Dielectric properties of CaZrO3 coatings made by plasma spraying and bulks fired by spark plasma sintering

Plasma spraying was used to prepare CaZrO3 coatings, whereas CaZrO3 bulks were fired by spark plasma sintering (SPS). Differences in the structure of thick coatings and SPS compacts were characterized by microscopy, density and porosity measurements. The deposits were striped-out from the substrate, in order to produce samples of planparallel plates with a smooth surface. These samples were studied in alternating electric field with frequency range from 1 kHz to 1 MHz. Relative permittivity was calculated. The dependences of permittivity and losses on the frequency were studied also for varying temperatures in the range from 20–150 °C. Volume resistivity was measured in DC field at room temperature. Influence of the SPS process and annealing on the microstructure and dielectric properties was studied as well. Decrease of porosity and rearrangement of grains after proper annealing brought improvements in the dielectric characteristics. [Display omitted] •Calcium zirconate CaZrO3 was plasma sprayed and spark plasma sintered from the same feedstock powder.•Dielectrics with relative permittivity stable versus frequency course and with satisfactory low loss factor were formed.•Very high volume DC resistivity was obtained in case of both techniques.•Medium level temperature annealing with high dwell time is shown as the best way how to improve the dielectric properties.•At plasma spray the problems with chemical reduction and induced space charge polarization were avoided. In this study, water stabilized plasma spraying (WSP) was used to prepare CaZrO3 coatings, whereas CaZrO3 bulk samples were fired using spark plasma sintering (SPS). The spraying feedstock was prepared from fine CaZrO3 powder by agglomeration (spray drying) and sintering. The initial fine CaZrO3 powder was used for SPS. In case of plasma sprayed materials, the influence of spraying process on the coating structure was studied. Differences in the structure of plasma sprayed thick coatings and SPS compacts were characterized using microscopy, density and porosity measurements. The deposits were striped-out from the substrate, ground and polished in order to produce samples in a shape of planparallel plates with a smooth surface. These samples – in principle monoblock capacitors – were subjected to low voltage alternating electric field with a frequency range from 1 kHz to 1 MHz and their capacitance and loss factor were measured. Relative permittivity was calculated afterwards from the measured