
Structural, elastic, electronic, and thermodynamic properties of MgAgSb investigated by density functional theory
JunFei Wang(王俊斐), XiaoNan Fu(富笑男), XiaoDong Zhang(张小东), JunTao Wang(王俊涛), XiaoDong Li(李晓东), ZhenYi Jiang(姜振益)
Chin. Phys. B, 2016, 25 (8):
086302.
DOI: 10.1088/16741056/25/8/086302
The structural, elastic, electronic, and thermodynamic properties of thermoelectric material MgAgSb in γ, β, α phases are studied with firstprinciples calculations based on density functional theory. The optimized lattice constants accord well with the experimental data. According to the calculated total energy of the three phases, the phase transition order is determined from α to γ phase with cooling, which is in agreement with the experimental result. The physical properties such as elastic constants, bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and anisotropy factor are also discussed and analyzed, which indicates that the three structures are mechanically stable and each has a ductile feature. The Debye temperature is deduced from the elastic properties. The total density of states (TDOS) and partial density of states (PDOS) of the three phases are investigated. The TDOS results show that the γ phase is most stable with a pseudogap near the Fermi level, and the PDOS analysis indicates that the conduction band of the three phases is composed mostly of Mg3s, Ag4d, and Sb5p. In addition, the changes of the free energy, entropy, specific heat, thermal expansion of γMgAgSb with temperature are obtained successfully. The obtained results above are important parameters for further experimental and theoretical tuning of doped MgAgSb as a thermoelectric material at high temperature.
