Order parameter and connectivity topology analysis of crystalline ceramics for nuclear waste immobilization.
Order parameter and connectivity topology analysis of crystalline ceramics for nuclear waste immobilization.
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用于核废料固定的晶体陶瓷的有序参数和连接拓扑分析。
DOI：
10.1088/0953-8984/26/48/485011
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Archer A
中科院分区：
文献类型：
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作者：
Archer A
我们应用键序和拓扑方法的问题分析的结果在陶瓷辐射损伤级联模拟。这两个修改的Steinhardt局部顺序和连接拓扑分析技术提供的结果，都是旋转和旋转不变的，并不依赖于一个特定的参考结构的选择。我们通过对高温超导体Gd 2 Ti 2 O 7和Gd 2 Zr 2 O 7中单级联的分子动力学模拟的新分析来说明这些方法，类似于先前报道的那些（Todorov等人，2006年，物理学杂志：康登斯事项18 2217）。从斯坦哈特和拓扑分析的结果是一致的，而往往提供补充信息，因为斯坦哈特参数是敏感的角度安排的变化，即使当整体拓扑连接是固定的。在高度非平衡条件下，在级联开始时，这两种技术揭示了显着的本地化的瞬态结构变化和变化的阳离子连接。在几皮秒之后，连接性在很大程度上是固定的，而顺序参数继续变化。在锆酸盐中，存在向阴离子无序体系的转变，而在钛酸盐中，存在实质性的逆转和愈合回到母体烧绿石结构。
We apply bond order and topological methods to the problem of analysing the results of radiation damage cascade simulations in ceramics. Both modified Steinhardt local order and connectivity topology analysis techniques provide results that are both translationally and rotationally invariant and which do not rely on a particular choice of a reference structure. We illustrate the methods with new analyses of molecular dynamics simulations of single cascades in the pyrochlores Gd 2 Ti 2 O 7 and Gd 2 Zr 2 O 7 similar to those reported previously (Todorov et al 2006 J. Phys.: Condens. Matter 18 2217). Results from the Steinhardt and topology analyses are consistent, while often providing complementary information, since the Steinhardt parameters are sensitive to changes in angular arrangement even when the overall topological connectivity is fixed. During the highly non-equilibrium conditions at the start of the cascade, both techniques reveal significant localized transient structural changes and variation in the cation connectivity. After a few picoseconds, the connectivity is largely fixed, while the order parameters continue to change. In the zirconate there is a shift to the anion disordered system while in the titanate there is substantial reversion and healing back to the parent pyrochlore structure.