Distribution of Cation in One-Dimensional Tunnel Structure of Priderite

在本研究中，我们试图从原子有序晶体结构的角度来理解功能材料的设计。Priderite是具有吸引力的一维超离子导体和放射性废物的SYNROC容器。在1200℃左右，x=1.45 ~ 1.80组分中存在一个铁素体固溶区，随着温度的升高，该固溶区逐渐缩小并收敛到ax=1.5组分。根据这些结果，从熔体中生长出ax=1.5的K-Al-、K-Fe-和k - mg - priteite。通过晶体结构分析，研究了阳离子在隧道中的分布及其与上层结构的关系。在隧道的六面体中发现了三种类型的遗址：隧道中心，瓶颈上的遗址和中心偏移的遗址。在此基础上，提出了相应的离子分布模型。从基本晶格到具有六倍c轴的上层结构，提出了六种模型。真实晶体在x射线单晶衍射中表现出不相称的超晶格。然后，我们得到了不匹配相是匹配相的共生的结果。

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.