Tuning the superconducting properties of magnesium diboride

摘要

The changes in normal state and superconducting properties of MgB 2 as a result of various perturbations have been investigated. Carbon doping was achieved using a two step reaction process wherein boron filaments were doped with carbon via a chemical vapor deposition technique. The subsequent filaments were then exposed to magnesium vapor to form the superconducting phase. Studies on the effects of defects introduced by neutron irradiation were performed on both pure and carbon doped MgB2 wires that were exposed to thermal neutron fluences in the range 1018-10 19 n/cm2;Different techniques for synthesizing carbon doped MgB2 powders were investigated. Bulk Mg(B1-xCx)2 samples were synthesized in sintered pellet form from mixtures of elemental Mg, B, and the binary compound B4C. Nano-scale carbon doped boron particles, that are ideally suited for powder-in-tube processing of superconducting wire, were synthesized by a gas phase plasma synthesis method;The effects of the various processing conditions on the critical current density are presented. Additionally, Ti was added to Mg(B1-xC x)2 filaments in order to explore the feasibility of creating TiBx precipitates in carbon doped MgB2 samples in order to enhance in-field critical current densities.