X Y Yuan

Fabrication and optical properties of TiO2 nanowire arrays made by sol-gel electrophoresis deposition into anodic alumina membranes

Ordered TiO2 nanowire arrays have been successfully fabricated into the nanochannels of a porous anodic alumina membrane by sol–gel electrophoretic deposition. After annealing at 500°C, the TiO2 nanowire arrays and the individual nanowires were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and x-ray diffraction (XRD). SEM and TEM images show that these nanowires are dense and continuous with a uniform diameter throughout their entire length. XRD and SAED analysis together indicate that these TiO2 nanowires crystallize in the anatase polycrystalline structure. The optical absorption band edge of TiO2 nanowire arrays exhibits a blue shift with respect of that of the bulk TiO2 owing to the quantum size effect.

A novel synthesis route to Y2O3:Eu nanotubes

Large-scale Y2O3:Eu nanotubes have been successfully fabricated by an improved sol–gel method within the nanochannels of porous anodic alumina templates. In this method, yttrium nitrate, europium nitrate and urea were used as precursors, yttrium nitrate and europium nitrate were acting as sources of europium and yttrium ions, and urea offered a basic medium through its hydrolysis. X-ray diffraction techniques, scanning electron microscopy, transmission electron microscopy and selected-area electron diffraction were used to characterize the Y2O3:Eu nanotubes obtained. It is found that the prepared Y2O3:Eu nanotubes can be indexed as a polycrystalline cubic structure and their outer diameters are about 50–80 nm, with the thickness of the tube wall estimated to be around 5 nm. The emission peaks of the as-prepared Y2O3:Eu nanotubes are broader than those of bulk Y2O3:Eu because of the disordering of the crystal phase possibly induced by the increase of the surface/volume ratio in the nanotubes.

Self-assembly synthesis and magnetic studies of Co–P alloy nanowire arrays

The paper describes the self-assembly synthesis of Co–P alloy nanowire arrays in an anodic alumina membrane (AAM) by electroless deposition and presents their corresponding magnetic properties. The images of Co–P alloy nanowire arrays and single nanowires are obtained by scanning electron microscopy and transmission electron microscopy, respectively. Selected area electron diffraction, x-ray diffraction and energy dispersive spectra are employed to study the morphology and chemical composition of the nanowires. The results show that Co–P alloy nanowire arrays are amorphous. The magnetic properties of Co–P alloy nanowire arrays is characterized using a vibrating sample magnetometer. The hysteresis loops indicate that the easily magnetized direction of Co–P nanowire arrays is parallel to the nanowire arrays and has obvious magnetic anisotropy as a result of the shape anisotropies. Electroless deposition can be extended to many other materials and opens up significant opportunities in nanoscalar fabrication magnetic materials for ultra-high-density magnetic recoding media. Compared with the electrodeposition method, electroless deposition need not supply power or sprinkle Au on one side of the AAM before deposition and some defects of electrodeposition can be overcome.

Synthesis of Zn nanofibres through simple thermal vapour-phase deposition

Zn nanowires and nanoribbons have been synthesized from Zn powders through a simple thermal-vapour deposition process.