Newswise —
MgB2 is a binary compound that acts as a superconductor at a moderate temperature of around -234°C. This temperature can be achieved using inexpensive coolants like liquid hydrogen or neon. MgB2 is also cheap, lightweight, non-toxic, and its raw materials are abundantly available. This makes it a better alternative to conventional superconductors that require expensive cooling and magnets based on rare elements.
MgB2 is a useful substance that can be used to make things like coils and magnets for various applications, such as in medical imaging and electric motors. Researchers have found that it can work well as a superconducting material but needs improvement in magnetic flux pinning. They have discovered that using nano-sized B particles as B precursors can help create nano-sized MgB2 grains with strong grain boundary pinning and high critical current density (Jc), making it more effective for use in various industries.
A group of scientists led by Prof. Muralidhar Miryala from Shibaura Institute of Technology, Japan, recently explored a better and cost-effective alternative to refine B nanoparticles to nanoscale sizes. Currently, B nanoparticles are produced by ball milling, pyrolysis, and sintering, which suffer from drawbacks such as low purity output and poor cost-effectivity. The scientists used high-energy ultra-sonication to refine coarse B powder dispersed in 2-propanol up to nanoscale sizes. Their work was published in the Journal of Alloys and Compounds on 14th April 2023.
According to Prof. Miryala, in the high-energy ultra-sonication technique, B particles in the solvent are accelerated to high speeds by ultrasonic vibrations, which cause them to collide with each other. The collisions generate friction, shear tearing, compression, and energy release, leading to the breakdown of B particles into nanometer sizes. Additionally, the tiny air bubbles produced during collision collapse, contributing to the process of breaking down the particles.
The scientists used 2-propanol as a solvent and ultrasonically refined cheap commercial B powder for 45 minutes to make oxide-free nano-sized B particles. These particles were then used to create bulk MgB2 that had no carbon impurities and exhibited superconductivity at 38.5 K. The researchers also found that the bulk MgB2 showed high critical current density (Jc) values of 500 and 380 kA cm-2 at 10 K and 20 K, respectively. The improved Jc was due to better grain boundary pinning in MgB2, as revealed by microstructural analysis and supported by the Dew-Hughes theory.
The researchers also conducted simulations and predicted that a disk made from ultrasonically refined B powder could exhibit high magnetic properties. They believe that these findings bring MgB2 superconducting magnets closer to commercialization in various forms such as tapes, wires, and films.
Indeed, with a sustainable and low-cost technique for developing high-performance MgB2 superconductors, the present work could unlock the potential of MgB2 super magnets!
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Reference
DOI: https://doi.org/10.1016/j.jallcom.2023.170146
About Shibaura Institute of Technology (SIT), Japan
Shibaura Institute of Technology (SIT) is a private university with campuses in Tokyo and Saitama. Since the establishment of its predecessor, Tokyo Higher School of Industry and Commerce, in 1927, it has maintained “learning through practice” as its philosophy in the education of engineers. SIT was the only private science and engineering university selected for the Top Global University Project sponsored by the Ministry of Education, Culture, Sports, Science and Technology and will receive support from the ministry for 10 years starting from the 2014 academic year. Its motto, “Nurturing engineers who learn from society and contribute to society,” reflects its mission of fostering scientists and engineers who can contribute to the sustainable growth of the world by exposing their over 8,000 students to culturally diverse environments, where they learn to cope, collaborate, and relate with fellow students from around the world.
Website: https://www.shibaura-it.ac.jp/en/
About Professor Muralidhar Miryala from SIT, Japan
Dr. Muralidhar Miryala is a Professor at the College of Engineering/Graduate School of Science and Engineering and a member of the Board of Councilor at Shibaura Institute of Technology (SIT). He is also the Chair and OB at World Technology University Network (WTUN). His primary research interests comprise solid state physics and materials science, particularly materials for energy and the environment, such as high-temperature superconductors. He has over 500 publications to his credit, including patents, books, review articles, research articles, press releases, etc. He has received several awards for his research contributions, including the prestigious 2021 Pravasi Bharatiya Samman Award from the President of India and the SIT Excellent Education Award (2021) by the Chairman of the Board of Directors.
Funding Information
This study was partly supported by Shibaura Institute of Technology (SIT) International Research Center for Green Electronics and Grant-in-Aid FD research budget code: 721MA56383 and the Strategy AV21 of the Czech Academy of Sciences, the research program AV21-VP3 “Energy storage in flywheels.”
