Sintering behavior, phase evolution and microwave dielectric properties of thermally stable (1−x)Li3NbO4−xCaTiO3 composite ceramic

Microwave dielectric ceramics with the composition of (1−x)Li3NbO4−xCaTiO3 (0.1≤x≤0.3) were prepared by the solid-state reaction method. The sintering behavior, phase structure, and microwave dielectric properties of (1−x)Li3NbO4−xCaTiO3 ceramics were investigated. The samples consisted of Li3NbO4 and CaTiO3 phases, and the amount of CaTiO3 phase increased with increasing x. The microwave dielectric properties of the sintered ceramics varied with increasing CaTiO3 content. In particular, the temperature coefficient of resonate frequency values (τf) can be adjusted to near-zero. Typically, 0.15 mol CaTiO3 added 0.85Li3NbO4–0.15CaTiO3 ceramic exhibited good microwave dielectric properties with a relative permittivity of 21.9, a Q×f value of 24,900 GHz, and a τf value of 5.6 ppm/°C. These results indicate that 0.85Li3NbO4–0.15CaTiO3 ceramic can be a candidate in microwave dielectric resonators.