Abstract
Our results show that a lower density of unreacted Mg + B material during an Mg solid-state synthesis reaction leads to a significant reduction in the quantity of the superconducting phase and lowers the homogeneity of the superconducting material. It also significantly reduces the irreversible magnetic field (Birr), critical temperature (Tc), upper magnetic field (Bc2), engineered critical current density (Jec), and n-value, despite high isostatic pressure (HIP) treatment and the use of nanoboron in the sample. Our measurements show that samples with large boron grains with an 8% higher density of unreacted Mg + B material allow better critical parameters to be achieved. Studies have shown that the density of unreacted material has little effect on Birr, Tc, Bc2, Jec, and the n-value for an Mg liquid-state synthesis reaction. The results show that the critical parameters during an Mg liquid-state synthesis reaction depend mainly on grain size. Nanoboron grains allow for the highest Birr, Tc, Bc2, Jec, and n-values. Scanning electron microscopy (SEM) images taken from the longitudinal sections of the wires show that the samples annealed under low isostatic pressure have a highly heterogeneous structure. High isostatic pressure heat treatment greatly improves the homogeneity of MgB2.
Highlights
MgB2 wires are the most promising material for superconducting coil applications due to their inexpensive components and ability to be cooled in liquid hydrogen, or by a cryocooler
The results in Fig-in nificantly increases the n-value in MgB2 wires ure 22a and [27] suggest that MgB2 wires with large grain boron after the high isostatic pressure (HIP) process can be used to build a medium field superconducting coil, e.g., B = 5 T. These results reveal that the Mg liquid state and an isostatic pressure of 1.1 GPa significantly improve the nvalue in MgB2 wires with large boron grains
Our measurements show that samples with large boron grains and an 8% higher filling density of unreacted Mg + B material significant decrease in the irreversible magnetic field, critical temperature, upper magnetic field, engineered critical current density, and n-value, despite the high isostatic pressure treatment and the use of nanoboron in the sample
Summary
MgB2 wires are the most promising material for superconducting coil applications due to their inexpensive components and ability to be cooled in liquid hydrogen, or by a cryocooler. The application of superconducting wires is dependent on several factors, e.g., engineering critical current density (Jec ), irreversible magnetic field (Birr ), critical temperature (Tc ), n-value (the log-log slope of the voltage vs electrical current curves during the transition of the superconducting material from a superconducting state to a normal state), and resistance in the normal state (Rn ). These parameters depend on the grain size and purity of magnesium and boron, heat treatment temperature, isostatic pressure, admixture, and wire sheath. These studies show that a greater number of structural defects in boron can accelerate the formation of the MgB2 superconducting phase
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
