Synthesis and electrical properties of Ba2Nb5-xZrxO9

The Ba2Nb5-xZrxO9 solid solution was first synthesized by the solid state r eaction, and Zr proved to be substituted selectively for Nb in the preferre d site of Ba2Nb5O9. The structure of Ba2Nb5-xZrxO9 consists of a NbO layer sandwiched by two Ba(Nb, Zr)O-3 perovskite blocks. The limit of Zr-substitu tion was estimated to be x=1.0, according to the change of c axis parameter against x. SEM observation showed that platy agglomerates preferred the or ientation of the 00l plane, and the particle size was reduced by up to 1/10 on the addition of Zr. The solid solution showed a metallic conductivity w ith a temperature independent magnetic susceptibility. Substitution of Zr f or Nb appeared to cause a change in electron density as a result of contrac tion of the Nb(2)O(3) distance, leading to the increase of electrical resis tivity. (C) 2000 Elsevier Science S.A. All lights reserved.