Conference Presentations by Alireza Babaei
In this study the characteristics of two La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) powders, one obtained from... more In this study the characteristics of two La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) powders, one obtained from an in-house synthesized by co-precipitation method and a commercial one from Fuel Cell Materials Co. (USA), were compared. The co-precipitated powder was processed by using ammonium carbonate as precipitating agent 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 commercial powder and also sub-micron agglomerates in co-precipitated LSCF powder can 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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Nano-structured manganese cobalt oxide (MnCo2O4) was successfully synthesized by co-precipitation... more Nano-structured manganese cobalt oxide (MnCo2O4) was successfully synthesized by co-precipitation method using metal nitrates as starting materials. The phase formation and morphology of the products were characterized by means of X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. The effects of pH and calcination temperature were investigated on the characteristics of MnCo2O4 powders. The results revealed that the MnCo2O4 phase was obtained easier at relatively higher pH values. XRD results showed that at the temperature of 450˚C the phase formation was not completed, while with increasing the calcination temperature to 1000˚C the desired phase was fully achieved. Furthermore, by increasing the calcination temperature from 550 to 1000˚C, the mean crystallite size of the powders increases from 30 to 140 nm. FESEM investigation shows that in the sample processed with OH-/NO3- =1.5 and calcined at 550˚C completely uniform particles with mean size of 45nm can be obtained.
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Journal Papers by Alireza Babaei
Nano-structured lanthanum strontium cobalt ferrite, La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), was successful... more Nano-structured lanthanum strontium cobalt ferrite, La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), was successfully synthesized via co-precipitation method using metal nitrates as starting materials. Effects of precipitating agent and calcination temperature on the phase composition and morphology of synthesized powders were systematically studied using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. XRD analysis revealed that a single phase La0.6Sr0.4Co0.2Fe0.8O3 perovskite was obtained in the processed sample using ammonium carbonate as precipitating agent with a NH4+/NO3-molar ratio of 2 after calcination at 1000C for 1 h. The phase composition of products was also affected by changing pH values. Moreover, using sodium hydroxide as a precipitant resulted in a mixture of La0.6Sr0.4Co0.2Fe0.8O3 and cobalt ferrite (CoFe2O4) phases. Careless washing of the precursors can also led to the formation of mixed phase after calcination of final powders. Mean crystallite size of the obtained powders was not noticeably affected by varying calcination temperature from 900 to 1050C and remained almost the same at 10 nm, however increasing calcination temperature to 1100C resulted in sharp structural coarsening. FESEM studies demonstrate that relatively uniform particles with mean particle size of 90 nm were obtained in the sample processed with a NH4+/NO3- molar ratio of 2 after calcination at 1000C for 1 h.
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Conference Presentations by Alireza Babaei
Journal Papers by Alireza Babaei