An Equivalent Cicuit for CuO Modified Surface Barrier Layer Capacitors

Abstract

Nb₂O₅-doped (Ba_0.8Sr_0.2)(Ti_0.9Zr_0.1)O₃ (BSTZ) is calcined at 1170°C for the complete formation of ABO₃ phases. After calcination, CuO is added to BSTZ as a liquid phase promoter and an insulating boundary layer material. After sintering in a reducing atmosphere, the fired ceramics are cooled to an annealing temperature, then the cermics are annealed in air. The loss tangents of the fabricated ceramics increase with amount of CuO addition, but the maximum grain growth and maximum dielectric constant will reveal in 1 wt% CuO-added BSTZ. For BSTZ with different amount of CuO addition, the effective dielectric constant increases with the sintering temperature and decreases critically with annealing temperature and annealing time. When 60 min is used as annealing time, lower the annealing temperature is, more broad dielectric constant-temperature curves are. It is believed that the semiconductive BSTZ, which is residual in the center of the reoxidized BSTZ, will dominate the result.