Effect of CuO-Bi_2O_3 Co-doping on Microwave Dielectric Properties of Ba_4Sm_(9.33)Ti_(18)O_(54) Ceramics

摘要

Ba_4Sm_(9.33)Ti)(18)O_(54) (BST) ceramics were prepared by conventional solid-state reaction method. The effect of CuO-Bi_2O_3 co-doping on the sintering behavior and microwave dielectric properties of BST ceramics has been investigated. The results indicated that when the total addition of CuO-Bi_2O_3 doping agent was 1.0wt%, the sintering temperature of BST ceramics was reduced to 1240°C as a result of liquid-phase sintering effect derived from CuBi_2O_4. When the total addition of CuO-Bi_2O_3 was fixed at 1.0wt%, the microwave dielelctric properties of BST were improved by adjusting the mass percentage of Bi_2O_3. With the increase of Bi_2O_3 amount from 20wt% to 80wt%, the dielectric constant (ε_r) decreased, the quality factor (Q.f) increased and the temperature coefficient of resonant frequency (τ_f) shifted from negative value to positive value. The excellent microwave dielectric properties of ε_r=82.51, Q.f=7878GHz and τ_f=+6.02ppm/°C were obtained for the sample with Bi_2O_3 amount of 80wt% when sintered at 1240°C for 3h.