It was noted that the degradation of barium titanate-based multi-layer capacitors resulted mainly from the migration and redistribution of O vacancies. An internal friction relaxation peak was observed here at around 70C. It was due to an O vacancy, and its relaxation strength differed markedly for specimens aged at 85C for 120h and at 150C for 5h. Two explanations were proposed. One was based upon symmetry-conforming short-range order, while the other was based upon interaction between the O vacancy and domain walls during aging. In either case, it was found that relaxation thermodynamics was a powerful tool for investigating the migration and redistribution of O vacancies in barium titanate ceramics.

Migration and Redistribution of Oxygen Vacancy in Barium Titanate Ceramics. L.Chen, X.M.Xiong, H.Meng, P.Lv, J.X.Zhang: Applied Physics Letters, 2006, 89[7], 071916 (3pp)