A novel LiNb0.6Ti0.5O3 microwave dielectric ceramic with Ca substitutions

A novel microwave dielectric ceramic LiNb0.6Ti0.5O3 (LNT) with Ca substitutions LiNb0.6Ti(0.5−x)Ca1.231xO3 was synthesized by solid-state method. It was found that with Ca substitutions, the temperature coefficient of resonant frequency τƒ could be adjusted to zero, due to the appearance of the second phase Ca5Nb4Ti3O21. The τƒ of the Ca5Nb4Ti3O21 phase is −144.3 ppm/°C through the simulation and numerical value calculation. Furthermore, the LiNb0.6Ti(0.5−x)Ca1.231xO3 ceramic shows a higher dielectric constant εr and a denser microstructure. The LiNb0.6Ti(0.5−x)Ca1.231xO3 ceramic with x = 0.03 sintered at 1100 °C for 2 h shows excellent microwave dielectric properties: εr = 76.89, Q × ƒ = 4064 GHz, τƒ = 0.25 ppm/°C.