Microstructures and Dielectric Properties of Pure and Doped KNbO 3 Ceramics

Regions consisting of grains of pronounced cubic develpment exist in pure KNbO 3 ceramics which exhibit a temperature dependence of dielectric constant very similar to that of KNbO 3 crystals. KNbO 3 ceramics doped with GeO 2 ‐K 2 O 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 KNbO 3 crystals.