Microstructural characteristics and microwave dielectric properties of Ba[Mg 1/3(Nb x/4 Ta (4− x)/4 ) 2/3]O 3 ceramics

Abstract

Sintering behaviors and microstructural characteristics in solid solutions of Ba[Mg 1/3(Nb x/4 Ta (4− x)/4 ) 2/3]O 3 (BMN x T 4− x , x = 0, 1, 2, 3 and 4) were investigated by X-ray diffraction, SEM and TEM. Microwave dielectric properties, such as the relative permittivity ( ɛ r), quality factor ( Q) value and temperature coefficient of resonator frequency ( τ f), were also measured. The excellent microwave dielectric property of Ba(Mg 1/3Ta 2/3)O 3 (BMT) sample imply the necessity to sinter at higher temperature (1650 °C) and to use longer soaking times (9 h), but not for Ba(Mg 1/3Ta 2/3)O 3 (BMN). The 1:2 B-site ordering was maintained at all Nb substitution contents and the 1:2 B-site ordering existed in the grains with antiphase domain boundaries (APBs). The Ba[Mg 1/3(Nb 1/4Ta 3/4) 2/3]O 3 specimen exhibited excellent microwave dielectric properties, ɛ r = 25.534, Qf = 140 666 GHz, and τ f = 4.8 (ppm/°C). The excellent microwave dielectric property is due to the improvement of sintering property by appropriate Nb atoms substitution in the BMT matrix and the maintaining of 1:2 ordering in the BMN x T 4− x series.