Microstructures of YBa2Cu3O7films prepared by magnetron sputtering on Al2O3substrate with a CeO2buffer layer

High-Tc superconducting YBa2Cu3O7 films with a CeO2 buffer layer, deposited onto sapphire substrates, were prepared by off-axis rf-magnetron sputtering. It is found that the microstructure of the buffer layer can be controlled by the substrate temperature, and is connected with the formation of the discontinuities in the film, which are the origin of micropores. The microstructural peculiarities of the YBa2Cu3O7/CeO2/Al2O3 films are studied and discussed.