Positive-Temperature-Coefficient Effect in Graphite–Cristobalite Composites |
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| Authors: | Toshitaka Ota Iwao Yamai Junichi Takahashi |
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| Affiliation: | Ceramics Research Laboratory, Nagoya Institute of Technology, Tajimi, 507, Japan;Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya, 466, Japan |
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| Abstract: | An anomalous positive temperature coefficient (PTC) of resistance was found in a conductor–insulator ceramic composite. The composite materials was composed of randomly dispersed conducting graphite and insulating cristobalite-form SiO2 particles. The PTC effect occurred at exactly 230°C, that is, at a reversible phase inversion point with a large thermal expansion of cristobalite. The magnitude of the PTC anomaly was high in composites located in the middle of the percolation curve, and loaded with large graphite and fine SiO2 particles. |
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| Keywords: | positive temperature coefficient of resistivity conductors cristobalite composites graphite |
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