Impurity Size Affects The Working Of Superconducting Materials

Researchers from North Carolina State University have examined the relationship between impurities and superconducting materials. They focused on how impurity size can affect or benefit a superconducting material.

A superconducting material conducts electricity without energy loss through leaks. These materials are used in MRI technology in the medical industry. They will play an important role in future energy technology development.

Bismut-Strontium-Calcium-Copper Oxide (Bi2212) is a superconducting material. It is currently the only material of its kind that can be wound at extremely high temperatures. It is expected to be used in all sectors related to high-energy physics. These sectors include transformers, power transmission lines, and motors.

Bi2212 will also be useful in applications that require large magnetic fields. Such applications include magnetic resonance imaging and electromagnets.

To use Bi2212, the material is heated to approximately 900 °C after being processed into a multifilament wire. The wire contains 500 to 1 000 Bi2212 filaments clad in silver. The process produces impurities, mainly porous particles and Bi2201.

Dr Justin Schwartz, author, Kobe Steel Professor, and Head of Department at NC State Materials Science and Engineering, states that porous particles are problematic. He noted that impurities are the most significant factor.

These impurities can affect Bi2212 performance positively or negatively. Research has shown that large impurities impede superconductivity by obstructing current flow. Researchers are working on an improved processing method to optimise superconductivity.

One way to improve Bi2212 performance as a superconductor is to incorporate nanoscale impurities ranging from 1.2 to 2.5 mm. These nanoscale impurities or defects serve as sites for the pinning of magnetic flux in place. This pinning stabilises the magnetic vortices, thereby preventing movement that would cause resistance and hinder superconductivity in a magnetic field.

Since Bi2212 is intended for generating high magnetic fields with electric current, pinning magnetic flux is essential. This measure is necessary for the material to function in a magnetic field.