Ionic conductivity of Bi4Ti0.2V1.8O10.7 polycrystalline ceramics obtained by the polymeric precursor route

BIMEVOX ceramics presenting the general formula Bi4V2(1-x)Me2xO(11 - 3x) have been synthesized by the polymeric precursor method. The composition that will be described in this work is Bi(4)ti(0.2)V(1.8)O(10.7). An analysis of X-ray diffraction patterns revealed that the Bi4Ti0.2V1.8O10.7 Phase was formed by heat-treating the composition at 650 degreesC for 3 h. Under this thermal treatment condition, the resulting powder presented a surface area of about 5.1 m(2) g(-1). Based on the features of this powder, polycrystalline samples with 98% relative density were obtained by sintering at 880degreesC for 8 h. The ionic conductivity of the compact sample was characterized by impedance spectroscopy measurements to separate the dc conductivity of other typical relaxation processes. Ionic conductivity was calculated as 1.48 x 10(-3) (Omega cm)(-1) at a temperature of 473 K, with, a carrier activation energy of 0.76 eV. The conductivity values obtained proved to be higher than those of materials prepared by other traditional nonchemical methods. (C) 2002 Elsevier Science B.V All rights reserved.