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.