High-Pressure Synthesis and the Crystal Chemistry of Novel Transition Metal Compounds

This research put emphasis on the synthesis of novel transition metal compounds under high pressure和temperature condition. Various 3d transition metal - metalloid compounds newly synthesizedin this study.这些包含转换metal diantimonides， digermanides，和triantimonides. The crystal chemistry of these intermetallic compounds是系统性的。discussed in terms of chemical bonding scheme and the pressure-induced phase transition.1. Two类型pressure-induced phase transitionsmarcasite- to pararammelsbergite-type and marcasite- to CuAlwere found in transition metal diantimonide family. The former occurs in NiSb D22 - D2 and can beexplained by effective packing of NiSb - D26 - D2 octahedra. The latter was found in CrSb - D22 - D2 and转换accompanied a change in bonding character form mixed ionic and covalent to metallic。High-pressure form of CrSb - 2 showed an itinirant electron ferromagnetic behavior with theCurie temperature of 160k .2. Various Group 14 elements could be inserted into the body-centeredvacant site of the CoSb - D23 - D2 skutterudite host lattice，resulting in the formation of new filled-skutterudite. the incorporated atom showed large thermalvibration amplitude,indicating a possible reduction of thermal conductivity of materials.它包含了atominsertion into the skutterudite host lattice is effective in developing new thermoelectricconversion materials。

This research put emphasis on the synthesis of novel transition metal compounds under high pressure and temperature condition. Various 3d transition metal - metalloid compounds were newly synthesized in this study. These include transition metal diantimonides, digermanides, and triantimonides. The crystal chemistry of these intermetallic compounds was systematically discussed in terms of chemical bonding scheme and the pressure-induced phase transition.1. Two types of pressure-induced phase transitions, marcasite- to pararammelsbergite-type and marcasite- to CuAlィイD22ィエD2-type, were found in transition metal diantimonide family. The former occurs in NiSbィイD22ィエD2 and can be explained by effective packing of NiSbィイD26ィエD2 octahedra. The latter was found in CrSbィイD22ィエD2 and the transition accompanied a change in bonding character form mixed ionic and covalent to metallic. High-pressure form of CrSbィイD22ィエD2 showed an itinirant electron ferromagnetic behavior with the Curie temperature of 160 K.2. Various Group 14 elements could be inserted into the body-centered vacant site of the CoSbィイD23ィエD2 skutterudite host lattice, resulting in the formation of new filled-skutterudite. The incorporated atom showed large thermal vibration amplitude, indicating a possible reduction of thermal conductivity of materials. It was concluded that the atom insertion into the skutterudite host lattice is effective in developing new thermoelectric conversion materials.