Effect of B₂O₃ and CuO on the Sintering Temperature and Microwave Dielectric Properties of Ba(Zn_1/3Ta_2/3)O₃ Ceramics

Abstract

Sintering temperature of the Ba(Zn 1/3 Ta 2/3 )O 3 (BZT) ceramic is about 1550°C and it decreased to 950°C when B 2 O 3 was added. The BaB 4 O 7 second phase whose melting temperature is 889°C was found in the B 2 O 3 added BZT ceramics. The BaB 4 O 7 second phase assisted the sintering of the BZT ceramics at 950°C. However, the B 2 O 3 added BZT ceramic was not sintered below 950°C and the microwave dielecric properties were not satisfactory. On the other hand, when the B 2 O 3 and the CuO were added, the BZT ceramic was sintered even at 870°C. The BaCu(B 2 O 5 ) phase which was found in the CuO and B 2 O 3 added BZT ceramics, existed as the liquid phase during the sintering and helped the densification of the BZT ceramics at temperatures lower than 950°C. Good microwave dielectric properties of Q × f =11,000 GHz, ε r =26 and τ f =0.0 ppm/°C were obtained from the BZT + 5.0 mol% B 2 O 3 + 10.0 mol% CuO ceramic sintered at 870°C for 2 h.