New high-permittivity AgNb1-xTaxO3 microwave ceramics: Part II, Dielectriccharacteristics

Ceramic samples with the AgNb1-xTaxO3 (0.46 < x < 0.54) composition were sy nthesized and analyzed, with respect to their dielectric properties, In a m icrowave-frequency range and at radio frequencies. The permittivity over th e compositional range 0.46 less than or equal to x less than or equal to 0. 52 was >410, whereas the Qxf value, measured at 2 GHz, reaches values of 64 0-900 GHz, Dependence of the resonant frequency on temperature was not line ar but did display a minimum at a particular temperature, which Teas depend ent on the composition of the ceramic. Samples that were measured at radio frequencies displayed low dissipation factors (tg delta = 7 x 10(-4)-18 x 1 0(-4)), a low aging rate (0.2% per time decade), and good dielectric streng th (8 V/mu m at a thickness of 0.6 mm). Microstructural investigations reve aled the presence of precipitates and transformation twins that should be e liminated during additional processing optimization.