LOCAL NONSTOICHIOMETRY IN SUPERCONDUCTING AND FERROELECTRIC-FILMS OF COMPLEX OXIDES

By analogy with ferroelectric deposits, in films of deposited high-temperature superconductor YBa2Cu3O7-delta there have been found surface and interface (film-substrate) layers, having a modified composition with respect to the main layer and different charge state of the constituent ions. However, in contrast to the ferroelectric films of BaTiO3 type, the specific habitus of microcrystals in the YBa2Cu3O7-delta films favours the formation of oriented layers already at the stage of annealing of the initially quasi-amorphous deposits, the stoichiometry of the main layer being preserved. Deterioration of the properties of the films on buffer layers may be explained by changes in the charge state of the film and substrate ions.