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Possible reduction to practice plus literature references for strategy and synthesis.
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==Exciton Coupling== |
==Exciton Coupling== |
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William A. Little<ref>Phys. Rev. 134 A1416-A1424 (1964), [http://prola.aps.org/abstract/PR/v134/i6A/pA1416_1 Possibility of Synthesizing an Organic Superconductor]</ref> proposed high temperature exciton-coupled superconductors, (—C(Ar)=(Ar)C—)<sub>n</sub> or (=(Ar)C—C(Ar)=)<sub>n</sub> where "Ar" is a polarizable chromphore (dye). |
William A. Little<ref>Phys. Rev. 134 A1416-A1424 (1964), [http://prola.aps.org/abstract/PR/v134/i6A/pA1416_1 Possibility of Synthesizing an Organic Superconductor]</ref> proposed high temperature exciton-coupled superconductors, (—C(Ar)=(Ar)C—)<sub>n</sub> or (=(Ar)C—C(Ar)=)<sub>n</sub> where "Ar" is a polarizable chromphore (dye). |
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Replace Bardeen-Cooper-Shrieffer large mass [[phonon]]s (quantized lattice vibrations re [[Debye temperature]]) with small mass [[exciton]]s (quantized bound states of electrons and holes), energies around 2 eV or 23,000° K. Exciton-mediated electron pairing offers very high critical temperatures even given weak coupling. |
Replace Bardeen-Cooper-Shrieffer large mass [[phonon]]s (quantized lattice vibrations re [[Debye temperature]]) with small mass [[exciton]]s (quantized bound states of electrons and holes), energies around 2 eV or 23,000° K. Exciton-mediated electron pairing offers very high critical temperatures even given weak coupling. |
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Aroom-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. The potential benefits for society and science if such a material did exist are profound.
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.
A report 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 said 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.
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.
William A. Little[10] proposed high temperature exciton-coupled superconductors, (—C(Ar)=(Ar)C—)n or (=(Ar)C—C(Ar)=)n where "Ar" is a polarizable chromphore (dye).
Replace Bardeen-Cooper-Shrieffer large mass phonons (quantized lattice vibrations re Debye temperature) with small mass excitons (quantized bound states of electrons and holes), energies around 2 eV or 23,000° K. Exciton-mediated electron pairing offers very high critical temperatures even given weak coupling.
Required are 1) A linear trans-polyacetylene core, 2) with pendant polarizable chromphores, 3) said chromophores' pi-clouds being no more than one sigma-bond from the core, and 4) the core being entirely enveloped by a cylindrical pi-cloud. Perhaps n— or p—dope the polymer. Solubility for polymer synthesis and fiber fabrication requires chains ("hair") on the chromphores: oligomers of hydrocarbon, fluorous chains, ethylene oxide, propylene oxide, dimethylsiloxane, etc.
Acyclic diene metathesis (ADMET)[11] living polymerization gives low dispersivity polymer and allows controlled block copolymer products (e.g., redox gradients, molecular diodes, quantum wells). Terminate with sulfur species for spontaneous attachment to gold electrodes.
diaryl benzil plus Tebbe methylenation[12] → 2,3-diarylbutadiene → plus ADMET (Schrock olefin catalysisorGrubbs' catalyst) → Little superconductor plus ethylene (irreversibly exsolved from reaction medium)[13]
O=C(Ar)—(Ar)C=O → H2C=C(Ar)—(Ar)C=CH2 → (=C(Ar)—(Ar)C=)n plus H2C=CH2
(Following png HyperChem stereograms omit hydrogens and multiple bonds for easy viewing). Three model systems directly obtain: Proof-of-synthesis polymer from benzil, then add pi-stacking and fluorescent excitation, then chromophore rotation into a supercon molecular coaxial cable. Little's long wavelength chromophores attach in kind. A good idea need only be testable. Theory predicts what observation tells it to predict.
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