Thermoelectric properties of Sb-doped Mg 2Si semiconductors

Abstract

The thermoelectric properties of Sb-doped Mg 2Si (Mg 2Si:Sb = 1: x(0.001 ≦ x ≦ 0.02)) fabricated by spark plasma sintering have been characterized by Hall effect measurements at 300 K and by measurements of electrical resistivity ( ρ), Seebeck coefficient ( S), and thermal conductivity ( κ) between 300 and 900 K. Sb-doped Mg 2Si samples are n-type in the measured temperature range. The electron concentration of Sb-doped Mg 2Si at 300 K ranges from 2.2 × 10 19 for the Sb concentration, where x = 0.001, to 1.5 × 10 20 cm −3 for x = 0.02. First-principles calculation revealed that Sb atoms are expected to be primarily located at the Si sites in Mg 2Si. The electrical resistivity, Seebeck coefficient, and thermal conductivity are strongly affected by the Sb concentration. The sample x = 0.02 shows a maximum value of the figure of merit ZT, which is 0.56 at 862 K.