Abstract
In the present work, we study the change of microstructural and current carrying properties of the YBa2Cu3O7−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 (Tc, on) decreases by 0.5 K as the ion fluence reaches 5.0 × 1010 ions/cm2. It is revealed that for the irradiated samples with the fluence higher than 1.0 × 108 ions/cm2, their negative magnetization is enhanced pronouncedly as the applied temperature is lower than Tc, on, which implies that there are more antimagnetic phases being resistant to magnetic fields in these irradiated samples. Besides, the critical current density (Jc) and the pinning force (Fp) increase with the increase of the Ta ion fluence. Particularly for the case of the fluence more than 5.0 × 1010 ions/cm2, Jc reached 8.74 × 106 A/cm2 at 1 T and 30 K and Fp reached 8.84 × 1010 N/m3 at 1 T and 30 K. As a consequence, the Jc 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 × 106 A/cm2 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.
Highlights
High-temperature oxide superconductors (HTSs) such as YBa2Cu3O7−δ (Y123 or YBCO), Bi–Sr–Ca–Cu–O(Bi2223; Bi2212), Tl– Ba–Cu–O(Tl2223), Hg–Ba–Ca–Cu–O(Hg1223), etc., have been known as the practical superconductors
It is revealed that for the irradiated samples with the fluence higher than 1.0 × 108 ions/cm2, their negative magnetization is enhanced pronouncedly as the applied temperature is lower than Tc, on, which implies that there are more antimagnetic phases being resistant to magnetic fields in these irradiated samples
The Jc 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 × 106 A/cm2 of the primitive sample
Summary
High-temperature oxide superconductors (HTSs) such as YBa2Cu3O7−δ (Y123 or YBCO), Bi–Sr–Ca–Cu–O(Bi2223; Bi2212), Tl– Ba–Cu–O(Tl2223), Hg–Ba–Ca–Cu–O(Hg1223), etc., have been known as the practical superconductors. Comparing with the traditional chemical doping route, the particle irradiation method will result in various types and sizes of defects with a uniform distribution by controlling the type, energy, and dose of applied particles Particles such as electrons, protons, neutrons, and heavy ions can be used for irradiation. Many works have been reported on irradiated YBCO films.19–24 In these studies, the fast heavy ion [Z > 2, Esn (the energy of a single nucleon) > 1 MeV/u] irradiation is an effective method due to its characteristics of high energy and large electron energy loss. The M–H hysteresis loops of the doped YBCO films irradiated by Ta ions with different fluences were mainly tested in the external field of from −7 to 7 T, which was applied to the c-axis direction of the YBCO
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