title: Predicted boron-carbide compounds: a first-principles study.
abstract: By using developed particle swarm optimization algorithm on crystal structural prediction, we have explored the possible crystal structures of B-C system. Their structures, stability, elastic properties, electronic structure, and chemical bonding have been investigated by first-principles calculations with density functional theory. The results show that all the predicted structures are mechanically and dynamically stable. An analysis of calculated enthalpy with pressure indicates that increasing of boron content will increase the stability of boron carbides under low pressure. Moreover, the boron carbides with rich carbon content become more stable under high pressure. The negative formation energy of predicted B5C indicates its high stability. The density of states of B5C show that it is p-type semiconducting. The calculated theoretical Vickers hardnesses of B-C exceed 40 GPa except B4C, BC, and BC4, indicating they are potential superhard materials. An analysis of Debye temperature and electronic localization function provides further understanding chemical and physical properties of boron carbide.
authors.affiliation: Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, People's Republic of China.
authors.forename: De Yu
authors.initials: de Y
authors.lastname: Wang
authors.affiliation: Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Yan
authors.affiliation: Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, People's Republic of China.
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.affiliation: Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, People's Republic of China.
authors.forename: Yuan Xu
authors.initials: YX
authors.lastname: Wang
authors.affiliation: Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, People's Republic of China.
authors.forename: Jueming
authors.initials: J
authors.lastname: Yang
authors.affiliation: Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004, People's Republic of China.
authors.forename: Gui
authors.initials: G
authors.lastname: Yang