Interplay between anion rotation and cation transport in the plastic high-temperature phase of sodium ortho-phosphate

被引：15

作者：

Funke, K ^{[1
]}

Wilmer, D ^{[1
]}

Banhatti, RD ^{[1
]}

Witschas, M ^{[1
]}

Lechner, RE ^{[1
]}

Fitter, J ^{[1
]}

Jansen, M ^{[1
]}

Korus, G ^{[1
]}

机构：

[1] Univ Munster, Inst Phys Chem, D-4400 Munster, Germany

来源：

DIFFUSION MECHANISMS IN CRYSTALLINE MATERIALS | 1998年 / 527卷

关键词：

D O I：

10.1557/PROC-527-469

中图分类号：

TQ174 [陶瓷工业]; TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

The high-temperature phase of sodium ortho-phosphate, alpha-Na3PO4, belongs to the class of ion conducting plastic crystals, i.e., it is characterized by a dynamic rotational disorder of its polyatomic anions and, at the same time, by a considerable translational mobility of its cations. During the past decade, the possibility, nature, and importance of a dynamic interplay between the two kinds of motion have been a subject of continued controversy. Proponents of a strong interplay coined the expression "paddle-wheel mechanism". In our present contribution we report, for the first time, on the results of dynamic experiments probing the elementary steps of anionic and cationic motion individually. The techniques utilized in this study are coherent quasielastic neutron scattering and high-frequency conductivity spectroscopy, respectively The data are complemented by an ab-initio molecular-dynamics simulation. Our results provide a view of the movement of anions and cations and of correlations between them. Strong dynamic coupling is detected between the octahedrally coordinated sodium ions and nearby oxygen ions. For translational sodium-ion transport, a chain mechanism appears to be operative.

引用

页码：469 / 480

页数：12