Researchers create first self-assembled superconductor

Cornell researchers create first self-assembled superconductor
The Wiesner Group at Cornell University has synthesized the first block copolymer self-assembly-derived nanostructured superconductor. Shown is an example of a bismuth-based superconductor levitating a magnet, with simulated and electron microscope images of the nanostructured material. Credit: Cornell University

Building on nearly two decades' worth of research, a multidisciplinary team at Cornell has blazed a new trail by creating a self-assembled, three-dimensional gyroidal superconductor.

Ulrich Wiesner, a materials science and engineering professor who led the group, says it's the first time a superconductor, in this case niobium nitride (NbN), has self-assembled into a porous, 3-D gyroidal structure. The gyroid is a complex cubic structure based on a surface that divides space into two separate volumes that are interpenetrating and contain various spirals. Pores and the superconducting material have structural dimensions of only around 10 nanometers, which could lead to entirely novel property profiles of superconductors.

Currently, superconductivity for practical uses such as in (MRI) scanners and fusion reactors is only possible at near absolute zero (-459.67 degrees Fahrenheit), although recent experimentation has yielded superconducting at a comparatively balmy -70 degrees C (-94 degrees F).

"There's this effort in research to get superconducting at higher temperatures, so that you don't have to cool anymore," Wiesner said. "That would revolutionize everything. There's a huge impetus to get that."

Wiesner and his co-author Sol Gruner had been dreaming for over two decades about making a gyroidal superconductor in order to explore how this would affect the superconducting properties. The difficulty was in figuring out a way to synthesize the material. The breakthrough was the decision to use NbN as the superconductor.

Superconductivity, in which electrons flow without resistance and the resultant energy-sapping heat, is still an expensive proposition. MRIs use superconducting magnets, but the magnets constantly have to be cooled, usually with a combination of liquid helium and nitrogen.

Wiesner's group started by using organic block copolymers to structure direct sol-gel niobium oxide (Nb2O5) into three-dimensional alternating gyroid networks by solvent evaporation-induced . Simply put, the group built two intertwined gyroidal network structures, then removed one of them by heating in air at 450 degrees.

The team's discovery featured a bit of "serendipity," Wiesner said. In the first attempt to achieve superconductivity, the niobium oxide (under flowing ammonia for conversion to the nitride) was heated to a temperature of 700 degrees. After cooling the material to room temperature, it was determined that superconductivity had not been achieved. The same material was then heated to 850 degrees, cooled and tested, and superconductivity had been achieved.

"We tried going directly to 850, and that didn't work," Wiesner said. "So we had to heat it to 700, cool it and then heat it to 850 and then it worked. Only then."

Wiesner said the group is unable to explain why the heating, cooling and reheating works, but "it's something we're continuing to research," he added.

Limited previous study on mesostructured was due, in part, to a lack of suitable material for testing. The work by Wiesner's team is a first step toward more research in this area.

"We are saying to the superconducting community, 'Hey, look guys, 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. This is worth looking into,'" Wiesner said.

The group's findings are detailed in a paper published in Science Advances, Jan. 29.

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More information: Block copolymer self-assembly–directed synthesis of mesoporous gyroidal superconductors, Science Advances,
Journal information: Science Advances

Provided by Cornell University
Citation: Researchers create first self-assembled superconductor (2016, January 29) retrieved 16 October 2019 from
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Jan 29, 2016
There are more than 30 room temperature superconductors. See for most of them.

Jan 29, 2016
Mark_Goldes, you shouldn't believe everything you read on the web.

Jan 29, 2016
And one should not ignore everything they read on the web.

To cut to the chase, the internet and what is on it, what emerges on it, is your last chance for freedom.

make the most of it, or die on the vine.

If you don't understand what this means, then I guess the message and the medium is lost on you.

Jan 30, 2016
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Jan 30, 2016
Brookhaven National Lab may be attempting to replicate Joe Eck's results.

Jan 30, 2016
The freedom to be misinformed and ignorant ?

Yes, the freedom to be misinformed and ignorant. By the way, that cuts both ways.

Study in an ivory tower environment is great because it allows you to focus on things free of any practicality issues that may come up. However, laser like focus in a single direction is often fraught with the danger of missing something in a larger picture. Do not sneer at those who seek answers in a more pragmatic manner.

Such elitism of presuming that only certain authorities know best is the sort of arrogance that turns many away from science. Science is supposed to be accessible, not elitist. Your attitude is the reason why so many think science is not for them. If you have any shame, you should apologize.

Jan 31, 2016
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