Two B-C-O Compounds: Structural, Mechanical Anisotropy and Electronic Properties under Pressure

Abstract

The structural, stability, mechanical, elastic anisotropy and electronic properties of two ternary light element compounds, B ₂CO ₂ and B ₆C ₂O ₅, are systematically investigated. The elastic constants and phonon calculations reveal that B ₂CO ₂ and B ₆C ₂O ₅ are both mechanically and dynamically stable at ambient pressure, and they can stably exist to a pressure of 20 GPa. Additionally, it is found that B ₂CO ₂ and B ₆C ₂O ₅ are wide-gap semiconductor materials with indirect energy gaps of 5.66 and 5.24 eV, respectively. The hardness calculations using the Lyakhov-Oganov model show that B ₂CO ₂ is a potential superhard material. Furthermore, the hardness of B ₆C ₂O ₅ is 29.6 GPa, which is relatively softer and more easily machinable compared to the B ₂CO ₂ (41.7 GPa). The elastic anisotropy results show that B ₆C ₂O ₅ exhibits a greater anisotropy in the shear modulus, while B ₂CO ₂ exhibits a greater anisotropy in Young’s modulus at ambient pressure.