Ab initio predictions of structure and physical properties of the Zr2GaC and Hf2GaC MAX phases under pressure

Muhammad Waqas Qureshi,Xinxin Ma,Guangze Tang,Ramesh Paudel

doi:10.1038/s41598-021-82402-1

Muhammad Waqas Qureshi, Xinxin Ma + Show 2 more

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https://doi.org/10.1038/s41598-021-82402-1

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Abstract

The electronic structure, structural stability, mechanical, phonon, and optical properties of Zr2GaC and Hf2GaC MAX phases have been investigated under high pressure using first-principles calculations. Formation enthalpy of competing phases, elastic constants, and phonon calculations revealed that both compounds are thermodynamically, mechanically, and dynamically stable under pressure. The compressibility of Zr2GaC is higher than that of Hf2GaC along the c-axis, and pressure enhanced the resistance to deformation. The electronic structure calculations reveal that M2GaC is metallic in nature, and the metallicity of Zr2GaC increased more than that of Hf2GaC at higher pressure. The mechanical properties, including elastic constants, elastic moduli, Vickers hardness, Poisson’s ratio anisotropy index, and Debye temperature, are reported with fundamental insights. The elastic constants C11 and C33 increase rapidly compared with other elastic constants with an increase in pressure, and the elastic anisotropy of Hf2GaC is higher than that of the Zr2GaC. The optical properties revealed that Zr2GaC and Hf2GaC MAX phases are suitable for optoelectronic devices in the visible and UV regions and can also be used as a coating material for reducing solar heating at higher pressure up to 50 GPa.

Highlights

The electronic structure, structural stability, mechanical, phonon, and optical properties of Zr2GaC and Hf2GaC MAX phases have been investigated under high pressure using first-principles calculations
The considered M2GaC (M = Zr, Hf) MAX phase crystallizes in the hexagonal structure with a space group P 63/mmc (No 194) in which M6C (M = Zr, Hf) edge shared octahedron is interleaved by atomic layer of Ga atom
The atoms in the M2GaC MAX phase are placed as follows: C atoms are at 2a (0, 0, 0), Ga atoms are at 2d (2/3, 1/3, 1/4), and M atoms are at 4f. (1/3, 2/3, zM), respectively where zM is known as the internal parameter

Summary

Introduction

The electronic structure, structural stability, mechanical, phonon, and optical properties of Zr2GaC and Hf2GaC MAX phases have been investigated under high pressure using first-principles calculations. The structural stability, electronic, mechanical, phonon, and optical properties of the M2GaC (M = Zr, Hf) MAX phase materials have been investigated under pressure ranging from 0 to 50 GPa using the first-principles plane-wave pseudopotential DFT within the generalized gradient approximation (GGA).

Results

Conclusion