Effect of processing on the positive temperature coefficient of resistivity in lead metaplumbate/polyethylene composites

The positive temperature coefficient of resistivity (PTCR) effect of a bari um metaplumbate/polyethylene [(BaPbO3)/PE] composite with 12 vol% of BaPbO3 was studied. The composite samples were prepared by hot-pressing a mixture of BaPbO3 ceramic and high-density polyethylene powders around the melting point of polyethylene. The composites exhibit a pronounced PTCR effect of up to a six-decade increase in resistivity within a narrow range of tempera ture (similar to 10 degrees C). The dependences of the room temperature res istivity and the magnitude of the resistivity jump an the pressing and anne aling temperature, and the electrical behavior after repeated heating-cooli ng cycles were investigated. The fracture surfaces of the composite samples were examined in a scanning electron microscope in order to correlate the electrical behavior with the microstructure.