Thermal and Electrical Properties of Tungsten Oxide (WO_3)

概要

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Thermal and electrical properties of tungsten oxide were observed in a wide range of temperature. An entirely new anomaly was found at 1230℃, where the rate of sublimation increased abruptly. The amounts of anomalous heat were found to be 330, 450, 280 and 120cal/mol at the 330℃, 740℃, 910℃ and 1230℃ transitions respectively, the entropy change being 0.55, 0.45, 0.23 and 0.08cal/mol-deg at each of the transition temperatures. Any anomalous heat larger than 6cal/mol was not observed near the -20℃ transition point. At the mentioned transition points the anomalies of electrical properties were observed. The d.c. resistance decreases, on heating from room temperature, like a typical semiconductor with the activation energies of nearly 2.2, 0.3, 1.7 and 1.3eV below 740℃, between 740℃ and 910℃, between 910℃ and 1230℃ and above 1230℃, respectively, the small value as 0.3 eV between 740℃ and 910℃ being especially noticeable. A non-linearly of I-V relation was observed, indicating some anomalous electrical property of this substance.
社団法人日本物理学会の論文
1956-12-05