Work presents the progress at National Institute of Materials Physics, Romania in processing and characterization of bulk MgB2 superconductor. Samples are pristine or with selected additives, (001) textured or randomly oriented, machinable by chipping or brittle and hard. Materials were obtained by ex situ spark plasma sintering (SPS) or by combining slip casting under elevated magnetic fields (12 T) and SPS. Structural, microstructural and superconducting characteristics were investigated. Some peculiar profiles in the shape of the pinning force curves with magnetic field were noted and it was not possible to fit these curves with the universal scaling procedure. Therefore, a new model sensitive to dissipation generated by the presence of slightly non-stoichiometric phases, defects, homogeneity, anisotropy, and texture within the Dew-Hughes scaling law predictions for a grain boundary pinning mechanism was proposed. In this model a connecting factor is used. This factor was found to be expressed through a connecting function that takes the form of a single or double peaked function, Gaussian or LogNormal.
In the second part of the presentation, the potential of MgB2 as a sustainable material will be examined based on our results and literature data. MgB2 emerges as a remarkable case study and reference when looking to materials from the viewpoint of their level of integration into nature cycles. Our analysis suggests that MgB2 has the ability to become a game-changing key material needed for the progress in the future sustainable economy.
Author acknowledges support from MCI-UEFISCDI Romania through Core Program PC2-PN23080202.
Keywords: MgB2 bulk, material processing, superconductivity, sustainability