Mod Preparation Of Ybco Hts Tapes Buffer Layer Of Srtio <sub> 3 </ Sub>

Due to its high irreversibility fields, low AC loses, good in-field performance, and low processing costs,the second-generation YBa₂Cu₃O₇-δ(YBCO) tapes become the most promising materials for the practical applications and attract the attention of material scientists of the whole world. The main difficulties in fabricating YBCO tape are lattice mismatch and the diffusion of oxygen and metal atoms. It is necessary to deposit buffer layers between flexible metal substrates and YBCO layer. To ensure that buffer layers can work as a good template for growth of YBCO layer and block the diffusion efficiently, buffer layers must be highly oriented, well textured, smooth, dense and crack-free.The most commonly used optimum structure consisted of cap layer/barrier layer/seed layer. It is usually fabricated by ion beam assisted deposition, Sputting or Pulsed laser deposition. These techniques need vacuum condition and are with higher processing costs. In this thesis, SrTiO₃ (STO) buffer layer was deposited on the rolling-assisted biaxially textured substrates (RABiTS) Ni-5at%W alloy with the non-vacuum Metal-organic depositon (MOD) method. To ensure that buffer layers can work as a good template for growing YBCO layer and block the diffusion efficiently, the deposition parameters were studied systematicly.The conditions that affect the stability of STO precursor solution were discussed. Strontium acetic and tetrabutyl titanate were used as raw materials. The temperature of reaction was in the range of 50～70℃. STO precursor solution was stable and clarity in one month.To ensure highly oriented and well textured buffer layer, the fabrication of seed layer was studied firstly. STO seed layer was more suitable than others. The optimal parameters were solution concentration being 0.06M, annealing temperature being 900～925℃and annealing time being 120min.STO buffer deposition process was studied more intensively and optimal parameters were obtained. XRD and AFM analysis methods were used to analyze the structure and surface of STO buffer layer. With optimum MOD technic parameters, STO thin film has shown a-axis single-oriented. The full width at half maximum (FWHM) of in-plane and out-of-plane scan are 6.5°and 6.0°, respectively. The root mean square roughness is no more than 3nm.