Design and Synthesis of Organic Superconductors (FY92 URI/RIP)

A number of mixed-valence 21, conducting salts of bisethylenedithiotetraselena-fulvalene BETS have been prepared. Four GaCl4, SbF6, CF3SO3 and CuNCN2Br have been characterized in detail X-ray crystallography, DC resistivity from 300-1 OK, rf penetration depth measurements 0.5K, pressure studies from 0.5-5 kbar at 4K, and tight-binding band calculations. The salts are highly metallic to low temperatures but do not exhibit superconductivity under the experimental conditions explored. The synthesis of a new synthetic metal precursor, bisethylenedithio tetrathionaphthalene BEDT-TTN, is about three-quarters completed. Spin density wave SDW and charge density wave CDW phenomena of three organic superconductors k-BEDT-TTFCuNCN2Cl, TMTSF2PF6, and TMTSF2ReO4, where BEDTTTF is bisethylenedithiotetrathiafulvalene and TMTSF is tetramethyltetraselenafulvalene have been studied in collaboration with Professor J.W. Brill Department of Physics, University of Kentucky. The three organic metals avert the SDW and CDW transitions under pressure and become superconductors. Organic superconductor, Synthesis, Structure, Resistivity, SDW, CDW.