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A.C. Impedance and Transport Number Measurements of Ba6 Ta2O11

Published online by Cambridge University Press:  28 February 2011

Takashi Goto
Affiliation:
Chemistry Department, Aberdeen University, Meston Walk, Aberdeen AB9 2UE, Scotland, U.K.
A.R. West
Affiliation:
Chemistry Department, Aberdeen University, Meston Walk, Aberdeen AB9 2UE, Scotland, U.K.
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Abstract

Ba6Ta2O11 with an oxygen—deficient perovskite—related structure, was prepared through solid state reaction of BaCO3 and Ta2O5 powders. The electrical conductivity of sintered Ba6Ta2O11 pellets was measured by a.c. impedance spectroscopy inthe temperature range between 200 and 800ºC. The conductivity at 800ºC was3.7x10-3 Ω-1 cm-1; the activation energy for bulk conduction was 0.93 eV at temperatures between 500 and 800ºC and 1.22 eV below 500ºC. The bulk conductivity was independent of atmosphere, while the grain boundary conductivity, with an activation energy of 1.08 eV, decreased as oxygen partial pressure increased. The oxygen ion transport number obtained from concentration cell measurements was 0.5 to 0.65 at temperatures from 450 to 820ºC.

Type
Research Article
Copyright
Copyright © Materials Research Society 1991

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