Enhanced flux pinning of air-processed GdBa2Cu3O7−δ superconductors with addition of ZrO2 nanoparticles

The authors investigate the influence of ZrO2 nanoparticles on microstructure and superconducting properties of GdBa2Cu3O7−δ (Gd123) single domain superconductors grown in air. Experiments show that before Gd123 crystallization ZrO2 nanoparticles react with Gd123 and yield BaZrO3. Transmission electron microscopy evidences that BaZrO3 disperses in Gd123 crystals with a size less than 50nm. A high Jc value of 100000A∕cm2 has been achieved in Gd123 with 0.4M% ZrO2 at 77K and self-field. Compared to the flux pinning effect of submicrometer Gd2BaCuO5 particles, BaZrO3 nanoparticles embedded in Gd123 significantly enhance critical current densities in a wide magnetic field range.