Sains Malaysiana 38(6)(2009): 857–861

Pencirian Mikrostruktur Katod La-Sr-Co-Fe-O bagi Sel Fuel Oksida

Pepejal Bersuhu Sederhana (IT-SOFC )

(Microstructure Characterization of La-Sr-Co-Fe-O Cathode for Intermediate

Temperature Solid Oxide Fuel Cell (IT-SOFC))

Noorashrina A. Hamid, Andanastuti Muchtar, Wan Ramli Wan Daud* & Norhamidi Muhamad

Institut Sel Fuel, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor, D.E., Malaysia

Diserahkan: 14 Januari 2009 / Diterima: 27 April 2009

ABSTRAK

Oksida perovskit La_1-xSr_xCo_0.2Fe_0.8O_3-δ (LSCF) dengan x = 0.3-0.5 telah dihasilkan melalui kaedah sol-gel. Ia merupakan pengalir berion campuran yang sangat baik sebagai bahan katod untuk sel fuel oksida pepejal bersuhu sederhana (IT-SOFC). Serbuk yang terhasil dicirikan dengan menggunakan teknik pembelauan sinar-X (XRD) dan keputusannya menunjukkan bahawa hablur perovskit yang tulen terhasil sepenuhnya setelah dikalsin pada suhu 900^oC. Kesan suhu pensinteran ke atas pelet LSCF dikenal pasti dengan menggunakan Mikroskop Elektron Imbasan (SEM). Keputusan menunjukkan bahawa perovskit LSCF mempunyai keliangan yang optimum sebanyak 30% setelah disinter pada suhu 900 ^oC. Keliangan optimum ini membolehkan tindak balas penurunan oksigen berlaku dengan lebih mudah. Analisis FTIR yang dijalankan menunjukkan kehadiran ikatan Fe-O dalam serbuk LSCF dan tiada bendasing yang wujud dalam serbuk LSCF.

Kata kunci: Lantanum strontium kobalt ferit oksida (LSCF); pencirian mikrostruktur; suhu pensinteran; sel fuel oksida pepejal (SOFC)

ABSTRACT

Perovskite oxide La_1-xSr_xCo_0.2Fe_0.8O_3-δ (LSCF) with x = 0.3-0.5, an excellent mixed-ionic conductor that can be used as cathode material for the intermediate temperature solid oxide fuel cell (IT-SOFC) has been developed using the sol-gel method. The resulting powder was characterised using X-Ray Diffraction (XRD) which showed that pure crystals of perovskite were fully formed after calcination at 900 ^oC. The effect of sintering temperature on the microstructure was observed using Scanning Electron Microscopy (SEM) analysis. The results showed that the LSCF perovskite have the optimum porosity of 30% after sintered at 900 ^oC and thus enable the oxygen reduction occurred easily. FTIR results revealed that only Fe-O bond exists in the LSCF powder and no impurities detected.

Keywords: Lanthanum strontium cobalt ferrite (LSCF); microstructure characterisation; sintering temperature; solid oxide fuel cell (SOFC)

RUJUKAN

Baqué, L. & Serquis, A. 2007. Microstructural characterization of La0.4Sr0.6Co0.8Fe0.2O3–δ films deposited by dip coating. Applied Surface Science 254: 213-218.

Brinker, C.J. 1990. Sol-gel science, the physics and chemistry of sol-gel processing. New York: Academic Press.

Eguchi, K. 1997. Ceramic Materials Containing Rare Earth Oxides for Solid Oxide Fuel Cells. Journal of Alloys and Compound 250: 486.

Jiang, S.P., Love, J.G., Zhang, J.P., Hoang, M., Ramprakash, Y., Hughes, A.E. & Badwal, S.P.S. 1999. The electrochemical performance of LSM/zirconia–yttria interface as a function of a-site non-stoichiometry and cathodic current treatment. Solid State Ionics 121 : 1-10.

Jin, W., Li, S., Huang, P., Xu, N. & Shi, J. 2000. Fabrication of La0.8Sr0.2Co0.8Fe0.2O3 mesoporous membrane on porous support from polymeric precursors. Journal of Membrane Science 170: 9-17.

Leng, Y.J., Chan, S.H. & Liu, Q.L. 2008. Development of LSCF-GDC composite cathodes for low-temperature solid oxide fuel cells with thin film GDC electrolyte International Journal of Hydrogen Energy 33: 3808-3817.

Li, K., Wu, F., Wang, D., Xie, T. & Li, T. 2001. Electron behavior and photoelectric gas-sensitive characters of nanocrystalline La1-xSrxFeO3. Materials Chemistry and Physics 71: 34-39.

Liu, S., Qian, X. & Xioa, J. 2007. Synthesis and characterization of La0.8Sr0.2Co0.5Fe0.5O3± δ nanopowders by microwave assisted sol-gel route. Journal of Sol-Gel Science Technology 44: 187-193.

Mogenson, M., Jensen, K. V., Jorgensen, M. J. & Primdahl, S. 2002. Progress in Understanding Solid Oxide Fuel Cells Electrodes. Solid State Ionics 150: 123.

Murata, K., Fukui, T., Abe, H., Naito, M. & Nogi, K. 2005. Morphology control of La(Sr)Fe(Co)O3-a cathodes for IT-SOFCs. Journal of Power Sources 145: 257-261.

Qiu, L., Ichikawa, T., Hirano, A., Imanishi, N. and Takeda, Y.,2002. Ln1−xSrxCo1−yFeyO3−δ (Ln=Pr, Nd, Gd; x=0.2, 0.3) for the electrodes of solid oxide fuel cells. Solid State Ionics 158: 55-65.

Tai, L. W., Nasrallah, M. M., Anderson, H. U., Sparlin, D. M., Sehlin, S. R. 1995. Structure and electrical properties of La_1-xSr_xCo_1-yFe_yO₃. Part 1. The system La0.8Sr0.2Co1-yFeyO3. Solid State Ionics 76: 259-271.

Stoichniol, G., Syskakis, E., Naoumidis, A. 1995. Chemical compatibility between strontium-doped lanthanum manganite and yttria-stabilized zirconia. Journal of American Ceramic Society 78: 929-932.

Wenshi, P. & Gaokui, L. 1982. Theoretical analyses of the infrared spectrum of baiyuneboite-(Ce). Chinese Journal of Geochemistry 9: 137-142.

Yamamoto, O., Takeda, Y., Kanno, R. & Noda, M. 1987. Perovskite-type oxides as oxygen electrodes for high temperature oxide FC. Solid State Ionics 22: 241-246.

*Pengarang untuk surat-menyurat; email: wramli@vlsi.eng.ukm.my