关键词: 钡铅氧化物陶瓷, 阻率, 正电阻温度系数, 微观结构

Abstract: A series of La-doped ceramics was prepared with the materials of BaCO₃-PbO powders in order to obtain the ceramics with high Curie point, low electrical resistivity and PTCR（Positive Temperature Coefficient of Resistivity）．It is found from experiments that as-sintered ceramics are of very low electrical resistivities and show the same conductor feature as metal conductors, that the BaPbO₃-based ceramic body with Al electrode displays the PTCR characteristic which can be improved by adjusting the La content．Microstructures of the ceramics were then analyzed by using scanning electron microscopy and transmission electron microscopy．The analytical results reveal that the low resistivity of the ceramic surface layer results from the nanosized BaPbO₃ orthorhombic phase which is of metallic properties, and that the ceramic interior is composed of the ferroelectric phase with domain structures, thus causing the PTCR effect in the ceramic body with Al electrode when the surface layer is removed．

Key words: BaPbO3ceramic, electrical resistivity, positive temperature coefficient of resistivity, microstructure