The microstructure and dielectric properties of (K0.5Na0.5)NbO3 - SrZrO3 were investigated. The dielectric constant is high and stable in a wide temperature range due to the core-shell structure composed of a K-rich shell and a Na-rich core, which have different Curie temperatures. This result shows that the rate of change in dielectric constant can be controlled by the core shell structure. This material can be used for high-temperature multilayer ceramic capacitors (MLCC), which have stable capacitance.
The oxygen vacancy migration that causes the insulation resistance degradation in BaTiO3 was investigated. From the result of thermally stimulated depolarization current (TSDC) of Mg doped BaTiO3, the distinct current peak associating the oxygen migration within the grain and across the grain boundary were found. In virgin and degraded Mg doped BaTiO3, the insulation resistance of the grain boundary decreased upon degradation, while that of the grain remained unchanged. Thus, oxygen vacancy migration across the grain boundary dominates insulation resistance degradation.