A New Resistor Having An Anomalously Large Positive Temperature Coefficient

A new thermistor, which shows an anomalously large positive temperature coefficient of electrical resistivity, has been found. The resistivity of the materials increases monotonically between 20°C and 85°C, and the resistivity at 85°C is 10 6 ∼10 8 times of that at 20°C. The sample is prepared by mixing graphite powder with a melted mixture of paraffin and polyethylene. The temperature sensitive electrical resistivity of the sample mainly depends on the resistivity of intergrain gaps between graphite particles. The resistance at the intergrain gaps is attributable to the tunneling current, because the field dependence of resistivity calculated theoretically based on the tunneling effect agrees well with the experimental data. The variation of electrical resistance of this mixture originates in the variation of the width of the intergrain gaps caused by the displacement of the graphite grains due to the rise of temperature.