Influences of Y2O3 nanoparticle additions on the microstructure and superconductivity of YBCO films derived from low-fluorine solution

► YBCO-Y2O3 nanocomposite films were prepared by low-fluorine sol-gel process. ► Y2O3 nanoparticles exhibit a random growth orientation. ► The Y2O3 nanoparticles with random growth orientation result in some crystal defects. ► 15-mol% yttrium-doped YBCO film shows the enhanced flux pinning at all magnetic field orientations.