Use of nuclear microanalysis to study the oxygenation mechanism of Y1Ba2Cu3O7-x thin films:: estimation of the oxygen diffusion coefficients

Superconducting Y1Ba2Cu3O7-x (YBCO) c-axis oriented thin films are grown "in situ" by cathodic sputtering of stoichiometric Y1BaCu3O7-x polycrystalline target on MgO single crystal substrates. The films are formed at 720 degreesC at p(O2) approximate to p(Ar) approximate to 3.5 x 10(-4) bar and subsequently cooled down "in situ" to the room temperature under different conditions. All measurements are performed "ex situ". The oxygen content and its distribution within the films are determined respectively by the nuclear reaction O-16(He-3, alpha) O-15 at 2.45 MeV and by the elastic scattering resonance O-16(alpha, alpha)O-16 at 3.045 MeV. The analysis of experimental results strongly suggests that the oxygen content of YBCO thin films during the high temperature in situ growth is near 7. By fitting the oxygen content and its distribution within the films, the oxygen diffusion coefficient in YBCO films was evaluated and compared to the literature data. A good agreement is found. The physical and applied aspects of these finding will be discussed. (C) 2002 Elsevier Science B.V. All rights reserved.