Cobaltites lanthanum

LaCoOs ceramic exhibits interesting electrical, magnetic, and catalytic properties, being used as cathode material for solid oxide fuel cells (SOFCs), catalysts for light hydrocarbon oxidation, and gas detection sensors. For other applications such as oxygen separation from air and for synthetic gas production, dense ceramic membranes with well-defined microstructure are required. 

Predoana et al. [119] studied the synthesis of the LaCoOs powders by the aqueous sol-gel method and established the correlation between their structure and properties and their sintering behavior to obtain fully densified ceramics with a perovskite structure. 

The obtained gels were thermally treated in air at 400 °C for 1 h and at 600 °C for 6h. From the annealed powders, pellets were made by uniaxial pressing under 80 MPa, without any binding material addition. The sintering of the pressed powders was realized in the 800-1200 °C interval. 

The best results have been obtained using LaCoOs powders prepared from nitrates, sintered at 1100 °C. 

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Figure 8.15 Calculated composition versus oxygen stoichiometry curves for Lai- SrjCoCb-s. [The two experimental points are taken from data in A. N. Petrov, V. A. Cherepanov, and A. Y. Zuev, Thermodynamics, Defect Structure and Charge Transfer in Doped Lanthanum Cobaltites An Overview, J. Solid State Electrochem., 10, 517-537 (2006).]...

Single-phase perovskite MIECs such as Sr-doped lanthanum cobaltite (LSC), lanthanum ferrite (LSF), lanthanum cobalt ferrite (LSCF) and samarium cobaltite (SSC), and Ca-doped lanthanum ferrite (LCF) [13] are sometimes used alone in SOFC cathodes, as depicted in the lower right-hand comer of Figure 6.1, but combining an... 

Pauli I.A., Avvakumov E.G., Poluboyarov V.A. et al. Influence of mechanical activation on the synthesis and catalytic properties of lanthanum cobaltite. Sib. Khim. Zhurn. 1992 3 133-37. 

FIGURE 3.10B Corrosion of stainless steel in cell operating conditions, (b) Treated coupon air side of dual atmosphere under constant current for 1,000 h. The porons structure above the scale is a lanthanum cobaltite layer added for electrical connection. 

Y. Denos, F. Morin and G. Trudel, Oxygen diffusivity in strontium substituted lanthanum cobaltite, in T.A. Ramanarayanan, W.L. Worrel and H.L. Tuller (Eds.), Proceedings of the 2nd International Symposium on Ionic and Mixed Conducting Oxide Ceramics. The Electrochemical Society, Pennington, NJ, 1994, pp. 150-158. 

Faaland S, Einarsmd MA, Grande T. Reactions between calcium and strontium substituted lanthanum cobaltite ceramic membranes and calcium silicate sealing materials. Chem Mater. 2001 13 723. 

The E-design stack, shown in Fig. lA, consists of a relatively thick metallic interconnect with machined gas channels on both sides and a metallic picture frame for the cell, brazed to the interconnect by a metal solder. Sealing is obtained by glass ceramic sealants applied to the planar cell and frame surfaces using an automated dispenser. A fine Ni-mesh is spot-welded to the fuel side of the interconnect in order to improve the electrical contact between interconnect and anode substrate. On the air side usually a lanthanum cobaltite (LC) contact layer is sprayed onto the ribs of the interconnect. 

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