Microwave Dielectric Properties of Ba(Mg_1/2W_1/2)O₃–BaTiO₃ Ceramics

Abstract

Ceramics with the chemical formula x Ba(Mg 1/2 W 1/2 )O 3 –(1- x ) BaTiO 3 ( x =0.40–1.0) are prepared for use as dielectric resonators. The specimens were investigated by X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy. As x decreased from 1.0 to 0.40, the temperature coefficient of resonant frequency increased gradually from -33 to +303.5 ppm/°C. At x =2/3, the Q × f value increased markedly. The crystal structure with a Mg–W ordered B-site sublattice changed to a crystal structure with a Mg–W–Ti ordered B-site sublattice at x =0.84–0.72. Ba(Mg 1/3 W 1/3 Ti 1/3 )O 3 is formed at x ∼2/3, and has excellent dielectric properties ( ε r =14.5, Q × f =107000 ( GHz), τ f =-7.6 ppm/°C). The B-site cation of Ti improved the stability of the temperature coefficient of resonant frequency (TCF) for Ba(Mg 1/2 W 1/2 )O 3 (τ f =-33 ppm/°C).