呼吸烧绿石晶格的形成：结构，热力学和晶体化学方面,CrystEngComm

当前位置： X-MOL 学术 › CrystEngComm › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

呼吸烧绿石晶格的形成：结构，热力学和晶体化学方面
CrystEngComm ( IF 2.6 ) Pub Date : 2020/01/02 , DOI: 10.1039/c9ce01635j
Mikhail V. Talanov _{1,

2,

3,

4} , Valeriy M. Talanov _{4,

5,

6,

7}

Affiliation

烧绿石晶格是角共享四面体的三维网络。由过渡金属原子形成的具有烧绿石晶格的晶体会产生大量的凝结相和由几何受挫引起的新现象。这种金属-金属距离不同的结构的一种类型称为呼吸烧绿石晶格。呼吸中的烧绿石晶格的形成在许多情况下伴随着聚集和奇特基态的出现，以及令人感兴趣的物理性质。以F [4与组合光子组合]

3 m为例研究了呼吸性烧绿石晶格的形成在基团理论分析，Landau热力学和晶体化学方面订购了烧绿石。在本文中，已经证明，描述的阶数参数Fd [3与组合光子组合]

m → F

3 m是通过位于初始母体烧绿石结构的16 c，16 d和48 f Wyckoff位置的原子的位移实现的，以及位于8 b和48 f处的原子的顺序Wyckoff位置（原子排序的类型分别为1：1）。对于某些有序烧绿石，我们估计了有序参数的大小及其对原子位移的贡献。基于Landau型相图，可能由于在三临界点附近发生第二阶和一阶相变而出现初始的高对称相和低对称相之间的相变的两个主要热力学路径。F [4与组合光子组合]

3 m的结构特征建立有序的烧绿石（呼吸烧绿石晶格，四面体结构单元之间的桥，呼吸四面体的六元环，有序的α-烧绿石中的阴离子中心簇以及有序的β-烧绿石中的笼状结构）。预计将存在继承F [4与组合光子组合]

3 m有序烧绿石结构特征的新型烧绿石类物质。

"点击查看英文标题和摘要"

Formation of breathing pyrochlore lattices: structural, thermodynamic and crystal chemical aspects

A pyrochlore lattice is a three-dimensional network of corner-sharing tetrahedra. Crystals with a pyrochlore lattice formed from the atoms of a transition metal give rise to a rich variety of condensed phases and novel phenomena caused by geometrical frustration. A type of this structure with different metal–metal distances is known as a breathing pyrochlore lattice. The formation of breathing pyrochlore lattices is accompanied in many cases by clustering and the appearance of exotic ground states, as well as intriguing physical properties. The formation of breathing pyrochlore lattices was investigated on the example of F [4 with combining macron]

3m ordered pyrochlores in terms of group-theoretical analysis, Landau thermodynamics and crystal chemistry. In this article, it has been shown that the order parameter described Fd [3 with combining macron]

m → F

3m phase transition is realized in the displacements of the atoms located at the 16c, 16d, and 48f Wyckoff positions of the initial parent pyrochlore structure, as well as the ordering of atoms located at the 8b and 48f Wyckoff positions (the type of atom ordering is 1 : 1 in each case). For some ordered pyrochlores, we estimate the order parameter magnitude and its contribution to atomic displacements. Two main thermodynamic paths of the phase transitions between initial high-symmetry and low-symmetry phases occurring as a result of both second- and first-order phase transitions in the vicinity tricritical point are possible based on the Landau-type phase diagram. The structural features of F [4 with combining macron]

3m ordered pyrochlores are established (breathing pyrochlore lattices, bridges between tetrahedral structural units, breathing six-member rings of tetrahedra, anion-centered clusters in the ordered α-pyrochlores, and cage-structures in the ordered β-pyrochlores). The existence of new classes of pyrochlore-like materials that inherit the structural features of F [4 with combining macron]

3m ordered pyrochlores is predicted.

更新日期：2020-02-17

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南