Li- and Mg-doping into icosahedral boron crystals, α- and β-rhombohedral boron, targeting high-temperature superconductivity: Structure and electronic states

Kohei Soga, Atsushi Oguri, Satoshi Araake, Masami Terauchi, Akihiko Fujiwara, Kaoru Kimura

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)

Abstract

The possibility of high TC superconductivity is suggested for lithium- and magnesium-doped icosahedral boron crystals, α- and β-rhombohedral boron. The doping of these elements was attempted by a vapor diffusion processing. Both lithium and magnesium are hardly doped into the α-rhombohedral boron, although small amounts of metallic parts are found in the sample. In only one Li-doped sample, the metallic part contained 0.02vol% of the superconductive phase (TC∼36K). Magnesium was successfully doped into β-rhombohedral boron homogeneously up to 4at% (Mg4.1B105), although considerable amount of impurity silicon was introduced together with magnesium. The structures of the doped samples were analyzed assuming co-doping of magnesium and silicon. The relation between the site occupancies of the dopants and the lattice expansion is discussed. The estimation of the density of states near the Fermi energy by EELS and magnetic susceptibility measurements suggested a metal transition of the β-rhombohedral boron by the doping of magnesium and silicon. The relation between the metal transition and the intrinsic acceptor level is also discussed.

Original languageEnglish
Pages (from-to)498-506
Number of pages9
JournalJournal of Solid State Chemistry
Volume177
Issue number2
DOIs
Publication statusPublished - 2004 Feb

Keywords

  • Boron
  • Cluster solids
  • Lithium
  • Magnesium
  • Superconductivity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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