Preferential growth of boron layer in magnesium diboride (MgB 2) by Mg diffusion method

摘要

AbstractGrowth mechanism and grain boundary (GB) contact of polycrystalline MgB2fabricated by Mg diffusion method are studied by STEM and EELS analyses. In contrast to the previous reports based on the computational calculation, preferential growth of (001) boron (B) layer and the B-B contact at MgB2GBs are confirmed by annular dark field (ADF) –STEM image and the combined EELS analyses. The effect of B-B contact at the GB on the superconductivity is further evaluated using First principles calculation. Superior GB linkage of the supercurrent flow via GB B-B contact is expected from the calculated density of states at Fermi level. B-terminated growth mechanism in Mg diffusion method and the effect of GB connectivity via B-B and Mg-Mg contacts are discussed. Finally, we suggest a model of GB linkage of supercurrent flow via B-B contact in polycrystalline MgB2.Highlights?Preferential growth of boron in polycrystalline MgB2has been firstly confirmed.?The B-terminated growth mechanism of an MgB2has been suggested.?The GB linkage via B-B contact in polycrystalline MgB2has been elucidated.]]>