By Dc Sputtering Ybco Strip Study

Due to its lower ac loses, better in-field performance, and lower processing costs over first-generation high-temperature superconductor(HTS) tapes, second-generation YBa2Cu3O7-δ(YBCO) HTS tapes (also called coated conductors) attract the attention of the reserchers worldwide. In this thesis, YBCO coated conductors were deposited on CeO2/YSZ/CeO2(CYC) buffered Ni-5at.%W substrate, and sputtering was used for the deposition of YBCO coated conductors because it is easy to control the process and the resulting sample characteristics can be repeated.1. In order to improve the deposition rate, plane target was used in the sputtering. According to comparable result, we found that the negative ions bombardment effect caused by the plane target could be avoided by the increase of the total gas pressure and the rolling of the substrate.2. The influence of the substrate temperature and sputtering gas pressure on the structure, surface state and performance of YBCO coated conductors has been studied. By analyzing the microstructure, orientation and surface state, optimum process parameters were obtained: temperature being 650℃, sputtering pressure being 75Pa, and PO2:PAr being 1:2. With opitmum parameters, YBCO thin film has shown c-axis single oriented. The full width at half maximum(FWHM) of in-plane and out-of-plane scan are 5.2°and 3.5°, respectively, with Jc being 0.75 MA/ cm2.3. The fabrication of YBCO by reel-to-reel technology has been studied. The structure and performance of single-layer thin film became worse with the increase of the deposition thickness. By using multi-layer structure, the a-axis oriention has been avoided, the root mean square roughness is no more than 10nm, with Jc being 0.13 MA/ cm2.