Le diagramme des phases du C60 continue d'être un sujet de discussion et de controverse, malgré la grande quantité de travaux expérimentaux et théoriques fait au fil des ans. Ceci est principalement dû au manque d'études in situ, a l'existence d´états désordonnés présentant des pics de diffraction très mal résolus et à la coexistence de plusieurs polytypes de faible densité. Ce manuscrit présente une étude systématique in situ des transformations hétérogènes du C60 sous haute pression et haute température dans la gamme 1-10 GPa et 300-1200 K. Afin de discriminer les poly(a)morphes de densité similaire dans des échantillons hétérogènes, nous avons utilisé une combinaison de micro-diffraction et micro-tomographie. Les échantillons ont été synthétisés dans une cellule Paris-Edimbourg et caractérisés à l'aide de diffraction des rayons X in situ en dispersion angulaire. Des images tridimensionnels à haute résolution ont été obtenus sur des échantillons trempés par la méthode de micro-tomographie de diffraction/diffusion. Cette méthode permet l'analyse 3D de l'intensité de diffusion reconstruite à partir de séries de projections 2D. Une telle analyse est non destructive et offre une grande sensibilité (0,1% en volume), une haute résolution spatiale (μm3) et peut être multimodale, fournissant des données quantitatives sur la morphologie, la densité, la composition élémentaire ou la structure des matériaux. En outre, nous décrivons le développement d´un système de micro-tomographie in situ sous haute pression et haute température en utilisant une nouvelle cellule rotative Paris-Edimbourg (RoToPEC), combinée avec le rayonnement synchrotron. La capacité à tourner complètement la chambre de l'échantillon sous charge, surmonte la contrainte d'ouverture angulaire limitée des cellules ordinaires et permet l'acquisition de projections tomographiques pour l'imagerie de plein champ ainsi que pour l'imagerie par micro-diffraction. Cette méthode innovante permet l´étude des matériaux sous conditions extrêmes de pression, température ou stress, et pourra être appliquée dans des domaines variés tels que la physique, la chimie, la science des matériaux ou la géologie. Le potentiel de cette nouvelle technique expérimentale est démontré par l'étude de la polymérisation de C60 sous haute-pression et haute température. Mots-clés: C60, diagramme de phase, diffraction, micro-tomographie, haute pression et haute température / The C60 reaction diagram continues to be a subject of discussion and controversy, despite the vast amount of experimental and theoretical work done over the years. This is mainly due the lack of in situ studies, the highly disordered-states showing poorly resolved diffraction peaks and the coexistence of several low-density polytypes. This manuscript presents a systematic in situ study of high-pressure–high-temperature forms C60 in the range of 1-10 GPa and 300-1200 K. In order to discriminate poly(a)morphs with similar densities in heterogeneous samples, we used a combination of microdiffraction and microtromography. The samples were synthesized in a Paris-Edinburgh cell and characterized using in situ angular dispersive X-ray diffraction. Three-dimensional submicron images were obtained on quenched samples using diffraction/scattering microtomography. This method provides 3D analysis of the scattering intensity reconstructed from sets of 2D microdiffraction projections. Such analysis is non-destructive and provides high sensitivity (0.1% volume), high spatial resolution (µm3) and can be multi-modal providing quantitative information on the morphology, density, elemental composition or structure of materials. Additionally, we describe the development of in situ high-pressure–high-temperature microtomography using a new rotating Paris-Edinburgh cell (RoToPEC) combined with synchrotron radiation. The ability to fully rotate the sample chamber under load, overcomes the limited angular aperture of ordinary high-pressure cells for acquiring tomographic projections in both, full-field imaging or microdiffraction modes. This innovative method enables dynamic studies of materials under extreme pressure-temperature-stress conditions, impacting areas such as physics, chemistry, materials science or geology. The potential of this new experimental technique is demonstrated on the in situ investigation of of high-pressure–high-temperature polymerization of C60 . Keywords: C60, phase diagram, diffraction, microtomography, high-pressure–high-temperature

In dieser Dissertation wird die Darstellung tetrelreicher Seltenerdmetall–Verbindungen in den Systemen SE:Tt (SE = La, Nd, Sm, Gd, Tb, Ho, Lu; Tt = Si, Ge) und die Charakterisierung ihrer Eigenschaften beschrieben. Diese Verbindungen, welche mittels der Hochdruck–Hochtemperatur–Methode dargestellt wurden, zeigen neuartige Verknüpfungsmuster in der Tetrel–Partialstruktur. Neben der Charakterisierung der Verbindungen hinsichtlich der thermischen Stabilität und der physikalischen Eigenschaften bei Normaldruck wurde bei den Germanium–reichen Seltenerdmetall–Verbindungen eine Untersuchung der Veränderungen der Kristallstruktur bei Variation des Drucks oder der Temperatur vorgenommen. Die dargestellten Seltenerdmetall–Trisilicide SESi3 (SE = Gd, Ho, Lu) kristallisieren tetragonal isotyp zu YbSi3. LuSi3 zeigt Supraleitung mit Tc = 7.0 K. In den Systemen Gd–Si und SE–Ge (SE = La, Nd, Sm, Gd, Tb) wurden die Verbindungen GdSi5 und SEGe5 (SE = La, Nd, Sm, Gd, Tb) synthetisiert. Sie kristallisieren orthorhombisch isotyp zu LaGe5. Durch in–situ Röntgenbeugungsexperimente bei erhöhten Temperaturen kann die Existenz metastabiler Germanium–ärmerer Verbindungen SE2Ge9 (SE = Nd, Sm) nachgewiesen werden. Es handelt sich um Defektvarianten der Verbindungen SEGe5 (SE = Nd, Sm). Die strukturelle Verwandtschaft zum Aristotyp SEGe5 wird anhand einer Gruppe–Untergruppe–Beziehung aufgezeigt. Eine alternative Synthesemethode zur Darstellung tetrelreicher Verbindungen mit Gerüststrukturen bei extremen Reaktionsbedingungen stellt das Spark–Plasma–Sinterverfahren (SPS) dar. Die Darstellung der Clathratphase Ba8Ga16±xGe30∓x (x = 0, 1) erfolgte mittels SPS aus den Precursoren BaGa2±x (x = 0, 0.125) und Germanium. Die Untersuchungen der thermoelektrischen Eigenschaften zeigen, dass durch Variation der nominellen Zusammensetzung sowohl n–leitende als auch p–leitende Eigenschaften erhalten werden können. / In this thesis the synthesis of tetrel–rich rare–earth metal compounds in the systems RE:Tt (RE = La, Nd, Sm, Gd, Tb, Ho, Lu; Tt = Si, Ge) and the characterization of their properties is described. These compounds, synthesized by means of high–pressure high–temperature method, show new structural motifs in the tetrel partial structure. The compounds were characterized with respect to their thermal stability and their physical properties at ambient pressure. In addition, the changes in the crystal structure of the germanium-rich rare–earth metal compounds by variation of pressure or temperature were investigated. The synthesized rare–earth trisilicides SESi3 (SE = Gd, Ho, Lu) crystallize tetragonal, isotypic to YbSi3. LuSi3 is a superconductor with Tc = 7.0 K. In the systems Gd–Si and SE–Ge (SE = La, Nd, Sm, Gd, Tb) the compounds GdSi5 and SEGe5 (SE = La, Nd, Sm, Gd, Tb) were synthesized. They crystallize orthorhombic isotypic to LaGe5. Using in-situ high–temperature X-ray experiments the metastable germanium-poorer compounds SE2Ge9 (SE = Nd, Sm) could be observed. These compounds are defect variants of the pentagermanides SEGe5 (SE = Nd, Sm). The structural relationship to the aristotype SEGe5 is given via a group-subgroup relation. An alternative synthesis route for the preparation of tetrel–rich compounds with framework structures at extreme reaction conditions is the spark plasma sintering method (SPS). The clathrate phase Ba8Ga16±xGe30∓x (x = 0, 1) was synthesized from the precursors BaGa2±x (x = 0, 0.125) and germanium by means of SPS. The investigation of the thermoelectric properties shows, that through variation of the nominal composition both n-type and p-type conduction properties can be obtained.

Denna rapport är gjord på ett examensarbete som var utfört på uppdrag av det svenska företaget Ranotor AB. Syftet var att utveckla en konceptuell lösning för en rotationsventil som skall fungera i en miljö med hög temperatur och högt tryck. Ventilen skall arbeta under höga rotationshastigheter, vilket kräver korta öppettider.Tekniska hjälpmedel såsom SolidWorks, ANSYS och MATLAB användes för att modellera och analysera de konceptuella lösningarna. Slutlösningen valdes från ett flertal olika koncept, varpå detta vidareutvecklades och optimerades. Betydande material och gastätningslösningar identifierades och utvärderades för att hitta den bästa lösningen. Optimering av individuella komponenter och hela anordningen gjordes med avseende på spänning, termisk- och dynamisk analys. De givna specifikationerna uppfylldes och resultaten var tillfredsställande. Resultaten ger en teoretisk bas för vidareutveckling och applicering av en rotationsventil in en miljö med hög temperatur och högt tryck. / This Master thesis is a project commissioned by the Swedish company Ranotor AB. The objective of this thesis is to develop a conceptual solution for a rotary valve mechanism that has to work efficiently in a high-temperature and high-pressure environment. The valve is to operate at high rotational speeds which calls for very short opening time.Modern engineering tools namely Solidworks, Ansys and Matlab, were employed for modelling and analysis of the conceptual solution.The best design solution was selected from three developed concepts, and the selected concept was further developed and optimized. Major material candidates and gas-tight sealing solution were identified and evaluated and the optimal material and seal design was chosen. Optimization of the individual components as well as the whole assembly was performed based on stress, thermal and dynamic analysis. The given design specifications and functions were fulfilled and the results were satisfactory. The obtained results provide a theoretical foundation for the development and application of a rotary valve in high-temperature and high-pressure environment.

No description available.

L’évolution des assemblages pétrologiques avec l’augmentation de pression et de température est couramment perçue à l’équilibre et figée dans le temps. Le développement des sources synchrotron de rayons X permet à présent de mesurer in situ et en temps résolu les vitesses de transformations minéralogiques à haute pression (HP), haute température (HT). Cette thèse présente l’utilisation de cette technologie dans 2 contextes géologiques. (i) Le potentiel sismogène de la déstabilisation des minéraux hydratés dans les plaques en subduction est vérifié. Les cinétiques de déshydratation du talc, de la phase à 10Å et de l’antigorite ont été mesurées à HP-HT en système clos. Nous avons identifié que l’antigorite se déshydrate en passant par un stade intermédiaire. Toutes les vitesses de libération de fluides associées sont plus rapides que la déformation visqueuse des roches et sont donc compatibles avec le déclenchement de rupture. (ii) Les cinétiques de transition olivine-ringwoodite ont été déterminées dans la loupe de costabilité pour des compositions riches en Fe. Elles mettent en évidence une amorphisation partielle de l'olivine en début de transformation. Cela pourrait perturber de manière significative la vitesse des ondes sismiques lors de leur passage au niveau de la zone de transition mantellique. Par ailleurs, les temps caractéristiques de réaction et la réduction conséquente de la taille des grains, indiquent qu’une telle transition de phase induit une atténuation sismique importante. Ces résultats expérimentaux in situ HP-HT révèlent des mécanismes originaux de transition de phase et contribuent ainsi à une meilleure compréhension des modèles géodynamiques / The evolution of petrological assemblies with increasing pressure and temperature is commonly perceived at equilibrium and fixed within time. The development of X-ray synchrotron sources now enable to measure in situ, time-resolved rates of mineralogical transformations at high pressure (HP), high temperature (HT). This thesis presents the application of this technology in two geological settings. (i) The seismogenic ability of breakdown of hydrated minerals within the subducting slab is checked. The dehydration kinetics of talc, 10Å phase and antigorite were measured at HP-HT in a closed system. We have found that antigorite dehydrates through an intermediate stage. All associated rates of released fluids are faster than the viscous deformation of rocks and are therefore compatible with the trigger of rupture. (ii) The kinetics of olivineringwoodite transition were determined within the co-stability loop for Fe-rich compositions. They show a partial amorphization of olivine at the beginning of the transformation. This could significantly affect the velocities of seismic waves when crossing the mantle transition zone. Moreover, the characteristic times of this reaction and the substantial reduction in grain size, indicate that such a phase transition may induce a significant seismic attenuation. These in situ HP-HT experimental results reveal novel mechanisms of phase transition and thus contribute to a better understanding of geodynamic models

It is known that boron containing compounds exhibit interesting chemical and physical properties. In the past 50 years modern preparative methods have led to an overwhelming number of different structures of novel and often unexpected boron–sulfur and boron–selenium compounds. Among all these new compounds, there was only one which comprises rare earth metal (RE), boron and heavier chalcogen, namely sulfur, the europium thioborate Eu[B2S4] [1]. Selenoborates of rare earth metals are hitherto unknown. On the other hand, rare earth oxoborates represent a well-known class of compounds [2] with a wide range of applications, especially in the field of optical materials. In addition, well-defined boron compounds containing the heavier group 16 elements are fairly difficult to prepare due to the high reactivity of in situ formed boron chalcogenides towards most container materials at elevated temperatures. The chalcogenoborates of the heavier chalcogens are sensitive against oxidation and hydrolysis and therefore have to be handled in an inert environment. Therefore, developing and optimization of preparative routes for the syntheses of pure and crystalline RE thio- and selenoborates was needed. In the course of this study, the application of different preparation routes, such as optimized high-temperature routes (HT), metathesis reactions and high-pressure high-temperature routes (Hp – HT), led to sixteen new rare earth thioborates. Their crystal structures were solved and/or refined from powder and single crystal X-ray diffraction data, while the local structure around rare earth metal was confirmed from the results of the EXAFS analyses. Quantum mechanical calculations were used within this work in order to investigate the arrangement of intrinsic vacancies on the boron sites in the crystal structures of rare earth thioborates. Thermal, magnetic and optical properties of these compounds are also discussed. The rare earth thioborates discovered during this work are the first examples of ternary thioborates containing trivalent cations. These compounds can be divided into two groups of isotypic compounds: the rare earth orthothioborates with general formula REIII[BS3] (RE = La – Nd, Sm, Gd and Tb) [3] and the rare earth thioborate sulfides with general formula REIII¦9B5S21, (RE = Gd – Lu, and Y) [4]. In the crystal structure of RE[BS3] (orthorhombic, space group Pna21, Z = 4), the sulfur atoms form the vertices of corrugated kagome nets, within which every second triangle is occupied by boron and the large hexagons are centered by RE cations. The structural features of the isotypic RE[BS3] phases show great similarities to those of rare earth oxoborates RE[BO3] and orthothioborates of alkali and alkaline earth metals as well as to thallium orthothioborate, yet pronounced differences are also observed: the [BS3]3– groups in the crystal structures of RE[BS3] are more distorted, where the distortion decreases with the decreasing size of the RE element, and the coordination environments of the [BS3]3– groups in the crystal structures of RE[BS3] are different in comparison with the coordination environments of the [BO3]3– groups in the crystal structures of λ-Nd[BO3] [5] and of o-Ce[BO3] [6]. The results of the IR and Raman investigations are in agreement with the presence of [BS3]3– anions in the crystal structure of RE[BS3]. Thermal analyses revealed the thermal stability of these compounds under inert conditions up to ~ 1200 K. Analyses of the magnetic properties of the Sm, Gd and Tb thioborates showed that both Gd and Tb phases order antiferromagnetically. The magnetic susceptibility for Sm orthothioborate approximately follows the Van-Vleck theory for Sm3+. Between 50 K and 62 K a transition appears which is independent of the magnetic field: the magnetic susceptibility becomes lower. This effect might indicate a discontinuous valence transition of Sm which was further investigated by means of XANES and X-ray diffraction using synchrotron radiation, both at low temperatures. The series of isotypic RE thioborate sulfides with composition RE9B5S21, was obtained by the application of Hp – HT conditions to starting mixtures with the initial chemical composition “REB3S6“, after careful optimization of the pressure, temperature and treatment time, as well as the composition of the starting mixtures. Their crystal structures adopt the Ce6Al3.33S14 [7] structure type (hexagonal, space group P63, Z = 2/3). The special features of the RE9B5S21 crystal structures, concerning boron site occupancies and different coordination environments of the two crystallographically independent boron sites, were investigated in more detail by means of quantum chemical calculations, electron diffraction methods, optical and X-ray absorption spectroscopy as well as by 11B NMR spectroscopy. The results obtained from these different experimental and computational methods are in good mutual agreement. The crystal structures of the RE9B5S21 compounds are characterized by two types of anions: tetrahedral [BS4]5– and trigonal planar [BS3]3– as well as [(S2–)3] units. Isolated [BS4]5– tetrahedra (all pointing with one of their apices along the polar [001] direction) represent a unique feature of the crystal structure which is observed for the first time in a thioborate compound. These tetrahedra are stacked along the three-fold rotation axes. Vacancies are located at the trigonal-planar coordinated boron site with preferred ordering –B–B––B–B–– along [001]. No superstructure is observed by means of electron diffraction methods as adjacent columns are shuffled along the c axis, giving rise to a randomly distributed vacancy pattern. Positions of the sulfur atoms within the [(S2–)3] substructure as well as planarity of the [BS3]3– units were investigated in more detail by means of quantum mechanical calculations. Results of the IR and Raman spectroscopy, as well as of the 11B NMR spectroscopy are in agreement with the presence of the boron atoms in two different coordination environments. Thermal analyses showed that compounds RE9B5S21 are stable under inert conditions up to ~ 1200 K. In accordance with the combined results of experimental and computational investigations, the chemical formula of the RE9B5S21 compounds is consistent with RE3[BS3]2[BS4]3S3. A short overview of investigations towards rare earth selenoborates, where in most of the cases only known binary rare earth selenides could be identified, is presented as well in this work. Investigations in the RE–B–Se systems were conducted by the application of different preparation routes by varying the experimental parameters and the initial compositions of the starting mixtures. Although no crystal structure of a ternary phase in these systems could be solved, there are indications that such phases exist, but further investigations are needed. [1] M. Döch, A. Hammerschmidt, B. Krebs, Z. Anorg. Allg. Chem., 2004, 630, 519. [2] H. Huppertz, Chem. Commun., 2011, 47, 131; and references therein. [3] J. Hunger, M. Borna, R. Kniep, J. Solid State Chem., 2010, 182, 702; J. Hunger, M. Borna, R. Kniep, Z. Kristallogr. NCS, 2010, 225, 217; M. Borna, J. Hunger, R. Kniep, Z. Kristallogr. NCS, 2010, 225, 223; M. Borna, J. Hunger, R. Kniep, Z. Kristallogr. NCS, 2010, 225, 225. [4] M. Borna, J. Hunger, A. Ormeci, D. Zahn, U. Burkhardt, W. Carrillo-Cabrera, R. Cardoso-Gil, R. Kniep, J. Solid State Chem., 2011, 184, 296; [5] H. Müller-Bunz, T. Nikelski, Th. Schleid, Z. Naturforsch. B, 2003, 58, 375. [6] H. U. Bambauer, J. Weidelt, J.-St. Ysker, Z. Kristallogr., 1969, 130, 207. [7] D. de Saint-Giniez, P. Laruelle, J. Flahaut, C. R. Séances, Acad. Sci. Ser. C, 1968, 267, 1029.

It is known that boron containing compounds exhibit interesting chemical and physical properties. In the past 50 years modern preparative methods have led to an overwhelming number of different structures of novel and often unexpected boron–sulfur and boron–selenium compounds. Among all these new compounds, there was only one which comprises rare earth metal (RE), boron and heavier chalcogen, namely sulfur, the europium thioborate Eu[B2S4] [1]. Selenoborates of rare earth metals are hitherto unknown. On the other hand, rare earth oxoborates represent a well-known class of compounds [2] with a wide range of applications, especially in the field of optical materials. In addition, well-defined boron compounds containing the heavier group 16 elements are fairly difficult to prepare due to the high reactivity of in situ formed boron chalcogenides towards most container materials at elevated temperatures. The chalcogenoborates of the heavier chalcogens are sensitive against oxidation and hydrolysis and therefore have to be handled in an inert environment. Therefore, developing and optimization of preparative routes for the syntheses of pure and crystalline RE thio- and selenoborates was needed. In the course of this study, the application of different preparation routes, such as optimized high-temperature routes (HT), metathesis reactions and high-pressure high-temperature routes (Hp – HT), led to sixteen new rare earth thioborates. Their crystal structures were solved and/or refined from powder and single crystal X-ray diffraction data, while the local structure around rare earth metal was confirmed from the results of the EXAFS analyses. Quantum mechanical calculations were used within this work in order to investigate the arrangement of intrinsic vacancies on the boron sites in the crystal structures of rare earth thioborates. Thermal, magnetic and optical properties of these compounds are also discussed. The rare earth thioborates discovered during this work are the first examples of ternary thioborates containing trivalent cations. These compounds can be divided into two groups of isotypic compounds: the rare earth orthothioborates with general formula REIII[BS3] (RE = La – Nd, Sm, Gd and Tb) [3] and the rare earth thioborate sulfides with general formula REIII¦9B5S21, (RE = Gd – Lu, and Y) [4]. In the crystal structure of RE[BS3] (orthorhombic, space group Pna21, Z = 4), the sulfur atoms form the vertices of corrugated kagome nets, within which every second triangle is occupied by boron and the large hexagons are centered by RE cations. The structural features of the isotypic RE[BS3] phases show great similarities to those of rare earth oxoborates RE[BO3] and orthothioborates of alkali and alkaline earth metals as well as to thallium orthothioborate, yet pronounced differences are also observed: the [BS3]3– groups in the crystal structures of RE[BS3] are more distorted, where the distortion decreases with the decreasing size of the RE element, and the coordination environments of the [BS3]3– groups in the crystal structures of RE[BS3] are different in comparison with the coordination environments of the [BO3]3– groups in the crystal structures of λ-Nd[BO3] [5] and of o-Ce[BO3] [6]. The results of the IR and Raman investigations are in agreement with the presence of [BS3]3– anions in the crystal structure of RE[BS3]. Thermal analyses revealed the thermal stability of these compounds under inert conditions up to ~ 1200 K. Analyses of the magnetic properties of the Sm, Gd and Tb thioborates showed that both Gd and Tb phases order antiferromagnetically. The magnetic susceptibility for Sm orthothioborate approximately follows the Van-Vleck theory for Sm3+. Between 50 K and 62 K a transition appears which is independent of the magnetic field: the magnetic susceptibility becomes lower. This effect might indicate a discontinuous valence transition of Sm which was further investigated by means of XANES and X-ray diffraction using synchrotron radiation, both at low temperatures. The series of isotypic RE thioborate sulfides with composition RE9B5S21, was obtained by the application of Hp – HT conditions to starting mixtures with the initial chemical composition “REB3S6“, after careful optimization of the pressure, temperature and treatment time, as well as the composition of the starting mixtures. Their crystal structures adopt the Ce6Al3.33S14 [7] structure type (hexagonal, space group P63, Z = 2/3). The special features of the RE9B5S21 crystal structures, concerning boron site occupancies and different coordination environments of the two crystallographically independent boron sites, were investigated in more detail by means of quantum chemical calculations, electron diffraction methods, optical and X-ray absorption spectroscopy as well as by 11B NMR spectroscopy. The results obtained from these different experimental and computational methods are in good mutual agreement. The crystal structures of the RE9B5S21 compounds are characterized by two types of anions: tetrahedral [BS4]5– and trigonal planar [BS3]3– as well as [(S2–)3] units. Isolated [BS4]5– tetrahedra (all pointing with one of their apices along the polar [001] direction) represent a unique feature of the crystal structure which is observed for the first time in a thioborate compound. These tetrahedra are stacked along the three-fold rotation axes. Vacancies are located at the trigonal-planar coordinated boron site with preferred ordering –B–B––B–B–– along [001]. No superstructure is observed by means of electron diffraction methods as adjacent columns are shuffled along the c axis, giving rise to a randomly distributed vacancy pattern. Positions of the sulfur atoms within the [(S2–)3] substructure as well as planarity of the [BS3]3– units were investigated in more detail by means of quantum mechanical calculations. Results of the IR and Raman spectroscopy, as well as of the 11B NMR spectroscopy are in agreement with the presence of the boron atoms in two different coordination environments. Thermal analyses showed that compounds RE9B5S21 are stable under inert conditions up to ~ 1200 K. In accordance with the combined results of experimental and computational investigations, the chemical formula of the RE9B5S21 compounds is consistent with RE3[BS3]2[BS4]3S3. A short overview of investigations towards rare earth selenoborates, where in most of the cases only known binary rare earth selenides could be identified, is presented as well in this work. Investigations in the RE–B–Se systems were conducted by the application of different preparation routes by varying the experimental parameters and the initial compositions of the starting mixtures. Although no crystal structure of a ternary phase in these systems could be solved, there are indications that such phases exist, but further investigations are needed. [1] M. Döch, A. Hammerschmidt, B. Krebs, Z. Anorg. Allg. Chem., 2004, 630, 519. [2] H. Huppertz, Chem. Commun., 2011, 47, 131; and references therein. [3] J. Hunger, M. Borna, R. Kniep, J. Solid State Chem., 2010, 182, 702; J. Hunger, M. Borna, R. Kniep, Z. Kristallogr. NCS, 2010, 225, 217; M. Borna, J. Hunger, R. Kniep, Z. Kristallogr. NCS, 2010, 225, 223; M. Borna, J. Hunger, R. Kniep, Z. Kristallogr. NCS, 2010, 225, 225. [4] M. Borna, J. Hunger, A. Ormeci, D. Zahn, U. Burkhardt, W. Carrillo-Cabrera, R. Cardoso-Gil, R. Kniep, J. Solid State Chem., 2011, 184, 296; [5] H. Müller-Bunz, T. Nikelski, Th. Schleid, Z. Naturforsch. B, 2003, 58, 375. [6] H. U. Bambauer, J. Weidelt, J.-St. Ysker, Z. Kristallogr., 1969, 130, 207. [7] D. de Saint-Giniez, P. Laruelle, J. Flahaut, C. R. Séances, Acad. Sci. Ser. C, 1968, 267, 1029.:I INTRODUCTION ......................................................................... 7 1. Motivation and scope of the work .............................................. 9 2. Literature overview .................................................................. 11 2.1. The binary subsystems of the ternary systems RE–B–Q (RE = rare earth metals, Y; Q = S, Se) ......................................................... 12 2.1.1. RE–Q ............................................................................... 12 2.1.2. RE–B ............................................................................... 19 2.1.3. B–Q ................................................................................. 22 2.2. Related ternary compounds ................................................... 25 2.2.1. RE oxoborates .................................................................. 25 2.2.2. Thio- and selenoborates of alkaline, alkaline earth, transition and post transition metals ......................................................................... 33 2.2.3. The RE thioborate Eu[B2S4]................................................ 45 II PREPARATIVE METHODS AND EXPERIMENTAL TECHNIQUES .......... 47 1. Starting materials and their characterization ............................... 49 2. Synthetic approaches and optimizations .................................... 51 2.1. High-temperature routes ...................................................... 52 2.2. Metathesis reactions ............................................................ 53 2.3. Spark Plasma Sintering (SPS) ............................................... 54 2.4. High-Pressure High-Temperature (Hp – HT) Syntheses ........... 55 3. Analytical methods and samples characterization ....................... 55 3.1. Powder X-ray diffraction ...................................................... 55 3.2. Crystal structure investigations using synchrotron radiation .... 57 3.3. Single crystal X-ray diffraction analysis .................................. 57 3.4. Metallographic investigations ................................................ 58 3.5. Electron microscopy ............................................................ 58 3.5.1. Scanning electron microscopy and energy dispersive X-ray spectroscopy ............................................................................ 58 3.5.2. Transmission electron microscopy ...................................... 59 3.6. Optical spectroscopy ........................................................... 59 3.6.1. Infra-Red spectroscopy .................................................... 59 3.6.2. Raman spectroscopy ........................................................ 60 3.7. X-ray absorption spectroscopy ............................................ 60 3.8. Thermal analysis ................................................................. 62 3.9. Magnetic susceptibility measurements ................................... 63 3.10. 11B NMR spectroscopy ..................................................... 63 3.11. Quantum chemical calculations ........................................... 64 3.11.1. Total energy calculations ................................................ 64 3.11.2. Charge transfer analysis ................................................ 64 3.11.3. Chemical bonding........................................................... 64 III RARE EARTH THIOBORATES ................................................. 67 1. Reinvestigation of the only reported rare earth thioborate – EuB2S4 ....69 2. RE[BS3] (RE = La – Nd, Sm, Gd, Tb) .................................... 69 2.1. Syntheses and phase analyses .......................................... 70 2.2. Crystal structure determinations ........................................ 74 2.3. X-ray absorption spectroscopy: EXAFS data analysis for Pr[BS3] ..... 79 2.4. Crystal chemistry .............................................................. 80 2.5. Optical spectroscopy ......................................................... 83 2.6. Thermal analysis ............................................................... 86 2.7. Magnetic susceptibility ....................................................... 88 2.8. X-ray absorption spectroscopy: XANES data analysis for Sm[BS3] .. 91 2.9. Crystal structure investigation at low temperature using synchrotron radiation ................................................................................... 91 2.10. Summary ......................................................................... 95 3. Gd[BS3] : Ce, Eu, Tb ............................................................. 97 3.1. Syntheses and phase analyses ............................................. 97 3.2. Crystal structure determinations ......................................... 101 3.3. Crystal chemistry .............................................................. 103 3.4. Optical spectroscopy ......................................................... 104 3.5. Thermal analysis ............................................................... 106 3.6. Summary ......................................................................... 107 4. RE9B5S21 (RE = Tb – Lu, Y) ................................................ 107 4.1. Syntheses and phase analyses ........................................... 108 4.2. Crystal structure determinations ........................................ 109 4.3. Crystal chemistry .............................................................. 112 4.4. Electronic structure, charge transfer and chemical bonding .... 115 4.5. X-ray absorption spectroscopy: EXAFS data analysis for Lu9B5S21 .............................................................................. 119 4.6. Thermal analysis ............................................................... 121 4.7. 11B NMR investigations ..................................................... 122 4.8. Optical spectroscopy ......................................................... 123 4.9. Summary ......................................................................... 126 IV ON THE WAY TO RARE EARTH SELENOBORATES .................... 127 1. Towards ternary phases in the systems RE–B–Se, with RE = Sm, Tb – Lu.......................................................................................... 129 2. The system La–B–Se ........................................................... 134 3. The system Gd–B–Se .......................................................... 136 4. The system Y–B–Se ............................................................ 137 5. Summary ........................................................................... 139 V SUMMARY AND OUTLOOK ..................................................... 141 VI APPENDIX .......................................................................... 149 VII REFERENCES .................................................................... 163 VIII LIST OF FIGURES ............................................................. 181 IX LIST OF TABLES ................................................................ 193 X CURRICULUM VITAE ........................................................... 199 XI VERSICHERUNG ............................................................... 203

Ziel der Arbeit war die Synthese von ZnS, welches strukturell natürlichen Sphalerit imitieren und für die Untersuchung und Optimierung von biologischen Laugungsexperimenten genutzt werden soll. Zur Herstellung von chemisch reinem sowie mit den Wertelementen Indium, Kupfer und Eisen dotierten ZnS wurden vier verschiedene Synthesemethoden getestet: Ofentempern, chemische Gasphasentransportreaktion (CVT), feldunterstütztes Sintern (SPS) und die Hochdruck-Hochtemperatur-Synthese (HP/HT). Es folgte die Charakterisierung der synthetisierten Produkte hinsichtlich der Realstruktur und chemischen Reinheit mittels XANES, REM, XRD, EPMA und nasschemischer Verfahren. Abschließend wurden die Synthesemethoden nach ihrer Effizienz evaluiert. Das Ziel, defektfreies kubisches ZnS zu erzeugen, wurde nur mittels CVT und HP/HT erreicht. In dieser Arbeit konnte weiterhin gezeigt werden, dass der Einbau von Indium ohne gleichzeitige Aufnahme von Kupfer bis zu 1 Ma-% möglich ist.:Abbildungsverzeichnis VII Tabellenverzeichnis XI Abkürzungen, Akronyme und Symbole XII Einheiten XV 1 Einleitung 1 2 Forschungsstand zur Synthese von Zinksulfid 6 2.1 Kristallographie von ZnS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.2 p-T -Phasendiagramm von ZnS . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3 Synthesematerial 15 3.1 Gefälltes ZnS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2 Dotierungsmaterialien . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.3 Recherche zu kommerziellen Metallsulfiden . . . . . . . . . . . . . . . . . . . . 18 4 Synthesemethoden 21 4.1 Ofentempern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.2 FAST-SPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 4.3 CVT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.4 HP/HT-Synthese . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 4.4.1 Toroid-Zelle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 4.4.2 HP/HT-Experimentalaufbau und -ablauf . . . . . . . . . . . . . . . . . 27 4.4.3 HP/HT-Kalibrierung . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 5 Analysemethoden 42 5.1 ICP-MS & ICP-OES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 5.2 XRD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 5.3 UV-VIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 5.4 REM-EDX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 5.5 EBSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 5.6 EPMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 5.7 XANES Spektroskopie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 5.8 Ramanspektroskopie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 5.9 Dichtebestimmung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 5.10 BET-Messung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 6 Ergebnisse 63 6.1 Charakterisierung industriell verfügbarer Materialien und natürlicher Proben . 63 6.1.1 Synthetische, industriell verfügbare Materialien . . . . . . . . . . . . . . 63 6.1.2 Referenzspektren für XANES-Analysen . . . . . . . . . . . . . . . . . . 65 6.2 Charakterisierung der Synthesematerialien . . . . . . . . . . . . . . . . . . . . 74 6.2.1 ZnS der Leuchtstoffwerke Breitungen GmbH (LWB) . . . . . . . . . . . 74 6.2.2 Dotierungsmaterialien In, Cu und Fe . . . . . . . . . . . . . . . . . . . . 77 6.3 Charakterisierung der synthetisierten Produkte . . . . . . . . . . . . . . . . . . 80 6.3.1 Einkristalle (CVT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 6.3.2 Polykristalline Produkte (Ofentempern, FAST-SPS und HP/HT) . . . . 112 6.4 Bestimmung des Stapelfehleranteils mittels Ramanspektroskopie? . . . . . . . . 152 7 Diskussion 155 7.1 Synthesematerialien und industriell verfügbare Materialien . . . . . . . . . . . 155 7.2 Syntheseprodukte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 7.2.1 Syntheseprodukte: Einkristalle (CVT) . . . . . . . . . . . . . . . . . . . 160 7.2.2 Syntheseprodukte: Polykristalline Produkte (Ofentempern, FAST-SPS und HP/HT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 7.2.3 Vergleich der Syntheseprodukte: Einkristalle und Polykristalline Produkte 202 8 Laugungsexperimente: Zusammenfassung und Schlussfolgerung 213 9 Schlussfolgerung 220 10 Zusammenfassung 221 Literaturverzeichnis 225 Anhang A Ergebnispräsentation auf internationalen Fachtagungen 247 B Pulver vs. Kompaktprobe-Diffraktometrie 249 C ZnSdis.str-Datei 252 D Bestimmung der Bandlücke 254 E Messpunkte EPMA 256 F Einwaagen der Synthese 258 G Texturfaktoren der Röntgenbeugung X-Ray Diffraction (XRD)-Analyse 260