Work

Lifting the Optical and Thermoelectric Properties of Mg 2 Si as a Function of Sn Incorporation—Potential Thermoelectric Materials

Year: 2021

Type: article

Abstract: By means of Density Functional Theory (DFT) study, we have performed the structural, electronic, optical and thermoelectric properties calculations of tin doped Mg 2 Si (Mg 2 Si 1−x Sn x , x = 0, 0.125, 0.25, 0.5, 0.75, 0.875, 1) using Full Potential Linearized Augmented Plane Wave (FP-LAPW) Method. The DFT study yields satisfactory results for electronic and thermoelectric properties of Sn doped Mg 2 Si compared with experimental values. With semiclassical Boltzmann transport theory, the transport properties of Mg 2 Si and Sn doped Mg 2 Si alloys has been investigated systematically. According to the calculated band structure, density of states and electron density, the parent Mg 2 Si/Sn materials having indirect energy gap (Γ−x) with ionic bonding; Sn doped ternary combinations Mg 2 Si 1−x Sn x , x = 0.125, 0.25, 0.5, 0.75, 0.875 having direct band gap (Γ−Γ) with a mixed covalent and ionic bonding nature. Band gap decreases linearly with the increase of Sn-concentration in each alloy system except for Mg 2 Si 0.75 Sn 0.25 combination. The optical properties calculations have been performed for the energy range between 0–13.5 eV. The thermoelectric properties have been calculated for the temperature range 100 K to 800 K. Out of the five studied materials, Mg 2 Si 0.75 Sn 0.25 found to be a better thermoelectric material with increased Power factor, Seebeck coefficient, electrical conductivity and corresponding thermal conductivity at high temperature range.

Source: ECS Journal of Solid State Science and Technology

DOI: 10.1149/2162-8777/ac1479