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

The structural, stability, mechanical, elastic anisotropy and electronic properties of two ternary light element compounds, B(2)CO(2) and B(6)C(2)O(5), are systematically investigated. The elastic constants and phonon calculations reveal that B(2)CO(2) and B(6)C(2)O(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(2)CO(2) and B(6)C(2)O(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(2)CO(2) is a potential superhard material. Furthermore, the hardness of B(6)C(2)O(5) is 29.6 GPa, which is relatively softer and more easily machinable compared to the B(2)CO(2) (41.7 GPa). The elastic anisotropy results show that B(6)C(2)O(5) exhibits a greater anisotropy in the shear modulus, while B(2)CO(2) exhibits a greater anisotropy in Young’s modulus at ambient pressure.