Electrical properties and sintering characteristics of zirconium doped CaBi2Nb2O9 ceramics

Abstract

High Curie-temperature CaBi2Nb2-xZrxO9 (abbreviated as CBNZr-100x) ceramics were prepared by a conventional solid-state sintering method. The effects of Zr4+ doping contents and sintering temperature on the microstructure and electrical properties of CBNZr-100x ceramics were investigated. Single-phase CBNZr-100x ceramics are determined by the X-ray diffraction and the calculated cell volume decreases with increasing Zr contents. Impedance analysis was conducted in wide ranges of temperature and frequency region. Results show that the introduction of Zr4+ ions could improve the electrical properties for both grain and grain boundary and subsequently increases the breakdown voltage of CBNZr-100x ceramics. Meanwhile, the Curie temperature of CBNZr-100x increases and the dielectric loss decreases with increasing Zr contents. The sintering temperature obviously affects the grain morphology of CBNZr-3 ceramics but its effects on the electrical properties are less obvious than those of Zr contents on CBNZr-100x ceramics, indicating that the ordered structure of the grain inside of CBNZr-3 ceramics changes little with different sintering temperature. However, the Curie temperature and the resistance for grain boundaries of CBNZr-100x ceramics decrease with increasing sintering temperature, which is probably because of the increasing impurities and defects in grain boundaries.