Correlations Between Superconducting Characteristics and Structure of MgB 2 -Based Materials, ab -Initio Modeling

The influence of technological parameters (composition of precursor powders, type of additions, temperature, and pressure) on the superconducting characteristics (transition temperature, critical current density, and critical magnetic fields) of MgB 2 -based materials (bulk, wires, and thin films) and the correlation with their microstructure were studied. Microstructural observations are in good agreement with ab -initio modeling. The X-ray, Auger spectroscopy, and SEM EDX study show that impurity oxygen and carbon (possibly as dopant) are present in the magnesium diboride structure. The elements are distributed inhomogeneously, thus creating the nanostructure (which can be purposefully changed by manufacturing conditions) responsible for flux pinning and other SC characteristics.