http://worldcat.org/entity/work/id/137448786

A Reexamination of (19)F NMR in Selected Solids, the Conductor Ag2F and Reference Insulators for Studies of YBaSub2CuSub3OSub7-Type Superconductors

Evidence of incorporated F in the so called '1-2-3-type', YBa2Cu3O7 derived compounds has been cited. The aim was to confirm an increase in Tc as Ovshinsky claimed in 1987 by substitution of F for O. One expects for the 1-2-3- type compounds, since they display metallic conductivity at room temperature, a downfield-shifted F NMR resonance. As a guideline for judging the line positions and shapes of fluorine incorporated in the 1-2-3-type compounds, we therefore reexamined the (19)F NMR signals in a metallic inorganic conductor(Ag2F), in the insulating starting materials used to synthesize the superconductor phases (YOF, EuOF, and YF3) and in BaF2 and CuF2 which could be formed during the synthesis. AgF and KF were used as reference samples. There appear to be only two inorganic compounds containing fluorine and showing high metallic conductivity: (1) Silver subfluoride, Ag2F, with NMR results reported by Nishihara et al., and (2) (Ag7O8)+(HF2)- reported by Hindermann.

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