Effects of oxide dispersion on thermoelectric properties of β-FeSi2

The effects of various oxide additions to hot-pressed β-FeSi ₂ on the thermoelectric properties were investigated. The oxides, such as TiO, SiO₂ or Y₂O₃, were dispersed in the β phase matrix by mechanical grinding. In the case of the sample with addition of an electric conductive oxide, TiO, the thermal conductivity. was reduced by TiO addition over the entire temperature range. On the other hand, the electrical resistivity of the sample with TiO addition was slightly lower than that of the sample without addition. From these results, the maximum figure of merit was obtained for the sample with 2 mass% TiO, which was about two times as large as that of the sample without addition. In the case of the sample with addition of an insulating oxide, SiO₂ or Y₂O ₃, the addition of these insulating oxides significantly decreased the thermal conductivity. The. electrical resistivity increased when these oxides, especially Y₂O₃, were added, in contrast to the result in the case of the TiO addition. On the other hand, the thermoelectric power in the low temperature range was significantly enhanced by the addition of these oxides, particularly by the addition of 2 mass% Y₂O₃. From these results, the addition of these insulating oxides increased the figure of merit