Selected aspects of dielectric behavior of plasma sprayed titanates

Abstract

XRD measurements were carried out on plasma sprayed titanates BaTiO3, CaTiO3, MgTiO3 and a mixture of the last two. Samples were tested as dielectrics and volume resistivities of the materials were also summarized. Microwave microscopy was used for mapping of the dielectric response of selected samples. The results show differences in the crystal structure between plasma sprayed coatings and feedstock powders in the case of BaTiO3 and MgTiO3 whereas CaTiO3 is crystalograffically identical with its feedstock. The reason can be found in larger sensitivity of BaTiO3 and MgTiO3 to the reductive conditions at plasma spraying whereas CaTiO3 seems to be rather inert from this viewpoint. However CaTiO3 exhibits anomalous dielectric losses because of intrinsic conductivity.