mécanisme à l'origine de la supraconductivité et la nature intrinsèque ou extrinsèque de la double transition supraconductrice vue en chaleur spécifique. <br /><br />Nous proposons une interpolation de la chaleur spécifique en phase normale en tenant compte des interactions magnétiques entre ions Pr. Nous extrayons alors un terme électronique de chaleur spécifique compris entre 300 et 750mJ/K2.mol(Pr). L'analyse du saut en chaleur spécifique à la transition supraconductrice confirme que les quasi-particules lourdes sont impliquées dans la supraconductivité et que la supraconductivité est en régime de couplage fort. Des caractérisations systématiques par chaleur spécifique, résistivité et susceptibilité indiquent que la double transition apparaît dans les meilleurs échantillons. Néanmoins nous apportons les premiers doutes sérieux sur sa nature intrinsèque, parce que nous avons trouvé plusieurs échantillons avec une unique transition étroite et parce qu'une forte dispersion dans la valeur du rapport des deux sauts en chaleur spécifique a été mise en évidence. De plus, en établissant les diagrammes de phase supraconducteurs sous champ magnétique et sous pression jusqu'à 4.2 GPa par chaleur spécifique alternative, nous montrons que les deux transitions <br />supraconductrices Tc1 et Tc2 présentent des comportements similaires. Nous avançons l'hypothèse que le fort changement dans l'évolution des Tc sous pression au dessus de 2 GPa est dû à un changement de nature de la supraconductivité (impliquant des fluctuations puis uniquement phononique à respectivement basse et haute pression) en lien avec l'augmentation du gap de champ cristallin des ions Pr sous pression. L'analyse du second champ critique Hc2(T) montrent la présence d'au moins deux bandes supraconductrices et conclue à la nature singulet du spin des paires de Cooper. Une forte distorsion du réseau de vortex, constante avec le champ et la température, est obtenue par diffraction de neutrons. Des mesures supplémentaires ou un nouveau calcul seraient nécessaires pour trancher entre une explication basée sur la présence de zéros dans le gap supraconducteur et une analyse basée sur la topologie de la surface de Fermi en symétrie Th.
22

La skutterudite PrOs4Sb12: supraconductivité et corrélations

Méasson, Marie-Aude 08 December 2005 (has links) (PDF)
La skutterudite PrOs4Sb12 est le premier composé à fermion lourd supraconducteur à base de Praséodyme. Cette thèse s'attache à répondre à plusieurs questions le concernant comme la détermination de l'intensité de la renormalisation <br />de la masse des quasi-particules, la nature et le mécanisme à l'origine de la supraconductivité et la nature intrinsèque ou extrinsèque de la double transition supraconductrice vue en chaleur spécifique. <br /><br />Nous proposons une interpolation de la chaleur spécifique en phase normale en tenant compte des interactions magnétiques entre ions Pr. Nous extrayons alors un terme électronique de chaleur spécifique compris entre 300 et 750mJ/K2.mol(Pr). L'analyse du saut en chaleur spécifique à la transition supraconductrice confirme que les quasi-particules lourdes sont impliquées dans la supraconductivité et que la supraconductivité est en régime de couplage fort. Des caractérisations systématiques par chaleur spécifique, résistivité et susceptibilité indiquent que la double transition apparaît dans les meilleurs échantillons. Néanmoins nous apportons les premiers doutes sérieux sur sa nature intrinsèque, parce que nous avons trouvé plusieurs échantillons avec une unique transition étroite et parce qu'une forte dispersion dans la valeur du rapport des deux sauts en chaleur spécifique a été mise en évidence. De plus, en établissant les diagrammes de phase supraconducteurs sous champ magnétique et sous pression jusqu'à 4.2 GPa par chaleur spécifique alternative, nous montrons que les deux transitions <br />supraconductrices Tc1 et Tc2 présentent des comportements similaires. Nous avançons l'hypothèse que le fort changement dans l'évolution des Tc sous pression au dessus de 2 GPa est dû à un changement de nature de la supraconductivité (impliquant des fluctuations puis uniquement phononique à respectivement basse et haute pression) en lien avec l'augmentation du gap de champ cristallin des ions Pr sous pression. L'analyse du second champ critique Hc2(T) montrent la présence d'au moins deux bandes supraconductrices et conclue à la nature singulet du spin des paires de Cooper. Une forte distorsion du réseau de vortex, constante avec le champ et la température, est obtenue par diffraction de neutrons. Des mesures supplémentaires ou un nouveau calcul seraient nécessaires pour trancher entre une explication basée sur la présence de zéros dans le gap supraconducteur et une analyse basée sur la topologie de la surface de Fermi en symétrie Th.
23

Etude de skutterudites de terres-rares (R) et de métaux d (M) du type RM4Sb12 : de nouveaux matériaux thermoélectriques pour la génération d'électricité

Bérardan, David 01 July 2004 (has links) (PDF)
Cette étude présente les propriétés de nouveaux composés de la famille des skutterudites, de formule générale Ry-pR'pFe4-x(Co/Ni)xSb12 (R et R' = Ce, Yb, Ba, La), d'une part du point de vue des propriétés physiques, et d'autre part du point de vue de leurs potentialités pour la conversion de chaleur en électricité par effet thermoélectrique. <br />La valence de Yb est non entière et elle décroît lorsque la fraction de Yb augmente. En revanche, elle ne dépend pas de la température ce qui met en évidence un état de valence mixte (deux sites pour deux états de valence). Le cérium est quant à lui toujours trivalent dans ces composés. Le système passe d'un régime d'interactions dominantes ferromagnétiques pour Yb0,9Fe4Sb12 avec Yb presque divalent à un régime d'interactions antiferromagnétiques pour Ce0,9Fe4Sb12 avec Ce trivalent. Le moment paramagnétique a été décomposé suivant les sous-systèmes R, R' et Fe4Sb12. La contribution de ce dernier ne dépend pas la nature et de la valence de R et R', mais elle décroît si Fe est substitué par Ni. Une transition magnétique est présente pour R = Yb et Ba à 6,5 K sans doute vers un état verre de spin. <br />Les propriétés de transport électrique et thermique ont été mesurées de 5K à 800K ce qui a permis de discuter des potentialités de ces matériaux pour la génération d'électricité par effet thermoélectrique. Le facteur de puissance et le facteur de mérite ZT sont plus élevés dans les composés de type Cey/2Yby/2Fe4-x(Co/Ni)xSb12 que dans ceux de type RyFe4-x(Co/Ni)xSb12 présentés dans la littérature.
24

Structural and Thermoelectric Properties of Binary and Ternary Skutterudite Thin Films

Daniel, Marcus 20 May 2015 (has links) (PDF)
Increasing interest in an effciency enhancement of existing energy sources led to an extended research in the field of thermoelectrics. Especially skutterudites with their high power factor (electric conductivity times Seebeck coefficient squared) are suitable thermoelectric materials. However, a further improvement of their thermoelectric properties is necessary. The relatively high thermal conductivity can be decreased by introducing loosely bound guest ions, whereas atom substitution or nanostructuring (as thin films) could yield an increased power factor. The present work proves the feasibility to deposit single phase skutterudite thin films by MBE technique. In this regard CoSby and FeSby film series were deposited with three different methods: i) codeposition at elevated temperatures, ii) codeposition at room temperature followed by post-annealing, and iii) modulated elemental reactant method. The structural and thermoelectric properties of these films were investigated by taking the thermal stability of the film and the substrate properties into account. Compared to the stoichiometric Sb content of skutterudites of 75 at.%, a small excess of Sb is necessary for achieving single phase skutterudite films. It was found, that the deposited single phase CoSb3 films reveal bipolar conduction (and therefore a low Seebeck coefficient), whereas FeSb3 films show p-type conduction and very promising power factors at room temperature. The need of substrates with a low thermal conductivity and a suitable thermal expansion coefficient is also demonstrated. A high thermal conductivity influences the measurements of the Seebeck coefficient and the obtained values will be underestimated by thermal shortening of the film by the substrate. If the thermal expansion coefficient of film and substrate differ strongly from each other, crack formation at the film surface was observed. Furthermore, the realization of controlled doping by substitution as well as the incorporation of guest ions was successfully shown. Hence, this work is a good starting point for designing skutterudite based thin film structures. Two successful examples for such structures are given: i) a thickness series, where a strong decrease of the resistivity was observed for films with a thickness lower than 10nm, and ii) a FexCo1-xSb3 gradient film, for which the gradient was maintained even at an annealing temperature of 400°C.
25

Reação de desinserção em SbxCoSb3-x

Miotto, Fernanda 16 July 2010 (has links)
O composto SbxCoSb3-x foi produzido em altas pressões e altas temperaturas em uma reação de auto-inserção a partir da escuterudita binária CoSb3. A reação de auto-inserção é caracterizada pelo colapso de átomos de Sb para o sítio 2a, no interior das cavidades formadas pelos átomos de Co e Sb na estrutura da escuterudita. A reação inversa, de desinserção de Sb, ocorre quando o composto SbxCoSb3-x é aquecido à pressão ambiente. O acompanhamento desta reação de desinserção por meio de medidas de calorimetria exploratória diferencial (DSC), difração de raios X (DRX) e de resistividade elétrica constitui o objetivo principal deste trabalho. A amostra de CoSb3 foi sintetizada conforme rota proposta pela literatura. A síntese foi confirmada por meio de DRX, e não foi observada a presença de fases contaminantes. Amostras cilíndricas da fase SbxCoSb3-x foram obtidas submetendo CoSb3 a pressões de 7,7 GPa e temperaturas de até 550ºC, com o auxílio de prensas hidráulicas e câmaras toroidais disponíveis no Laboratório de Altas Pressões e Materiais Avançados LAPMA no Instituto de Física da Universidade Federal do Rio Grande do Sul IF/UFRGS. A presença da fase SbxCoSb3-x foi comprovada por meio de análises de DRX. Para determinação da resistividade elétrica de amostras ricas de fase SbxCoSb3-x foi desenvolvido um sistema DC, aplicável a amostras cilíndricas de pequeno volume tal como as obtidas em altas pressões e altas temperaturas. A aferição do sistema foi feita através de medidas de resistividade elétrica de materiais de referência (NIST-SRM 1461 e NIST-SRM 8426). As medidas de DSC revelaram a presença de dois eventos térmicos. Um pico endotérmico foi observado em 118ºC e não está associado a alterações estruturais e nem a variações significativas na resistividade elétrica. O evento exotérmico, que inicia em 180ºC, constitui a assinatura da desinserção dos átomos de Sb do interior da escuterudita, como verificado por análises de DRX e medidas elétricas. Após aquecimento até 350ºC, a amostra rica na fase SbxCoSb3-x retorna à fase estável, CoSb3. A reação de desinserção obedece a uma cinética de primeira ordem, cuja entalpia de transição é de aproximadamente 50 J /g e uma energia de ativação de 83 kJ/mol. A resistividade elétrica à temperatura ambiente de amostras ricas em SbxCoSb3-x é cerca de dez vezes inferior à do CoSb3. Este resultado, aliado possivelmente a uma baixa condutividade térmica, sugere que a fase de auto-inserção SbxCoSb3-x pode constituir um material termoelétrico de alto desempenho. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-03T19:52:12Z No. of bitstreams: 1 Dissertacao Fernanda Miotto.pdf: 1202367 bytes, checksum: b66708b3e1d417eab6ba5104702a3458 (MD5) / Made available in DSpace on 2014-06-03T19:52:12Z (GMT). No. of bitstreams: 1 Dissertacao Fernanda Miotto.pdf: 1202367 bytes, checksum: b66708b3e1d417eab6ba5104702a3458 (MD5) / The compound SbxCoSb3-x was produced at high pressures and high temperatures in a self-insertion reaction from the binary skutterudite CoSb3. The self-insertion reaction is characterized by the collapse of Sb atoms to the 2a site, into the cage formed by the Co and Sb atoms in the skutterudite structure. The opposite reaction, i.e., Sb desinsertion, occurs when the SbxCoSb3-x compound is heated at room pressure. This desinsertion reaction was followed by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electrical resistivity measurements, and its study constitutes the main objective of this work. The CoSb3 sample was synthesized as described in the literature. The synthesis was confirmed by XRD, and the presence of contaminant phases was not observed. Cylindrical samples of the SbxCoSb3-x phase were obtained by submitting CoSb3 at pressures of 7.7 GPa and temperatures up to 550ºC, with the aid of a toroidal high pressure cell available at the Laboratório de Altas Pressões e Materiais Avançados - LAPMA in the Instituto de Física of the Universidade Federal do Rio Grande do Sul - IF/UFRGS. The presence of the SbxCoSb3-x phase was confirmed by XRD analysis. In order to determine the electrical resistivity of samples rich in SbxCoSb3-x phase, a DC system was developed which is applicable to small volume cylindrical samples such as those obtained at high pressures and high temperatures. The calibration of the DC system was made by measurements of the electrical resistivity of reference materials (NIST-SRM 1461 and NIST-SRM 8426). The DSC measurements revealed the presence of two thermal events. An endothermic peak was observed at 118ºC which is not associated to structural changes neither significant variation in the electrical resistivity. The exothermic event that starts at 180ºC is the signature of the desinsertion of Sb atoms from the skutterudite cage, as verified by XRD analysis and electrical measurements. After heating to 350°C, the sample rich in the SbxCoSb3-x phase converts back to the stable phase, CoSb3. The desinsertion reaction follows a first-order kinetics, with a transition enthalpy of approximately 50 J/g and an activation energy of 83 kJ/mol. The electrical resistivity at room temperature of samples rich in SbxCoSb3-x is about ten times smaller than that of CoSb3. This result, along with a possible low thermal conductivity, suggests that SbxCoSb3-x may constitute a high performance thermoelectric material.
26

Reação de desinserção em SbxCoSb3-x

Miotto, Fernanda 16 July 2010 (has links)
O composto SbxCoSb3-x foi produzido em altas pressões e altas temperaturas em uma reação de auto-inserção a partir da escuterudita binária CoSb3. A reação de auto-inserção é caracterizada pelo colapso de átomos de Sb para o sítio 2a, no interior das cavidades formadas pelos átomos de Co e Sb na estrutura da escuterudita. A reação inversa, de desinserção de Sb, ocorre quando o composto SbxCoSb3-x é aquecido à pressão ambiente. O acompanhamento desta reação de desinserção por meio de medidas de calorimetria exploratória diferencial (DSC), difração de raios X (DRX) e de resistividade elétrica constitui o objetivo principal deste trabalho. A amostra de CoSb3 foi sintetizada conforme rota proposta pela literatura. A síntese foi confirmada por meio de DRX, e não foi observada a presença de fases contaminantes. Amostras cilíndricas da fase SbxCoSb3-x foram obtidas submetendo CoSb3 a pressões de 7,7 GPa e temperaturas de até 550ºC, com o auxílio de prensas hidráulicas e câmaras toroidais disponíveis no Laboratório de Altas Pressões e Materiais Avançados LAPMA no Instituto de Física da Universidade Federal do Rio Grande do Sul IF/UFRGS. A presença da fase SbxCoSb3-x foi comprovada por meio de análises de DRX. Para determinação da resistividade elétrica de amostras ricas de fase SbxCoSb3-x foi desenvolvido um sistema DC, aplicável a amostras cilíndricas de pequeno volume tal como as obtidas em altas pressões e altas temperaturas. A aferição do sistema foi feita através de medidas de resistividade elétrica de materiais de referência (NIST-SRM 1461 e NIST-SRM 8426). As medidas de DSC revelaram a presença de dois eventos térmicos. Um pico endotérmico foi observado em 118ºC e não está associado a alterações estruturais e nem a variações significativas na resistividade elétrica. O evento exotérmico, que inicia em 180ºC, constitui a assinatura da desinserção dos átomos de Sb do interior da escuterudita, como verificado por análises de DRX e medidas elétricas. Após aquecimento até 350ºC, a amostra rica na fase SbxCoSb3-x retorna à fase estável, CoSb3. A reação de desinserção obedece a uma cinética de primeira ordem, cuja entalpia de transição é de aproximadamente 50 J /g e uma energia de ativação de 83 kJ/mol. A resistividade elétrica à temperatura ambiente de amostras ricas em SbxCoSb3-x é cerca de dez vezes inferior à do CoSb3. Este resultado, aliado possivelmente a uma baixa condutividade térmica, sugere que a fase de auto-inserção SbxCoSb3-x pode constituir um material termoelétrico de alto desempenho. / The compound SbxCoSb3-x was produced at high pressures and high temperatures in a self-insertion reaction from the binary skutterudite CoSb3. The self-insertion reaction is characterized by the collapse of Sb atoms to the 2a site, into the cage formed by the Co and Sb atoms in the skutterudite structure. The opposite reaction, i.e., Sb desinsertion, occurs when the SbxCoSb3-x compound is heated at room pressure. This desinsertion reaction was followed by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electrical resistivity measurements, and its study constitutes the main objective of this work. The CoSb3 sample was synthesized as described in the literature. The synthesis was confirmed by XRD, and the presence of contaminant phases was not observed. Cylindrical samples of the SbxCoSb3-x phase were obtained by submitting CoSb3 at pressures of 7.7 GPa and temperatures up to 550ºC, with the aid of a toroidal high pressure cell available at the Laboratório de Altas Pressões e Materiais Avançados - LAPMA in the Instituto de Física of the Universidade Federal do Rio Grande do Sul - IF/UFRGS. The presence of the SbxCoSb3-x phase was confirmed by XRD analysis. In order to determine the electrical resistivity of samples rich in SbxCoSb3-x phase, a DC system was developed which is applicable to small volume cylindrical samples such as those obtained at high pressures and high temperatures. The calibration of the DC system was made by measurements of the electrical resistivity of reference materials (NIST-SRM 1461 and NIST-SRM 8426). The DSC measurements revealed the presence of two thermal events. An endothermic peak was observed at 118ºC which is not associated to structural changes neither significant variation in the electrical resistivity. The exothermic event that starts at 180ºC is the signature of the desinsertion of Sb atoms from the skutterudite cage, as verified by XRD analysis and electrical measurements. After heating to 350°C, the sample rich in the SbxCoSb3-x phase converts back to the stable phase, CoSb3. The desinsertion reaction follows a first-order kinetics, with a transition enthalpy of approximately 50 J/g and an activation energy of 83 kJ/mol. The electrical resistivity at room temperature of samples rich in SbxCoSb3-x is about ten times smaller than that of CoSb3. This result, along with a possible low thermal conductivity, suggests that SbxCoSb3-x may constitute a high performance thermoelectric material.
27

Kobaltbergbau und Blaufarbenindustrie im sächsischen Erzgebirge

Förster, Jörg 30 April 2019 (has links)
Das Element Cobalt gewinnt als Technologiemetall und kritischer Rohstoff zunehmend an Bedeutung. Weitgehend in Vergessenheit geraten ist hingegen die Bedeutung des Cobalts für den historischen Erzbergbau im Erzgebirge. Auch die Weiterverarbeitung der Kobalterze in den historischen Blaufarbenwerken ist ein nahezu vergessenes Kapitel der sächsischen Wirtschaftsgeschichte. Es existiert keine zusammenfassende Literatur, die sich mit allen Facetten des historischen Kobalterzbergbaus im Erzgebirge befasst. Das Ziel dieser Masterarbeit ist ein Desiderat, das einen zusammenfassenden und integrativen Überblick über den historischen sächsischen Kobalterzbergbau und der eng damit verknüpften Blaufarbenindustrie schafft. Es wird der Frage nachgegangen, in welchen Lagerstättentypen Kobalterze mineralisierten und wie sich deren räumliche Verbreitung im Erzgebirge beschreiben lässt. Durch Auswertung von Akten des Bergarchivs Freiberg und anderen historischen Quellen erfolgt eine qualitative als auch quantitative Beurteilung der historischen erzgebirgischen Kobaltlagerstätten. Unter Anwendung analytischer Methoden (XRD, REM-EDX) und weiterführenden Literaturauswertungen wurde unter Zuhilfenahme von Sammlungsproben des Museums für Mineralogie und Geologie in Dresden (MMGDD) die mineralogische Zusammensetzung des bedeutendsten Kobalterzes, dem Skutterudit, analysiert. Darauf aufbauend werden die Besonderheiten der Kobalterzverarbeitung in den Blaufarbenwerken dargestellt. Standortgeographische Voraussetzungen werden ebenso erläutert, wie regionale und überregionale Handelsbeziehungen. Des Weiteren wird die Bedeutung der Blaufarbenindustrie für das Glasmacher- und Keramikhandwerk aufgezeigt. Angedeutet wird ebenfalls, wie sich der historische Kobalterzbergbau und Wissenschaft und Technik gegenseitig beeinflussten und so die sächsischen Blaufarbenwerke trotz Erfindung des kostengünstigeren Ultramarins um 1828 noch bis zu Beginn des 20. Jhd. marktbeherrschend blieben. Darüber hinaus werden die heutigen global bedeutendsten Kobaltlagerstätten und die Relevanz dieses Technologiemetalls vorgestellt. / Cobalt is becoming increasingly important as a technology metal and critical raw material. Largely forgotten, however, is the important role of cobalt for the historical ore mining and the subsequent industrial processing in the historical cobalt blue industries in the Erzgebirge mountains of Saxony. In the absence of a comprehensive modern literature the aim of this Master thesis is a desideratum that provides an overview of the historic cobalt ore mining and the closely related cobalt blue industries in the Saxon Erzgebirge. It examines the question in which types of mineral deposits cobalt was mineralised and how their spatial distribution can be described. As a result of evaluating documents of the Bergarchiv Freiberg and other historical sources, a qualitative as well as quantitative assessment of the historical cobalt deposits in the Erzgebirge is carried out. The most important cobalt ore, Skutterudite, was analyzed by using analytical methods (XRD, REM-EDX) and further literature reviews. For this purpose, collection samples from the Museum of Mineralogy and Geology in Dresden (MMGDD) were available. In addition, the peculiarities of further industrial processing of cobalt ore in the cobalt blue industries are presented, as well as their specific geographic prerequisites. Furthermore, the importance of the cobalt blue industry for the old crafts of glassmaking and ceramics is shown, just as the mutual influence with science and technology. Last but not least, the todays world's most important cobalt deposits and the relevance of this technology metal are presented.
28

Structural and Thermoelectric Properties of Binary and Ternary Skutterudite Thin Films

Daniel, Marcus 02 April 2015 (has links)
Increasing interest in an effciency enhancement of existing energy sources led to an extended research in the field of thermoelectrics. Especially skutterudites with their high power factor (electric conductivity times Seebeck coefficient squared) are suitable thermoelectric materials. However, a further improvement of their thermoelectric properties is necessary. The relatively high thermal conductivity can be decreased by introducing loosely bound guest ions, whereas atom substitution or nanostructuring (as thin films) could yield an increased power factor. The present work proves the feasibility to deposit single phase skutterudite thin films by MBE technique. In this regard CoSby and FeSby film series were deposited with three different methods: i) codeposition at elevated temperatures, ii) codeposition at room temperature followed by post-annealing, and iii) modulated elemental reactant method. The structural and thermoelectric properties of these films were investigated by taking the thermal stability of the film and the substrate properties into account. Compared to the stoichiometric Sb content of skutterudites of 75 at.%, a small excess of Sb is necessary for achieving single phase skutterudite films. It was found, that the deposited single phase CoSb3 films reveal bipolar conduction (and therefore a low Seebeck coefficient), whereas FeSb3 films show p-type conduction and very promising power factors at room temperature. The need of substrates with a low thermal conductivity and a suitable thermal expansion coefficient is also demonstrated. A high thermal conductivity influences the measurements of the Seebeck coefficient and the obtained values will be underestimated by thermal shortening of the film by the substrate. If the thermal expansion coefficient of film and substrate differ strongly from each other, crack formation at the film surface was observed. Furthermore, the realization of controlled doping by substitution as well as the incorporation of guest ions was successfully shown. Hence, this work is a good starting point for designing skutterudite based thin film structures. Two successful examples for such structures are given: i) a thickness series, where a strong decrease of the resistivity was observed for films with a thickness lower than 10nm, and ii) a FexCo1-xSb3 gradient film, for which the gradient was maintained even at an annealing temperature of 400°C.:Contents 1 Introduction 2 Nanostructured thermoelectric materials 2.1 Thermoelectric materials and ZT 2.2 Recent developments in improving ZT in thin films 3 Thermoelectric transport theory 3.1 Electronic transport coefficients 3.2 Lattice thermal conductivity 4 Skutterudites as promising thermoelectric material 4.1 CoSb3 4.1.1 Structural properties of skutterudites 4.1.2 Band structure of CoSb3 and density of states 4.1.3 Thermoelectric properties of CoSb3 4.1.4 Synthesis of CoSb3 thin films 4.2 FeSb3 4.2.1 Structural and thermoelectric properties of FeSb3 thin films 4.2.2 Synthesis of FeSb3 thin films 5 Experimental methods 5.1 Basic methods for structural characterization 5.2 Electric characterization: Resistivity and Hall measurements using van der Pauw geometry 5.3 Thermoelectric characterization (Seebeck coefficient) 5.4 Thermal characterization methods 6 Deposition of skutterudite thin films 6.1 Deposition chamber and deposition parameters 6.2 Deposition methods 6.3 Composition control of skutterudite films 7 Control of structural properties by the used deposition method 7.1 Structural properties of CoSb3 thin films 7.1.1 Crystallization characteristics of CoSb3 films 7.1.2 Comparison of films deposited with different deposition methods 7.1.3 Influence of different deposition parameters on the film properties 7.2 Structural properties of FeSb3 thin films 7.2.1 Crystallization behaviour 7.2.2 Structural properties of post-annealed Fe-Sb films prepared by codeposition 7.2.3 Influence of the heating rate on the film properties 8 CoSb3 and FeSb3 composition series 8.1 CoSby composition series 8.1.1 Films deposited at elevated temperatures 8.1.2 Annealed films 8.2 FeSby composition series 9 Influence of various substrates on the film properties 9.1 Substrate influence on the film morphology 9.2 Substrate influence on thermoelectric properties and measurements 10 FexCo1-xSb3 - controlled doping by substitution of Co with Fe 10.1 Properties of codeposited FexCo1-xSb3 films 10.2 Properties of FexCo1-xSb3 films deposited via MERM 11 Filled CoSb3 thin films 12 Examples for nanostructured thin film approaches 12.1 CoSb3 thickness series 12.2 FexCo1-xSb3 gradient films 13 Summary and Outlook

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