In addition to increasing the temperature, scientists have also decreased
the pressure necessary to produce superconductivity.
Researchers from the University of Rochester have achieved a remarkable
feat by developing a superconducting material with low enough temperature
and pressure for use in real-world uses.
Ranga Dias, an associate professor of mechanical engineering and of
physics, and his colleagues claim that with the development of this
substance, ambient superconductivity and applied technologies have finally
come. The scientists describe a nitrogen-doped lutetium hydride (NDLH) that
displays superconductivity at 69 degrees Fahrenheit and 10 kilobars (145,000
pounds per square inch, or psi), in a paper that was published on March 8 in
the magazine Nature.
Pressure at sea level is about 15 psi, so 145,000 psi may still seem like a
very high pressure, but strain engineering methods are frequently used in
chip production, for example, and integrate materials kept together by even
greater internal chemical pressures.
This development in condensed matter physics has been the focus of research
for more than a century. Electrical resistance disappears, and magnetic
fields that are emitted travel around the superconducting substance, which
is one of their two main characteristics. These compounds might allow:
networks that transfer electricity without losing the energy it transmits
by up to 200 million megawatt hours (MWh) per year due to resistance in the
lines
Levitating, frictionless high-speed trains
Techniques for medical imaging and screening that are more reasonably
priced include MRI and magnetocardiography
Electronics that are quicker and more effective for use in digital logic
and memory device technology
Tokamak devices that contain plasmas using magnetic fields to accomplish
fusion as an infinite source of power
The Dias team previously published articles in Nature and Physical Review
Letters describing the creation of two materials, carbonaceous sulfur
hydride and yttrium superhydride, which are superconducting at 58 degrees
Fahrenheit/39 million psi and 12 degrees Fahrenheit/26 million psi,
respectively.
Given the significance of the new finding, Dias and his team took unusual
measures to record their work and fend off critique that emerged after the
previous Nature paper, which resulted in the journal's editors retracting
the article. According to Dias, the earlier article has been resubmitted to
Nature with fresh evidence corroborating the earlier findings. The new
information was gathered in the open, in front of scientists who witnessed
the superconducting shift firsthand, at the Argonne and Brookhaven National
Labs. The new study has adopted a similar strategy.
Nathan Dasenbrock-Gammon, Elliot Snider, Raymond McBride, Hiranya Pasan,
and Dylan Durkee are named as co-lead writers along with other graduate
students from Dias's lab. Everyone in the company participated in carrying
out the tests, according to Dias. "It was really a team endeavor,"
A startling change can be seen.
Researchers have recently discovered an intriguing "working formula" for
making superconducting materials, which involves combining rare earth metals
with hydrogen, followed by adding nitrogen or carbon. Technically speaking,
rare earth metal hydrides take the shape of cage-like structures called
clathrates, where the rare earth metal ions serve as carrier donors and
supply enough electrons to promote the breakup of the H2 molecules. Carbon
and nitrogen aid in substance stabilization. The bottom line is that
superconductivity can arise at lower pressures.
Researchers have also used other rare earth elements besides yttrium.
However, at pressures or temps that are still impractical for uses, the
resulting compounds turn superconductive.
Therefore, Dias turned his gaze elsewhere on the periodic chart this
time.
As for a "good option to test," Dias says lutetium appeared. Its f orbital
arrangement contains 14 highly localized fully-filled electrons, which
reduce phonon softening and improve the electron-phonon interaction
necessary for superconductivity to occur at room temperature. How will we
stabilize this to reduce the needed pressure was the crucial issue. In this
situation, nitrogen entered the scene.
According to Dias, nitrogen strengthens the low-frequency optical phonons
and, like carbon, has a solid atomic structure that can be used to build a
more secure, cage-like lattice within a substance. Because of the durability
of this structure, superconductivity can exist at reduced pressures.
A pure sample of lutetium was put in a reaction container with a gas
combination made of 99 percent hydrogen and 1 percent nitrogen. The mixture
was then allowed to react for two to three days at 392 degrees
Fahrenheit.
According to the study, the resulting lutetium-nitrogen-hydrogen compound
had a "lustrous bluish hue" at first. A "startling visual change" took place
when the compound was squeezed in a diamond anvil cell. It went from blue to
pink at the beginning of superconductivity to a brilliant red metallic state
that wasn't superconducting.
It was a very vivid crimson, according to Dias. "I was astounded to see
such vivid hues. We jokingly proposed the code name "reddmatter" for the
substance at this stage after the substance Spock invented in the well-liked
2009 Star Trek film. The cipher moniker endured.
The prior low pressure produced in Dias's lab is nearly two orders of
magnitude higher than the 145,000 psi pressure needed to cause
superconductivity.
Machine learning for predicting novel superconducting materials
It has been determined that superconducting material can exist at ambient
temps and pressures low enough for useful uses thanks to financing from
Dias's National Science Foundation CAREER award and a grant from the US
Department of Energy.
The development of magnetic confinement for fusion, as well as a route
toward superconducting consumer devices, energy transmission lines, and
transit, according to Dias, are now possible. We think that the contemporary
superconducting age has arrived.
For instance, Dias believes that the development of tokamak machines will
advance significantly faster thanks to the nitrogen-doped lutetium hydride.
Tokamaks depend on strong magnetic fields produced by a doughnut-shaped
enclosure to capture, hold, and spark super-heated plasmas rather than using
strong, convergent laser beams to implode a fuel pellet. NDLH "will be a
game-changer" for the developing technology, according to Dias, as it
generates a "enormous magnetic field" at room temperature.
The potential to combine and match from thousands of different possible
combinations of rare earth metals, nitrogen, hydrogen, and carbon is
particularly exciting, according to Dias, because it could be used to teach
machine-learning algorithms to forecast other potential superconducting
materials.
We use a variety of metals in our daily lives for various purposes, so Dias
asserts that we will also require a variety of superconducting materials.
"We need more ambient superconductors for various uses, just as we use
different metals for different applications."
Keith Lawlor, a co-author, has already started creating programs and
performing computations using the supercomputing capabilities offered by the
Center for Integrated Research Computing at the University of
Rochester.
A center for superconducting elements in rural New York?
Recently, the study team of Dias relocated to a bigger lab on the third
level of Hopeman Hall on the River Campus. He claims that this is the first
phase of an audacious plan to establish the University of Rochester's Center
for Superconducting Innovation (CSI), which will award degrees.
In order to progress the study of superconductivity, the center would
foster an environment that would attract new academics and researchers to
the university. The pool of scholars in the area would grow as a result of
the trained pupils.
The goal, according to Dias, is to establish rural New York as a center for
superconducting technology.
