Search for Organic Superconductors.
Research and development rept.,
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD
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Five saltsand acids of bile were examined both magnetically and electrically to determine the properties of these salts with respect to their possible behavior as organic superconductors. It was found that these materials have characteristics that are similar in some respects to metallic superconductors. Specifically, the following properties were observed or reduced These materials are bulk insulators. Small inclusions within the materials due to clustering of the carboxylate groups produce diamagnetic shifts with temperature. The diamagnetic frequency shifts respond to magnetic fields in a way similar to that of a metallic superconductor. With sodium desoxycholate, a field of 8.1 kilogauss destroys the diamagnetic shift. Each of the salts or acids were similarly structured, differeing only in the number of OH groups attached to the ring section R group. On removing any OH group from the ring section, the transition temperature was observed to approximately double. Sodium cholate which has three OH groups was observed to have a transition temperature of 30 K. Sodium desoxycholate which has two OH groups was observed to have a transition temperature of 60 K. Sodium cholanate which has no OH group was observed to have a transition temperature of 277 K. By measurement of the dissipation of the bulk compound, it was observed that the island clusters had a marked increase in conductivity at the transition temperature. This increase was similar to that observed of a 6 by volume mixture of niobium powder and an organic insulator Sodium desoxycholate in this case. The frequency shifts were experimentally shown not to be attributed to dielectric effects.
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