Room-temperature superconductor
A room-temperature superconductor is a hypothetical material which would be capable of exhibiting superconducting properties at operating temperatures above 0° C (273.15 K). While this is not strictly "room temperature" (which would be approx. 20–25 °C), it is the temperature at which ice forms and can be reached and maintained extremely easily in an everyday environment.
It is unknown whether any such material exists. The interest in its discovery arises from the repeated discovery of superconductivity at temperatures previously unexpected or held to be impossible, and the profound benefits for society and science if such a material did exist.
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[edit] Reports
Since the discovery of high-temperature superconductors, several materials have been reported to be room-temperature superconductors.
In 2008 a Canadian-German team reported the discovery of superconductivity when silane (SiH4) was compressed to a solid at high pressure.[1][2] Silane was unfortunately not a room-temperature superconductor; an EE Times article grossly exaggerated this achievement and claimed that room-temperature superconductivity had been achieved. In reality, the transition temperature was 17 K at 96 and 120 GPa.
Palladium hydride: In 2003 a group of researchers published results on high-temperature superconductivity in palladium hydride (PdHx: x>1)[3] and an explanation in 2004.[4] In 2007 the same group published results suggesting a superconducting transition temperature of 260 K.[5] The superconducting critical temperature increases as the density of hydrogen inside the palladium lattice increases.
An unverified claim of 'room temperature' superconductivity was made in 2000 by J. F. Prins within a phase formed on the surface of oxygen-doped type IIa diamonds in a 10-6 mbar vacuum.[6] Prins claimed to be able to explain this in terms of a self-developed theory using a Wigner-type mechanism.[7][8] As of 2010[update] there is no record of any independent investigation which has either confirmed or disproved these results.
[edit] Theory
Theoretical work by Neil Ashcroft predicted that solid metallic hydrogen at extremely high pressure (~500 GPa) should become superconducting at approximately room-temperature because of its extremely high speed of sound and expected strong coupling between the conduction electrons and the lattice vibrations.[9] This prediction is yet to be experimentally verified. As yet the pressure to achieve metallic hydrogen is not known but may be of the order of 500 GPa.
[edit] References
- ^ EE Times corrects story on silane as a potential superconductor. EE Times. 24 March 2008. http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=206904213. Retrieved 2009-05-05
- ^ M. I. Eremets, I. A. Trojan, S. A. Medvedev, J. S. Tse, Y. Yao (2008). "Superconductivity in Hydrogen Dominant Materials: Silane". Science 319 (5869): 1506–1509. Bibcode 2008Sci...319.1506E. doi:10.1126/science.1153282. PMID 18339933.
- ^ Physica C 388-389 (2003) p.571-572 Possibility of high temperature superconducting phases in PdH,
- ^ Physica C 408-410 (2004) p.350-352 Superconductivity in PdH: phenomenological explanation
- ^ Tripodi et al; Di Gioacchino, Daniele; Vinko, Jenny Darja (2007). "A review of high temperature superconducting property of PdH system,". International Journal of Modern Physics B (International Journal of Modern Physics B) 21 (18&19): 3343–3347. Bibcode 2007IJMPB..21.3343T. doi:10.1142/S0217979207044524. http://www.worldscinet.com/cgi-bin/details.cgi?id=pii:S0217979207044524&type=html.
- ^ http://rtn.elektronika.lt/mi/0304/2prins.pdf
- ^ Johan Prins (September 2010). "23. The Mechanism". The Physics Delusion. Sage Wise 66 (Pty) Ltd. ISBN 978-0-620-48462-6. http://www.cathodixx.com/pdfs/SingleMechanism.pdf.
- ^ "Room temperature superconductivity: One step closer to the Holy Grail of physics". physicsorg.com. 9 July 2008. http://www.physorg.com/news134828104.html. Retrieved 2011-05-16.
- ^ N. W. Ashcroft (1968). "Metallic Hydrogen: A High-Temperature Superconductor?". Physical Review Letters 21 (26): 1748–1749. Bibcode 1968PhRvL..21.1748A. doi:10.1103/PhysRevLett.21.1748.
