Structural, electronic, elastic, magnetic, phonon and thermodynamic properties of inverse-Heusler-Ti2FeX (X=Si, Ge, and Sn): Insights from DFT-based computer simulation

Abstract

The structural, mechanical, electronic and lattice dynamic properties of Ti2FeX (X = Si, Ge, and Sn) inverse-Heusler alloys have been explored via first-principles calculations based on density functional theory. The equilibrium lattice constant, bulk modulus, electronic band structure and magnetic moment values of these alloys have been computed to be consistent with prior studies. Several mechanical parameters such as elastic constants Cij, bulk modulus B, Young modulus E, shear modulus G and Poisson’s ratio υ are calculated, and based on these calculations, mechanical stability is examined. The calculated values of the total magnetic moments are in close agreement with the existing theoretical data and comply with the Slater-Pauling rule. From their calculated electronic band structure, Ti2FeSi, Ti2FeGe and Ti2FeSn are found as half-metallic alloys at the equilibrium lattice constant with a minority-spin energy gap of 0.820, 0.850 and 0.780 eV, respectively. The full phonon spectra, and their total and partial density of states of these alloys have been carried out via the direct method. The calculated phonon spectrum points out dynamic stableness of these alloys. Furthermore, the thermodynamic properties such as the heat capacity, thermal expansion, entropy and Grüneisen parameter have been investigated in the Debye model using the Gibbs2 code with a series of temperature from 0 to 1500 K.