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

新型过渡金属化合物的高压合成和晶体化学

基本信息

批准号：
09450238
负责人：
TAKIZAWA Hirotsugu
金额：
$ 8.32万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

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.

本研究着重于在高温高压条件下合成新型过渡金属化合物。本研究新合成了多种三维过渡金属-类金属化合物。这些包括过渡金属二锑化物、二锗化物和三锑化物。从化学键合和压致相变两个方面系统地讨论了这些金属间化合物的晶体化学.在过渡金属二锑化物族中发现了两种压力诱导相变类型：白铁矿-副芳硫砷铁矿型和白铁矿-CuAl双相D22双相D2型。前者发生在NiSb D22 D2中，可以通过NiSb D26 D2八面体的有效堆积来解释。后者在CrSb合金D22中发现，其转变伴随着成键性质的变化，即从离子和共价键的混合成键转变为金属键。高压态的CrSb合金D22-D23具有电子铁磁行为，居里温度为160 K.不同的14族元素可以插入CoSb方钴矿主体晶格的体心空位中，从而形成新的填充方钴矿。掺入的原子表现出较大的热振动幅度，表明材料的热导率可能降低。结果表明，在方钴矿基质晶格中插入原子是开发新型热电转换材料的有效途径。