The electrical-insulation degradation of BaTiO3 was now of growing interest as the BaTiO3-based dielectric layers of multilayer ceramic capacitors were getting thinner to sub-micron thicknesses. The degradation was understood to be due to the electrotransport of O vacancies and may be monitored by the colours emanating from the cathode and/or anode. In the case of single crystal BaTiO3, a brown colour emanated from the anode and a blue colour from the cathode. The generation of the colours in BaTiO3 in electric fields were experimentally reviewed, and their origins and the kinetics of colour front migration were considered. From this, the O vacancy mobility at 150 to 500C was subsequently determined and compared with the published data that had normally been estimated using other means at elevated temperatures.

Electrocoloration and Oxygen Vacancy Mobility of BaTiO3. H.I.Yoo, M.W.Chang, T.S.Oh, C.E.Lee, K.D.Becker: Journal of Applied Physics, 2007, 102[9], 093701