文献类型：期刊文献

英文题名：Synthesis of a new series of compounds RE₂Co_2/3Nb_4/3O₇ and stability field diagram of RE₂B_2/3′B_4/3"O₇ pyrochlore compounds

作者：Xuan, Y; Liu, R; Jia, YQ

机构：[1]E China Univ Sci & Technol, Dept Chem, Shanghai 200237, Peoples R China

年份：1998

卷号：53

期号：3

起止页码：256

外文期刊名：MATERIALS CHEMISTRY AND PHYSICS

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000073423200014)】；

语种：英文

外文关键词：stability field diagram; pyrochlore compounds; synthesis

摘要：A new series of pyrochlore compounds RE2Co2/3Nb4/3O7 (RE = Nd, Sm and Eu) have been synthesized by using a wet chemical method and the crystal structures of these compounds have also been determined. The crystal structure of RE2Co2/3Nb4/3O7 belongs to a hexagonal system. The assignments for the absorption bands in the infrared spectra of Eu2Co2/3Nb4/3O7 have also been given. The results of the crystal structure and the infrared spectra can demonstrate that the compounds are pyrochlore ones. The experimentally measured density and the calculated one indicate that they have 24 formulae in each unit cell. On the basis of the polarizability and the ionic radius of the B' ion and B" ion, a stability field diagram for the RE2B2/3'B-4/3"O-7 pyrochlore compounds with different symmetry is presented. The diagram shows that most pyrochlore compounds with a formula RE2B2/3'B-4/3"O-7 will belong to a hexagonal or tetragonal system anti, especially, possess a large cell structure, similar to the superstructure. The electric measurements indicate that RE2Co2/3Nb4/3O7 is an insulator and the electric resistivity of the compounds is larger than 10(5) ohm cm(-1) at room temperature. (C) 1998 Elsevier Science S.A. All rights reserved.