What question did this study set out to answer?

The research aims to identify minimal enthalpy structures of magnesium-based ternary alloys under pressure.

March 6, 20260 citationsOpen Access

Magnesium based Si-Ge alloys under pressure: DFT evolutionary search results

Key Points

The research aims to identify minimal enthalpy structures of magnesium-based ternary alloys under pressure.
Used USPEX software for evolutionary search combined with density functional theory
Explored different stoichiometries of magnesium alloys under pressures up to 6 GPa
Investigated phonon spectra to assess the stability of the compounds
Discovered several new ternary compounds with negative enthalpy of formation
First five compounds indicated to be stable without imaginary frequencies
Identified compounds have metallic properties comparable to binary silicides

Abstract

The search of minimal enthalpy structures of ternary magnesium alloys of different stoichiometry MgxSiyGez under pressure P ≤ 6 GPa has been performed using the software suite USPEX implementing the evolution algorithm combined with the density functional theory (DFT) approach. The evolutionary search has yielded new possible ternary compounds of the stoichiometries Mg12Ge3Si, Mg6Ge4Si3, Mg6Ge3Si4, Mg6GeSi3, Mg4Ge3Si2, Mg4Ge3Si2, Mg4SiGe, and Mg2GeSi, which have negative enthalpy of formation at pressures in the range of 0 to 10 GPa and which are not substitution solutions of Ge on Mg2Si matrix (or Si on Mg2Ge matrix). These compounds have metallic properties and formation enthalpies comparable to those of binary silicides Mg2Si. Phonon spectra investigations indicate that only first five of them are stable showing no imaginary frequencies.

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