Effects of C, Cu, and Be substitutions in superconducting (formula presented)

Density functional calculations are used to investigate the effects of partial substitutional alloying of the B site in (formula presented) with C and Be alone and combined with substitution of Mg by Cu. The effect of such substitutions on the electronic structure, electron-phonon coupling, and superconductivity are discussed. We find that Be substitution for B is unfavorable for superconductivity as it leads to a softer lattice and weaker electron-phonon couplings. Replacement of Mg by Cu increases the lattice stiffness and electron count. We estimate that with full replacement of Mg by Cu and fractional substitution of B by C, (formula presented) values of 50 K may be attainable. © 2001 The American Physical Society.

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Author Michael J Mehl Thomas Lord Department of Mechanical Engineering and Materia ...