title: Valence control of α-rhombohedral boron by electronic doping.
abstract: It was previously predicted that doping Li into semiconducting boron (α-rhombohedral) brought metallic character to the matrix and possibility a high-T(c) superconductor. However, experiments show that Li doping of α-rhombohedral boron is difficult. In this paper, the potential for Li doping of boron is re-examined using the ab initio pseudopotential method. Based on the calculated formation enthalpy, an efficient method for doping is proposed. The method utilizes high pressure, such as 10 GPa. Slight changes in the structural parameters for Li insertion are also resolved, which may be useful for the experimental detection of Li in boron. The stability of α-rhombohedral boron at high pressures is also compared to that of Ga-type structure, which has been put forth as a candidate for the high-pressure phase. The present study gives further confirmation of the stability of α-rhombohedral boron at least up to 70 GPa.
authors.affiliation: Nanoscience and Nanotechnology Center, ISIR, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Dekura
authors.forename: Koun
authors.initials: K
authors.lastname: Shirai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Katayama-Yoshida