摘要
Liquid-phase sintering method was used to prepare BaTiO3 powders and the struc- ture and electrical properties of （1-x）BaTiO3-]-（x）La2/3Srl/3Mn03 （LSMO） compos- ites were investigated. The results of X-ray diffraction showed that the prepared BaTiO3 powders were pure and fine, indicating that sintering temperature was effec- tively lowered when the NaC1 sintering aid was added. X-ray diffraction patterns of （1-x）BaTiO3＋（x）La2/3Srl/3Mn03 （LSMO） composites showed that LSMO and BaTiO3 phases were coexistent and no other phases were detected. The impedance spectra showed that the resistance of grain boundaries for LSMO-doped samples was suppressed. The resistivity-temperature measurements showed that room- temperature resistivity of the composites was lowered from insulator for pure BaTiO3 ceramic to 103 ~.m for the x----0.3 sample. The sample of x_〈0.2 showed the positive temperature coefficient （PTC） effect whereas the x=0.3 sample exhibited PTC effect at temperatures below 68 ~C and then negative temperature coefficient （NTC） effect at temperatures above 68 ~C. The related mechanism has been elucidated.
Liquid-phase sintering method was used to prepare BaTiO3 powders and the struc- ture and electrical properties of （1-x）BaTiO3-]-（x）La2/3Srl/3Mn03 （LSMO） compos- ites were investigated. The results of X-ray diffraction showed that the prepared BaTiO3 powders were pure and fine, indicating that sintering temperature was effec- tively lowered when the NaC1 sintering aid was added. X-ray diffraction patterns of （1-x）BaTiO3＋（x）La2/3Srl/3Mn03 （LSMO） composites showed that LSMO and BaTiO3 phases were coexistent and no other phases were detected. The impedance spectra showed that the resistance of grain boundaries for LSMO-doped samples was suppressed. The resistivity-temperature measurements showed that room- temperature resistivity of the composites was lowered from insulator for pure BaTiO3 ceramic to 103 ~.m for the x----0.3 sample. The sample of x_〈0.2 showed the positive temperature coefficient （PTC） effect whereas the x=0.3 sample exhibited PTC effect at temperatures below 68 ~C and then negative temperature coefficient （NTC） effect at temperatures above 68 ~C. The related mechanism has been elucidated.
