Improved radio-frequency dielectric properties of novel high-permittivity BaMoO4 matrix with CaTiO3 addition.

The structural and dielectric properties of BaMoO4 - CaTiO3 advanced ceramics in the Radio Frequency (RF) region (< 300 MHz) were studied in the present work. X-ray diffraction and Rietveld refinement showed no evidence of secondary phases, indicating no reaction between the BaMoO4 (BMO) and CaTiO3 (CTO) phases. Complex Impedance Spectroscopy (CIS) analysis demonstrated that BMO presents greater permittivity than composites can be explained by the low densification of the composites. Nyquist diagrams were fitted employing an equivalent circuit with two associations of R-CPE (constant phase element) related to the grain and the grain boundary effects. The composites showed a decrease in the values of Temperature Capacitance Coefficient (TCC) with CTO (CaTiO3) content increase, whereas composites BMO20 and BMO40 showed TCC values equal to zero at 1 MHz. Moreover, as obtained by CIS analysis, the activation energy of thermo-activated processes decreases with CTO concentration increase. [ABSTRACT FROM AUTHOR]