Edge dislocation and superstructure in MgB2 superconducting crystals
Abstract:Hexagonal plate-shaped MgB2 crystals have been prepared at ambient pressure. A superconducting transition has been observed at 37 K with a large transition width of ΔTc~22 K. The lattice strain (0.7%) is calculated from the FWHM of XRD data. Both an edge dislocation with Burgers vector b = -a, and a Mg (nano-agglomerate) self-ordering superstructure with lattice constant 2a0 have been directly detected in the  direction by HRTEM. The very broad transition may be caused by these defects in the crystals.
Document Type: Research Article
Publication date: November 1, 2005