Theoretical study of novel B–C–O compounds with non-diamond isoelectronic

Abstract

Two novel non-isoelectronic with diamond (non-IED) B–C–O phases (tI16-B8C6O2 and mP16-B8C5O3) have been unmasked. The research of the phonon scattering spectra and the independent elastic constants under ambient pressure (AP) and high pressure (HP) proves the stability of these non-IED B–C–O phases. Respective to the common compounds, the research of the formation enthalpies and the relationship with pressure of all non-IED B–C–O phases suggests that HP technology performed in the diamond anvil cell (DAC) or large volume press (LVP) is an important technology for synthesis. Both tI16-B8C6O2 and tI12-B6C4O2 possess electrical conductivity. mP16-B8C5O3 is a small bandgap semiconductor with a 0.530 eV gap. For aP13-B6C2O5, mC20-B2CO2 and tI18-B4CO4 are all large gap semiconductors with gaps of 5.643 eV, 6.113 eV, and 7.105 eV, respectively. The study on the relationship between band gap values and pressure of these six non-IED B–C–O phases states that tI16-B8C6O2 and tI12-B6C4O2 maintain electrical conductivity, mC20-B2CO2 and tI18-B4CO4 have good bandgap stability and are less affected by pressure. The stress-strain simulation reveals that the max strain and stress of 0.4 GPa and 141.9 GPa respectively, can be sustained by tI16-B8C6O2. Studies on their mechanical properties shows that they all possess elasticity moduli and hard character. And pressure has an obvious effect on their mechanical properties, therein toughness of tI12-B6C4O2, aP13-B6C2O5, mC20-B2CO2 and tI18-B4CO4 all increases, and hardness of mP16-B8C5O3 continue to strengthen during the compression. With abundant hardness characteristics and tunable band gaps, extensive attention will be focused on the scientific research of non-IED B–C–O compounds.