Abstract
Thermal desorption studies and electrical conductivity measurements have been used to investigate the solubility of hydrogen defects in barium titanate ceramics in oxidizing atmospheres. Hydrogen is found to dissolve in the perovskite lattice of undoped and acceptor‐doped BaTiO3 by the formation of hydroxide ions on regular oxygen ion sites. The hydrogen defects act as mobile donors and may substitute the oxygen vacancies in compensating fixed acceptors. From the dependence of the solubility on the water vapor pressure and the dopant concentration, the incorporation/desorption equilibrium reaction is deduced. A defect model is derived which consistently extends previously proposed models. The influence of Ba2TiO4 and Ba6Ti17O40 second phases on the solubility of hydrogen defects is discussed.

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