Microwave dielectric properties of low-temperature sintered Ca[(Li1/3Nb2/3),Ti]O3−δ ceramics

Ca[(Li1/3Nb2/3)1−xTix]O3−δ (0.5⩾×⩾0) solid solutions with additives were fabricated to develop a new microwave resonator with a low sintering temperature. With the addition of 2.0 wt.%B2O3, the maximum densities of Ca[(Li1/3Nb2/3)1−xTix]O3−δ (0.1⩾×⩾0.3) ceramics were obtained after sintering at 1000 °C. The Ca[(Li1/3Nb2/3)1−xTix]O3−δ ceramics exhibit an orthorhombic phase with the 1:2 ordered structure. As the x composition increases from 0 to 0.5, the dielectric constant, ε, increases from 30 to 60, the quality factor, Q×f, decreases from 30 000 to 14 900 GHz, and the temperature coefficient of resonant frequency, τf, in creases from −17 to 83.6 ppm/°C. Typically, at x=0.2, the specimen shows the optimum dielectric properties: ε=40, Q×f =20 500 GHz (at 8 GHz), and τf=4.7 ppm/°C. Furthermore, the addition of both B2O3 and Bi2O3 was found to be effective in reducing the sintering temperature of Ca[(Li1/3Nb2/3)0.7Ti0.3]O3−δ ceramics to 920 °C without a significant degradation of the microwave dielectric properties.