Florida State University researchers have discovered a novel way to improve the performance of electrical wires used as high-temperature superconductors (HTS), findings that have the potential to power a new generation of particle accelerators.
[...] The researchers found that the individual grains have a long rectangular shape, with their longer side pointing along the same axis as the wire—a so-called biaxial texture. They are arranged in a circular pattern following the path of the wire, so that orientation is only apparent at very small scale. Those two properties together give the Bi-2212 grains a quasi-biaxial texture, which turned out to be an ideal configuration for supercurrent flow.
"By understanding how to optimize the structure of these grains, we can fabricate the HTS round wires that carry higher currents in the most efficient way," said Abiola Temidayo Oloye, a doctoral candidate at the FAMU-FSU College of Engineering, researcher at the National High Magnetic Field Laboratory (MagLab) and the paper's lead author.
[...] "The microstructural characterization used is unique in analyzing the crystal structure of Bi-2212 round wires," Kametani said."The technique is usually used for analyzing metals and alloys, and we have adapted it to develop novel sample preparation methods to further the optimization of Bi-2212 HTS wire technologies."
[...] "Since it is the only high-temperature superconductor available in round wire form, the material can more easily replace existing technologies using LTS wires made from other materials," Oloye said. "Other HTS such as REBCO and Bi-2223 are only available in tape form, which adds a layer of complexity to magnet design."
T A Oloye, M Matras, J Jiang, et al. Correlation of critical current density to quasi-biaxial texture and grain boundary cleanliness in fully dense Bi-2212 wires - IOPscience, Superconductor Science and Technology (DOI: 10.1088/1361-6668/abd575)