On the anomaly in residual polarization of BaTiO3 ceramics

Spontaneous polarization of barium-titanate (BaTiO3) ceramics has been noted in research for its ferroelectricity and for its practical use. It is natural that a great deal of interest has been attached to spontaneous polarization as the property is quite essential in the ferroelectric phenomena. Nevertheless when measurements of residual polarization of BaTiO3 were being made, the authors found that a very large amount of polarization occurred at times and it could not be attributed to spontaneous polarization in any case.1 Blood and his co-workers2 also found large residual polarization more than 150 μcoul/cm2 (microcoulomb/centimeter2) in BaTiO3 ceramics accompanied by the anomalous phenomena in piezoelectric oscillation. After examining the phenomena it was recognized that some sort of polarization should be superposed upon the proper spontaneous polarization. As such phenomena are never favorable to the practical use of ferroelectric substance, investigations have been made especially to find a way to diminish their effect. Thus it was found that the mixing ratio of raw materials of the ceramics seemed to have a remarkable relation to the anomalous polarization, and the reduction of BaTiO3 seemed to exist in accompaniment with such phenomena. The result obtained is reported in this paper.