Papers by Author: De Sheng Ai

Abstract: Double-perovskite Sr₂Fe_1-xMn_xNbO_6-δ (x = 0, 0.1, 0.2, 0.3, 0.5, 0.8) (SFMN) powders which will be applied to the electrode of solid oxide electrolysis cells (SOEC) were synthesized by Solid State Reaction Method. The mixed oxide powders SrCO₃, Fe₂O₃, MnO₂ and Nb₂O₅, were homogeneously calcined at different temperatures and in different atmospheres. The influence of the preparation process on the structure and the morphology of the powder were investigated by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It is found that the formation of perovskite structure is directly related to the content of Mn and calcining temperature. Controllable synthesis of pure phase of double perovskite powders was realized after calcining for12h at 1150 °C in air. Moreover, the experimental results show that the perovskite structure of SFMN is stable in whether oxidizing or reducing atmosphere, which indicates that this material has a potential to be used as electrode of solid oxide electrolysis cell.

Abstract: Two different types of morphology are observed in synthesis of SiC nanowires by catalyst-assisted pyrolysis of polymeric precursor while Au acts as the catalyst. Both two types of SiC nanowires are well oriented and uniform in diameter. The results indicate that longer (~20 μm) and slimmer (~100 nm) nanowires are tends to be produced in high temperature (1450°C), while shorter (~10 μm) and thicker (200~300 nm) ones are tends to be produced in low temperature (1420°C). Then we make a discussion on the mechanism of the growth of SiC nanowires based on the VLS (Vapor-Liquid-Solid) process.

Abstract: Double-perovskite Sr2Fe1-xScxMoO6- (x = 0, 0.05, 0.1, 0.2, 0.3, 0.4) powders have been synthesized by sol-gel citrate method. Initial powders were calcined in different temperature and atmosphere (air, H2(4vol%)/Ar), then analyzed by using the methods of X-ray, scanning electron microscopy (SEM), as well as thermal analysis. It is found that the formation of perovskite structure is related to the content of Sc, pH value, calcination temperature and sintering atmosphere. Especially, a pure perovskite structure almost completely formed after three hours sintering in atmosphere of H2(4vol%)/Ar. Although the formation of perovskite structure also happened in the air atmosphere, at the same time the SrMoO4 structure formed undesirably as a result of oxidization of Mo.

Abstract: Pr-doped ceria solid solutions have attracted much attention as promising mixed electronic-ionic conductor and oxygen storage materials. However, little effort has been made to synthesize Pr-doped ceria with one-dimensional nanostructure. In this paper, Pr-doped ceria nanorods were prepared via a facile hydrothermal method using Pr(NO3)3, Ce(NO3)3 and NaOH as raw materials. X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED) indicated that the as-prepared Pr-doped ceria nanorods had a cubic fluorite structure, with the length around 200 ~ 400 nm and the diameters around 10 ~ 18 nm. The effect of alkaline concentration has been systematically studied and the results indicated that higher alkaline concentration was favorable for the formation of nanorods.