Distribution of Cation in One-Dimensional Tunnel Structure of Priderite

在这项研究中，我们试图了解基于原子有序晶体结构的功能材料的设计。在x=1.45-1.80的范围内，发现了一个固溶体区域，随着温度的升高，固溶体区域变窄，并向x =1.5的范围收敛。在此基础上，从熔体中生长出ax=1.5的K-Al-、K-Fe-和K-Mg-柱晶，通过晶体结构分析，研究了阳离子在孔道中的分布以及占位与超结构的关系。在隧道内的六面体中发现了三种不同的位置：隧道中心、瓶颈位置和偏离中心的位置。根据现场情况，提出了隧道内离子分布的公度模型。提出了六种类型的模型，从基本晶格到具有六倍c轴的超结构。X射线单晶衍射表明，真实的晶体具有无公度超晶格结构。然后，我们得到了无公度相是公度相共生的结果。

In this study, we attempted to understand the design of functional materials based on the atomic order crystal structure. Priderite is attractive for one-dimensional super ionic conductors and SYNROC containers for radioactive waste.A solid solution region of priderite was found in the x=1.45-1.80 compositions at about 1200C and the region becomes narrow and converges to ax=1.5 composition with rising temperature. From these results, K-Al-,K-Fe- and K-Mg-priderite with ax=1.5 composition were grown from the melts.Distributions of cations in the tunnel and the relationship between occupancy and super structure were studied by crystal structure analysis. Three kinds of sites were found in the hexahedra located in the tunnels: the center of the tunnel, a site on the bottle neck and a displaced site from the center. Commensurate models of distribution of ions in the tunnel were proposed based on the sites. Six types of models were proposed from the fundamental lattice to a superstructure with six-times the c-axis. Real crystals showed an incommensurate super lattice by X-ray single crystal diffraction. Then, we obtained a result where the incommensurate phase is intergrowth of commensurate phases.