Superconductivity in diamond

We survey methods of synthesis of boron doped diamond with high pressure-high temperature techniques. New route is proposed for synthesis of relatively large heavily boron doped diamond single crystals, which exhibit superconductivity. Superconducting boron-doped diamond samples were synthesized with isotopes of (10)B, (11)B, (13)C and (12)C. We claim the presence of a carbon isotope effect on the superconducting transition temperature, which supports the diamond-carbon-related nature of superconductivity and the importance of the electron-phonon interaction as the mechanism of superconductivity in diamond. Isotope substitution permits us to relate almost all bands in the Raman spectra of heavily boron-doped diamond to the vibrations of carbon atoms. The 500 cm(-1) Raman band shifts with either carbon or boron isotope substitution and may be associated with vibrations of paired or clustered boron. (C) 2009 Elsevier B.V. All rights reserved.