Biaxially Textured Ni-w Baseband Reactive Sputter Deposition Of Oxide Seed Layer Film

High-temperature superconductor (HTSC) wires had been regarded as advanced materials because of their extensive applications in the modern technology. The first generation of HTSC wires are bismuth strontium calcium copper oxide (BSCCO) in Ag tubes. The second generation of HTSC wires are yttrium barium copper oxide(YBCO) thin films on metallic tapes. It is called coated conductors. Comparing with the first generation wires, the second generation HTSC wires have the potential to be less expensive and to perform better. For the preparation of coated conductors, one of the most important issues is the growth of seed layer (the first buffer layer), which provide a continuous, smooth, and chemically inert surface for the growth of the YBCO film while transferring the biaxial texture from the substrate to the HTSC layer. The fabrication of epitaxial, biaxially aligned seed layers (CeO₂ and Y₂O₃) on rolling-assisted biaxially textured substrates (RABiTS) were studied in this thesis.The CeO₂ and Y₂O₃ seed layers were deposited on the biaxially textured Ni-5at% W alloy with direct current magnetron reactive sputtering. Two deposition processes were experimented for the growth of CeO₂ films. The first one was called one step process or isothermal deposition and annealing process. In this process, the CeO₂ layers were formed at high temperature and oxidative atmosphere and then annealed at the same temperature. The relationship between the growth parameters and the textured degree of CeO₂ thin film was systematically studied, and the optimal growth parameters were summaried. The optimum deposition temperature is between 720℃and 850℃. The annealing time is equal or longer than 40 min. Water steam was used as oxidant, and the optimum water steam partial pressure is between 1×10-4 and 5.5×10-4 Pa. Under the optimum growth parameters, a CeO₂ seed layer with highly textured degree was successfully prepared. Beside the one step process was experimented in this dissertation, the two step process was proposed and studied to further improve the quality of CeO₂ seed layer. In the two step process, about 15 nm thick of Ce metal layer was deposited on metallic substrate at the first step, then water steam was introduced in the chamber, and the CeO₂ thin films were subsequently deposited with reactive sputtering in the...