Electrical and thermal properties of a varistor at cryogenic temperatures
A ZnO-based varistor composition has been found whose I-V characteristic is essentially unaffected by temperature (4.2–300 K) or intense magnetic fields at 4.2 K (up to 10 T). Electrical measurements are reported at various temperatures for current densities in the range 10−11–10−3 A/cm2 . Specific-...
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Veröffentlicht in: | Journal of applied physics 1988-10, Vol.64 (8), p.4223-4228 |
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Hauptverfasser: | , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | A ZnO-based varistor composition has been found whose I-V characteristic is essentially unaffected by temperature (4.2–300 K) or intense magnetic fields at 4.2 K (up to 10 T). Electrical measurements are reported at various temperatures for current densities in the range 10−11–10−3 A/cm2 . Specific-heat and thermal conductivity data are reported at 1.7–300 K. The specific heat below 10 K and above 100 K is dominated by defect modes, and the data can be understood based on simple defect models. The thermal conductivity displays a broad maximum at about 80 K (0.65 W cm−1 K−1 ), and it is concluded that the defect modes do not carry heat. The small temperature dependence of the prebreakdown conductivity is found to be in excellent agreement with a variable-range-hopping model, suggesting that this composition is just above the percolation threshold. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/1.341288 |