Microstructure and superconductivity of highly ordered YBa2Cu3O7-δ nanowire arrays

In order to explore the fundamental properties of one-dimensional nanostructured high-temperature superconductors and enhance their promising applications, a universal and general method for the synthesis of high-quality YBa2Cu3O7-delta (YBCO) nanowire arrays is developed, which involves the combination of a novel sol-gel process to lower the crystallization temperature of YBCO, and porous anodic alumina (PAA) as an effective morphology-directing hard template. Field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) results indicate that the as-prepared YBCO nanowires have average diameters of about 50 nm and lengths up to several microns. The structures of the samples were analysed by x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDX) and inductively coupled plasma (ICP) analysis, which indicate that the nanowires are well crystallized with orthorhombic YBCO-123 structure. The magnetization measurement under zero-field-cooled (ZFC) mode indicates that the superconducting transition temperature (T-c) of the nanowires is about 92 K, which is in agreement with that of a bulk YBCO sample.