Papers by Author: Yuan Hong Gao

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Authors: Lian Ping Chen, Yuan Hong Gao, Jian Xiong Yuan, Qing Hua Zhang, Yan Hong Yin, Chun Xiang Wang
Abstract: It is hardly possible to obtain rare earth doped CaWO4 thin films directly through electrochemical techniques. A novel post processing has been proposed to synthesize CaWO4:Eu3+ thin films at room temperature. X-ray diffraction, X-ray photoelectron spectrometry, spectrophotometer were used to characterize their phase, composition and luminescent properties. Results reveal that Eu3+-doped CaWO4 films have a tetragonal phase; the content of Eu in the near surface region is much higher than that of the bulk; under the excitation of 310 nm, a sharp emission peak at 616 nm has been observed for Ca0.9WO4:Eu0.13+ thin films.
Authors: Yuan Hong Gao, Jian Gao Yang, Bai Tao Su, Lian Ping Chen
Abstract: Hydrogen is widely used to prepare tungsten from tungsten oxides. Such a gas is combustible and strict measures must be taken. However, assisted by Mg or Li3N, tungsten can be prepared through the ball milling at room temperature. Al powder is supposed to be one of the proper reducers. Simulations on the loss of Gibbs energy of these reactions have been investigated. Studies reveal that the reduction of Na2WO4 is feasible when reducers such as Al, Mg and Li3N are used; and the intermediate tungsten oxides such as WO2, WO2.72 and WO2.9 can be seldom generated. In addition, the calculation favors that NH3 does not react with Na2WO4 or WO3 theoretically.
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