The high-pressure semiconducting phase of LiBC

A high-pressure hexagonal semiconducting phase (space group P6(3)mc, 2f.u./cell) of LiBC stable above 108GPa was predicted through first-principles calculations combined with unbiased swarm structure searching techniques. This new phase consisted of three-dimensional B-C networks which originate from the dramatic out-of-plane distortions of the graphene-like B-C sublattice in the low-pressure P6(3)/mmc phase under compression. Contrary to the metallizations of LiBC under high pressure previously proposed, the resulting three-dimensional B-C framework lacks the system of p bonds with mobile electrons and has more localized electrons, as a result of the semiconducting nature of this high-pressure LiBC phase. Copyright (C) EPLA, 2016