Resumo

CAICEDO, J. C. et al. Superconducting depression in thin films of YBa₂Cu₃O_7-δ based on the variation of the relative humidity and the time. Superf. vacío [online]. 2007, vol.20, n.3, pp.6-10. ISSN 1665-3521.

Thin films of YBa₂Cu₃O_7-δ grown on SrTiO₃ (100) single crystal substrates by sputtering DC technique to high oxygen pressures were put under different conditions of relative humidity from 24 to 100% and different times of exposition. The electrical, morphologic and structural characteristics of the films by means of curves R-T, atomic force microscopy (AFM) and X-ray diffraction (XRD) were analyzed. The effect on structural and transport properties with the environmental conditions of relative humidity and with time were systematically studied. Samples under relative humidity around 24% measured just later of deposition showed a critical temperature (T_C) of 92 K, and thin films exposed around 90% of relative humidity with times greater to 10⁴ s (1 day) showed a T_C of 16 K, while samples under a relative humidity 100% do not showed the superconductive phase. The degradation's causes of superconductive properties in this system were investigated.

Palavras-chave : Relative humidity and time; D.C sputtering; YBa₂Cu₃O_7-δ.