Mechanical Properties and Thermoelectric Transport Performance of Mg2Sn from First-Principle Calculations. (English)

The narrow-band gap semiconductor Mg2Sn is an excellent candidate for medium and low temperature thermoelectric materials due to its high abundance, low density, non-toxicity and environmental friendliness. Based on density functional theory, the elastic coefficient, phonon vibration spectrum and electron band structure of Mg2 Sn crystal were systematically analyzed in combination with different forms of electron exchange correlation energy in this paper. The thermoelectric properties of Mg2Sn were also calculated based on the non-equilibrium Boltzmann transport theory. The results show that GGA-PBE as the electron exchange correlation energy can well fit the mechanical properties of Mg2Sn in cubic, when the phonon vibration spectrum has no virtual frequency, and the bulk elastic modulus of Mg2Sn in cubic is 42. 1 GPa and isotropic. Mg2Sn has low phonon thermal conductivity due to the fact that the Debye temperature curve of Mg2Sn tends to flat and no higher than 315 K in the test temperature region above 300 K. The electronic structure near the Fermi level of Mg2Sn can be estimated by using B3LYP as the electron exchange correlation energy,and triple degeneracy states are found near the top of the valence band. Then, the results of the thermoelectric optimal value (ZT value) present that p-type doping Mg2Sn is better than that of n-type doping, which can reach 1.05. The results of this study provide theoretical basis for further improving the thermoelectric properties of Mg2 Sn. [ABSTRACT FROM AUTHOR]

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