Ab initio studies of ternary semiconductor BeB2C2

First principles calculations are performed to investigate the structural, mechanical, electronic, and thermodynamic properties of BeB2C2. Our calculated lattice parameters are in good agreement with the experimental data. Orthorhombic BeB2C2 phase is found to be mechanically stable at ambient pressure. The Young’s modulus and shear modulus as a function of crystal orientation for the BeB2C2 have been systematically investigated. Further mechanical properties demonstrated that BeB2C2 is strongly prone to brittle and possesses high Vickers hardness of 26.5–28.6 GPa. Density of states and electron topological analysis show that chemical bonding among Be, B, and C atoms in BeB2C2 is a complex mixture of covalent and ionic characters. Based on the quasi-harmonic Debye model, the dependence of Debye temperature, Grüneisen parameter, heat capacity, and thermal expansion coefficient on the temperature and pressure are systematically explored in the whole pressure range from 0 to 20 GPa and temperature range from 0 to 1200 K.

Orientation dependence of the Young’s modulus (a) and orientation dependence of the shear modulus (b) in BeB2C2.Figure optionsDownload as PowerPoint slideHighlights
► The elastic moduli as a function of crystal orientations have been investigated.
► The chemical bonding is interpreted as displaying a mixed ionic/covalent character.
► Thermodynamic properties are predicted under high pressure and high temperature.