Selected aspects of dielectric behavior of plasma sprayed titanates

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.