Addition of alternate phase nanoparticle dispersions to enhance flux pinning of Y-Ba-Cu-O thin films

Nanoparticle dispersions of various phases were added to YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO or 123) thin films by multilayer pulsed laser deposition, to determine their effect on flux pinning. The different pinning materials examined include Y/sub 2/BaCuO/sub 5/ (Y211 or green-phase), La/sub 2/BaCuO/sub 5/ (La211 or brown-phase), Y/sub 2/O/sub 3/, CeO/sub 2/, and MgO, with lattice constant mismatches varying from 0.5% to 12% with respect to YBCO. Y211 and Y/sub 2/O/sub 3/ provided significant pinning increases at temperatures of 65 K and 77 K, however other phases provided enhancements only at 65 K (for CeO/sub 2/ and La211) for limited range of applied field strengths. An interesting correlation between T/sub c/ transition widths and pinning strengths was observed. The additions produced markedly different nanoparticle and film microstructures, as well as superconducting properties.