Low temperature coefficient bulk dielectrics in the Ca₂Nb₂O₇-Ca₂Ta₂O ₇ system

The dielectric properties of bulk polycrystalline ceramics in the binary Ca₂Ta₂O₇-Ca₂Nb₂O ₇ system are reported. Measurements of the dielectric constant at 1 MHz were made at temperatures between O and 100°C. The large negative (for the niobate) and positive (for the tantalate) temperature coefficients for the dielectric constants in the pure materials in the vicinity of room temperature can be balanced in a two-phase region near x = 0.36 in Ca₂Ta_2-xNb_xO₇. At this composition, the dielectric constant is approximately 30, and the temperature coefficient of the dielectric constant is approximately 2 ppm/°C. The Q in our unoptimized polycrystalline ceramic at 1 MHz is approximately 5000.