直流磁控反应溅射法制备YYC缓冲层

【作者】 柴刚；

【导师】 蒋书文； 陶伯万；

【作者基本信息】 电子科技大学 ， 材料科学与工程， 2010， 硕士

【摘要】 第二代YBCO高温超导带材具有更高的临界电流密度和更优的高场下性能,使其成为最具发展应用前景的超导带材,为各国所广泛关注。而在柔性的NiW合金基带上进行YBCO薄膜的生长,必须解决超导层与金属基带的晶格失配和互扩散问题。因此,高质量缓冲层的制备就成为了YBCO带材发展的关键。由于磁控反应溅射具有工艺简单、易于操作等特点,本论文使用直流磁控反应溅射法在Ni-5at.%W合金基带上进行三层缓冲层Y₂O₃/YSZ/CeO₂（YYC）的研究制备。具体内容如下:1、采用直流磁控反应溅射方法制备Y₂O₃种子层,通过对沉积温度、水分压、总气压及卷绕速率的研究,寻找到最优薄膜生长工艺。在此工艺下制备的Y₂O₃种子层为完全c轴取向,面内外半高宽（△φ,△ω）分别为5.4°, 4.4°,表面均方根（RMS）粗糙度为4.3nm。2、在Y₂O₃种子层的基础上继续进行阻挡层YSZ和模板层CeO₂的生长,成功制备出面内外半高宽分别为5.8°和3.9°,表面粗糙度（RMS）为6.2nm的YYC缓冲层。采用电子背散射衍射（EBSD）分析CeO₂模板层的均匀性,结果表明CeO₂表面均匀致密,小角度晶界均在10度以下。3、对YYC缓冲层进行双面一致性分析得到,双面缓冲层的面内外半高宽差异均小于0.3°,晶粒粒径均小于70nm,表面粗糙度（RMS）差异小于0.5nm。50cm缓冲层带材各层薄膜△φ在5°与6°之间,△ω在4°与6°之间,模板层CeO₂的△φ变化量小于0.5°,△ω变化量小于1°,表面粗糙度RMS在6nm与7nm之间。4、在YYC三层缓冲层上进行YBCO超导层的生长,分别从种子层、阻挡层和模板层研究各层对YBCO超导层的影响。在YYC缓冲层上制备的YBCO带材面内外取向分别为5.3°和3.2°,单面最高Jc值为1.3MA/cm²,双面最高Jc值为1.0 MA/cm²。更多还原

【Abstract】 Due to its higher critical current density and better in-field performance, YBa2Cu3O7-δ（YBCO） coated conductor becomes the most promising superconductor tape. The main problems in growth of YBCO film on NiW substrate are lattice mismatch and the diffusion of metal atoms and oxygen. Deposition of high-quality buffer layers is one of the key points of YBCO tape development. In this thesis, DC magnetron reactive sputtering was used to grow Y₂O₃/YSZ/CeO₂（YYC）buffer layers because of its simple process, easy control, and good repeatability.1. Y₂O₃ seed layer was deposited on the Rolling Assisted Biaxially Textured Substrate （RABiTS） Ni-5at%W alloy. The parameters such as substrate temperature, H2O pressure, total gas pressure, and reel speed were adjusted to optimize the growth condition. Under the optimum condition, Y₂O₃ films with single c-axis orientation were obtained. The full width at half maximum （FWHM） of in-plane and out-of-plane scan were 5.4°and 4.4°. The typical root mean square of surface roughness （RMS） was 4.3nm.2. YSZ （Yttrium Stabilized Zirconia） barrier layer and CeO₂ cap layer were deposited consecutively on Y₂O₃/NiW. YYC buffer stack was single c-axis orientation. The FWHM of in-plane and out-of-plane were 5.8°and 3.9°, respectively. RMS was 6.2nm. Electron backscatter diffraction （EBSD） observation showed that CeO₂ cap layer was dense and homogeneous. Small angle grain boundary was distributed in the range of less than 10 degrees.3. Double-sided uniformity of YYC buffer layer was characterized. Differences of in-plane FWHM and out-plane FWHM of double sides were all less than 0.3°. Difference of surface roughness RMS was less than 0.5nm. Uniformity was characterized along 50cm long tape as following: Layers of YYC,△φranged between 5°and 6°, out-plane FWHM ranged between 4°and 6°. As for Layer of CeO₂, differences of△φand△ωwere 0.5°and 1°, respectively. RMS ranged from 6 to 7nm.4. YBCO film was deposited on Y₂O₃/YSZ/CeO₂. Its△φand△ωwere 5.3°and 3.2°. The supreme Jc value of single-sided YBCO film deposited on YYC/NiW was 1.3MA/cm². The supreme Jc value of double-sided YBCO films deposited on YYC/NiW/YYC was 1.0 MA/cm² for each side.更多还原