Superconductivity from doping boron icosahedra

We propose an alternative route to achieve the superconducting state in boron-rich solids, the hole doping of B₁₂ icosahedra. For this purpose we consider a prototype metallic phase of B₁₃C₂. We show that in this compound the boron icosahedral units are mainly responsible for the large phonon frequencies logarithmic average, 65.8 meV, and the moderate electron-phonon coupling λ=0.81. We suggest that this high T_c could be a general feature of hole-doped boron icosahedral solids. Moreover our calculated moderate value of λ excludes the formation of bipolarons localized on the icosahedral length scale as suggested by previous authors.