Microwave dielectric properties of Ba(Mg1/3Ta2/3)O3 materials synthesized by inverse-microemulsion process

Microwave dielectric properties of Ba(Mg1/3Ta2/3)O3 (BMT) materials have been improved by using an inverse-microemulsion process for preparing the BMT powders. The as-prepared powders, which are amorphous clusters about 100 nm in size, can be converted into pure perovskite phase BMT materials without the formation of undesired secondary phase (Ba5Ta4O15) by calcination process. BMT materials with high enough density [95% theoretical density (TD)] of BMT samples can be obtained only by sintering the materials at 1600 °C for 24 h. Low sinterability of thus prepared BMT powders is ascribed to the formation of aggregates in calcinations process. However, the sintered BMT samples exhibit very good microwave dielectric properties. The quality factor thus obtained, Q×f=65 200 GHz, is markedly better than that of the BMT materials prepared by conventional mixed oxide routes. The prime factor improving the microwave dielectric properties of the inverse-microemulsion processed BMT materials is presumably the fine grain microstructure (1–2 μm) of the samples.