Ag(Nb,Ta)O3-based ceramics with suppressed temperature dependence of permittivity

Different methods for the suppression of the temperature coefficient of permittivity of Ag(Nb,Ta)O3-based ceramics have been experimentally tested, as a result two methods, isovalent doping on the B-site and microstructural engineering, were combined to produce a Ag(Nb,Ta)O3-based ceramic with a temperature stable dielectric constant. Although the AgNbO3 and AgTaO3 exhibit complete solid solubility, special attention was devoted to maintaining the highest possible level of non-equilibrium in the Ag(Nb,Ta)O3-based ceramics. The influence of particular compositional and processing parameters on the microstructure and temperature dependence of permittivity was investigated. Based on our observations, the powder processing, phase composition and the firing conditions were optimized to produce Ag(Nb,Ta)O3-based ceramics with a permittivity of 430, a temperature coefficient of permittivity <50 ppm/K, tanδ=2·10−4 (at 1 MHz) and a Q-value (at 1 GHz)=700.