Electronic and Thermoelectric Properties of Al doped Mg2Si Material: DFT Study

Abstract

Magnesium Silicide and related alloys are very important for thermoelectric applications because of their non toxic nature, thermal stability, low density, relative abundance and low cost of production. In the present paper we have calculated electronic and thermoelectric properties of Al doped Mg2Si material (Mg2-xAlxSi, x=0.125, 0.25, 0.375) using Pseudo potential plane wave method based on DFT and Semi classical Boltzmann theory. Mg2Si semiconductor shows metallic nature when doped with Al atom and the conduction bands near Fermi level are composed of Si 3p, Mg 3s,3p and Al 3p. The calculations show ntype conduction, indicating that the electrical conduction is due to electron. The electrical conductivity increases with temperature; the negative value of Seebeck Coefficient also shows that the conduction is due to electron. The thermal conductivity increases slightly upon Al doping with increasing temperature due to the much larger contribution of lattice thermal conductivity over electronic thermal conductivity. In this paper we have calculated Seebeck coefficient, electrical conductivity and electronic contribution of thermal conductivity. The thermoelectric properties of doped system have been calculated in this temperature range 100K-1200K.