Structural electronic and vibrational properties analysis of Li₂CaX (X = Sn, Pb) heusler alloys: a comparative study

Abstract

This study was focused on structural, electronic and vibrational properties of Li 2 CaSn and Li 2 CaPb with density functional theory. All properties of these compounds were computed by implementing General Gradient Approximation and using Quantum Espresso software programme. As a result of the calculations, it was found that the lattice parameter is 6.967 Å and bulk modulus is 33.94 GPa for Li 2 CaSn. Also, these values are 7.062 Å and 29.574 GPa for Li 2 CaPb. The calculated lattice parameters are in good agreement with the available experimental data. There is no previous theoretical calculation for Li 2 CaSn and Li 2 CaPb compounds. It was calculated that Li 2 CaSn and Li 2 CaPb have a semi-metal property. The full phonon dispersion curves of Li 2 CaSn and Li 2 CaPb compounds in the Heusler type structure were examined using the linear response method. Under 0 kbar pressure, Li 2 CaPb was unstable while Li 2 CaSn was dynamically stable. Calculations showed that when 38.42 kbar pressure is applied to the Li 2 CaPb compound, the Li 2 CaPb compound becomes dynamically stable. It is believed that this study will shape future studies.

A new semiconducting full Heusler Li2BeX (X = Si, Ge and Sn): first-principles phonon and Boltzmann calculations

“…is the total energy of unite cell, E E andE , solid Li solid Be solid X are the calculated total energies for Li, Be and X (X=Ge, Si and Sn), respectively. The obtained values of the calculated formation energy for Li 2 BeX (X=Ge, Si and Sn) are listed in table 1, compared with the theoretical data available for similar lithium-based materials [29][30][31]. The computed values of the formation energy are all negative, this sign implies that these compounds are thermodynamically stable, which confirms that they are more likely to form during synthesis [28,32].…”

Crystal structure, stability, and transport properties of Li2BeAl and Li2BeGa Heusler alloys: a DFT study

“…If the lowest frequency TO mode has a lower frequency than the TA mode, the thermal conductivity falls. Since low-frequency TO modes scatter significant amounts of TA modes, they reduce the material's ability to conduct heat 43 . In Fig.…”