Preparation and properties of high Q microwave dielectrics in the (Ca, Sr, Ba) zirconate system

Effects of powder synthesis and processing parameters on non-stoichiometric CaZrO3 with added SrO and BaO were studied in order to optimize microstructure and microwave dielectric properties. Nitrate precursors of the constituent oxides were mixed in aqueous solutions to give the desired composition. The effect of solution pH (1-10) on powder characteristics and gel formation in the system were examined. Optimally high surface areas (31.4 m2/g), small particle size (0.05 μ), and uniform, dense microstructure were obtained only for the acidic (pH ∼ 1) powders. Ceramic parts with uniform microstructures, high dielectric constants εr = 30-35, and high Q (>4000) were prepared from these powders