Microwave dielectric properties of CaTiO3-CaAl1/2Nb1/2O3 ceramics doped with Li3NbO4

Abstract

The microwave dielectric properties of CaTi1-x(Al1/2Nb1/2)(x)O-3 solid solutions (0.3 less than or equal to x less than or equal to 0.7) have been investigated. The sintered samples had perovskite structures similar to CaTiO3. The substitution of Ti4+ by Al3+/Nb5+ improved the quality factor Q of the sintered specimens. A small addition of Li3NbO4 (about 1 wt%) was found to be very effective for lowering sintering temperature of ceramics from 1450-1500degrees to 1300degreesC. The composition with x = 0.5 sintered at 1300degreesC for 5 h revealed excellent dielectric properties, namely, a dielectric constant (epsilon(r)) of 48, a Q X f value of 32 100 GHz, and a temperature coefficient of the resonant frequency (tau(f)) of -2 ppm/K. Li3NbO4 as a sintering additive had no harmful influence on tau(f) of ceramics.