Identification of chemical and structural impurities in YBa2Cu3O7-delta films by Raman spectroscopy

Raman spectroscopy has been applied to the identification of chemical and c rystal structural impurities on the surfaces of YBa2Cu3O7-delta (YBCO) film s. The surfaces of the two YBCO films studied have been shown to contain si gnificant a-oriented components. Film A was prepared at a higher temperatur e than film B, with oxygen partial pressure remaining about the same. Compa red with film A, film B presented a more uniform and shiny surface when obs erved with the naked eye. On film A, the surface was decorated by mutually perpendicular or parallel strings of beads (or particulates), while on film B, the particulates were more randomly distributed. The particulates were found to be BaCuO2, but the bead strings were mixtures of BaCuO2 and Ba2Cu3 O5.9, grown concurrently with YBCO during vacuum deposition. (C) 1998 Publi shed by Elsevier Science B.V. All rights reserved.