4 ms·
Hydrides come within a whisker of room temperature superconductivity
- lachlan-sneff 7y agoI wonder if the path to room-temperature superconductors involves finding ways of containing hydrides at very high pressures, rather than finding materials that superconduct and ambiant temperatures and pressures.
- sp332 7y agoWrap them in carbon nanotubes :)
- lachlan-sneff 7y agoMy immediate thought was to wrap them in some sort of diamondoid shell through some sort of mechanosynthesis process, but maybe a carbon nanotube would be stronger?
- the_seraphim 7y agocouple it with some double walled carbon nanotubes and you can get upto 700 GPa https://www.nextbigfuture.com/2019/01/fabrication-of-ultrastrong-700-gigapascal-fused-double-walled-carbon-nanotubes.html https://www.nextbigfuture.com/2019/01/fabrication-of-ultrast...
- DiseasedBadger 7y agoI wonder if one could just stuff the tubes with hydrogen, then lanthanum powder, then just let them expand? They might auto-heat from the pressure, and assemble themselves, if you just unfroze them.
- qcj 7y agoI have the feeling it will be more economical to just use a low-temperature superconductor and cool it down with a closed-cycle cryocooler, rather than try to get a large enough pressure vessel that can maintain such high pressures.
- lachlan-sneff 7y agoWith current technology, definitely.
- velosol 7y agoA few years ago, that was the thinking when a 'high temperature' (much colder than room temperature) superconducting cable was trialed in Germany [1]. [1]: https://www.tdworld.com/overhead-distribution/ampacity-project https://www.tdworld.com/overhead-distribution/ampacity-proje... [2 with follow-up presentation]: https://snf.ieeecsc.org/abstracts/stp475-ampacity-project-%E2%80%93-update-world%E2%80%99s-first-superconducting-cable-and-fault-current https://snf.ieeecsc.org/abstracts/stp475-ampacity-project-%E...
- marcosdumay 7y agoYou want high temperature superconductors because they can stand larger magnetic fields. So, it is certainly easier to keep them cool than pressurized, but the cold ones are much less useful.
- Zenst 7y agoI would love a CPU that ran at room temperature. OK, it's a cart and horse affair as it is the resistance that causes the heat, but I'm mindful how lab work pans out into real-work. But even reducing resisting a bit in a practical, consumer useful way has massive benefits.
- cr0sh 7y agoTechnically, yes, "resistance causes the heat" - but why? Well - because in a CPU, voltages are being manipulated. Those voltages represent binary values. Usually a positive voltage is designated as a binary "1" and a zero voltage as a binary "0". Putting a "1" into a register (or whatever) is easy - just add the appropriate voltage. But how do you change that "1" into a "0"? You do so by "grounding" the circuit - that is, a circuit is made where the voltage level representing the "1" is connected to the reference voltage level that represents "0". Since that voltage level is "0 volts" (usually - but not always - but it is usually lower than the voltage level representing "1"); that change in voltage happens to occur across a conductor, and that conductor has some resistance, and that ultimately is what generates the heat. ASIDE: It is possible to reverse all of this - that is, use a negative or zero voltage to represent a "1" and a positive voltage to represent a "0", and so on - I'm not sure, though, that this is done in common practice, but I am certain it has been done somewhere at least once. So - what does that mean? Well - it means that in a CPU, just by the fact that it is manipulating voltages that represent the binary symbols "1" and "0" - it is going to end up generating some amount of heat. The fasting these changes occur, the more heat that is output. The larger the voltages involved, the more heat is output (note how this explains why, as CPUs have gotten faster, their operating voltages have become lower). How do you combat this? Well - it ain't easy - but what if you could, instead of grounding a voltage representing a "1" to make it a "0" - you instead used it elsewhere (in some manner) to generate a "1". That is, instead of wasting that voltage and energy as heat due to resistance, you used it instead to perform the opposite function elsewhere in the CPU? Well - you can - though it ain't easy from what I understand. It's called: https://en.wikipedia.org/wiki/Reversible_computing https://en.wikipedia.org/wiki/Reversible_computing
- hwillis 7y ago
- deleted 7y ago[deleted]
- Causality1 7y agoIs there a measurement for how much power a superconductor of a given diameter can actually conduct? Of course we're all familiar with the "resistance = 0" concept but I don't think that means you could pump ten billion amps through a superconductor the diameter of a hair, or does it? What other forces limit high-density current flow besides simple resistance?
- fvffchffdv 7y agoMagnetic fields, which are created by the current, destroy the super conducting effect. The colder you run a superconductor, the more current it can conduct. T quoted for superconductivity is the phase transition for I = 0 A
- lachlan-sneff 7y agoI'm not an expert, but I believe that after a certain point, the magnetic field created by the wire destroys the superconducting state.
- willis936 7y agoThe term "critical current" is often used for the current that generates the maximum magnetic field a superconductor of a given size/geometry can sustain. In practice the actual maximum current before quench is much lower (orders of magnitudes in some cases, I've heard) due to imperfections in metallic lattices. This [1] is worth a few listens. 1. https://omegataupodcast.net/285-superconductivity/ https://omegataupodcast.net/285-superconductivity/
- qcj 7y agoThe limiting factor is the critical field of the superconductor. Superconductors tend to expel magnetic fields, but if the field is strong enough it will bring the material back to normal conduction. Since a current will generate a magnetic field, this is what sets the maximum current. e: looks like you got your answer haha
- skykooler 7y agoWhat limits it is that superconductors can only handle a certain density of magnetic flux; more than that will make it stop superconducting. (This property was used in the "cryotron", an electrical switch used in some early computers before transistors became common for the same function.) Any current-carrying wire produces a magnetic field; so, with a strong enough current, the magnetic flux will cause the superconductor to switch itself off. This can be limited by using a larger superconductor, so the flux density is lower.
- gok 7y agoThis article is from January but things do seem to be suddenly getting exciting around room temperature superconductors again. The preprint mentioned in the paper became an article in Nature in May. Moreover, the fact that there now seem to be way to design superconductive materials rather just stumble into them could be a game changer.
- lachlan-sneff 7y agoA few months back, a team reported that they'd found room-temperature superconduction in gold/silver nanoparticles. Unfortunately, there has been no more news about it since.
- d--b 7y ago> Attaining superconductivity requires the diamond anvil cell to exerts pressures of up to 200GPa, two million times that of the Earth’s atmosphere.
- _Microft 7y agoAt high pressure might be to superconductivity research what in mice is to medical research. That doesn't mean that it is not useful to conduct these experiments. They could give further insights into how superconductivity comes to be - or maybe discover a superconducting material that requires high (but not too high * ) pressures to form but remains stable when they are lowered back to normal pressure similar to how diamonds are stable at normal pressures but are require high pressure to be formed. * Pressures only reachable by using diamond anvils would be highly impractical to produce any useful amount of material ;)
- IshKebab 7y agoI think he must meant that the headline is misleading. The holy gain is room temperature superconductivity at room pressure.
- mjevans 7y agoDepending on the application, mechanically useful pressures and higher temperatures might be good enough.
- wahern 7y ago"Room temperature" already makes this concession as it means above 0C. In the context of superconductivity I would assume "room pressure" to fairly encompass pressures higher than 1 atm, though I don't know if there's a practical cut-off as there is for temperature.
- cc439 7y agoI wonder if there might be a way to utilize the same effect that creates a Prince Rupert's drop to create that sort of stress in a superconductor. Sure, it would be fragile but it would also be stable without external forces applied. The stresses contained within the surface layer of the bulbous end reach as high as 700mpa which might be increased by using better materials and colder "shock" processes.
- acd 7y agoI ponder if the sun is a really large super conductor? Since the sun has really high pressure like in the article and it has largely a lot of hydrogen like in the article. https://en.wikipedia.org/wiki/Sun https://en.wikipedia.org/wiki/Sun
- Ididntdothis 7y agoDo these concepts even make sense at the temperature of the sun?
- deleted 7y ago[deleted]
- codedokode 7y agoI don't know if it is superconductor, but plasma is somewhat conductive because it is consists of charged particles.
- magicalhippo 7y agoIt's also a lot hotter than room temperature, especially where the high pressure is.
- m3kw9 7y agoIs it correct to think that because of entropy of heat, it is harder to make atomic structures stable enough to form a perfect path for electrons to run without loss at higher temps?
- acchow 7y agoI hope this is the right description because it would make such intuitive sense. But superconductivity is also a quantum phenomenon so it probably defies intuition.