Microstructures and Dielectric Properties of Pure and Doped KNbO3 Ceramics

Regions consisting of grains of pronounced cubic develpment exist in pure KNbO3 ceramics which exhibit a temperature dependence of dielectric constant very similar to that of KNbO3 crystals. KNbO3 ceramics doped with GeO2‐K2O additives have small grains, semiconducting resistance, and a different curve of dielectric constant versus temperature. As the average grain size decreases, the shape of the curve differs increasingly from that of KNbO3 crystals.