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Issue 14, 2019
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Surface termination of MgB2 unveiled by a combination of adsorption experiments and theoretical calculations

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Abstract

Superconductivity in polycrystalline and thin-film MgB2 is strongly affected by the termination of its surface, but a reliable determination of the surface termination is still a challenging task of surface chemistry. Here, the surface properties of superconducting MgB2 were investigated using a combination of inverse gas chromatography and van der Waals corrected density functional theory calculations. The dispersive surface energy was measured as a function of the surface coverage and its value (58 mJ m−2 to 48 mJ m−2) was verified by high-level non-local EXX + RPA calculations, which predicted that the dispersive contribution to the cleavage energy was 56 mJ m−2. The isosteric adsorption enthalpies of cyclohexane, dioxane, acetone and acetonitrile molecules were measured on an MgB2 sample and compared to the DFT calculated enthalpies for the Mg-terminated MgB2, B-terminated MgB2 and MgO(001) surfaces. The close agreement between theory and experiment for the Mg-terminated surface suggested that the magnesium termination is the dominant surface phase of MgB2. Thus, combining inverse gas chromatography experiments with theoretical calculations may provide information about the surface termination.

Graphical abstract: Surface termination of MgB2 unveiled by a combination of adsorption experiments and theoretical calculations

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Publication details

The article was received on 07 Feb 2019, accepted on 06 Mar 2019 and first published on 07 Mar 2019


Article type: Paper
DOI: 10.1039/C9CP00771G
Citation: Phys. Chem. Chem. Phys., 2019,21, 7313-7320

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    Surface termination of MgB2 unveiled by a combination of adsorption experiments and theoretical calculations

    B. Prudilová, E. Otyepková, J. Fanfrlík, D. Hnyk, J. Holub, M. Petr, J. Filip, K. Čépe, P. Lazar and M. Otyepka, Phys. Chem. Chem. Phys., 2019, 21, 7313
    DOI: 10.1039/C9CP00771G

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