(Zn,Al)Oへの不純物添加による熱電性能の改善

概要

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n-type semiconductor is formed by addition of Al2O3 to ZnO. As an oxide thermoelectric material, the electrical resistivity of (Zn, Al)O is higher than 10−5 (Ωm) and the Seebeck coefficient is not so high. The thermal conductivity at room temperature is high value of 40 (W/mK), therefore dimensionless figure of merit is not high enough. The aim of our research is to reduce the thermal conductivity by addition of an oxide to Zn0.98Al0.02O. The added oxide in this research is Co3O4. The thermal conductivity in 0.5 mol% added-sample was reduced by around 20% at room temperature and became to be 7 (W/mK) at 873K, while the standard sample showed 10 (W/mK) at the same temperature. Furthermore, Seebeck coefficient of the 0.5mol% added-sample increased by 20% in absolute value as compared with that of the standard at room temperature. The value of the Seebeck coefficient increased with increasing temperature. On the other hand, electrical resistivity increased with increasing added amount of Co3O4. However, the 0.1mol% added-sample showed almost the same electrical resistivity as the standard, and moreover it did not much change with temperature. The highest Z and ZT in the 0.1mol% added-sample were 0.06 × 10−3 (1/K) and 0.05 at 873K, normatively.
社団法人粉体粉末冶金協会の論文
2007-05-15