Kawakita Yukinobu, Tahara Shuta, Fujii Hiroyuki, Kohara Shinji, Takeda Shin'ichi
Department of Physics, Faculty of Sciences, Kyushu University, 4-2-1 Ropponmatsu, Fukuoka 810-8560, Japan.
J Phys Condens Matter. 2007 Aug 22;19(33):335201. doi: 10.1088/0953-8984/19/33/335201. Epub 2007 Jul 4.
Neutron and high-energy x-ray diffraction analyses of molten AgI have been performed and the partial structures are discussed in detail with the aid of the structural modelling procedure of the reverse Monte Carlo (RMC) technique by comparison with those of molten CuI and AgCl. It is well known that AgI and CuI have a superionic solid phase below the melting point, in which the cations favour a tetrahedral configuration, while solid AgCl has a rock-salt structure with an octahedral environment around both Ag and Cl atoms. Even in the molten states, there is a significant difference between superionic and non-superionic melts. The cation is located on the triangular plain formed by three iodine ions in molten AgCl and CuI, while molten AgCl favours a 90° Cl-Ag-Cl bond angle, which is understood to maintain a similar local environment to that in the solid state. The atomic configurations of the RMC model suggest that the cation distributions in superionic melts of CuI and AgI exhibit large fluctuations, while Ag ions in the non-superionic melts of AgCl are distributed much more uniformly.
对熔融碘化银进行了中子和高能X射线衍射分析，并借助反向蒙特卡罗（RMC）技术的结构建模程序，通过与熔融碘化铜和氯化银的结构进行比较，详细讨论了其部分结构。众所周知，碘化银和碘化铜在熔点以下具有超离子固相，其中阳离子倾向于四面体构型，而固态氯化银具有岩盐结构，银和氯原子周围均为八面体环境。即使在熔融状态下，超离子熔体和非超离子熔体之间也存在显著差异。在熔融氯化银和碘化铜中，阳离子位于由三个碘离子形成的三角形平面上，而熔融氯化银倾向于90°的Cl-Ag-Cl键角，据认为这是为了保持与固态中相似的局部环境。RMC模型的原子构型表明，碘化铜和碘化银超离子熔体中的阳离子分布表现出较大的波动，而氯化银非超离子熔体中的银离子分布则更为均匀。
