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.