Self-Compensation Property and Bonding Conversion of V-and-Mg- or V-and-Li-Codoped β-Rhombohedral Boron

摘要

Magnesium (Mg) or lithium (Li) was doped into pre-vanadium (V)-doped β-rhombohedral boron (β-B), targeting the codoping of V and Mg or Li into β-B, which is composed of B_(12) icosahedral clusters. The structure and electrical property of V-and-Mg- or V-and-Li-codoped β-B were revealed by X-ray powder diffraction analysis using the Rietveld method and by electrical conductivity measurement, respectively. The structure and electrical property of lowconcentration Mg-monodoped β-B were also studied to clarify its self-compensation property. The removal of interstitial B and the generation of vacancies by Mg doping into β-B were observed. It was found that electron doping is compensated for by the removal of B as in Li-doped β-B. Meanwhile, V removal is induced by Mg or Li doping into V-doped β-B in order to compensate for the electron doping. V removal is interpreted as extended self-compensation since the removed element was extended to V from B. V removal is also interpreted as metallic-ionic bonding conversion since part of the bonding nature of B is converted from metallic to ionic owing to V removal.