Predicting thermoelectric performance of eco-friendly intermetallic compound p-type CaMgSi from first-principles investigation

In this paper, we report the thermoelectric performance of nontoxic compound CaMgSi using first-principles method combined with Boltzmann transport theory. Our calculation demonstrates that only when using the more accurate HSE06 functional can we correctly reproduce the semiconducting nature of this compound. The result from HSE06 functional shows that CaMgSi compound is a semiconductor with narrow direct band gap of 0.29eV and such narrow band gap may enhance the thermoelectric performance. The calculated thermoelectric transport parameters of p-type CaMgSi, such as Seebeck coefficient, electrical conductivity and lattice thermal conductivity, were described carefully in a wide range of temperature. In addition, the possible techniques to improve ZT value were discussed. The results reveal the thermoelectric performance of CaMgSi exhibits strong temperature dependence and a maximum ZT value of 1.76 can be achieved at 800 K by tuning the carrier concentration, which suggests its appealing thermoelectric application.