Double-perovskite Sr2Fe1-xMnxNbO6-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.
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.
The LSGM-carbonate composite electrolyte is a new type of medium and low temperature SOFC electrolyte material, which has great application potential. In this paper, the molten salt infiltration method was used to prepare the LSGM-carbonate composite electrolyte. The results of SEM test proved that the molten salt infiltration method was more appropriate in preparing the LSGM-carbonate composite electrolyte comparing with direct mixing method. The influence of the type and content of pore forming agent was investigated. The result showed that the polymethyl methacrylate (PMMA) had an excellent pore forming performance and could create interconnected pore structures successfully in LSGM matrix. The XRD result indicated that the LSGM-carbonate composite electrolyte showed almost a single LSGM phase and the carbonate remained glass state. Four terminal method was used to measure the conductivity. The result showed that the conductivity of the LSGM-carbonate composite electrolytes was increased by one order of magnitude compared with pure LSGM. The conductivity of LSGM-carbonate composite electrolytes increased firstly and then decreased with the increasing of PMMA. The LSGM-carbonate composite electrolyte prepared by 25 wt.% PMMA addition has the highest conductivity during the whole range of test temperature and reached 0.3 S.cm-1 at 600°C.
The double-perovskite La0.4Sr1.6CoNbO6-δ(LSCN) powders were synthesized by the solid-state reaction method. The electrical conductivities of LSCN samples were tested in air and 5 vol%H2/Ar. The results show that the conductivity of LSCN in 5 vol%H2/Ar (8.12 Scm-1) at 850 °C was higher than that in air (7.03 Scm-1). The activation energy obtained from the Arrhenius function was 0.821 eV in air and 0.707 eV in 5 vol%H2/Ar. The analysis of XPS shows that there exit three valence states of Co (Co+2, Co+3, Co+4) and two of Nb (Nb+4, Nb+5). The loss of lattice oxygen in LSCN not only produces oxygen vacancies, but also generates excess electrons, which contributes to the electrical conductivity of the LSCN samples.
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.
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