Stability, deformation, physical properties of novel hard B2CO phases.

Two B₂CO phases (oP8′ with sp²-sp³ hybridization coexist and mP16 with unitary sp³ hybridization) were predicted via structure searching and stability analysis. The study of formation enthalpy reveals that high pressure (HP) technology performed maybe an important method for synthesis. oP8′ and mP16 both have large mechanical modulus and they are typical materials with high hardness. Pressure has a positive correlation with its mechanical modulus. The simulated tensile stress–strain relationship reveals that the maximum stress that oP8′ can bear is 64.7 GPa in the direction [100], and the maximum tensile is 0.24. Among all isoelectronic with diamond (IED) B-C-O phases, oP8′ has the smallest gap and mP16 has the widest gap. With pressure increasing, for B₂CO phases with high symmetry and composed of sp³ hybridization, their band gaps all increases monotonically; for B₂CO phases composed by sp³-sp² hybridization coexist or with low symmetry like mP16, their band gaps increased first and then decreased. [ABSTRACT FROM AUTHOR]