Exploring configurations and properties of boron carbide by first principle

Based on the first principle, the formation energy, phonon vibration, physical property of three common B₄C models were extensively study. Through the calculation of thermodynamic formation energy, it is confirmed po model has the most stable energy configuration. Combined the simulated x-ray and experimental data, it is found that the experimental boron carbide is actually composed of a variety of configurations, the majority of which is po model. Via the analysis of phonon vibration, the highest phonon frequencies of the different configurations were identified as the result of stretching vibrations from the triatomic chain. The research of electrical properties of three B₄C models clarify B₄C is a semiconductor but will transform to conductor at specific high pressure. The calculation of the mechanical property states that B₄C is hard material while the hardness will gradually decrease with pressure increases. Both the relationship of their electrical properties and mechanical properties with pressure illustrate that the po model has the fastest structural change and ch model has the slowest change. (paper)