Enhancement of figure of merit (ZT) by doping Bi in Mg2Si for energy harvesting applications

Magnesium Silicide is one of the interesting thermoelectric materials known for relative abundance of its constituents, thermal stability, non-toxicity and environmental friendly nature. In this paper we have theoretically studied Bi doped Mg2Si. The electronic structure calculations predict non-existence of the energy gap for Mg2Si1−xBix with (0.125≤ x≤0.5). It has been found that the system with x=0.125 exhibits highest Seebeck coefficient and electrical conductivity. Due to low thermal conductivity at x=0.125, Mg2Si0.875Bi0.125 attained maximum value of dimensionless figure of merit 0.67 at 1200 K. With increase in concentration of Bi, the value of figure of merit decreases.