High-Pressure Synthesized Superconducting Nanostructural Magnesium Diboride-Based Materials

摘要

A high pressure-synthesized (HPS) magnesium-diboride-based material shows at 20 K critical current density higher than 100 kA/cm~2 up to 3 T field and higher than 10 kA/cm~2 to 5 T field. The monocrystalline magnesium diboride nanosized inclusions in the Mg-B-O superconductive "matrix" of the material strongly affect its superconducting characteristics: the samples with higher critical current density and irreversible fields exhibit a higher concentration of the Mg-B inclusions, so the Mg-B nanosized particles seem strongly influence the pinning forces in the material. Additions of Ta, Ti, Zr can increase critical current density of HPS magnesium-diboride-based material due to the absorption of impurity hydrogen to form hydrides of Ta, Ti, Zr, which prevents harmful magnesium hydride impurity phase from appearing, may prevent hydrogen from being introduced into the material structure and promotes the formation of a higher amount of Mg-B inclusions in the Mg-B-O matrix.