Regensburg 2013 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 18: Computational Materials Modelling - Phase Stability I
MM 18.1: Talk
Tuesday, March 12, 2013, 10:15–10:30, H24
Stability and superconductivity of Ca-B under pressure — •Sheena Shah1 and Aleksey Kolmogorov2 — 1University of Oxford, UK — 2Binghamton University - SUNY, USA
In the search for MgB2-like phonon-mediated superconductors, we have carried out a systematic DFT-based evolutionary crystal structure search of the whole CaxB1−x system at gigapascal pressures. A set of diverse ground state boron structures are identified for CaB, CaB2, CaB4 and CaB6. The monoboride is predicted to be superconducting at 5 K. Others are predicted to be superconducting at lower temperatures, demonstrating the inverse correlation between thermodynamic stability and superconducting properties. Finally, structural rules have been established for the thermodynamic stability of these alkaline earth metal borides with pressure. For example, we show that ThB4-type CaB4 is stable at ambient pressure since the ionic radius of Ca2+ is an ideal fit for the boron network.