Baochang Cheng

The vibrational properties of one-dimensional ZnO:Ce nanostructures

Different morphological one-dimensional ZnO:Ce nanostructures were synthesized on a large scale. The microstructures and vibrational properties were investigated by x-ray diffraction, electron microscopy, Raman spectroscopy, and infrared spectroscopy. The results show that Ce can effectively control the growth of ZnO nanostructures. The change of the morphology and local structure of ZnO under the influence of Ce results in the variation of vibrational properties. In Raman spectra of doped samples, some classical modes, such as A1 and E1 modes, disappear, and two anomalous modes at 527 and 667 cm−1 are observed, whose intensity decreases with the increase of synthesis temperature. In infrared spectra, some surface phonon modes appear. Compared with those of the undoped sample, all the normal modes observed in the Ce-doped samples blueshift, and the extent of the blueshift decreases with increasing synthesis temperature in the Raman and infrared spectra.

Porous ZnAl2O4 spinel nanorods doped with Eu3+: synthesis and photoluminescence

Eu3+-doped zinc aluminate (ZnAl2O4) nanorods with a spinel structure were successfully synthesized via an annealing transformation of layered precursors obtained by a homogeneous coprecipitation method combined with surfactant assembly. These spinel nanorods, which consist of much finer nanofibres together with large quantities of irregular mesopores and which possess a large surface area of 93.2 m(2) g(-1) and a relatively narrow pore size distribution in the range of 6 - 20 nm, are an ideal optical host for Eu3+ luminescent centres. In this nanostructure, rather disordered surroundings induce the typical electric-dipole emission (D-5(0) --> F-7(2)) of Eu3+ to predominate and broaden.

Synthesis of nanocrystalline TiC powder by mechanical alloying

Synthesis of nanocrystalline TiC was investigated. The raw powders are Ti and C element, respectively. The ratio of Ti and C elements is 1:1 (mol). Mechanical alloying has been applied to obtain nanocrystalline TiC. The microstructure of nanocrystalline TiC has been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the nanocrystalline TiC powder was fabricated by mechanical alloying in a very short time at room temperature. The formation mechanism is self-propagating reactive synthesis conducted by mechanical alloying.

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.