Microwave dielectric properties of the (1-x)(Mg_0.9Co_0.1)TiO₃ - x(Ca_0.61La_0.26)TiO₃ ceramics

The microwave dielectric properties of the (1-x)(Mg_0.9Co_0.1)TiO₃ - x(Ca_0.61La_0.26)TiO₃(MCT-CLT) ceramics were investigated. The system was prepared using a conventional solid-state ceramic route. The objective of the present work is to compensate for the negative temperature coefficient of resonant frequency (τ_f) of (Mg_0.9Co_0.1)TiO₃ (MCT) by the addition of (Ca_0.61La_0.26)TiO₃ (CLT). The microwave dielectric properties are strongly correlated with the sintering temperature and the composition. Very dense MCT-CLT ceramics were prepared by sintering at 1300°C. When the ceramics were sintered at temperatures above 1300°C, the bulk density decreased and the dielectric properties deteriorated. With the increasing of x, the relative dielectric constant (ε_r) of the ceramics increases and the product of quality factor and resonant frequency (Q×f) decreases. For practical application, 0.87(Mg_0.9Co_0.1)TiO₃ - 0.13(Ca_0.61La_0.26)TiO₃ (87MCT-13CLT) ceramics sintered at 1300°C with a dielectric constant ε_r=22.4, a Q×f value of 35000 GHz and a temperature coefficient of resonance frequency (τ_f) of -8.7×10^-6/°C was proposed in this paper.