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Surface degradation ofYBa2Cu3O7−δsuperconductors on exposure to air and humidity

1991; American Physical Society; Volume: 44; Issue: 2 Linguagem: Inglês

10.1103/physrevb.44.727

1095-3795

Temel Büyüklimanli, Joseph H. Simmons,

Copper-based nanomaterials and applications

Surface modifications from exposure of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ pellets and thin films of the 1:2:3 composition to ambient atmosphere and 85% relative humidity at 50 \ifmmode^\circ\else\textdegree\fi{}C were measured using x-ray photoelectron spectroscopy and scanning Auger electron multiprobe. Surface formation of ${\mathrm{BaCO}}_{3}$ and Ba(OH${)}_{2}$ was detected. The surface layer of the sintered pellets did not have any Cu after 48 h of moisture treatment. The degradation in the thin-film samples was substantially less. The rate of degradation appears to be controlled by grain-boundary diffusion.