Doping effects of Mn~(2+) on the dielectric properties of glass-doped BaTiO_3-based X8R materials

摘要

In this paper, Mn~(2+) and calcium borosilicate glass (CBS) were used as effective dopants to prepare environmentally friendly dielectric materials satisfying EIA X8R specification. The effects of various Mn~(2+) concentrations on the dielectric properties of BaTiO_3 (BT) ceramics were investigated when CBS amount was fixed. The dielectric measurements showed that the permittivity was decreased continuously with increasing Mn~(2+) concentrations, resulted from the existence of paraelectric regions caused by Mn~(2+) doping. The dielectric loss was decreased at the beginning and then increased with increasing Mn~(2+) concentrations, whereas the resistivity showed an opposite movement. The SEM images and X-ray diffraction curves corresponding to BT ceramics doped with different Mn~(2+) amounts proved that Mn~(2+) can promote the crystallization of CBS glass to form the secondary phase Ca_4Mn_4Si_8O_(24), which determines the intensity of the high temperature peak (at about 125 ℃) of the variation rate curve of capacitance. Moreover, the modification effects of Mn~(2+) on the dielectric properties of BT have been investigated. It is revealed that a proper usage of Mn~(2+) can improve the dielectric properties significantly, and Mn~(2+) and CBS co-doped BT ceramics are promising to develop X8R MLCs.