The effect of the crystalline phase on the sintering and microwave dielectric properties of CuO-doped (Bi0.95Sm0.05)NbO4 ceramics

The crystalline phase and the microwave dielectric properties of the 0.5 wt %-CuO-added (Bi0.95Sm0.05)NbO4 Ceramics are developed. The intensity of the low temperature form of the (Bi,Sm)NbO4 (alpha -form) first increases, rea ches a saturation value at 1000 degreesC, and then decreases with the incre ase of the sintering temperature. The alpha -form (Bi,Sm)NbO4 disappears at 1040 degreesC, the high temperature form of the (Bi,Sm)NbO4 (beta -form) s tarts to appear at 980 degreesC and then the intensity of the beta -form (B i,Sm)NbO4 increase with the increase of the sintering temperature. The diel ectric constants (epsilon (r)) show no apparent change but the quality valu es (Q x f) first increase, reach a maximum at 1020 degreesC, and then decre ase with the increase of the sintering temperature. As the sintering temper ature increases from 1020 degreesC to 1040 degreesC, the temperature coeffi cients (tau (t)) critically change from - 15.1 ppm/degreesC to -203.5 ppm/d egreesC.