New temperature record: Hydrogen sulfide becomes superconductive under high pressure at minus 70 degrees Celsius

August 18, 2015
The apparatus the team led by Mikhail Eremets at the Max Planck Institute for Chemistry in Mainz uses to generate extremely high pressures, is amazingly handy. The researchers press the metal cell with Allen screws together. The high pressure thus created in the center of the cell, only diamonds resist. The gems operate like anvils that compress a sample. Credit: Thomas Hartmann

Up until now, no material has been able to conduct current with no resistance at such high temperatures: Researchers at the Max Planck Institute for Chemistry in Mainz and the Johannes Gutenberg University Mainz observed that hydrogen sulfide becomes superconductive at minus 70 degree Celsius—when the substance is placed under a pressure of 1.5 million bar. This corresponds to half of the pressure of the earth's core. With their high pressure experiments the researchers in Mainz have thus not only set a new record for superconductivity—their findings have also highlighted a potential new way to transport current at room temperature with no loss.

For many solid-state physicists, superconductors that are suitable for use at room temperature are still a dream. Up until now, the only materials known to conduct current with no and thus no loss did so only at very low temperatures. Accordingly, special copper ceramics (cuprates) took the leading positions in terms of —the temperature at which the material loses its resistance. The record for a ceramic of this type is roughly minus 140 degrees Celsius at normal air pressure and minus 109 degrees Celsius at . In the ceramics, a special, unconventional form of superconductivity occurs. For conventional superconductivity, temperatures of at least minus 234 degrees Celsius have so far been necessary.

A team led by Mikhael Eremets, head of a working group at the Max Planck Institute for Chemistry, working in collaboration with the researchers at Johannes Gutenberg University Mainz has now observed conventional superconductivity at minus 70 degrees Celsius, in (H2S). To convert the substance, which is a gas under normal conditions, into a superconductor the scientists did however have to subject it to a pressure of 1.5 megabar (1.5 million bar), as they describe in the latest edition of the science magazine Nature.

The transition temperature of conventional superconductivity knows no limits

"With our experiments we have set a new record for the temperature at which a material becomes superconductive," says Mikhael Eremets. His team has also been the first to prove in an experiment that there are conventional superconductors with a high transition temperature. Theoretical calculations had already predicted this for certain substances including H2S. "There is a lot of potential in looking for other materials in which conventional superconductivity occurs at ," says the physicist. "There is theoretically no limit for the transition temperature of conventional superconductors, and our experiments give reason to hope that superconductivity can even occur at room temperature."

The researchers generated the extremely high pressure required to make H2S superconductive at comparatively moderate negative temperatures in a special pressure chamber smaller than one cubic centimeter in size. The two diamond tips on the side, which act as anvils, are able to constantly increase the pressure that the sample is subjected to. The cell is equipped with contacts to measure the electrical resistance of the sample. In another high-pressure cell, the researchers were able to investigate the magnetic properties of a material that also change at the transition temperature.

After the researchers had filled the pressure chamber with liquid hydrogen sulfide, they increased the pressure acting on the sample gradually up to roughly two megabar and changing the temperature for each pressure level. They took measurements of both resistance and magnetization to determine the material's transition temperature. The magnetization measurements provide very useful information, because a superconductor possesses ideal magnetic properties.

Hydrogen atoms facilitate superconductivity at high temperatures

The researchers believe that it is mainly hydrogen atoms that are responsible for hydrogen sulfide losing its electrical resistance under high pressure at relatively high temperatures: Hydrogen atoms oscillate in the lattice with the highest frequency of all elements, because hydrogen is the lightest. As the oscillations of the lattice determine the conventional superconductivity—and do this more effectively the faster the atoms oscillate—materials with high hydrogen content exhibit a relatively high transition temperature. In addition, strong bonds between the atoms increase the temperature at which a material becomes superconductive. These conditions are met in H3S, and it is precisely this compound that develops from H2S at high pressure.

Mikhael Eremets and his team are now looking for materials with even higher transition temperatures. Increasing the pressure acting on the hydrogen sulfide above 1.5 megabar is not helpful in this case. This has not only been calculated by theoretical physicists, but now also confirmed in experiments performed by the team in Mainz. At even higher temperatures the electron structure changes in such a way that the transition temperature slowly begins to drop again.

Wanted: hydrogen-rich materials with a higher transition temperature

"An obvious candidate for a high transition temperature is pure hydrogen," says Mikhael Eremets. "It is expected that it would become superconductive at room temperature under high pressure." His team has already begun experimenting with pure hydrogen, but the experiments are very difficult as pressures of three to four megabar are required.

"Our research into hydrogen sulfide has however shown that many hydrogen-rich materials can have a high transition temperature," says Eremets. It may even be possible to realize a high-temperature superconductor worth the name in terms of common temperature perception without high pressure. The researchers in Mainz currently need the high pressure to convert materials that act electrically insulating like hydrogen sulfide into metals. "There may be polymers or other hydrogen-rich compounds that can be converted to metals in some other way and become superconductive at ," says the physicist. If such materials can be found, we would finally have them: superconductors that can be used for a wide range of technical applications.

Explore further: 'Long-awaited explanation' for mysterious effects in high-temperature superconductors

More information: "Conventional superconductivity at 203 K at high pressures." Nature, August 17, 2015. DOI: 10.1038/nature14964 . Available at: http://arxiv.org/abs/1506.08190

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20 comments

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betterexists
5 / 5 (1) Aug 18, 2015
Recently they made up 25 new materials using Sandwiching Technique; Hopefully, 1 of them or a derivative them will serve the needed purpose!
TheGhostofOtto1923
5 / 5 (8) Aug 18, 2015
Could these pressures be attained in a wire encased in a nanotube?
marko
4.7 / 5 (3) Aug 18, 2015
The National Ignition Facility at Lawrence Livermore National Laboratory in California, has experience with compressing pellets of hydrogen to enormous pressures for fusion research.

Perhaps they could use another suitably hydrogen rich target material and fire a detuned laser beam at it to get the required critical pressures through inertial confinement.

You don't need an atom bomb to prove room temperature superconductivity.

Captain Stumpy
3.9 / 5 (7) Aug 18, 2015
Could these pressures be attained in a wire encased in a nanotube?
@Otto
not likely: from the SciMag article
But there's a catch: Hydrogen sulfide works its magic only when squeezed to more than 100 million times atmospheric pressure, roughly one-third as high as the pressure in Earth's core. This condition makes it impractical for most applications
here: http://news.scien...rc=email

i don't think we have the tech to maintain that pressure in a nanotube wire that i've seen
Captain Stumpy
4.4 / 5 (7) Aug 18, 2015
@Noumenon
what was so wrong about the post, eh?
couldn't understand it?

or simply bulk downvoting again because you don't like mainstream provable science ... since it isn't subjective enough for you to add in your commentary or philosophical musings?
Macksb
1 / 5 (3) Aug 18, 2015
This is a particularly clear BCS illustration of my theory of coupled periodic oscillators as the underlying mechanism for superconductivity of all types--BCS, mag diboride and the new high temp cuprates and pnictides,

As the article states, in this BCS example there are three principal ingredients: oscillations of hydrogen atoms, strong bonds between atoms and high pressure. The latter two promote coupling of the periodic oscillations of the atoms. High pressure produces H3S, in which the bonds are stronger.

These ingredients, their combined features and the onset of superconductivity here all track closely with Winfree's theory, which I have described in many prior Physorg posts.

TechnoCreed
5 / 5 (7) Aug 18, 2015
@Captain Stumpy
It has been a while how are you? You and Noum have a funny way to greet each other, tough love I guess :-)
Captain Stumpy
4.4 / 5 (7) Aug 18, 2015
@Captain Stumpy
It has been a while how are you? You and Noum have a funny way to greet each other, tough love I guess :-)

Yeah, Nou doesn't like things that can be proven with empirical evidence...

been on vacation !
how have you been?

i see absolutely NOTHING has changed.... except the trolls are getting more numerous
one more reason to consider sticking to moderated sites, IMHO
Uncle Ira
3.7 / 5 (12) Aug 18, 2015
@ Capt-Skippy. How you are Cher? I am good me, we sure have missed you.

i see absolutely NOTHING has changed....


Well you are right about that one. Check out this one because this is something you know about like I do.

http://phys.org/n...gun.html
Captain Stumpy
4.2 / 5 (5) Aug 18, 2015
@ Capt-Skippy. How you are Cher? I am good me, we sure have missed you.

i see absolutely NOTHING has changed....


Well you are right about that one. Check out this one because this is something you know about like I do.

http://phys.org/n...gun.html
good, thanks Ira

thanks for the link... that is a sore subject to a lot of people, and destined to bring out all the best trolls (LOL)

the more things change, the more things stay the same!

TechnoCreed
5 / 5 (9) Aug 18, 2015
i see absolutely NOTHING has changed.... except the trolls are getting more numerous
one more reason to consider sticking to moderated sites, IMHO.
Many are much less active since the 'ignore user' function have been implemented. They crave for a public who would react to their nonsense; this crowd is not there anymore.
docile
Aug 18, 2015
This comment has been removed by a moderator.
Erico
5 / 5 (2) Aug 19, 2015
An implication of this that might have escaped the researchers, is that the Sun and large hydrogen based planets might be superconductive.
swordsman
not rated yet Aug 19, 2015
As the temperature of a monolithic molecular material decreases, it approaches the point of crystallization. At some point prior to full crystallization, superconductivity is possible. This condition is more likely to occur for atoms with an uneven number of electrons. The point at which crystallization occurs is lower for the lighter atoms, which have fewer numbers of electrons. Therefore, the crystallization of pure hydrogen occurs at lower temperatures. On the other hand, hydrogen has only a single electron and a single proton, and the atom has a tendency to vibrate mechanically. These factors tend to conflict with one another. However, hydrogen atoms can more easily be affected by external electromagnetic waves, which apparently is a main controlling factor. My computer program analysis defines the effects of the atomic voltages produced by electronic velocity vectors in the near field, which will lead to the prediction of external field effects.
mohnish_kumar
not rated yet Aug 20, 2015
If H-bonds are important, how about methane(CH4)?
Lex Talonis
not rated yet Aug 20, 2015
When you get confused about science, just ask each other, "What would Jesus do?".
anonymous_9001
5 / 5 (2) Aug 20, 2015
If H-bonds are important, how about methane(CH4)?


C-H bonds do not participate in hydrogen bonding. "Hydrogen bond" doesn't refer to any X-H bond, just a few particular ones with a high enough electronegativity difference.

https://en.wikipe...gen_bond
Baseline
not rated yet Aug 23, 2015
When you get confused about science, just ask each other, "What would Jesus do?".


I am sorry invoking magic has never solved anything despite your desperate belief that it does.
Macksb
not rated yet Aug 23, 2015
Following up on my prior comment, near the top of this thread:

Details here are as follows. Under pressure, two units of H2S become H3S and elemental sulfur. The loose S atoms produce metallic behavior.

Within H3S molecules, hydrogen and sulfur atoms are coupled more ways than in H2S. Their oscillations coordinate within a certain frequency range. Rich phase behavior, complex non-linear system. Pressure forces the compatible oscillations to interact in most consistent manner. This is Art Winfree's law of coupled oscillators.

In addition, same Winfree law causes these coordinated oscillations to form Cooper pairs in the metallic pool of free S atoms--because phonons (oscillations, lattice vibrations of H3S molecules) are naturally tuned, also, to electrons of free S atoms. Cooper pairs are paired by spin up, spin down electrons; and by electron orbits that are 180 degrees out of phase to each other.

Cooper pairs are classic Winfree patterns twice over.
Macksb
not rated yet Aug 23, 2015
Winfree's law of coupled oscillators is entirely consistent with BCS theory. But it uses a different point of view--periodic oscillations, the tendency of such oscillators to coordinate the phases of such oscillations, and the mathematically permissible ways in which such coordination may occur.

This different point of view is more general than BCS theory, and expansive enough to encompass the non BCS superconducting phenomena--cuprates, pnictides and mag diboride. Thus the Winfree Macksb theory has the potential to satisfy Occam's Razor. Same theory for all superconductivity. Not four different theories.

BCS theory is a special case of Winfree's general law. IMO.

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