Since this is the second story about this kind of research that has been posted this week, I feel it should be made clear that the purpose of this kind of experiment is not to develop room temperature superconductors for use in devices, but to study the physics of BCS (normal, "low temperature" superconductivity seen in metals like mercury, as opposed to that seen in materials like YBCO) superconductivity in materials with much lighter nuclei, and to get an idea of what might occur in theoretical states of matter like metallic hydrogen. It is only "applied" in the sense that it allows one to understand the mechanisms behind superconductivity, no one doing this research thinks that this will be a useful mechanism for making superconducting transmission lines or whatever.
Yeah, this seems like it might possibly be not worth the effort. I'm curious as to applications for this - that's a pressure and temperature that's not practical either.
I mean, unless intel is really committed to it's 14 nm node.
A group of these superconductors was discovered by a computer simulation [1], they are not meant to be used in technology, but better understanding of mechanism by which superconductors work, and improvements in quantum mechanical simulations may help in the future to create materials where some atoms are squeezed together by the interaction with other atoms in the material instead of external pressure.
I wonder if the cross section area of the superconductor is relevant. If it is not then it could conceivably be enclosed inside a carbon nanotube to hold its pressure. A carbon nanotube can hold about 620,000 atmospheres of pressure. Not quite 2.5 million but maybe another substance can be found that can superconduct at a lower pressure. Perhaps multi-walled tubes could be made. I'm sure someone has already thought about this though.
It's been a long time since I learnt this, so I may be misremembering, but superconductors have a current saturation limit. You can only pass so much current.
It doesn't even have to be nanotube? Just regular diamond tube or something else that can hold the pressure. Maybe it could be done in the same way diamonds are made, just put the superconducting stuff inside first.
They use diamond anvils to create the required pressures though. I wonder if it's somehow possible to lock these kind of molecules or other stuff inside an unbroken diamond carbon lattice and what would happen.
Can we please change the meaning of “high temp superconductors” to “material that start being super conductors and high temperature and low pressures” ? Everyone agrees that these records don’t mean anything in term of direct applications. I agree that they give us a way to check our theoretical models, which might help getting to usable stuff, but all the “record shattering” language is really not making science look very smart IMO.
I think this argument is quite facile. These people are scientists trying to understand superconductivity at a basic level, and this theoretical research (as well as the experimental results posted on this forum earlier this week) are a genuine advancement in that field. You are judging this research based on how it is directly applicable to making handheld devices with room temperature superconductors when that is not what these people are attempting to do at all. The fact that a superconducting state can be maintained at these temperatures at all is, indeed, "record shattering". We do not have the ability to simply engineer a material that can superconduct at ambient temperature and pressure at will. I don't mean to be to confrontational, but reading the comments on these articles it really pisses me off to see the hard work of actual scientists judged by the rubric of whatever science fiction garbage internet commenters think should be possible.
To me the most important thing here is that we can finally make an educated guess regarding the circumstances in which something becomes a superconductor.
From a safety point of view, it depends on how compressible it is. A very stiff material under high pressure still isn't going to release much energy when the pressure gets released because it doesn't move by very much. (This is why pressurised air becomes dangerous at much lower pressures than pressurised water)
The linked article is a bit ambiguous about it, I think, but the abstract [1] is clear: the pressure must be applied for the material to be superconducting:
> Here, we identify an alternative clathrate structure in ternary Li2MgH16 with a remarkably high estimated Tc of ∼473 K at 250 GPa [...]
"The newly predicted superconductor — a compound of hydrogen, magnesium and lithium — [...] must be squeezed to extremely high pressure, nearly 2.5 million times the pressure of Earth’s atmosphere [...]"
It doesn't seem to be a gas, so applying pressure would be as easy as tightening the enclosure, like fastening a bolt. Cables could be made by just sticking a superconducting core inside a compression sleeve, although they'd probably have to be segmented, and breaking the sleeve in any place could make the core stop superconducting and overheat pretty fast. Other than that, it should be perfectly safe.
The values suggested are north of the ultimate tensile strength for carbon nanotubes and graphene. It’s in the ballpark of the center of the earth. I don’t think it’s as simple as tightening a bolt.
Hell, I'd even call it "not incomparable to the pressure at the center of the Sun". I mean, it's still like ~100x smaller than the smallest estimates, but it's also only 100x less pressure than is plausibly at the center of the Sun.
What's risky about heating hydrogen, magnesium and lithium and squeezing them hard together? Apart from any addition of oxygen blowing out the building?
Depends on how much it compresses and can expand when breached. The blast radius from uncompressible liquids like water is close to zero no matter the pressure, a metal shouldn't be much different.
I'm not a physicist, but I work adjacent to people who do neat stuff with superconductors... hopefully they wouldn't be too mad about the broad strokes I'm using here.
Superconductivity isn't just a property of a material -- it's a property of an arrangement of atoms. When you put a material under extreme pressures, the atoms are smashed closer together; and the properties of the material can change significantly. For example, diamonds are made by smashing graphite at extreme pressures -- sufficiently high pressure can completely rearrange the crystalline structure.
That prepares us for the question; what's superconductivity? The answer is complicated, physicists don't really know the full story; but here's a simplified intuitive picture. We imagine atoms as being positively-charged nuclei with clouds of negatively-charged electrons. When these atoms are packed into a crystalline lattice, and the resulting material is a conductor, then the electrons are fairly free to move about the whole lattice -- they aren't bound to a single atom. When the electrons move about, they attract nearby nuclei -- the atoms in the lattice shift towards them! In a superconductor, something quite amazing happens: when atoms shift towards one electron, it can make room for another electron -- this process causes the electrons to buddy up, and act in a coordinated fashion. These two electrons quickly make other friends, and in short order they're all acting in concert!
So, back to high-pressure superconductivity. We've applied a high amount of pressure to a material which isn't normally superconducting. Its atoms have rearranged themselves into a new crystalline lattice, which is quite densely packed. The electrons, too, must be densely packed -- so they have greater opportunities to make friends.
The high pressure pre-distorts the lattice making it easier for cooper pairs to form. A cooper pair allows an electron to essiantly be in two places at once, which causes superconductivity:
An electron in a metal normally behaves as a free particle. The electron is repelled from other electrons due to their negative charge, but it also attracts the positive ions that make up the rigid lattice of the metal. This attraction distorts the ion lattice, moving the ions slightly toward the electron, increasing the positive charge density of the lattice in the vicinity. This positive charge can attract other electrons. At long distances, this attraction between electrons due to the displaced ions can overcome the electrons' repulsion due to their negative charge, and cause them to pair up.
