Effect of Sn4+ B-site substitution on the microstructure and dielectric properties of Ba(Mg1/3Ta2/3)O3 microwave ceramics

The effect of Sn4+ (BaSnO3) B-site substitution on the microstructure and dielectric properties of Ba(Mg1/3Ta2/3)O-3 microwave ceramics was investigated. X-ray diffraction shows that a complex perovskite material Ba(Mg1/3Ta2/3)O-3 was prepared. As Sn4+ content x increases in the (1-x) Ba(Mg1/3Ta2/3)O-3-xBaSnO(3) (x=0.00 similar to 0.20) system, the dielectric constant generally keeps unchanged, while TCF changes from positive to negative. Although the addition of Sn4+ reduces the ordering degree, Qf(0) is still increased when the ceramics density increases. This trend implies that Qf(0) of this system is mostly determined by ceramics density rather than ordering degree. After sintering at 1500 degrees C for 3 h, the system with x=0.15 was found to have excellent dielectric properties as follows: epsilon approximate to 25, Qf(0)>= 300,000 GHz at 7 GHz, TCF=-0.6x10(-6)/degrees C.