Fabrication, Microstructure and Dielectric Properties of CaTi_1-x (Ni_1/3Nb_2/3)_xO₃ Ceramics

A series of CaTi_1-x(Ni_1/3Nb_2/3)_xO₃(0.4.≤x≤0.6)ceramics were prepared through conventional solid-state reaction method. The effects of doping, sintering temperature and annealing process on the phase composition, microstructure and dielectric properties of CaTi_1-x(Ni_1/3Nb_2/3)_xO₃ ceramics were investigated. The X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis results indicated that all the sintered samples adopted single perovskite phase. As x increased o.4 to 0.6, ε_r decreased from 59.52 to 44.97, Q×f values decreased from 13736 GHz to 6420 GHz, and the τ_f varied from +57.6 ppm/°C to -21.0 ppm/°C. A near zeroτ_f of -4.8 ppm/°C, dielectric contant of 47.3 and Q×f value of 11873.2 GHz were obtained at the sintering temperature of 1540 °C. Moreover, by annealing at 1400°C, the Q×f value was improved to 16130.6GHz. (paper)