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High-Temperature Metal Superconductor Beckons
drkrypton writes: "The Globe and Mail is reporting on a new metal which has a superconducting temperature of -234 C or approx. 39 K. While this is still much colder than some ceramic superconductors (which have superconducting temperatures of around -113 C or 160 K) it still may have some ramifications in electronics. Hey, I triple dog dare you to lick it." Perhaps it will one day be routine to start a computing session by dumping in some liquid nitrogen onto a yet-higher-temperature superconducting CPU.
Whoa...you're WAY off. The "old theory" of superconductivity (the BCS theory, developed by Bardeen, Cooper, and Schreiffer) is still very much correct. NOTHING about this discovery implies that the theory is wrong, incomplete, or anything of the sort. What's remarkable is that noone expected to find a "conventional" (I'll explain below what I mean by "conventional") superconducting metal with a transition temperature much above the ~20K temperatures which have already been achieved in niobium alloys.
So anyway, on to what I mean by "conventional" superconductor. Electrons in metals interact with the underlying crystalline lattice; momentum is exchanged by causing the lattice to vibrate. Normally, two electrons will repel each other, since they both have negative electric charges. However, in a crystal, the lattice can mediate an effective ATTRACTIVE interaction between electrons (an electron-phonon-electron interaction, for those who like terminology). Thus the electrons can form bound pairs, which behave quite differently than lone electrons (they behave like "bosons"), and the system can enter the superconducting state (which is rather similar to the superfluid state in, e.g., liquid helium-4). Just what that state is would require a much longer explanation.
As a consequence of the fact that the electron pairing is due to the lattice, the transition temeperature (and other properties) of a conventional superconductor is influenced by the mass of the nuclei in the lattice. This phenomenon is known as the "isotope effect", and was a key piece of evidence which lead to the development of the BCS theory. I felt I had to correct the parent post precisely because of this fact. This recently discovered superconductor shows a variation of transition temperature with boron isotope mass which is just about exactly what the theory of the isotope effect predicts. This is STRONG evidence that this new MgB2 superconductor is a conventional superconductor, albeit one with an unexpectedly high transition temperature.
The "high-Tc" (ceramic, YBCO, etc.) superconductors seem to have a different pairing mechanism (i.e. not electron-phonon-electron, as in BCS), and thus require a different theoretical explanation. That doesn't mean BCS is wrong, just that the ~15 year-old ceramics are in a different class of materials.
The Washington Post has a nice article on it.
I thought that you had to do that now to keep the Pentium 4 from overheating?
Ok my karma is maxed out. When do I become Enlightened?
God I hope not. Remnants of that one X-Files episode where that poor unfortunate sap falls into the liquid nitrogen abound.
I can just see myself probing around in my computer case, accidentally hyper-freezing it and then smashing it to pieces against my desk.
- I don't care if they globalize against free speech. All my best free thoughts are done in my head.
I'm not nearly as impressed by the high-temperature ability of this conductor as I am by the fact that it can "beckon." That's gotta be pretty cool. I bet the technician who first noticed the behavior sh-t himself...
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It would do 550 with air + heat sink so i borrowed some liquid N2 from my physics lab, cut a coke can in half and strapped to cpu and poured in the Liquid nitrogen. CPu booted to windows at 700 mhz but then the power suppy exploded as i forgot to vent cold gasses out the case
Maglev trains wouldn't be so electric thristy, no loss long distance power cable, super efficient turbines and of course fast processors. Which do you think is going to be the most important apllication of super conducters?
I think that the most important applications are going to be the ones that are impractical to accomplish with conventional conductors (logically enough). All of the applications you mention would be _helped_ by superconductors, but are getting by adequately without them (wheels work fine on most trains, for instance).
One of the more interesting applications on the horizon is plasma manipulation. We already have many tools that use plasma as a working medium (etchers, torches), but there are a number of fun things you can build if you don't have to worry about resistance in your magnet coils and related circuits.
My personal favourite plasma application is a fabricator that uses patterned plasma deposition. This would work with a wide variety of materials, unlike normal fabricators. You need a plasma because otherwise it's difficult to confine and pattern your source materials. Superconductors would be useful because the most interesting fabricator design I can think of requires wobbling of a very strong magnetic field TV-scan-style, which would have horrible resistive losses if implemented with conventional components.
Fabrication by plasma deposition is much too expensive to be competitive for most things, but there are niche markets.
Fusion power is one of the more interesting plasma applications, though superconductors may not ever be up to the task. You can Brute Force a better fusion reactor by using a stronger magnetic field, but resistive heating of the magnet coils is only part of the problem. Outward pressure on the coils due to magnetic is one of the main engineering design limits to magnetic confinement reactors. There's also the problem of superconductors breaking down in strong magnetic fields, which renders them useless for high-field applications. High-temperature superconductors are especially bad for this.
In practice, problems with fusion are likely to be solved by clever design as opposed to brute force and ignorance solutions.
Thinking of more applications is left as an exercise to the reader; these are just my personal favourites.
I work for Physical Review Letters (and related journals at the American Physical Society) which is publishing the papers from the Ames, Iowa group. Interestingly enough, the first published paper (in the print journal today, available online since last week at http://link.aps.org/abstract/prl/v86/p1877) has set some new records in our office, in part thanks to increasingly all-electronic processing:
Manuscript received: 30 January 2001
sent to 2 referees: 31 January
Both referees report: 1 February
approved: 2 February
scheduled for an issue: 2 Feb
Updated manuscript received: 2 Feb
proofs available to author: 6 Feb
Author returned proofs (on the web): 8 Feb 2001
A final proof of the article available just over one week after being submitted, and going through a complete peer-review cycle!
More typically each step takes a week or two, though times have been generally improving lately.
But these new superconductors are pretty important!
Also interesting is that Nature has a nice "prepublication" look at the article on the original research, which they are publishing March 1 - Nature in the past has had an "embargo" policy preventing scientists from even talking to journalists about their work before the official publication date, but they've had this page up roughly since we published our related article online. The nature of scientific publishing is changing too here...
Energy: time to change the picture.
The important thing here is that they have a metal that superconducts at ~40K. That is much higher than any other metalic superconductor (typical Tc ~ 4-10K). Metals are very easy to draw and make into wires, ceramics are not.
Also, the first ceramic high Tc superconductors were found at 40K and were quickly tuned to reach higher temperatures.
Also, MgB2 is non-toxic and available in mass quantities cheaply. If it can be made to superconduct at 77K (liquid nitrogen temperatures) with an appreciable current density, it truly would be a revolutionary advancment for superconducting applications.
That is why Nature posted the article on their website before it had been reviewed or published-- it truly is an amazing and potentially revolutionary discovery.
High-Temperature Superconductors: http://slashdot.org/article.pl?sid=01/02/23/191222