Microwave dielectric properties and microstructures of cCa1-xNd2x/3TiO3-Li1/2Nd1/2TiO3 ceramics

The microwave dielectric properties and microstructures of (1-y)Ca1-xNd2x/3TiO3-yLi1/2Nd1.2TiO3 ceramic, prepared by a mixed oxide route, have been investigated. A maximum quality factor Q x f = 8600GHz (where f is the resonant frequency) was achieved for samples with v = 0 and x = 0.39, although the dielectric properties varied with sintering temperature. The Q x f value of (I-x)Ca1-xNd2x/3TiO3-yLi1/2TiO3 increased up to 1400 C, after which it decreased. The decrease in dielectric properties was coincident with the onset of rapid grain growth. In the (1-y)Ca1-xNd2x/3TiO3-yLi1/2Nd1/2TiO3 system, as y increased, the temperature coefficient of resonant frequency (tau(r)) decreased from 800 to 8 ppm/degreesC for y = 0.52 (x = 0.39). However, the optimum combination of microwave dielectric properties as achieved at 1400 C for samples where y = 0.45 (x = 0.39) with a dielectric constant epsilon(r) of 101, a Q x f value of 5300 (at 7.2 GHz) and a tau(r) value of + 13 ppm/degreesC.