Scientists from Cornell University have developed an entirely new superconducting material that is capable of self-assembly. Unlike the magnets present inside an MRI machine, which are usually quite hard and rigid, the new substance is remarkably soft, almost like a plastic bottle. According to the researchers, it can arrange itself into a three-dimensional, gyroidal structure with incredible superconducting abilities.
The result of 20-year-long research, the breakthrough marks the first time that scientists have been able to create a self-assembling superconductor. Recently published in the Science Advances journal, the study could pave the way for highly versatile, scalable superconductors that offer greater control over the way magnetic fields passing through them get moved. Built using niobium nitride (NbN), the superconductor is designed to self-assemble into a 3-D porous form, shaped like a gyroid. Gyroid is an intricate cubic structure, with a surface that separates space into identical and interpenetrating labyrinthine passages.
Superconductivity as a phenomenon plays a major role in MRI machines and fusion reactors, and usually requires temperatures near absolute zero (-459.67°F or around −273.15°C). While recent research has yielded superconductivity at slightly higher temperatures of about 94 degrees below zero, the ability to pass electrons without any resistance or energy drainage is still an expensive affair. The superconducting magnets in MRIs, for instance, have to be continuously cooled using a combination of liquid nitrogen and helium. Speaking about the project, Ulrich Wiesner, a professor of engineering and materials science at Cornell and the study’s author, said:
There’s this effort in research to get superconducting at higher temperatures, so that you don’t have to cool anymore. That would revolutionize everything. There’s a huge impetus to get that.
The current research focuses on how self-assembling, gyroidal forms affect the superconducting properties of a material. To develop the plastic-like substance, the scientists used organic block copolymers to shape sol-gel nionium oxide (Nb2O5) into special three-dimensional, gyroidal networks, through a process of solvent evaporation-induced self assembly. Of the two intertwined gyroidal channels, one was removed by heating the material in air at temperatures of around 450 degrees.
To check for superconductivity, the team first heated the niobium oxide to nearly 700°C (approx. 1292°F), exposing it to ammonia for conversion into niobium nitride. When cooled to room temperature, however, the material was not found to be superconducting. According to the scientists, re-heating the substance to about 850°C (or 1562°F) caused it to achieve superconductivity. While the exact reason behind this rather convoluted process is not yet clearly understood, the researchers are hopeful that it could lead to the development of mesostructured superconductors. Wiesner added:
There’s something that happens to the material when we heat the material to 700 and then cool it and heat it to 850 again is different than direct heating it to 850, and whatever that is isn’t clear to us.
As the team points out, the superconducting material boasts multiple pores, measuring around 10 nanometers in diameter, all along its surface. This in turn has several advantages. Superconductors, in general, tend to expel magnetic fields of energy. The pores allow scientists to direct the magnetic fields surrounding the superconductor right into the pores. Wiesner esplained:
We can fill the pores with a second material, that may be magnetic or a semiconductor, and then study the properties of these new superconducting composites with very large interfacial areas… these organic block copolymer materials can help you generate completely new superconducting structures and composite materials, which may have completely novel properties and transition temperatures.
Source: Cornell University