2005 年 46 巻 7 号 p. 1497-1501
The effects of rare earth oxide dispersion on the thermoelectric properties of the Mn-doped p-type β-FeSi2 (Fe0.9Mn0.1Si2) were investigated. The Fe0.9Mn0.1Si2 powders were mechanically alloyed with Y2O3 powder (0.5–4 mass%) and subsequently hot pressed. The added Y2O3 was dispersed in the β phase matrix as a fine particles around 10 nm in size. The thermal conductivity of the sample was significantly reduced by Y2O3 addition, which was caused by enhancing phonon scattering due to fine Y2O3 dispersion. It was also found that the added Y2O3 was partially decomposed in the sample, resulted in solution of elemental Y in the β phase as a p-type dopant. The Seebeck coefficient was slightly improved when a small amount of Y2O3 (0.5 and 1 mass%) was added. The improvement of the Seebeck coefficient could not be explained only by the fine dispersion of Y2O3 and the Y doping as a p-type dopant. The slight increase in the Seebeck coefficient was also observed in the case of the samples with addition of small amounts of La2O3 powder.