Formation of High-Field Pinning Centers in Superconducting MgB2 Wires by Using High Hot Isostatic Pressure Process

• Published in: Journal of superconductivity and novel magnetism 2017-12, Vol.30 (12), p.3397-3402
• Main Authors: Gajda, D., Morawski, A., Zaleski, A. J., Akdoğan, M., Yetiş, H., Karaboğa, F., Cetner, T., Belenli, İ.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Magnetic Materials; Magnetism; Original Paper; Physics; Physics and Astronomy; Strongly Correlated Systems; Superconductivity
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-017-4161-y

This paper demonstrates the effects of hot isostatic pressure (HIP) on the structure and transport critical parameters of in situ MgB 2 wires without a barrier. Our results show that only HIP and nano-boron allow the formation of more high-field pinning centers, which lead to the increase in critical current density ( J c ) at high applied magnetic fields. Nano-boron and annealing at a low pressure increase the J c in the low magnetic field. This indicates that nano-particles create more high-field pinning centers. In addition, the results show that nano-boron improves the connection between the grains. Scanning electron microscope results show that HIP increases the reaction rate between Mg and B, density, and homogeneity of the MgB 2 material. Additionally, HIP allows to create a structure with small grains and voids and eliminates the significance of the number of voids. High isostatic pressure allows to obtain high J c of 10 A/mm 2 (at 4.2 K) in 10 T and increases irreversible magnetic field ( B irr ) and upper critical field ( B c2 ). Measurements show that these wires have high critical temperature of 37 K.