Effect of Heat Treatments under High Isostatic Pressure on the Transport Critical Current Density at 4.2 K and 20 K in Doped and Undoped MgB<sub>2</sub> Wires
Daniel Gajda,
Andrzej J. Zaleski,
Andrzej J. Morawski,
Malgorzata Małecka,
Konstantin Nenkov,
Matt Rindfleisch,
Md Shahriar A. Hossain,
Tomasz Czujko
Affiliations
Daniel Gajda
Institute of Low Temperature and Structure Research PAS, Okolna 2, 50-422 Wroclaw, Poland
Andrzej J. Zaleski
Institute of Low Temperature and Structure Research PAS, Okolna 2, 50-422 Wroclaw, Poland
Andrzej J. Morawski
Institute of High Pressure Physics PAS, Sokolowska 29/37, 01-142 Warsaw, Poland
Malgorzata Małecka
Institute of Low Temperature and Structure Research PAS, Okolna 2, 50-422 Wroclaw, Poland
Konstantin Nenkov
Institute for Solid State and Materials Research Dresden, P.O. Box 270016, D-01171 Dresden, Germany
Annealing undoped MgB2 wires under high isostatic pressure (HIP) increases transport critical current density (Jtc) by 10% at 4.2 K in range magnetic fields from 4 T to 12 T and significantly increases Jtc by 25% in range magnetic fields from 2 T to 4 T and does not increase Jtc above 4 T at 20 K. Further research shows that a large amount of 10% SiC admixture and thermal treatment under a high isostatic pressure of 1 GPa significantly increases the Jtc by 40% at 4.2 K in magnetic fields above 6 T and reduces Jtc by one order at 20 K in MgB2 wires. Additionally, our research showed that heat treatment under high isostatic pressure is more evident in wires with smaller diameters, as it greatly increases the density of MgB2 material and the number of connections between grains compared to MgB2 wires with larger diameters, but only during the Mg solid-state reaction. In addition, our study indicates that smaller wire diameters and high isostatic pressure do not lead to a higher density of MgB2 material and more connections between grains during the liquid-state Mg reaction.
