School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran
In this study the characteristics of two different kinds of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) powders, one in-house synthesized powder by a co-precipitation method and another one purchased from Fuel Cell Materials Co. (FCM Co., USA), were compared. The co-precipitated powder was prepared by using ammonium carbonate as precipitant with a NH4+/NO3- molar ratio of 2 and calcination at 1000C for 1 h. Phase composition, morphology and particle size distribution of powders were systematically studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and laser particle size analysis (LPSA), respectively. The synthesized and commercial LSCF powders were overlaid on Yttria-stabilized zirconia (YSZ) electrolyte having a gadolinium-doped ceria (GDC) interlayer. Electrochemical Impedance Spectroscopy (EIS) measurement was carried out at various operating temperatures in the range of 600-850C. XRD and FESEM analysis revealed that single phase nano-crystalline LSCF powder with a mean crystallite size of 14 nm and mean particle size of 90 nm is obtained after calcination at 1000C. The presence of hard agglomerated particles larger than few microns in the commercial powder and also sub-micron agglomerates in the co-precipitated LSCF powder might be related to the final mechanical milling process and high calcination temperature of powders, respectively. LPSA results show identical mean particle size of about 1.5μm for both LSCF powders. EIS results revealed almost identical polarization resistance for both LSCF powders.
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