Influence of CuO or MnCO3 additive on the dielectric properties of Ca0.65Ti0.65La0.35Al0.35O3 Ceramics

The influence of CuO or MnCO3 additive on the sinterability, microstructure and microwave dielectric properties of Ca0.65Ti0.65La0.35Al0.35O3, i.e., CTLA, ceramics was investigated in this paper. The results indicated that the density and dielectric properties of CTLA ceramics can be improved by both low-level doping of CuO (up to 1 wt%) and MnCO3 (up to 0.75 wt%). The sintering temperature of CTLA ceramics with addition of CuO/MnCO3 can be effectively reduced from 1450°C to 1320°C due to the liquid phase effect. No secondary phase was observed for the addition at the amount of 0.5-1 wt% CuO and 0.25-0.75 wt% MnCO3. With the addition of CuO/MnCO3, the dielectric constant (er) and the temperature coefficient of resonant frequency (tf) of the samples were not significantly affected, while the unloaded quality factors Q were effectively promoted. Excellent microwave dielectric properties were achieved for the ceramic Ca0.65Ti0.65La0.35Al0.35O3 + 0.75wt% CuO/ MnCO3 sintered at 1320°C for 2 h, with values of Q×f = 32,800 GHz, er = 43 and tf = +10 ppm/°C.