Effect of Zn doping on improving crystal quality and thermoelectric properties of borosilicides

Abstract

Transition-metal (Mo, Mn, Fe, Rh, Ti, Cu, Zn) doping was carried out on the borosilicide compound REB₄₄Si₂ (RE = rare earth). REB₄₄Si₂ compounds exhibit Seebeck coefficients greater than 200 µV K⁻¹ at high temperatures and unlike most compounds, the figure of merit shows a steep increase at T > 1000 K making them promising high-temperature thermoelectric materials. Although zinc itself does not remain in the final product, zinc doping was found to improve the crystal quality, which has been a long-standing problem for the borosilicides. As a result, a significant increase of the thermoelectric power factor by more than 30% was achieved.