Cyc And Yyc Buffer Layer Of Ybco Sputtering

Due to its low ac loss, good in-field performance, and low processing cost, second-generation YBa2Cu3O7-δ(YBCO) high temperature super-conductor tape, which is also called coated conductor, attracts the attention of the researchers worldwide. In this thesis, YBCO coated conductors were deposited on buffered Ni-5at.%W substrate. Sputtering was used to grow YBCO coated conductor because of its easy control, simple process, and good repeatability.1. Owing to the buffer layers'influence on YBCO thin films, CeO2/YSZ/CeO2 (CYC) buffer layers which have different structure were used to deposit YBCO coated conductors to investigate the influence of buffer layers. Studying the variation of the microstructure, surface morphology and superconductor property of YBCO thin films, we found that only those buffer layers with all c-axis orientated, high aligned of in-plan and out-plan crystallization, and good surface morphology, could provide good growth template for YBCO thin films.2. YBCO thin films were prepared on the CYC buffer layers by direct current sputtering. The parameters are as follow: substrate temperature being 680℃, sputtering pressure being 32 Pa, and PO2: PAr being 1:2. With these parameters, YBCO thin film has shown single c-axis orientation. The full width at half maximum (FWHM) of in-plane and out-of-plane scan are 4.8°and 3.4°, respectively. The Jc value of this sample is 0.8 MA/cm2.3. To enhance the critical current density, Y2O3/YSZ/CeO2 (YYC) buffered substrates have been used to study the influence of substrate temperature and gas pressure for YBCO films. With the similar parameters used on CYC buffer layers, c-axis oriented YBCO film has been obtained. And the full width at half maximum (FWHM) of in-plane and out-of-plane scan are 6.0°and 3.6°, respectively. The Jc value reached to 1.0 MA/ cm2, slightly higher than that of films on CYC buffer.