Ca5Nb2TiO12 and Ca5Ta2TiO12: Low temperature coefficient low loss dielectric materials

The 1 MHz dielectric properties for single-phase polycrystalline ceramics o f the Ca5Nb2TiO12 and Ca5Ta2TiO12 perovskites are reported. In the vicinity of ambient temperature, the dielectric constants are approximately 35 and 23, respectively, and the dielectric losses are low, with Qs on the order o f 5000, the upper limit of our measurement technique. Ceramics with a tempe rature coefficient of dielectric constant (TCK) less than 5 ppm/degrees C a re reported. The dielectric properties are found to be systematically depen dent on processing conditions. The data suggest that an order-disorder tran sition among the B-site ions plays a major role in the determination of the temperature dependence of the dielectric constant for both compounds. (C) 1999 Elsevier Science Ltd.