Effects of Dy and BHO Additions on Performances of MOD-YBa ₂ Cu ₃ O _7-δ Films by Two-step Method

The two-step film growth method is proved in the present work to obtain high-performance YBa<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>Cu<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-δ</sub> (YBCO) tapes in the preparation of thick films as 2.4 µm, especially in improving the flux pinning and in-field performances of the BHO-added YBCO tapes. Furthermore, the effects of Dy doping on the properties of YBCO tapes and the combination of Dy doping and BHO nanocrystal addition are investigated. The results show that Dy doping significantly enhances the self-field performance of YBCO tapes. The subsequent addition of BHO nanocrystals after Dy doping further improves the self-field performance by 250 A/12 mm-w. In contrast, the low-temperature field performance of Dy-doped and BHO-added YBCO tapes decreases significantly when compared to pure YBCO tapes. Such results suggest that different rare earth substitutions can play different roles in improving the self-field and in-field properties of YBCO superconducting films.