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An organic superconductor is a synthetic organic compound that exhibits superconductivity at low temperatures. As of 2007 the highest achieved critical temperature for an organic superconductor at standard pressure is 33 kelvin, observed in the alkali-doped fullerene RbCs2C60.〔The Physics of Organic Superconductors and Conductors, A.G. Lebed (Ed.), (Springer Series in Materials Science , Vol. 110, 2008), ISBN 978-3-540-76667-4〕〔J. Singleton and C. Mielke ("Quasi-two-dimensional organic superconductors: a review." ) at (arXiv )〕 In 1979 Klaus Bechgaard synthesized the first organic superconductor (TMTSF)2PF6 (the corresponding material class was named after him later) with a transition temperature of TC = 1.1 K, at an external pressure of 6.5 kbar. Many materials may be characterized as organic superconductors. These include the Bechgaard salts and Fabre salts which are both quasi-one-dimensional, and quasi-two-dimensional materials such as ''k-BEDT-TTF2X'' charge-transfer complex, ''λ-BETS2X'' compounds, graphite intercalation compounds and three-dimensional materials such as the alkali-doped fullerenes. Organic superconductors are of special interest not only for scientists, looking for room-temperature superconductivity and for model systems explaining the origin of superconductivity but also for daily life issues as organic compounds are mainly built of carbon and hydrogen which belong to the most common elements on earth in contrast to copper or osmium. ==One-dimensional Fabre and Bechgaard salts== Fabre-salts are composed of tetramethyltetrathiafulvalene (TMTTF) and Bechgaard salts of tetramethyltetraselenafulvalene (TMTSF). These two organic molecules are similar except for the sulfur-atoms of TMTTF being replaced by selenium-atoms in TMTSF. The molecules are stacked in columns (with a tendency to dimerization) which are separated by anions. Typical anions are for example octahedral PF6, AsF6 or tetrahedral ClO4 or ReO4. Both material classes are quasi-one-dimensional at room-temperature only conducting along the molecule stacks and share a very rich phase diagram containing antiferromagnetic ordering, charge order, spin-density wave state, dimensional crossover and of course superconductivity. Only one Bechgaard salt was found to be superconducting at ambient pressure which is (TMTTF)2ClO4 with a transition temperature of TC = 1.4 K. Several other salts become superconducting only under external pressure. The external pressure one would have to apply to drive most Fabre-salts to superconductivity is so high, that under lab conditions superconductivity was observed only in one compound. A selection of the transition temperature and corresponding external pressure of several one-dimensional organic superconductors is shown in the table below. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Organic superconductor」の詳細全文を読む スポンサード リンク
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