Chemistry of carbon compounds – Miscellaneous organic carbon compounds – C-metal
Patent
1983-03-22
1985-05-14
Sneed, Helen M. S.
Chemistry of carbon compounds
Miscellaneous organic carbon compounds
C-metal
C07F 990, C07F 506, C07F 724, C07F 112
Patent
active
045171211
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to supraconductive compounds and more particularly to a process for increasing the supraconductive critical temperature in organic quasi-one-dimensional supraconductive compounds and the organic supraconductive compounds thus obtained.
The supraconductive properties provided by certain bodies at very low temperatures and observed for the first time, when occurring on mercury, in 1911 by Kamerlingh-Onnes, have recently come to light to be in carbon-hydrogen and selenium organic compounds. This discovery, which has been made by the staff to which pertained the inventors of the present application, has been the object of a communication to the "Academie des Sciences" of Paris on 14th January 1980, published in the "Journal de Physique-Lettres", volume 290, 1980, serial B, pages 27 to 30, the contents of which as well as the literature are supposed to be integrated herein as a reference.
This publication relates to the existence of supraconduction at lower temperature (lower than 1.degree. K.) in an organic conductor (TMTSF).sub.2 X where X=PF.sub.6, (di-.DELTA..sup.2,2' -bi-4.5-dimethyl -1,3-diselenolhexafluorophosphate) shaped as crystals obtained by an electrochemical procedure when starting from ultrapure constituents. The compounds (TMTSF).sub.2 X have, shaped as monocrystals, a structure made of chains of organic stacked molecules, the ions X being staggered in stacks between the organic chains, as shown in FIG. 1 (wherein X shows PF.sub.6.sup.-). This structure has a highly conductive axis (vertical as shown in FIG. 1) enabling them to be designated as "molecular conductors having quasi-one-dimensional transfer property" (QID). When studying the compounds of said class, it has been seen that, whereas the critical temperature below which is established a nil resistant state, is in the range of T.sub.c3 =1.degree. K.), previous supraconductive signs, designated as "supraconductive fluctuations" may be observed within a temperature range extending up to 40.degree. K. FIG. 2 shows a comparison between the thermal variation of the resistance of a usual supraconductive metal (curve I) (occurring as lead) at low temperature and that of a quasi-one-dimensional conductor QID of the stated type (curve II). The slight resistance and the high dependence in temperature of the compound QID must be accurately awarded to the above-mentioned supraconductive fluctuation.
Besides, it is known that long researches have enabled to manufacture intermetallic conductors, based for instance on Nb, Al, Ge, having a supraconductivity up to 23.2.degree. K., i.e. with a too slight gap with respect to the temperature of liquid hydrogen (20.degree. K.), as to forecast, on purpose to use them, that liquid hydrogen should be substituted for liquid helium, the many disadvantages of which, (as regards the manufacture costs as well as the storage thereof) are well known of the experts in cryogenic procedures.
Thus, there exists, especially in view of the large use field forecasts for the supraconductors, a very marked need to have compounds provided with supraconductive properties at temperatures higher than that of liquid helium and, better, higher than that of liquid hydrogen.
The object of the present invention is precisely to provide a process of increasing the critical supraconductive temperature in quasi-unidimensional organic supraconductive compounds on purpose to render them supraconductive while far away from usual critical temperature T.sub.c3 of the compounds.
Another object of the present invention is to provide new compounds of the considered type, having supraconductibility properties in liquid hydrogen.
For this aim, according to a feature of the present invention, the process comprises the step of cross-linking the chains of such a molecular conductive compound having quasi-one-dimensional transfer properties with foreign atoms from at least one potentially conductive body.
According to another feature of the present invention, the process comprises the step of diffusing in a compound (TMTSF)
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patent: 3984593 (1976-10-01), Hilti et al.
Chemical Abstracts 84, 135562q, (1976).
Chemical Abstracts 91, 192326j, (1979).
Chemical Abstracts 86, 99384p, (1977).
Chemical Abstracts 93, 248884a, (1980).
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Chemical Abstracts 90, 186049j, (1978).
D. Jerome, A. Mazaud, M. Ribault, Superconductivity in a Synthetic Organic Conductor (TMTSE).sub.2 PF.sub.6 (+), Physics Abstracts-Letters 41, 1980, pp. L95-L98.
Dominique Jerome, Les Conducteurs Organiques des Materiaux d'Avenir-La Recherche, vol. 11, No. 116, Nov. 1980, (Paris, FR), pp. 1334-1336.
Ribault et al., Supraconductivite et Absence d'Anomalie de Kohn dans le Conducteur Organique Quasi Unidimensionnel: (TMTSF)2AsF6 Comptes Rendus, Series A & B Sciences Mathematiques & Physique, vol. 291, No. 5, Oct. 1980, (Paris FR), pp. 145-148.
Bechgaard Klaus
Delrieu Jean-Marc
Fabre Jean M.
Fournel Andre
Giral Louis
Centre National de la Recherche Scientifique
Sneed Helen M. S.
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