Staging Phenomena in Lithium-Intercalated Boron-Carbon

摘要

Hole-doped LiBC has become of great interest as a candidate for high-temperature superconductivity with its structural similarity to MgB2 and as a possible cathode for rechargeable lithium batteries with the large graphene like BC hexagons. The limitation on synthesis studies has detracted from the structural and electronic properties and application studies of LixBC. Here, we present the successful synthesis of hole-doped Li0.5BC and its structural and electronic characterization using detailed structural modeling based on a unique stage-2 Daumas-Herold-type domain structure consistent with X-ray diffraction data. The strong intralayer motion of the guest Li island induces extraordinary structural properties, such as staging and staging disorder, which are confirmed by the compressibility results obtained from Li0.8BC (anisotropic cell compressibility with B-0 similar to 134 GPa) and Li0.48BC (isotropic cell compressibility with B-0 similar to 190 GPa). Li deficiency increases the conductivity; however, the temperature-dependent conductivity is dominated by the thermal excitation of carriers in a strongly disordered regime with well-defined localized states.