Phys.org May 1, 2023
Magnesium diboride (MgB2), a binary compound, behaves as a superconductor at a moderate temperature of around 39 K (-234°C). It can replace conventional low-temperature superconductors. However, it suffers from weak magnetic flux pinning. To enhance pinning, it is essential to tune the pinning centers in MgB2—the boundaries of grains or small crystals that constitute MgB2. An international team of researchers (Japan, Czech Republic) used high-energy ultra-sonication for refining coarse B powder dispersed in 2-propanol up to nanoscale sizes. Utrasonic vibrations imparted high speeds to B particles in the solvent, leading to collisions. The resulting friction and shear tearing, compression, and energy release by the collapse of tiny air bubbles produced during collision broke down B particles to nanometer sizes. They utilized them to fabricate bulk MgB2 with scarce oxide and no carbon impurities, which showed superconductivity at around 38.5 K. It had high Jc values of 500 and 380 kA cm-2 at 10 K and 20 K, respectively.; this was an 80% improvement. The increase in Jc was due to better grain boundary pinning in MgB2. According to the researchers their findings bring MgB2 superconducting magnets, which can be fabricated in the form of tapes, wires, and films, a step closer to their commercialization… read more. Open Access TECHNICAL ARTICLEÂ
Simulation setup. Credit: Journal of Alloys and Compounds, Volume 955, 10 September 2023, 170146Â