Huawa Yu

ZnO thin films produced by the RF magnetron sputtering

ZnO thin films with (002) orientation have been deposited on Si(100) substrate by radio frequency (RF) magnetron sputtering technique. The influence of RF power and oxygen ratio on the the grain size-, the residual stress and optical properties was investigated by X-ray diffraction, transmission spectra and photoluminescence spectra. The results show that the ZnO film deposited with sputtering power (100W) and oxygen ratio(60%), can obtain its best c-axis orientation and crystallization and that tension stress of the film reaches the lowest, and a strong UV photoluminescence(PL) peak and a weak blue emission peak were observed.

Synthesis of Monodisperse Walnut-Like SnO2 Spheres and Their Photocatalytic Performances

Novel walnut-like SnO2 spheres have been synthesized using a one-step hydrothermal reaction with SnCl2·2H2O and KOH as raw materials. The morphology, microstructure, and optical properties of the products were characterized by X-ray powder diffraction (XRD), Raman spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and ultraviolet-visible (UV-Vis) absorption spectroscopy. The detailed studies revealed that these synthesized spheres are highly monodisperse and have a uniform size of approximately 250 nm. Photocatalytic activity of the prepared SnO2 spheres was evaluated by the degradation of methylene orange. The synthesized SnO2 spheres exhibited excellent photocatalytic degradation. In addition, a possible formation mechanism of the walnut-like nanostructures was proposed based on reaction time-dependent experiments.

Research on extinction characteristics of polaroids in near-infrared region

In the research of detecting extinction ratio of polarimeter, some significant characters are discovered. One polaroid has perfect extinction ratio in the visible, but its extinction ratio becomes weak in near infrared (NIR) region, and the transmittance of a pair of vertical polaroid becomes strong in NIR region. This phenomenon has been found in several other polaroids as well. The transmittance increases greatly in NIR even if the crystal Glan-Taylor prism polarimeter with good polarization is used. The extinction ratio of the polaroid changes from 3:100 in visible to 98:100 in NIR. More experiments have shown that the weakening of extinction ratio and the enhancement of transmittance of a pair of vertical polaroid in NIR are closely associated with the intensity of incident light. When the light intensity increases, the effect becomes clearer. The transmittance exceeds the theoretical results from classical physical optics, reaching 98%. Our results provide two aspects of applications. First, because the extinction ratio of the polaroid is related to the wavelength of incident light, the polaroid can be used in definite spectral range. Second, a pair of vertical polaroid can perfectly filter the visible light, while making NIR light transmit. This research result can provide some conveniences at IR spectrum, IR photography, IR imaging and IR detection.