Microwave dielectric property adjustment of CoZrNb2O8 ceramics by CaTiO3 addition

Abstract

Temperature stable microwave dielectric ceramics CoZrNb2O8-xCaTiO3 (x = 1/60 ~ 1/10) were fabricated by a solid-state technique. The phase formation and sintering behavior were detected for the purpose of structure–property relationship exploration. Appropriate rate of CaTiO3 addition was benefit to the sintering temperature decrease of CoZrNb2O8. From x = 1/50 to x = 1/10, unexpected CaNb2O6 and Ti2Nb10O29 phases both formed, consequent on the chemical reaction between CoZrNb2O8 and CaTiO3. Co-based oxide might separate out in the form of liquid phase and decrease the sintering temperature. Increasing CaTiO3 ration degraded the quality factor Q × f, but at the same time enhanced the dielectric constant er and temperature coefficient of resonant frequency τf. According to the Lichtenecker mixing rule, the estimated microwave dielectric properties basically agreed well with the measured values at first. However, excessive CaTiO3 incorporation caused lattice defects and gave noticeable deviation. In current work, CoZrNb2O8-1/40CaTiO3 composite displayed a rather small τf with Q × f= 64,600 GHz at 1225 °C.