Strongly enhanced flux pinning in the YBa2Cu3O7 −x films with the co-doping of BaTiO3 nanorod and Y2O3 nanoparticles at 65 K**Project supported by the National Natural Science Foundation of China (Grant No. 51272250), the National Basic Research Program of China (Grant No. 2011CBA00105), the National High Technology Research and Development Program of China (Grant No. 2014AA032702), and the Natural Science

Abstract

YBa2Cu3O7 − x (YBCO) films with co-doping BaTiO3 (BTO) and Y2O3 nanostructures were prepared by metal organic deposition using trifluoroacetates (TFA-MOD). The properties of the BTO/Y2O3 co-doped YBCO films with different excess yttrium have been systematically studied by x-ray diffraction (XRD), Raman spectra, and scanning electron microscope (SEM). The optimized content of yttrium excess in the BTO/Y2O3 co-doped YBCO films is 10 mol.%, and the critical current density is as high as ∼17 mA/cm2 (self-field, 65 K) by the magnetic signal. In addition, the Y2Cu2O5 was formed when the content of yttrium excess increases to 24 mol.%, which may result in the deterioration of the superconducting properties and the microstructure. The unique combination of the different types of nanostructures of BTO and Y2O3 in the doped YBCO films, compared with the pure YBCO films and BTO doped YBCO films, enhances the critical current density (JC) not only at the self-magnetic field, but also in the applied magnetic field.