Effect of Ta irradiation on microstructure and current carrying properties of YBCO coated conductors with element doping

摘要

In the present work, we study the change of microstructural and current carrying properties of the YBa_2Cu_3O_(7-δ) (YBCO) coated conductors (CCs) doped with mixed elements of Ta, Zr, Hf, Mn, and Sn after the irradiation of 1.9 GeV Ta ions. Magnetic property measurement system measurement was applied to study the current carrying properties of the irradiated YBCO CCs. The critical transition temperature (T_(c, on)) decreases by 0.5 K as the ion fluence reaches 5.0 × 10~(10) ions/cm~2. It is revealed that for the irradiated samples with the fluence higher than 1.0 × 10~8 ions/cm~2, their negative magnetization is enhanced pronouncedly as the applied temperature is lower than T_(c, on), which implies that there are more antimagnetic phases being resistant to magnetic fields in these irradiated samples. Besides, the critical current density (J_c) and the pinning force (F_p) increase with the increase of the Ta ion fluence. Particularly for the case of the fluence more than 5.0 × 10~(10) ions/cm~2, J_c reached 8.74 × 10~6 A/cm~2 at 1 T and 30 K and F_p reached 8.84 × 10~(10) N/m~3 at 1 T and 30 K. As a consequence, the J_c value of the studied YBCO CCs is improved by 4.4 times at 1 T and 30 K compared with the value of 1.98 × 10~6 A/cm~2 of the primitive sample. Moreover, the sectional microstructures of the YBCO superconducting layer observed by a field emission transmission electron microscope show the columnar defects with the size of about 9 nm form in the doped YBCO films after the irradiation, confirming traces of continuous latent tracks exist as the evidence of effective mixed-pinning landscapes.