Abstract

MEBREK, M.; BERBER, M.; DOUMI, B.  and  MOKADDEM, A.. First-principles study of the structural, electronic, and elastic properties of Sc₂SiX (X=C, N). Rev. mex. fis. [online]. 2021, vol.67, n.3, pp.500-508.  Epub Feb 21, 2022. ISSN 0035-001X.  https://doi.org/10.31349/revmexfis.67.500.

Using ab-initio calculations, we studied the structural, elastic, and electronic properties of Sc2SiX compounds with, (X=C, N). The negative formation energy and the positive cohesive energy indicate that these compounds are energetically stable and can be synthesized in normal conditions. Sc2SiC and Sc2SiN compounds are mechanically stable, estimated by the individual elastic constants. Elastic constants and modulus increase when C is substituted by N. The elastic anisotropy in Sc2SiC is high compared to Sc2SiN. Both nanolaminates are fragile in nature. Sc2SiC is more conductive than Sc2SiN. The calculated electron band structures and the density of states imply that the chemical bond in two compounds is a combination of covalent, ionic, and metallic nature. The main factors governing the electronic properties are the hybrid states Sc- 3d, Si-3p, and C -2p and the bond (p-d) stabilizes the structure. Fermi’s surface characteristics have been studied for the first time, which are changed when replacing N by C. Based on the estimate of the total energy, we conclude that the replacement of C by N will lead to a stabilization of the hexagonal structure and a decrease of the metallic support.

Keywords : MAX phases; ab-initio calculations; structural properties; electronic properties; elastic properties.

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