Influence of nanoparticles on critical current properties in TFA-MOD processed YGdBCO coated conductor

For investigation of the flux pinning properties of nanoparticles in TFA-MOD processed Y_1−xGd_xBa₂Cu₃O_y (YGdBCO) coated conductors, the critical current density was compared in various directions of the magnetic field for YGdBCO+BaZrO₃ (BZO) and YGdBCO coated conductors with the superconducting layer of 0.5 μm thickness. It was found that J_c for θ = 0° (B//e) is larger but J_c for θ = 90° (B//ab) is smaller in YGdBCO+BZO than in YGdBCO. The increase in the normal field is attributed to the pinning of nanoparticles, while the decrease in the parallel field is considered to be caused by limitation of extension of stacking faults by distributed BZO nanoparticles. In addition, the n-value (E ∝ jⁿ) decreases by introduction of BZO nanoparticles for θ = 90°, while it is unchanged for θ = 0°. These results are well described by a theoretical model of flux creep and flow.