Things are heating up for superconductors
Date:
March 22, 2022
Source:
Linko"ping University
Summary:
Researchers have, by way of a number of theoretical calculations,
shown that magnesium diboride becomes superconductive at a higher
temperature when it is stretched. The discovery is a big step
toward finding superconductive materials that are useful in
real-world situations.
FULL STORY ========================================================================== Researchers at Linko"ping University have, by way of a number of
theoretical calculations, shown that magnesium diboride becomes
superconductive at a higher temperature when it is stretched. The
discovery is a big step toward finding superconductive materials that
are useful in real-world situations.
========================================================================== "Magnesiumdiboride or MgB2 is an interesting material. It's a hard
material that is used for instance in aircraft production and normally
it becomes superconductive at a relatively high temperature, 39 K, or
-234 CDEG," says Erik Johansson, who recently completed his doctorate
at the Division of Theoretical Physics.
Erik Johansson is also principal author of an article published in the
Journal of Applied Physics that have attracted broad attention. The
results have been identified by the editor as particularly important
for the future.
"Magnesium boride has an uncomplicated structure which means
that the calculations on the supercomputers here at the National
Supercomputer Centre in Linko"ping can focus on complex phenomena like superconductivity," he says.
Access to renewable energy is fundamental for a sustainable world, but
even renewable energy disappears in the form of losses during transmission
in the electrical networks. These losses are due to the fact that even materials that are good conductors have a certain resistance, resulting
in losses in the form of heat. For this reason, scientists worldwide
are trying to find materials that are superconductive, that is, that
conduct electricity with no losses at all. Such materials exist, but superconductivity mostly arises very close to absolute 0, i.e. 0 K or
-273,15 DEGC. Many years of research have resulted in complicated new
materials with a maximum critical temperature of maybe 200 K, that is,
-73 DEGC. At temperatures under the critical temperature, the materials
become superconductive. Research has also shown that superconductivity
can be achieved in certain metallic materials at extremely high pressure.
If the scientists are successful in increasing the critical temperature,
there will be greater opportunities to use the phenomenon of
superconductivity in practical applications.
"The main goal is to find a material that is superconductive at normal
pressure and room temperature. The beauty of our study is that we present
a smart way of increasing the critical temperature without having to
use massively high pressure, and without using complicated structures
or sensitive materials.
Magnesium diboride behaves in the opposite way to many other materials,
where high pressure increases the ability to superconduct. Instead, here
we can stretch the material by a few per cent and get a huge increase
in the critical temperature," says Erik Johansson.
In the nanoscale, the atoms vibrate even in really hard and solid
materials. In the scientists' calculations of magnesium diboride, it
emerges that when the material is stretched, the atoms are pulled away
from each other and the frequency of the vibrations changes. This means
that in this material, the critical temperature increases -- in one case
from 39 K to 77 K. If magnesium diboride is instead subjected to high
pressure, its superconductivity decreases.
The discovery of this phenomenon paves the way for calculations and tests
of other similar materials or material combinations that can increase
the critical temperature further.
"One possibility could be to mix magnesium diboride with another
metal diboride, creating a nanolabyrinth of stretched MgB2 with a high superconductive temperature," says Bjo"rn Alling, docent and senior
lecturer at the Division of Theoretical Physics and director of the
National Supercomputer Centre at Linko"ping University.
The research has been funded by the Knut and Alice Wallenberg Foundation,
the Swedish Research Council and the Swedish Foundation for Strategic
Research, among others. It has been conducted with support from the government's strategic venture, Advanced Functional Materials, AFM,
at Linko"ping University.
========================================================================== Story Source: Materials provided by Linko"ping_University. Original
written by Monica Westman Svenselius. Note: Content may be edited for
style and length.
========================================================================== Journal Reference:
1. Erik Johansson, Ferenc Tasna'di, Annop Ektarawong, Johanna Rosen,
Bjo"rn
Alling. The effect of strain and pressure on the electron-phonon
coupling and superconductivity in MgB2--Benchmark of theoretical
methodologies and outlook for nanostructure design. Journal of
Applied Physics, 2022; 131 (6): 063902 DOI: 10.1063/5.0078765 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220322111303.htm
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