Crystal structures of disordered A2Mn3+ M5+O6 (A= Sr, Ca; M = Sb, Nb, Ru) perovskites

被引：47

作者：

Lufaso, MW ^{[1
]}

Woodward, PM ^{[1
]}

Goldberger, J ^{[1
]}

机构：

[1] Ohio State Univ, Dept Chem, Columbus, OH 43210 USA

来源：

JOURNAL OF SOLID STATE CHEMISTRY | 2004年 / 177卷 / 4-5期

基金：

美国国家科学基金会;

关键词：

cooperative Jahn-Teller distortions; cation ordering; orbital ordering; neutron powder diffraction; perovskites; octahedral tilting;

D O I：

10.1016/j.jssc.2003.12.020

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

Polycrystalline samples of A(2)MnMO(6) (A = Sr, Ca; M = Nb, Sb, Ru) were prepared by conventional solid state synthesis and their crystal structures were determined using neutron powder diffraction data. All Six Compounds can be classified as distorted, disordered perovskites. The Mn3+/M5+ distribution is disordered in all six compounds. The strontium containing compounds, Sr2MnMO6 (M = Nb, Sb, Ru), undergo out of phase rotations of the octahedra about the c-axis (tilt system a(0)a(0)c(-)) leading to tetragonal I4/mcm space group symmetry. The calcium containing compounds, Ca2MnMO6 (M = Nb, Ru, Sb), have orthorhombic Pnma space group symmetry, as a result of a GdFeO3-type octahedral tilting distortion (tilt system a(-)b(+)a(-)). A cooperative Jahn-Teller distortion is observed in SrMnSbO6 and Sr2MnRuO6, but it is much smaller than the distortion observed in LnMnO(3) (Ln = lanthanide ion) perovskites. It is possible that Jahn-Teller distortions of the MnO6 octahedra take place on a short-range length scale in the other four compounds, but there is little or no evidence for cooperative ordering of the local distortions. These findings demonstrate a link between orbital ordering, cation ordering and octahedral tilting. (C) 2004 Elsevier Inc. All rights reserved.

引用

页码：1651 / 1659

页数：9

共 35 条

[1] Evolution of the Jahn-Teller distortion of MnO6 octahedra in RMnO3 perovskites (R = Pr, Nd, Dy, Tb, Ho, Er, Y):: A neutron diffraction study [J].