Semiconductors

Mg$_2$Ge germanide under pressure: first principle evolutionary search results

Yu. V. Luniakov

Institute for Automation and Control Processes, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia

Abstract: The search of optimal structures of magnesium germanide Mg$_2$Ge under pressure has been performed using the software suite USPEX implementing the evolution algorithm combined with the density functional theory (DFT) approach. It is found that at pressures $P\ge$ 15 GPa the triclinic P1 and P-1, monoclinic P2$_1$/c, orthorhombic Amm2 and trigonal P3m1 structures can coexist besides the well-known cubic Fm3m, orthorhombic Pnma and hexagonal P63/mmc ones. The new discovered structures are unstable due to potential relief complexity. They transform into orthorhombic Pnma structure at pressures $P<$ 14 GPa or hexagonal P6$_3$/mmc structure at pressures $P>$ 17 GPa.

Keywords: Mg$_2$Ge, crystal structure, phase transitions, hydrostatic pressure, evolutional search, Density Functional Theory.

Received: 16.03.2022
Revised: 19.05.2022
Accepted: 20.05.2022

DOI: 10.21883/FTT.2022.10.53087.316

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