Room Temperature Superconductor Found

[Gord_in_Toronto]

Nobody's paying attention. It was found by Ranga Dias and his colleagues. Emily Conover just wrote the article.

And the paper was just published on 14 October 2020 in Nature.
https://www.nature.com/articles/s41586-020-2801-z

 

[Ziggurat]

They traded low temperature for high pressure. And even then only at a single point. So not really any closer to practical applications than before.

A superconductor is worthless if the power needed to pressurize it or supercool it is greater than the power it's supposed to be conducting.

Cooling to liquid nitrogen temperature is actually fairly cheap. High pressure does not require much energy at all, and can be maintained without energy input indefinitely. But it's not even possible to get to static pressures this large outside of diamond anvil cells, and thus it's useless for any applications.

 

[sphenisc]

Cooling to liquid nitrogen temperature is actually fairly cheap. High pressure does not require much energy at all, and can be maintained without energy input indefinitely. But it's not even possible to get to static pressures this large outside of diamond anvil cells, and thus it's useless for any applications.

Which raises the question "What's the next level down for pressure generation and how much cheaper/easier is it?"

 

[Ziggurat]

Which raises the question "What's the next level down for pressure generation and how much cheaper/easier is it?"

High pressure in physics terms is orders of magnitude higher than high pressure in industrial terms. The kinds of pressure industrial techniques use to create pressure on large scales (for example, pressurize water lines) isn't enough to really move the needle on something like superconductivity temperatures. Basically there's no real way to do what would need to be done on the scale of something like a power line. The in-principle stuff, even below a diamond anvil cell, would be so expensive there's no point in even trying to calculate the costs.

 

[GodMark2]

Cooling to liquid nitrogen temperature is actually fairly cheap. High pressure does not require much energy at all, and can be maintained without energy input indefinitely. But it's not even possible to get to static pressures this large outside of diamond anvil cells, and thus it's useless for any applications.

I see this is as a practical manifestation of the adage "When a measure becomes the target, it ceases to be a good measure". For so many years, the only measure of the 'goodness' of a semiconductor was "How high is it's transition temperature". That was fine, when comparing samples in otherwise unchanged conditions. But somewhere, it changed from "Transition temperature is a good way to measure our progress toward a widely useful semiconductor" to "Transition temperature IS progress in semiconductors". This completely forgets the "widely useful" portion of the equation.

Which raises the question "What's the next level down for pressure generation and how much cheaper/easier is it?"

As long as they keep getting new funding each time they increase the transition temperature, transition temperature is what they'll focus on. As long as that is the case, improvements in other usability areas (like pressure) are likely to go investigated. They might find something accidentally, but they won't focus on looking for it, because the guaranteed funding is elsewhere.

 

[Ziggurat]

I see this is as a practical manifestation of the adage "When a measure becomes the target, it ceases to be a good measure". For so many years, the only measure of the 'goodness' of a semiconductor was "How high is it's transition temperature". That was fine, when comparing samples in otherwise unchanged conditions. But somewhere, it changed from "Transition temperature is a good way to measure our progress toward a widely useful semiconductor" to "Transition temperature IS progress in semiconductors". This completely forgets the "widely useful" portion of the equation.

<nitpick> Superconductors, not semiconductors. </nitpick>

While that may be a contributing factor, the issue is a bit more fundamental than that.

The bigger problem is simply that cuprate superconductor research (where the high-Tc stuff began) has essentially run out of steam. Most of what can be tried, has been tried. There's still a lot to be figured out in terms of the fundamental physics, but that's been very resistant to understanding on a deep level, and so a breakthrough there may be tomorrow, or maybe decades away.

So where else do you go with new research? High pressure is one of the few places where (1) we know it makes superconductivity more likely, and (2) there's a hell of a lot of material phase space left unexplored. If you're a new professor hoping to get tenure, you need to spend your time doing research that's going to get you publishable results. And working on high pressure phase diagrams is a pretty reliable way to do that. The record Tc's are nice, but they aren't actually the driving force here. Any new material that superconducts under pressure is going to get you a paper, whether or not the Tc is record-setting.

If there was a reliable avenue for developing better superconductors even at lower temperatures, people would pursue those avenues. The unfortunate reality is that we don't know of any.

As I mentioned already, liquid nitrogen is cheap. We already have materials that can superconduct at those temperatures without high pressures. But they aren't good materials for making wires out of. If you could develop a material that would superconduct at liquid nitrogen temperature and ambient pressure AND which was good for making wires, then you'd be rich. The reason that hasn't happened yet isn't because people have been blinded by chasing record Tc's. It's because we've already tried everything we can think of, and people have run out of good ideas. Sadly, it may not even be possible.