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The Crystal chemistry of the mineral solid solution by EXAFS spectroscopy.

通过 EXAFS 光谱分析矿物固溶体的晶体化学。

基本信息

批准号：
62420017
负责人：
KOTO Kichiro
金额：
$ 20.22万
依托单位：
The University of Tokushima (1988-1989)Osaka University (1987)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62420017/
关键词：
Solid Solution EXAFS X-ray Spectroscopy Minerals Local Structure Crystal Chemistry エクザフス

项目摘要

Rock-forming minerals, sulfides and various metal oxides generally form solid solutions with wide compositional range. Microstructures of atomic scale are basically important to elucidate the crystal chemistry, thermal history and physical property. This study has been done to clarify the crystal chemistry of the solid solution based on the local structure obtained from the analysis of EXAFS spectroscopy. The main results are summarized as follows; (1)The rock-forming mineral olivines with the various compositions in the Mg_2SiO_4 - Fe_2SiO_4 system have been investigated by EXAFS. The local structure of Fe atom in the olivine solid solution is independent on the composition and is nearly the same as in the structure of fayalite. (2) The sulfides minerals, cubanite and chalcopyrite have been investigated using the EXAFS at the Fe-K and Cu-K edges. The local structures of these minerals in the ordered phase are maintained even in the disordered phase of the high temperature form. The results are essentially important to elucidate the order-disorder transition mechanism in these compounds. (3) The stability and ionic conductivity versus composition of the fluorite- type solid solution in the Bi_2O_3-Gd_2O_3 system were explained by forming clusters of regular oxygen cube around Gd ions, which is compared with distorted oxygen polyhedra around Bi ions. It has been clarified in this study that the local structure of the specific kinds of atoms in the solid solution has close relation with its chemical composition, stability and physical property.

造岩矿物、硫化物和各种金属氧化物一般形成固溶体，组成范围很广。原子尺度的微观结构对阐明晶体化学、热史和物理性质具有重要意义。本研究是基于EXAFS光谱分析获得的局部结构来阐明固溶体的晶体化学。主要研究结果总结如下：(1)用EXAFS对Mg_2SiO_4 - Fe_2SiO_4体系中不同组成的造岩矿物橄榄石进行了研究。橄榄石固溶体中铁原子的局部结构与组成无关，与橄榄石结构基本一致。(2)利用EXAFS对Fe-K和Cu-K边缘的硫化物矿物、cubanite和黄铜矿进行了研究。这些矿物在有序相中的局部结构即使在高温形态的无序相中也保持不变。这些结果对阐明这些化合物的有序-无序过渡机制具有重要意义。(3) Bi_2O_3-Gd_2O_3体系中氟石型固溶体的稳定性和离子电导率与组成的关系是通过在Gd离子周围形成规则氧立方簇来解释的，并与在Bi离子周围形成扭曲氧多面体进行了比较。本研究阐明了固溶体中特定种类原子的局部结构与其化学组成、稳定性和物理性质密切相关。