Flux pinning characteristics of Sn-doped YBCO film by the MOD process

Abstract Compared with the undoped YBa 2 Cu 3 O 7− δ (YBCO) film, 10 mol% Sn-doped YBCO film exhibited significantly enhanced critical current densities ( J c ) in magnetic fields up to 5 T at 65 and 77 K for H//c , indicating that the Sn-doped YBCO film possesses more effective flux pinning centers. Both samples were grown on the SrTiO 3 (STO) (1 0 0) single crystal substrates by the metal-organic deposition (MOD) process. Larger J c (77 K, 1 T) values of Sn-doped YBCO film are observed over a wide field-orientation angle ( θ ) except the field-orientations close to the ab -plane of YBCO (85°  θ J c values for 85°  θ ab -plane due to high density Sn-containing nanoparticles trapped in the YBCO matrix. The effective pinning centers in Sn-doped YBCO film are attributable to Sn-containing nanoparticles trapped in the YBCO matrix which could be identified as the YBa 2 SnO 5.5 (YBSO) phase by STEM (scanning transmission electron microscopy)-EDS (energy dispersive X-ray spectroscopy) analysis. Further analyses by HR-TEM (high resolution-transmission electron microscopy) revealed that YBSO nanoparticles completely surrounded by the YBCO matrix had random orientation with YBCO while those located at the interface of YBCO/STO substrate had epitaxial relationship with YBCO.