Single crystalline YBa2Cu3O7−δ nanowires from a template-directed sol–gel route

A simple sol–gel template route was developed to prepare single crystalline YBa2Cu3O7−δ (YBCO) nanowires with average diameters of ∼50 nm and lengths up to ∼40 μm in porous alumina membrane. Nanowires could be obtained selectively and reproducibly depending on the experimental conditions. Scanning electron microscopy (SEM) confirmed that the monodisperse cylindrical pores of alumina membrane were filled with nanowire arrays with a narrow distribution of diameters. The X-ray diffraction (XRD) pattern of the obtained nanowires was assessed as orthorhombic YBCO 123 lattice after heating gels at ∼950 °C for crystallization. As determined by transmission electron microscopy (TEM) and electron diffraction (ED) analysis, the nanowires were essentially single crystalline in nature. High-resolution transmission electron microscope (HRTEM) images further revealed the single crystalline nature of the as-prepared nanowires.