Reduction in electrical resistivity and enhancing the thermoelectric power factor of β-FeSi2 bulk materials by Se doping

Abstract

Se-doped FeSi2 (FeSi2−xSex, x = 0, 0.01, 0.03 and 0.05) bulk samples were fabricated by the hot-pressing method. Temperature dependence of electrical resistivity and the Seebeck coefficient were investigated from 365 to 762 K. X-ray diffraction (XRD) results detected the crystalline and impurity phases of β-FeSi2. Field emission scanning electron microscopy (FESEM) images revealed finer crystal grains after Se doping in FeSi2. Electrical resistivity decreased while the Seebeck coefficient increased at higher temperatures. Low electrical resistivity of 40.1 μΩ m at 762 K was obtained for FeSi1.95Se0.05, lower than β-FeSi2 (154 μΩ m). The Seebeck coefficient and power factor values were 65.3 μV K−1 and 15.3 μW m−1 K−2 at 762 K, respectively for FeSi1.97Se0.03 and higher than undoped FeSi2. Results suggested Se doping as a promising technique to enhance the power factor of β-FeSi2 bulk materials.