Fabrication of Ba_(6-3x)(Sm_(0.2)Nd_(0.8))_(8+2x)Ti_(18)O_(54)(x=2/3) Ceramics by Solid State Reaction

摘要

Effects of calcining and sintering temperatures on the microstructure and the microwave dielectric properties of Ba_(6-3x)(Sm_(0.2)Nd_(0.8))_(8-2x)Ti_(18)O_(54)(x=2/3) ceramics were studied. When the calcining temperature was lower (1373K), the dielectric constant ￡ and the Qf factor initially increased with increasing sintering temperature, but decreased when sintering temperature was higher than 1603K. As a whole, the temperature coefficients of the resonant frequency τ_f tended to increase with increasing sintering temperature. The microstructure of the sintered ceramic consisted mainly of columnar and block-shape grains. The grain size increased with increasing sintering temperature. When the calcining temperature was higher (1473K), ε_r and τ_f were nearly independent of sintering temperature. The excellent microwave dielectric properties were achieved in the Ba_(6-3x)(Sm_(0.2)Nd_(0.8))_(8+2x)Ti_(18)O_(54) (x=2/3) ceramic calcined at 1373K and sintered at 1603K for 3 h: ε = 80.8, Qf = 8114 (GHz) and τ_f= 5.6.