Effects of Ti4+ substitution on microwave dielectric properties of (Pb0.2Ca0.8)[(Ca1/3Nb2/3)1−xTix]O3 ceramics

Microwave dielectric properties of (Pb0.2Ca0.8)[(Ca1/3Nb2/3)1−xTix]O3 (PCCNT) ceramics were investigated as a function of Ti4+ content (0.05≤x≤0.35). A single perovskite phase with the CaTiO3-type structure was obtained from x=0.05 to 0.15, and TiO2 and CaNb2O6 were detected as a secondary phase beyond x=0.2. The structure was changed from orthorhombic at x=0.05 to cubic at 0.35. Dielectric constant (K) was increased with increase of Ti4+ content and decrease of the cube of the average radius of B-site cation, however, Qf value was decreased, which due to the decrease of grain size and the formation of secondary phase. The temperature coefficient of resonant frequency (TCF) could be adjusted from −27.4 to +18.4 ppm/°C. Typically, K of 51.67, Qf of 7268 (GHz), TCF of 0 ppm/°C were obtained in the (Pb0.2Ca0.8)[(Ca1/3Nb2/3)0.8Ti0.2]O3 specimen.