Local structure of Pb(Sc1/2,Ta1/2)O3 and related compounds

被引:79
作者
Dmowski, W
Akbas, MK
Davies, PK
Egami, T
机构
[1] Univ Penn, Dept Mat Sci & Engn, Philadelphia, PA 19104 USA
[2] Univ Penn, Res Struct Matter Lab, Philadelphia, PA 19104 USA
关键词
ceramics; X-ray scattering; crystal structure; ferroelectricity;
D O I
10.1016/S0022-3697(99)00286-3
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The atomic structure of Pb(Sc1/2Ta1/2)O-3 (PST), and related Pb(A,B)O-3 type mixed perovskites was studied by diffraction using synchrotron X-rays and pulsed neutrons. The Rietveld refinement was carried out to determine the average, long-range crystallographic structure, while the pair-density function (PDF) analysis was used in studying the local atomic structure. The compounds examined, relaxer ferroelectric Pb(Sc2/3W1/3)O-3 (PSW) and Pb(Mg1/3Ta2/3)O-3-PbZrO3 (PMT-PZ) in addition to PST, all exhibit long range 1:1 B-site cation ordering. The Rietveld refinement showed that the degree of long range 1:1 (NaCl-type) chemical ordering on the B-sites is up to 90%. For all samples including the nominally ordered PST the local atomic structure determined by the PDF analysis, was found to be significantly different from the average crystallographic structure determined by the Rietveld analysis. Local deviations are greater for O and Pb atoms than the B-site cations. The direction of the local Pb displacement in PST is [100], even though the macroscopic easy axis of polarization appears to be [111]. These results show that the conflict between the local structural preference and the average structure is not limited to relaxer ferroelectric oxides, but may be widely prevalent in mixed-ion ferroelectrics. (C) 1999 Elsevier Science Ltd. All rights reserved.
引用
收藏
页码:229 / 237
页数:9
相关论文
共 21 条
[21]   DIFFUSE PHASE-TRANSITIONS AND RANDOM-FIELD-INDUCED DOMAIN STATES OF THE RELAXOR FERROELECTRIC PBMG1/3NB2/3O3 [J].
WESTPHAL, V ;
KLEEMANN, W ;
GLINCHUK, MD .
PHYSICAL REVIEW LETTERS, 1992, 68 (06) :847-850