Yuan Fangli

Preparation and properties of zinc oxide nanoparticles coated with zinc aluminate

Zinc oxide nanoparticles coated with zinc aluminate have been prepared by performing Al2O3 precipitation on the precursor basic carbonate of zinc (BCZ) of zinc oxide. TEM shows that a homogeneous layer is formed on the surface of the zinc oxide nanoparticles, and the coated particle size is about 50–60 nm. The thickness of the layer estimated by high magnification transmission electronic micrography is about 4–5 nm. Results of X-ray photoelectron spectroscopy (XPS) show that the elements in the coating at the surface of the ZnO nanoparticles are Zn, O and Al. X-Ray diffraction and lattice fringe data show that the coating is of the ZnAl2O4 phase formed by the reaction of basic carbonate of zinc and basic carbonate of aluminium. The zinc aluminate coating is effective in reducing the catalytic activity of zinc oxide nanoparticles. Zinc oxide nanoparticles coated with zinc aluminate not only retain a high UV absorptivity, but also increase their reflectance of visible light.

Shape-Controlled Synthesis of ZnS Nanostructures: A Simple and Rapid Method for One-Dimensional Materials by Plasma

In this paper, ZnS one-dimensional (1D) nanostructures including tetrapods, nanorods, nanobelts, and nanoslices were selectively synthesized by using RF thermal plasma in a wall-free way. The feeding rate and the cooling flow rate were the critical experimental parameters for defining the morphology of the final products. The detailed structures of synthesized ZnS nanostructures were studied through transmission electron microscope, X-ray diffraction, and high-resolution transmission electron microscope. A collision-controlled growth mechanism was proposed to explain the growth process that occurred exclusively in the gas current by a flowing way, and the whole process was completed in several seconds. In conclusion, the present synthetic route provides a facile way to synthesize ZnS and other hexagonal-structured 1D nanostructures in a rapid and scalable way.

Effect of Plasma Spheroidization Process on the Microstructure and Crystallographic Phases of Silica, Alumina and Nickel Particles

During the plasma spheroidization process powders undergo different changes in their microstructures and crystal phases. In this paper, simple calculation of heat transfer between the plasma and a suspended particle was performed based on three hypotheses for the purpose of guiding experiments. Experimental investigation of the crystal phases and microstructural changes during the plasma processing was made using silica, alumina and nickel powders as starting materials. It has been revealed from the experimental results that these materials undergo different changes in crystal phases and microstructures, and these changes are essentially determined by the structures, properties and aggregate states of the starting materials.

Finite size effect on the Raman frequency of phonons in nano-semiconductors

A comprehensive study on Raman spectroscopy with different excitation wavelengths, sample sizes, and sample shapes for optic phonons (OPs) and acoustic phonons (APs) in polar and non-polar nano-semiconductors has been performed. The study affirms that the finite size effect does not appear in the OPs of polar nano-semiconductors, while it exists in all other types of phonons. The absence of the FSE is confirmed to originate from the long-range Frohlich interaction and the breaking of translation symmetry. The result indicates that the Raman spectra of OPs cannot be used as a method to characterize the scale and crystalline property of polar nano-semiconductors.