Die Anzahl der Ca2 ‐Ionen auf [1014] Spaltflächen von Calcit‐Einkristallen wurde über den Ca‐"Ca‐Isotopenaustausch ermittelt und mit dem auskristallographischen Daten bestimmten Wert verglichen.
La0.25Sr0.25Ca0.40Ti0.95Ni0.05-xSnxO3–δ (x=0...0.05) mixed ionic electronic conductor (MIEC) materials were studied as possible fuel electrodes for solid oxide cell. Initial characterization of the materials aimed to understand whether tin occupied the A- or the B-site in the material through precise control of material stoichiometry using thermogravimetric analysis (TGA) and XRD characterization. Thereafter, a set of La0.25Sr0.25Ca0.40Ti0.95Ni0.05-xSnxO3–δ materials were synthesized and characterized to understand the influence of the B-site dopant on the phase purity and time-stability in reducing atmosphere. Finally, initial electrochemical characterization has been conducted for some of the synthesized materials.
In this work, we studied the effect of A-site deficiency and B-site chemical composition on electrical performance of (La0.25Sr0.25Ca0.45)yTi0.95Ni0.05-xMnxO3-δ (x=0-0.05) (y=1, 0.9474) (LSCTNM-x) fuel electrode. The doped compositions were successfully synthesized by the glycine-nitrate combustion method and then characterized by XRD and SEM to confirm the phase purity and visualize the microstructure of studied electrode layers. Furthermore, the DC four-probe conductivity measurements of porous electrode layers has been done to understand the impact of MIEC material composition on electrical conductivities of LSCTNM. Conductivities have been measured at two different atmospheres: 1% H2 + 1.7% H2O + 97.3% Ar and 98.3% H2 + 1.7% H2O. Results of this study demonstrate that the conductivity is considerably dependent on composition and the LSCTNM materials with 10% A-site deficiency showed the maximal total electrical conductivity of porous electrode layers in 98.3% H2 + 1.7% H2O atmosphere.
(La1–ySry)xCr0.5Mn0.45Ni0.05O3–δ
(LSCMN) is a perovskite (ABO3) type mixed ionic-electronic conductive (MIEC) oxide and has been proposed as an electrode material for high temperature fuel cell. The material is catalytically active for oxidation of hydrogen and hydrocarbons. A significant amount of attention has been paid to stability issues if the material is used as an anode in a solid oxide fuel cell. So far, there is a lack of information about the dependence between A-site stoichiometry and stability performance of LSCMN surface. The La/Sr ratio and deficiency of A-site, i.e. A-site stoichiometry of (La1–ySry)xCr0.5Mn0.45Ni0.05O3–δ
were varied and chemical composition of LSCMN surface and lattice parameters was studied. The chemical and structural changes of the material surface (segregation of some LSCMN components onto the surface and decomposition of perovskite phase) have a key role in the electrochemical performance and initial degradation rate of the electrode. XRD results for studied electrode powders showed significant dependence of the lattice parameters on the A-site composition. Materials were treated in synthetic air and in H2 environment. TOF SIMS analysis demonstrated the dependence of the surface stoichiometry on the A-site composition of bulk electrode as well as on the different gas environments after heat treatment. To improve the durability of the solid oxide cell fuel electrodes, it is inevitable to understand the degradation mechanisms during the cell operation and during cell fabrication.
Mit Hilfe der UHV‐Gravimetrie wird die Kinetik der isothermen Oxidation von Cu zu Cu2O an den (100)‐Oberflächen von Au2Cu3‐Einkristallen im Temp.‐Bereich 775‐885 K und bei O2‐Drücken zwischen 5 μTorr und 2 mTorr untersucht.
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