Thin films of YBa2Cu3O7-δ were grown onto a Nb-doped SrTiO3 substrate by using a pulsed laser deposition method, and were characterized by means of scanning transmission electron microscopy Z-contrast imaging and electron energy loss spectroscopy. The Nb distribution was found to be uniform and unchanged across the interface. The coexistence of 124 and 125 Cu3Ba2YO7 defect structure phases, which appeared as planar defects in a Cu3Ba2YO7 thin film, was observed. Dispersed Y2O3 nanoparticles were also observed in the thin film. The interaction of these defect structures with Y2O3 nanoparticles was thought to be beneficial to flux-pinning throughout the entire film thickness.

Interface and Defect Structures in YBa2Cu3O7-δ and Nb:SrTiO3 Heterojunction. L.F.Fu, N.D.Browning, W.Ramadan, S.B.Ogale, D.C.Kundaliya, T.Venkatesan: Journal of Physics D 2007, 40[1] 187-91