Construction of Crystal Structures of Metal Oxide Phosphates Containing Dynamic Distortions

含有动态畸变的金属氧化物磷酸盐晶体结构的构建

基本信息

批准号：
14340204
负责人：
IMOTO Hideo
金额：
$ 8.38万
依托单位：
Utsunomiya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

This research was aimed to develop new materials by combining MO_6 octahedral units and XO_4 tetrahedral units. At the first stage of the research, compounds with the tetrahedra : octahedra ratio of 1:1 were systematically searched and the existence of a series of isostructural compounds were revealed. These compounds contained Ti, Zr, Ru, Mn, or Nb as M^<IV>, Nb or Ta as M^V, and K, Rb, or Cs as A. The relation of dielectric properties of these compounds with the elements composing the compounds was clarified. At the later stages of the research, the research was extended to the compounds with the tetrahedra : octahedra ratio smaller than 1:1, and especially the compounds with the ratio 1:3 were studied. In this study, new compounds including K_<2+x>Ti_xNb_<3-x>O(PO_4)(0.5 <x <0.6) were synthesized. In the niobium-phosphate system, where we focused our efforts, unexpected compounds were discovered in the last year of the research period. The compounds showing the X-ray diffraction pattern which showed isostructural relationship with pyrochlore structure. The pyrochlore structure has the network consisting only of MO6 octahedra while the compounds prepared contained the tetrahedral element (P). The only compound which has similar structural feature is CsAsTiO_5 and the compounds prepared in this research showed the possibility of many compounds in which MO_6 octahedra were replaced by XO_4 tetrahedra. We attempted also the preparations with XO4 units other than phosphates. We prepared a new germanium compound Cs_8Nb_<10>Ge_6O_<41> ain germanate system, and obtained a new arsinate RbZrO(AsO_4) which seems to have a new structure.

本研究旨在结合MO_6八面体单元和XO_4四面体单元开发新材料。研究的第一阶段，系统地寻找了四面体：八面体比例为1：1的化合物，并揭示了一系列同构化合物的存在。这些化合物含有Ti、Zr、Ru、Mn或Nb作为M^<IV>，Nb或Ta作为M^V，以及K、Rb或Cs作为A。这些化合物的介电性能与组成元素的关系化合物得到澄清。研究后期，研究范围扩大到四面体：八面体比例小于1：1的化合物，特别是对比例为1：3的化合物进行了研究。本研究合成了K_<2+x>Ti_xNb_<3-x>O(PO_4)(0.5 <x <0.6)等新化合物。在我们集中精力的铌磷酸盐系统中，在研究期的最后一年发现了意想不到的化合物。该化合物的X射线衍射图显示与烧绿石结构的同构关系。烧绿石结构具有仅由MO6八面体组成的网络，而制备的化合物含有四面体元素(P)。唯一具有相似结构特征的化合物是CsAsTiO_5，本研究制备的化合物表明许多MO_6八面体被XO_4四面体取代的化合物的可能性。我们还尝试了除磷酸盐之外的 XO4 单元的制备。我们在锗酸盐体系中制备了一种新的锗化合物Cs_8Nb_<10>Ge_6O_<41>，并得到了一种新的砷酸盐RbZrO(AsO_4)，其似乎具有新的结构。