Investigation of the sintering of barium titanate ceramics by oxygen coulometry

The oxygen coulometry method by solid electrolyte circonia cells was applie d to investigate the sintering process of Ba1-xLaxTiO3 ceramics (0 less tha n or equal tox less than or equal to0.05). During the heating, three differ ent oxygen release phenomena were observed: (1) the O-2 release due to the formation of Schottky-type oxygen vacancies; (2) the O-2 release caused by the incorporation of the donor impurity during grain growth; and (3) an irr eversible oxygen release with an onset temperature between 1000 and 1150 de greesC, for which the cause is not clear. The quantitative data of the effe ct (2) can be explained on condition that the donors are charge compensated both by electrons and by cation vacancies. (C) 2001 Elsevier Science Ltd. All rights reserved.