Study on advanced Ce0.9La0.1O2/Gd2Zr2O7 buffer layers architecture towards all chemical solution processed coated conductors
Study on advanced Ce0.9La0.1O2/Gd2Zr2O7 buffer layers architecture towards all chemical solution processed coated conductors
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DOI：
10.1039/c5ta00153f
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发表时间：
2015-06
影响因子：
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通讯作者：
Yue Zhao;Lin Ma;Wei Wu;H. Suo;J. Grivel
中科院分区：
文献类型：
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作者：
Yue Zhao;Lin Ma;Wei Wu;H. Suo;J. Grivel
化学溶液沉积是一种以低成本沉积功能氧化物薄膜的通用技术。在本研究中，该方法被用来生长具有高超导性能的多层第二代高温超导体(“涂层导体”)。采用金属-有机沉积方法，在织构NiW衬底上依次沉积了Ce0.9La0.1O2/Gd2Zr2O7缓冲层和200 nm厚的YBa2Cu3O7(YBCO)超导层。当薄膜厚度增加到80 nm时，Gd2Zr2O7阻挡层的表面织构恶化，尽管如传统的X射线衍射所确定的那样，整体织构保持了明显的双轴取向。在沉积Ce0.9La0.1O2薄膜作为帽层后，我们特别注意改善表面质量，包括晶体取向和局部平坦度。通过对电子背散射衍射的表面形貌和取向图的综合分析，发现这些改善主要归因于：(1)Ce0.9La0.1O2晶体在具有理想取向的Gd2Zr2O7颗粒上优先形核；(Ii)Ce0.9La0.1O2晶体在层内以二维生长为主。此外，对YBCO超导层的微观结构和超导性能进行了详细的表征，并与采用相同技术在单晶衬底上沉积的超导薄膜进行了比较。在这种全化学衍生结构上获得了2.2MA cm−2(77K，自场)的有希望的临界电流密度，这证明了缓冲层堆栈的高质量以及利用所有化学溶液路线制造低成本镀膜导体的可行性。
Chemical solution deposition is a versatile technique to deposit functional oxide films with low cost. In this study, this approach was employed to grow multi-layered, second-generation, high-temperature superconductors (“coated conductors”) with high superconducting properties. The Ce0.9La0.1O2/Gd2Zr2O7 buffer layer stack and the 200 nm thick YBa2Cu3O7 (YBCO) superconducting layer were sequentially deposited on textured NiW substrates using metal–organic deposition routes. The surface texture of the Gd2Zr2O7 barrier layer deteriorates when the film thickness increases to 80 nm, although the global texture retains a sharp biaxial orientation, as determined by conventional X-ray diffraction. We paid particular attention to improving the surface quality in terms of crystallographic orientation and local flatness after depositing a Ce0.9La0.1O2 thin film as a cap layer. From a comprehensive analysis of the surface morphology and misorientation maps constructed by electron backscattering diffraction, it is found that these improvements are mainly attributed to: (i) the preferential nucleation of Ce0.9La0.1O2 crystals on the Gd2Zr2O7 grains with desirable orientations; and (ii) the predominant two-dimensional growth of the Ce0.9La0.1O2 crystals in the layer. Moreover, the microstructure and superconducting performance of the YBCO superconducting layer were thoroughly characterized and compared with those of films deposited on single-crystal substrates using the same technique. A promising critical current density of 2.2 MA cm−2 (77 K, self-field) was achieved on such an all chemical derived configuration, demonstrating the high quality of the buffer layer stack and the feasibility of using all chemical solution routes for the fabrication of low-cost coated conductors.