Medium range correlation of Ag ions in superionic melts of Ag2Se and AgI by reverse Monte Carlo structural modelling -Connectivity and void distribution-
Medium range correlation of Ag ions in superionic melts of Ag2Se and AgI by reverse Monte Carlo structural modelling -Connectivity and void distribution-
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通过反向蒙特卡罗结构模型计算 Ag2Se 和 AgI 超离子熔体中银离子的中程相关性 -连通性和空隙分布 -
DOI：
10.1088/0953-8984/23/23/235102
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
and S. Takeda
中科院分区：
文献类型：
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作者：
S. Tahara;H. Ueno;K. Ohara;Y. Kawakita;S. Kohara;S. Ohno;and S. Takeda
对熔融Ag 2 Se 进行高能X 射线衍射测量。根据我们新的 X 射线和早期发布的中子衍射数据，通过逆蒙特卡罗 (RMC) 结构建模推导出部分结构因子和径向分布函数。将这些部分功能与熔融 AgI 的部分功能进行了比较。 AgI 和 Ag 2 Se 在熔化前均具有超离子固相。对熔融 AgI 进行了新的 RMC 结构建模，以修改我们之前的模型，并通过键角限制来减少非物理 Ag 三角形的数量。熔融 AgI 的精细模型表明，Ag 离子形成的孤立的无支链是 Ag 中序有序的原因。与熔融的 AgI 相比，熔融的 Ag 2 Se 具有“笼状”结构，大约七个 Ag 离子围绕一个 Se 离子。连通性分析表明，熔融Ag 2 Se中的大多数Ag离子彼此之间的距离在2.9 Å以内，并且仅发现很小的空隙，这与熔融AgI中Ag空隙半径的广泛分布形成鲜明对比。据推测，需要Ag离子通过小空隙的集体运动来实现众所周知的Ag离子在熔融Ag 2 Se中的快速扩散，这与熔融AgI中的快速扩散相当。
High-energy x-ray diffraction measurements on molten Ag 2 Se were performed. Partial structure factors and radial distribution functions were deduced by reverse Monte Carlo (RMC) structural modelling on the basis of our new x-ray and earlier published neutron diffraction data. These partial functions were compared with those of molten AgI. Both AgI and Ag 2 Se have a superionic solid phase prior to melting. New RMC structural modelling for molten AgI was performed to revise our previous model with a bond-angle restriction to reduce the number of unphysical Ag triangles. The refined model of molten AgI revealed that isolated unbranched chains formed by Ag ions are the cause of the medium-range order of Ag. In contrast with molten AgI, molten Ag 2 Se has' cage-like'structures with approximately seven Ag ions surrounding a Se ion. Connectivity analysis revealed that most of the Ag ions in molten Ag 2 Se are located within 2.9 Å of each other and only small voids are found, which is in contrast to the wide distribution of Ag-void radii in molten AgI. It is conjectured that the collective motion of Ag ions through small voids is required to realize the well-known fast diffusion of Ag ions in molten Ag 2 Se, which is comparable to that in molten AgI.