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Liquid-phase sintering method was used to prepare BaTiO 3 powders and the structure and electrical properties of (1-x)BaTiO 3 +(x)La 2/3 Sr 1/3 MnO 3 (LSMO) composites were investigated. The results of X-ray diffraction showed that the prepared BaTiO 3 powders were pure and fine, indicating that sintering temperature was effectively lowered when the NaCl sintering aid was added. X-ray diffraction patterns of (1-x)BaTiO 3 +(x)La 2/3 Sr 1/3 MnO 3 (LSMO) composites showed that LSMO and BaTiO 3 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 roomtemperature resistivity of the composites was lowered from insulator for pure BaTiO 3 ceramic to 10 3 ·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 BaTiO 3 powders and the structure and electrical properties of (1-x) BaTiO 3 + (x) La 2/3 Sr 1/3 MnO 3 (LSMO) composites were investigated. The results of X-ray diffraction showed showed that the prepared BaTiO 3 powders were pure and fine, indicating that sintering temperature was substantially lowered when the NaCl sintering aid was added. X-ray diffraction patterns of (1-x) BaTiO 3 + (x) La 2 / 3 Sr 1/3 MnO 3 (LSMO) composites showed that LSMO and BaTiO 3 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 roomtemperature resistivity of the composites was lowered from insulator for pure BaTiO 3 ceramic to 10 3 · 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 temperature below 68 C a nd then negative temperature coefficient (NTC) effect at temperatures above 68 C. The related mechanism has been elucidated.