Possible Room Temperature Superconductor Achieved 264
TechkNighT_1337 sends news that surfaced on the Next Big Future blog, concerning research out of the University of Bengal, in India. The report is of a possible superconducting effect at ambient room temperatures. Here is the paper on the ArXiv. (Note that this research has not been peer-reviewed or published yet.) "We report the observation of an exceptionally large room-temperature electrical conductivity in silver and aluminum layers deposited on a lead zirconate titanate (PZT) substrate. The surface resistance of the silver-coated samples also shows a sharp change near 313 K. The results are strongly suggestive of a superconductive interfacial layer, and have been interpreted in the framework of Bose-Einstein condensation of bipolarons as the suggested mechanism for high-temperature superconductivity in cuprates. ... The fact that the results described above have been obtained from very simply-fabricated systems, without the use of any sophisticated set-up and any special attention being given to crystal purity, atomic perfection, lattice matching, etc. suggests that the physical process is a universal one, involving only an interface between a metal and an insulator with a large low-frequency dielectric constant. We note in passing that PZT and the cuprates have similar (perovskite or perovskite-based) crystal structures. This resemblance may provide an added insight into the basic mechanism of high-temperature superconductivity."
The catches (Score:5, Informative)
There has been a number of fraud reports of high temperature superconductivity, and while there are some confirmed examples of superconductivity at very high temperatures ( like -70C ) they usually involve some microscopic crystal or other structure which is not very useful for most practical applications.
In addition, that something super conducts does not imply it can handle a very large current at high temperatures. The current creates a magnetic field, and superconductors can only work when the magnetic field is less than some fixed value that depends on the material. If I'm not mistaken this value is at its highest when the temperature is very low, and thus it's quite plausible you could get a room temperature superconductor which can't carry any significant current unless cooled to more traditional temperatures.
Re:This will later be known as... (Score:5, Informative)
No he didn't.
The Other Important Question (Score:4, Informative)
How much current can it carry? Superconductors tend to lose superconductivity in the presence of a large magnetic field, limiting the amount of current they can carry. I don't know if the high Tc superconductors are more susceptible than the regular ones, but it's something to keep in mind.
If they can take a really high magnetic field then that would be really cool for projects like the LHC. A large part of what makes that project dangerous, difficult, and expensive is the large number of He cooled superconducting magnets it needs. The danger comes in when you get a cosmic ray or something that increases the temperature of the magnet so that even a small part loses its superconductivity. When that happens, the non-superconducting part rapidly starts heating up the rest of the magnet in a process called "quenching." The results of a quench can be quite catastrophic.
Re:The catches (Score:4, Informative)
Even if it had a low critical current, the alleged room-temperature superconductor would be useful for SQUIDs and Josephson junctions.
Re:Room Temperature in UK, maybe not in India? (Score:1, Informative)
yes
Extraordinary claims require evidence. (Score:5, Informative)
I'm a condensed matter physicist. This claim is weak beyond belief, and it pains me to no end to see it get picked up by slashdot and other sites (nextbigfuture.com). To demonstrate superconductivity, you need to show (a) zero resistance over some range of current; (b) the Meissner effect (expulsion of magnetic flux, seen via magnetometry); (c) a characteristic feature of a phase transition in the heat capacity. This paper shows exactly none of these things. The noise level in the resistance measurements is so poor, you could not tell the difference between zero and 0.01 Ohms (which would be totally believable considering there is already a metal film in the system). This paper in its present form is not fit for publication. Seriously, you don't have to be an expert at this stuff to see that this is weak - just look at the noise level in the current-voltage curves and use some common sense!
Re:Extraordinary claims require evidence. (Score:3, Informative)
Seriously, you don't have to be an expert at this stuff to see that this is weak
Uh, yeah you do. I consider myself to be pretty smart, what with the 160 IQ and the medical degree and all. But superconductors just aren't my field. Put a bunch of words together that don't trigger alarm bells and sound plausible, and I'm a believer. Perhaps you need to take a look in the mirror and realize that you know more about this stuff than the average person. You are certainly more of an expert than I am :)
Re:...really? (Score:3, Informative)
Re:Of course! (Score:5, Informative)
*sigh* It's even worse than that. IAAP and I was very excited to see this ... at first. The article by the way is very well written (serious science - not a crank). The problem is that the data (figure 2 in the arxiv paper - everyone should check this out btw) on which the author hangs all his hopes is seriously noisy (compared to the size of the "kink" that he superposes on the graph). In other words, if you imagine erasing the drawn-in kink, such artifacts occur several places in the data and are generally not above the noise level.
So, I would say that the conclusion is highly unwarranted given the state of the existing signal to noise. However, if the author truly feels there's something promising, he simply has to go about improving his signal. To be fair, the /. title is far more ambitious compared to the original article (indications of ...). He's merely putting this out in the wild to get feedback from other researchers in the field (which is solely what Arxiv is used for by serious researchers, not as a publication destination).
As it stands, the "kink" seems to be nothing more than (one of several) noise bumps. I'll be keeping an eye on this guy of course. Maybe something might come out of this, who know?
Re: move along now (Score:3, Informative)
Riddle me this: if "considering the source" is the only valid criterion on which a person's authority on a subject rests, then how the hell does said person achieve enough authority to ever pass the "consider the source" test?
You author a paper alongside someone who's already an authority in the subject. In the field of Mathematics, for instance, this is measured as the Erdos number [wikipedia.org] though similar schemes exist for other [wikipedia.org] fields as well.
Re: move along now (Score:2, Informative)
In this case, there are a few ways in which the author could have made his paper more credible, all without requiring anything resembling authority:
1. Collaborated with other condensed matter physicists.
2. Submitted paper for publication in prestigious journal (with a high-profile discovery like room-temperature superconductivity, this would be a discovery fit for such a journal).
3. Worked to get more comprehensive data before claiming room-temperature superconductivity.
Re:Cold Fusion (Score:5, Informative)
Cold Fusion has more than just political problems: it's a matter of energy scales. To overcome the Coulomb barrier between deuterium and tritium, after which the strong interaction takes over, requires an energy of about 4.5 x 10^7 Kelvin. This is the lowest energy fusion reaction. Now imagine how much energy you can get from the strongest chemical reaction. How about thermite: 2500 K, you're still off by four orders of magnitude. That's the main reason why physicists avoid Cold Fusion.
The current superconductivity article is better, in that the underlying physics is at least plausible, but as a previous poster pointed out, the signal to noise ratio is low, even after smoothing has been applied. Also 4000 Angstroms of deposited Al seems to be somewhat on the thick side for the dielectric to have any effect. But it's certainly worth trying to reproduce the results. (IAAP specializing in superconductivity).
Re:...really? (Score:3, Informative)
Re:Of course! (Score:5, Informative)
Re: move along now (Score:3, Informative)
The correct pronoun in a single author paper is still "we". If you are unaware of this then why would anything else that you say about the state of the literature be credible?
For the [citation needed] crowd. [dsv.su.se]