REBCO mixtures with large difference in rare-earth ion size: superconducting properties of chemical solution deposition-grown Yb1−xSmxBa2Cu3O7−δ films

Yb1-xSmxBa2Cu3O7-d films have been prepared by chemical solution deposition following the Extremely-Low-Fluorine route, which allows reducing the fluorine content by 93% with respect to standard TFA solutions. The obtained results show that, on the one hand, Tc remains stable at ~ 90 K with Sm content up to x = 0.5 where Tc starts to increase towards the values of pure SmBCO films of ~ 95 K. On the other hand, the critical current densities Jc of the pure SmBCO films are the largest at 77 K, where the influence of a higher Tc is very relevant, while at lower temperatures and low fields, the mixed films reach larger values. This demonstrates that mixing rare earth elements RE in REBa2Cu3O7-d causes a change in the pinning properties of the films and reveals the importance of selecting adequate REBCO compounds according to the temperature and magnetic field region where a specific application operates.

采用极低碳氟路线（Extremely-Low-Fluorine route）的化学溶液沉积法（chemical solution deposition）制备了Yb₁₋ₓSmₓBa₂Cu₃O₇₋δ薄膜，该路线相较于标准三氟乙酸（TFA）溶液可将氟含量降低93%。所得结果表明，一方面，当Sm掺杂量x≤0.5时，临界温度（Tc）稳定在约90 K；x超过0.5后，Tc开始升高，逐渐接近纯钐钡铜氧（SmBCO）薄膜约95 K的临界温度值。另一方面，纯SmBCO薄膜的临界电流密度（Jc）在77 K时达到最大，此时较高Tc的影响十分显著；而在更低温度和低磁场下，掺杂薄膜的Jc值更大。这表明，在REBa₂Cu₃O₇₋δ中混合稀土元素（RE）会改变薄膜的钉扎特性（pinning properties），并揭示了根据特定应用所处的温度和磁场区域选择合适稀土钡铜氧（REBCO）化合物的重要性。