Crystal structure analysis of Scheelite and Zircon type thorium germanates: A neutron diffraction study

被引：20

作者：

Achary, S. N.

Patwe, S. J.

Krishna, P. S. R.

Sindhe, A. B.

Tyagi, A. K. ^{[1
]}

机构：

[1] Bhabha Atom Res Ctr, Div Chem, Bombay 400085, Maharashtra, India

[2] Bhabha Atom Res Ctr, Solid State Phys Div, Bombay 400085, Maharashtra, India

来源：

JOURNAL OF ALLOYS AND COMPOUNDS | 2007年 / 438卷 / 1-2期

关键词：

germanates; structure; zircon;

D O I：

10.1016/j.jallcom.2006.08.025

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

In this communication we report the detailed crystal structure of two polymorphs of ThGeO4 (scheelite and zircon type) by Rietveld refinement of the neutron diffraction data of polycrystalline samples. Both of crystal structures consist of ThO8 (bisdisphenoid) and GeO4 tetrahedra. Scheelite type structure is a meta-stable polymorph and densely packed lattice, with a little larger average bond lengths of Th-O and Ge-O bonds to accommodate better packing. This is responsible for zircon to scheelite transformation under pressure. However, the average anion-anion contact and cation-cation contacts are shorter in scheelite structure compared to the zircon structure, which would causes the meta-stability in the scheelite structure. (C) 2006 Elsevier B.V. All rights reserved.

引用

页码：274 / 278

页数：5

共 16 条

[1] High temperature crystal chemistry and thermal expansion of synthetic powellite (CaMoO4):: A high temperature X-ray diffraction (HT-XRD) study [J].