PTCR Properties of Composites Consisted of Metals with Low Melting Point and Conductive Ceramics

Abstract

Many metals show the steep increase of their specific resistivity on melting. This phenomenon was applied for producing new PTCR materials in the Pb-TiO₂ and Sn-TiO₂ systems. The xPb-(100-x)Ti_0.99Nb_0.01O₂ samples with x>15 showed the steep increase of resistivity (PTCR properties) around 327°C, and it was noted that the temperature coefficient of resistivity below the PTCR temperature changes from negative to positive with increasing Pb content. The xSn-(100-x)Ti_0.99Nb_0.01O₂ samples showed PTCR properties around the melting point of Sn (232°C), but PTCR properties are less significant than those observed in the Pb-TiO₂ system.