Fossati Paul C M, Chartier Alain, Boulle Alexandre
DES-Service de Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), CEA Saclay, Université Paris Saclay, Gif-sur-Yvette, France.
Institut de Recherche sur les Céramiques (IRCer), CNRS UMR 7315, Université de Limoges, Centre Européen de la Céramique, Limoges, France.
Front Chem. 2021 Oct 18;9:723507. doi: 10.3389/fchem.2021.723507. eCollection 2021.
Some binary compounds with the fluorite structure (space group ) are well-known examples of materials exhibiting transitions to ionic superconducting phases at high temperatures below their melting points. Such superionic states have been described as either highly defective crystals or part-crystal, part-liquid states where the ions retain their crystalline order whilst the ions undergo partial melting. However, no detailed description of the structure of these phases exists. We present here the results of our investigation of the structural changes that occur during these transitions and the structural characteristics of the resulting superionic materials. This work is based on atomic-scale molecular dynamics modelling methods as well as computational diffraction techniques. We employed a set of empirical potentials representing several compounds with the fluorite structure to investigate any potential-dependent effect. We show the importance of small-scale structure changes, with some local environments showing a hexagonal symmetry similar to what is seen in the scrutinyite structure that has been documented for example in UO.
一些具有萤石结构（空间群 ）的二元化合物是材料的著名例子，这些材料在低于熔点的高温下会转变为离子超导相。这种超离子态被描述为要么是高度缺陷的晶体，要么是部分晶体、部分液体的状态，其中 离子保持其晶体有序性，而 离子发生部分熔化。然而，这些相的结构尚无详细描述。我们在此展示了我们对这些转变过程中发生的结构变化以及所得超离子材料的结构特征的研究结果。这项工作基于原子尺度的分子动力学建模方法以及计算衍射技术。我们采用了一组代表几种具有萤石结构化合物的经验势来研究任何与势相关的效应。我们展示了小规模结构变化的重要性，一些局部环境呈现出类似于例如在UO中记录的 scrutinyite结构中所见的六边形对称性。
