Influence of spraying parameter on performance of La0.6Sr0.4Co0.2Fe0.8O3 films for IT-SOFCs A. P. Jamale, A. U. Chavan, S. P. Patila, L. D. Jadhav, and C. H. Bhosale Citation: AIP Conf. Proc. 1447, 625 (2012); doi: 10.1063/1.4710158 View online: http://dx.doi.org/10.1063/1.4710158 View Table of Contents: http://proceedings.aip.org/dbt/dbt.jsp?KEY=APCPCS&Volume=1447&Issue=1 Published by the American Institute of Physics.
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Influence of Spraying Parameter on Performance of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 Films for IT-SOFCs A.P. Jamalea*, A.U. Chavana, S.P. Patila, L.D. Jadhavb and C.H. Bhosalea a
Department of Physics, Shivaji University, Kolhapur- 416 004,Maharashtra, India Department of Physics, Rajaram college, kohapur- 416 004, Maharashtra, India. * Email:
[email protected]
b
Abstract. The crack free nanocrystalline, La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) membrane with high in plane conductivity have been successfully deposited on dense Ce 0.9 Gd 0.1 O 1.95 (GDC) by the Spray Pyrolysis Technique (SPT). The film with nominal 1Pm thickness, get crystallizes on annealing at 800qC for 4 hrs. The effect of deposition temperature on microstructure, crystallization and conductivity has been systematically studied. The film deposited at 300qC shows higher in plane conductivity of 26.6 SCm-1 with activation energy of 0.23 eV over the range of 400qC-800qC. The higher conductivity attributed towards the uniform, thin & dense microstructure of deposited film which is clarify from Scanning Electron Microscope (SEM) images. No interfacial reaction product between LSCF and GDC were detected from X-ray diffraction (XRD) studies upon annealing at 800qC. Keywords: LSCF, GDC, SPT, Microstructure, Activation energy, XRD, SEM. PACS: 68.55.-a
proportion in order to achieve the stiochiometric thin film. These metal nitrates were dissolved in the double distilled water to maintain the total salt concentration of 0.025mol/lit. The said precursor was sprayed on the preheated GDC substrate held at 200qC, 250qC and 300qC by keeping other parameters constant. Since, the deposited film was amorphous in nature, the post deposition heat treatment chosen to be 800qC for 4 hrs. which promotes crystallization of LSCF. Then annealed film was characterized with XRD, SEM and in plane electric conductivity with two probe method by striping two silver contacts 1 cm a parts.
INTRODUCTION The main goal of the recent research is to reduce the operating temperature of solid oxide fuel cell (SOFC) to 500-700qC, which unable the use of low cost materials and avoid the problem facing with the degradation. Thus, current research trend is to search highly catalytic active cathode and anode materials at the lower temperature and to develop the thin film components which facilitate the fabrication of PSOFC. In GDC based SOFC, the LSCF was considered as compatible electrode as its conductivity and thermal expansion coefficient (TEC) can be tailored with variation of Sr and Fe contains [1]. The TEC for GDC and LSCF has values of 11.4×10íKí and 15.3u10-6K1 respectively which are almost equal to one other. Moreover, its ionic conductivity improved with doping of Fe contains. Thus, La 1-x Sr x Co 1-y FeyO 3 doped with 40% of Sr and 80% of Fe satisfies both the criterion. Mostly, the thin film cathode deposit through the SPT due to the simple experimental setup, morphology and stoichiometry of materials can be easily control.
RESULTS AND DISCUSSION Phase identification Fig. 1 indicates the XRD pattern of LSCF thin film deposited at three different temperatures and further annealed at 800 qC for 4 hrs. The reflection peak in this pattern indexed in accordance to the JCPDS (#821961) data which imply the phase pure LSCF forms at all deposition temperature with no extra phases. The lattice parameter calculated for the rhombohedral structure found to be a = b = 5.51Å and c = 13.418Å which are in good agreement with reported one. The peak observed at 2T = 32.5q appears as shoulder peak
EXPERIMENTAL For the preparation of precursor solution, the metal nitrates of La, Sr, Co and Fe were taken in the desired
Solid State Physics AIP Conf. Proc. 1447, 625-626 (2012); doi: 10.1063/1.4710158 © 2012 American Institute of Physics 978-0-7354-1044-2/$30.00
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of (111) originated from substrate. The relative intensity of shoulder peak (104) implies the film deposited at higher temperature shows more crystalline than other and this may be due to enhanced growth mechanism. .
Conductivity Measurement
FIGURE 3. DC conductivity of LSCF film deposited at 200qC, 250qC and 300qC in the range of 50qC - 800qC.
The DC conductivity measurement of LSCF thin film was carried out over the range of 50qC - 800qC, at rate of 3qC/min (Fig. 3). The plot shows the decreasing trends about 300qC attributed toward the reduction behavior of cathode materials. The sample L250 reduces at relatively lower temperature in comparison to L200 and L300. Also, electrical conductivity rapidly increased by two orders of magnitude above the 300qC, indicate the onset of crystallization which establish the long-rang order of Fe-O-Fe bond through which polaron hoping take place [3]. All the film shows the Arrhenius behavior between conductivity and temperature above the 400qC with highest conductivity of 26.6 S/Cm at 700qC for L300 which is still higher than other two.
FIGURE 1. XRD pattern of LSCF thin film deposited on GDC10 substrate at a) 200qC, b) 250qC, c) 300qC.
Scanning Electron Micrograph
CONCLUSIONS The film deposited at 300qC shows higher crystallanity with uniform and dense microstructure. The in plane conductivity measurement implies higher value with lower value of activation energy for the film deposited at higher temperature.
FIGURE 2. SEM images of surface a), b), c) for sample deposited at 200qC, 250qC and 300qC respectively
Deposition of film carried out in the range of 200 to 300qC at the difference of 50qC which is still higher than the boiling point of solvent (water). Thus, there is no problem with the formation of cracks on the surface while removal of trapped water during the annealing [2]. But still rise of deposition temperature over boiling point affects the uniformity and porosity in final microstructure of film. The Fig. 2 a), b), c) shows SEM images of surface of film deposited at 200, 250 and 300qC and heat treated at 800qC for 4 hrs. The fig. 2 a) and b) shows the non-uniform distribution of the particle with observation pores on the surface while the Fig. 2 c) shows the uniform and denser morphology.
ACKNOWLEDGMENT The Authors was grateful toward the UGC for providing financial support through UGC meritorious fellowship.
REFERENCES 1. Yihong Li, Randall Gemmen, Xingbo Liu, J, of Power Source 195 (2010) 3345–3358. 2. D. Beckel, A. Dubach, A. R. Studart, L. J. Gauckler, J. Electroceram (2006) 16:221–228. 3. Bo-Kuai Lai, Kian Kerman, Shriram Ramanathan, J. of Power Source 195 (2010) 5185–5196.
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