Properties of CeO2 (GDC and SDC) Fibers
Gd2O3 and Sm2O3 doped ceria fibers with aspect ratio of 110 were synthesized by
chemical co-precipitate method at 90oC with the addition of citric acid and sodium
hydroxide. With different ratio of sodium hydroxide and citric acid, additional three
types of Ce-contained precipitates were formed, including spherical colloidal particles,
stick-in-bundle, and flakes.
The kinetic reaction of the fiber synthesis was analyzed by ICP-AES technology.
Zero-order reaction of the fiber and stick-in-bundle synthesis was confirmed, in which
the reaction rate coefficient were 1371 ppm/hr and 172 ppm/hr, respectively. With
starting concentration of 0.1 mc of Ce3+, the reaction of fiber synthesis completed in less
than 10 hr. Before the appearance of fiber, there were water soluble colloidal particles
found in reaction bath. With calcination at temperature higher than 300oC, the cubic
ceria phase formed. Crystallinity of the doped ceria fibers was identified by TEM
technology.
Properties of LSM Powders
Two LSM powders were synthesized either by sol-gel routs, including Pechini
132
method (P-LSM) and the method with PAA as gelling agent (A-LSM). For both cases,
the LSM phase formed at calcination temperature higher than 600oC. A carbon
contained phase of La2CO5 was found in P-LSM that thermally treated at 500oC or
600oC. After 700oC calcination, pure LSM phase was obtained for both LSM powders.
The quantitative analysis by SEM-EDS revealed a better chemical composition
distribution and homogeneity of P-LSM powder. The microstructure, however,
indicated a better grain size distribution of A-LSM due to carbon content.
Porous LSM layer with a thickness of 6 μm was fabricated by spray coating. In
order to offer enough interface strength between LSM and YSZ, the sintering
temperature of LSM/YSZ half cell must be higher than 1200oC. The length of TPB was
about 1.5 μm/μm2 after the 1200oC thermal treatment. The residual carbon content was
successfully reduced by careful control of thermal treatment procedure for P-LSM with
thermal treatment at 900oC. After the 1200oC thermal treatment, the residual carbon
content in all the LSM powders was reduced to less than 200 ppm. The ASR between
LSM and YSZ is low, but does not show a strong correlation with the residual carbon..
Fabrication of Electrolyte Supported SOFC Single Cell
A dense 8Y-YSZ electrolyte plate with thickness of 75 μm could be obtained by
133
1500oC sintering. Its activation energy for the diffusion of oxygen was 109 kJ/mole.
Through screen printing, porous LSM cathode layer with 5 μm in thickness and
NiO/YSZ anode in a thickness of 8 μm could be fabricated on the YSZ electrolyte plate
by 1200oC sintering.
134
References
¾ I. Abrahams, A. Kozanecka-Szmigiel, F. Krok, W. Wrobel, S.C.M. Chan, and J.R.
Dygas, “Correlation of defect structure and ionic conductivity in δ-phase solid solutions in the Bi3NbO7-Bi3YO6 system,” Solid State Ionics, 177, 1761-65 (2006)
¾ A. Abreu Jr., S. M. Zanetti, M. A. S. Oliveira, and G. P. Thim, “Effect of urea on lead zirconate titanate-Pb(Zr0.52Ti0.48)O3-nanopowders synthesized by the Pechini method,” J. Eur. Ceram. Soc., 25, 743-8 (2005)
¾ A-M. Azad, T. Matthews, and J. Swary, “Processing and characterization of electrospun Y2O3-stabilized ZrO2 (YSZ) and Gd2O3-doped CeO2 (GDC) nanofibers,” Materials science and engineering B, 123, 252-8 (2005)
¾ G. B. Balazs, and R. S. Glass, “ac impedance studies of rare earth oxide doped ceria,” Solid State Ionics, 76, 155-62 (1995)
¾ E. Barsoukov and J. R. Macdonald, Impedance Spectroscopy Theory, Experiment, and Applications 2ndeddition, Wiley-Interscience, p.170-1 ,2005
¾ F. Chen and M. Liu, “Preparation of yttria-stabilized zirconia (YSZ) films on La0.85Sr0.15MnO3 (LSM) and LSM-YSZ substrates using an electrophoretic deposition (EPD) process,” J. Eur. Ceram. Soc., 21, 127-34 (2001)
¾ K. Chen, Z. Lü, N. Ai, Z. Chen, J. Hu, X. Huang, and W. Su, “Effect of SDC-impregnated LSM cathodes on the performance of anode-supported YSZ films for SOFCs,” J. of Power Sources, 167, 84-9 (2007)
¾ Y.-Y. Chen, and W.-C. J. Wei, “Processing and characterization of ultra-thin yttria-stabilized zirconia (YSZ) electrolytic films for SOFC,” Solid Static Ionics, 177, 351-7 (2006)
¾ Y.-M. Chiang, D. P. Birnie III, and W. D. Kingery, Physical Ceramics Principles for Ceramic Science and Engineering, John Wiley & Sons, Inc., 26, 1997
¾ Y.-M. Chiang, D. P. Birnie III, and W. D. Kingery, Physical Ceramics Principles for Ceramic Science and Engineering, John Wiley & Sns, Inc., 136-9, 1997
¾ B. D. Cullity and S. R. Stock, Elements of X-Ray Diffraction, 3rd edition, Prentice Hall, 167-71, 2001
¾ M. Gaudon, C. Laberty-Robert, F. Ansart, P. Stevens, and A. Rousset, “Preparatoin of characterization of La1-xSrxMnO3+δ (0≤x≤0.6) powder by sol-gel processing,”
Solid State Sciences, 4, 125-33 (2002)
¾ X. Guo, “Physcial origin of the intrinsic grain-boundary resistivity of stabilized-zirconia: Role of the space-charge layers,” Solid State Ionics, 81, 235-42 (1995)
¾ X. Guo, E. Vasco, S. Mi, K. Szot, E. Wachsman, and R. Waser, “Ionic conduction
135
in zirconia films of nanometer thickness,” Acta Materialia, 53, 5161-6 (2005)
¾ X. Guo, S. Wilfried, and M. Joachim, “Blocking Grain Boundaries in Yttria-Doped and Undoped Ceria Ceramics of High Purity,” J. Am. Ceram. Soc., 86 [1] 77-87 (2003)
¾ A. Hagiwara, N. Hobara, K. Takizawa, K. Sato, H. Abe, and M. Naito,
“Microstructure control of SOFC cathodes using the self-organizing behavior of LSM/ScSZ composite powder material prepared by spray pyrolysis,” Solid State Ionics, 178, 1123-34 (2007)
¾ A. Hagiwara, N. Hobara, K. Takizawa, K. Sato, H. Abe, and M. Naito,
“Preparation of LSM/ScSZ composite powder materials by spray pyrolysis for the pre-fabrication of SOFC cathodes,” Solid State Ionics, 178, 1552-62 (2007)
¾ T. P. Harrigan and R. W. Mann, “Characterization of microstructural anisotropy in orthotropic materialsl using a second rank tensor,” J. Mater. Sci., 19, 761-7 (2984)
¾ D. C. Harris, Quantitative Chemical Analysis (Fifth Edition), W. H. Freeman and Company, 74-81, 2001
¾ W. Huang, P. Shuk, and M. Greenblatt, “Hydrothermal Synthesis and Properties of Ce1-xSmxO2-x/2 and Ce1-xCaxO2-x Solid Solutions,” Chem. Mater., 9, 2240-5 (1997)
¾ H.-R. Hsu, Fabrication and characterization of LSM electrode, MS thesis, NTU (2003)
¾ W. P. Hsu, L. Rönnquist, and Egon Matijević, “Preparation and Properties of Monodispersed Colloidal Particles of Lanthanide Compounds. 2. Cerium(IV),”
Langmuir, 4, 31-7 (1988)
¾ H. J. Hwang, J. Moon, M. Awano, and K. Maeda, “Sol-gel rout to porouslanthanum cobalite (LaCoO3) thin films,” J. Am. Ceram. Soc., 83 [11]
2852-4
¾ H. Inaba, H. Tagawa, “Ceria-based solid electrolytes,” Solid State Ionics, 83, 1-16 (1996)
¾ G.-B. Jung, T.-Jen. Huang, and C.-L. Chang, “Effect of temperature and dopant concentration on the conductivity of samaria-doped ceria electrolyte,” J. Solid State Electrochem, 6, 225-30 (2002)
¾ J.A. Kilner, “Fast oxygen transport in acceptor doped oxides,” Solid State Ionics, 129, 13-23 (2000)
¾ W. D. Kingery, H. K. Bowen, and D. R. Uhlmann, Introduction to Ceramics (2nd Edition), Wiley, p.416-7, 1976
¾ T. Kudo, and H. Obayashi, “Mixed Electrical Conduction in the Fluorite-Type Ce1-xGdxO2-x/2,” J. Electrochem. Soc., 123, 415-9 (1976)
136
¾ J. H. Kuo and H. U. Anderson, “Oxidatin-Reduction Behavior of Undoped and Sr-Doped LaMnO3: Defect Structure, Electrical Conductivity, and Thermoelectric Power,” J. Solid State Chem., 87, 55-63 (1990)
¾ L. Minervini, M. O. Zacate, and R. W. Grimes, “Defect cluster formation in M2O3-doped CeO2,” Solid State Ionics, 116, 339-49 (1999)
¾ N. Q. Minh, “Ceramic Fuel Cells,” J. Am. Ceram. Soc., 76 [3] 563-88 (1993)
¾ M. Mogensen, N. M. Sammes, and G. A. Tompsett, “Physical, chemical and electrochemical properties of pure and doped ceria,” Solis State Ionics, 129, 63-94 (2000)
¾ M. Mori, Y. Hiei, T. Yamamoto, and H. Itoh, “Lanthanum Alkaline-Earth Manganitets as a Cathode Material in High-Temperature Solid Oxide Fuel Cells,” J.
Electrochem. Soc., 146 [11] 4041-7 (1999)
¾ M. Ohnuki, K. Fujimoto, and S. Ito, “Preparation of high-density La0.90Sr0.10Ga1-yMgyO3-δ (y=0.20 and 0.30) oxide ionic conductors using HIP,”
Solid State Ionics, 177, 1729-32 (2006)
¾ M. J. L. Østergård, C. Clausen, C. Bagger, and M. Mogensen, “Manganite-Zirconia Composite Cathode for SOFC: Influence of Structure and Composition,”
Electrochim Acta, 40 [12] 1971-81 (1995)
¾ J. W. Patterson, “Conduction Domains for Solid Electrolytes,” J. Electrochem. Soc., 118, 1033-9 (1971)
¾ M. Pechini, “Method of Preparing Lead and Alkaline-Earth Titanates and Niobates and Coating Method Using The Same to Form A Capacitor,” U.S. Pat. No.
3330697 (1967)
¾ R. Peng, C. Xia, Q. Fu, G. Meng, and D. Peng, “Sintering and electrical properties of (CeO2)0.8(Sm2O3)0.1 powders prepared by glycine-nitrate process,” Materials Letters, 56, 1043-7 (2002)
¾ S. Pignard, H. Vincent, J. P. Sénateur, and P. H. Giauque, “Chemical vapor deposition and structural study of La0.8MnO3-δ thin films,” Thin Solid Films, 347, 161-6 (1999)
¾ F. W. Poulsen, “Defect chemistry modeling of oxygen-stoichiometry, vacancy concentrations, and conductivity of (La1-xSrx)yMnO3+δ,” Solid State Ionics, 129, 145-62 (2000)
¾ J. M. Ralph, J. Przydatek, J. A. Kilner, and T. Seguelong, “Novel Doping Systems in Ceria,” Ber. Bunsenges. Phys. Chem., 101, 1403-7 (1997)
¾ J. I. M. Rupp, A. Infortuna, and L. J. Gauckler, “Thermodynamic Stability of Gadlinia-Doped Ceria Thin Film Electrolytes for Micro-Solid Oxide Fuel Cells,” J.
137
Am. Ceram. Soc., 90 [6] 1792-7 (2007)
¾ R. D. Shannon, “Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides,” Acta Cryst., A32, 751-67 (1976)
¾ A. Sin, Yu. Dubitsky, A. Zaopo, A.S. Arico, L. Gullo, D. La Rosa, S. Siracusano, V.
Antonucci, C. Oliva, and O. Ballabio, “Preparation and sintering of Ce1-xGdxO2-x/2
nanopowders and their electrochemical and EPR characterization,” Solid State Ionic, 175, 361-6 (2004)
¾ S. C. Singhal, and K. Kendall, High Temperature Solid Oxide Fuel Cells:
Fundamentals, Design and Applications, Elsevier Science, 81-94, 2003
¾ S. C. Singhal, and K. Kendall, High Temperature Solid Oxide Fuel Cells:
Fundamentals, Design and Applications, Elsevier Science, 91, 2003
¾ S. C. Singhal, and K. Kendall, High Temperature Solid Oxide Fuel Cells:
Fundamentals, Design and Applications, Elsevier Science, p.229-50, 2003
¾ S. C. Singhal, and K. Kendall, High Temperature Solid Oxide Fuel Cells:
Fundamentals, Design and Applications, Elsevier Science, 238, 2003
¾ S. C. Singhal, “Advances in solid oxide fuel cell technology,” Solid State Ionics, 135, 305-13 (2000)
¾ S. J. Skinner, and J. A. Kilner, “Oxygen ion conductors,” Materials Today, 6 [3]
30-7 (2003)
¾ T. Suzuki, I. Kosacki, and H. U. Anderson, “Microstructure-electrical conductivity relationships in nanocrystalline ceria thin films,” Solid State Ionics, 151, 111-21 (2002)
¾ H. L. Tuller, and A. S. Nowick, “Doped Ceria as a Solid Oxide Electrolyte,” J.
Electrochem. Soc., 2, 255-9 (1975)
¾ U.S. Department of Energy, Office of Fossil Energy, and National Energy Technology Laboratory, Fuel Cell Handbook (seventh Edition), EG&G Technical Services, Inc., p.1-12, 2004
¾ J. A. M. van Roosmalen, P. van Vlaanderen, and E. H. P. Cordfunke, “Phases in the Perovskite-Type LaMnO3+δ Solid Solution and the La2O3-MnO3 Phase Diagram,” J.
Solid State Chem., 114, 516-23 (1995)
¾ Y. Wang, T. Mori, J-G. Li, and Y. Yajima, “Low-temperature fabrication and electrical property of 10 mol% Sm2O3-doped CeO2 ceramics,” Science and Technology of Advanced Materials, 4, 229-38 (2003)
¾ H. Xu, D-H. Qin, Z. Yang, and H-L Li, “Fabrication and characterization of highly ordered zirconia nanowire arrays by sol-gel template method,” Mater. chem. phys.,
138
80, 524-8 (2003)
¾ H. Yahiro, Y. Eguchi, K. Eguchi, and H. Aria, “Oxygen ion conductivity of ceria-samarium oxide system,” J. Appl. Electrochem., 18, 527-31 (1988)
¾ H. Yahiro, Y. Eguchi, K. Eguchi, and H. Arai, “Oxygen ion conductivity of the ceria-samarium oxide system with fluorite structure,” J. Appl. Electrochem., 18, 527-31 (1988)
¾ H. Yahiro, T. Ohuchi, K. Eguchi, and H. Arai, “Electrical properties and microstructure in the system ceria-alkaline earth oxide,” J. Mater. Sci., 23, 1036-41 (1988)
¾ J. Yan, Z. Hou, and K.-L. Choy, “The electrochemical properties of LSM-based cathodes fabricated by electrostatic spray assisted vapour deposition,” J. Power Sources, 180, 373-9 (2008)
¾ C.-C. T. Yang, Processing and Characterization of High Temperature Interfacial Reactions of Electrolytic Ceramics and Electrodes of Planar Solid Oxide Fuel Cells (SOFCs), PhD thesis, NTU (2003)
¾ C-C. T. Yang, W-C. J. Wei, and A. Roosen, “Electrical conductivity and microstructures of La0.65Sr0.3MnO3-8 mol% yttria-stabilized zirconia,” Mater.
Chem. phys., 81, 132-42 (2003)
¾ X. Yang, C. Shao, Y. Liu, R. Mu, and H. Guan, “Nanofibers of CeO2 via an electrospinning technique,” Thin solid films, 478, 228-31 (2005)
¾ H.-C. Yu and K.-Z. Fung, “Electrode properties of La1-xSrxCuO2.5-δ as new cathode materials for intermediate-temperature SOFCs,” J. Power Sources, 133, 162-8 (2004)
¾ S. Zha, C. Xia, and G. Meng, “Effect of Gd (Sm) doping on properties of ceria electrolyte for solid oxide fuel cells,” J. Power Sources, 115, 44-8 (2003)
¾ H. B. Zhang, and M. J. Edirishinghe, “Electrospinning Zirconia Fiber From a Suspension,” J. Am. Ceram. Soc., 89 [6] 1870-75 (2006)
¾ T. S. Zhang, J. Ma, H. Cheng, and S.H. Chan, “Ionic conductivity of high-purity Gd-doped ceria solid solutions,” Mater. Res. Bull., 41, 563-8 (2006)
¾ X. Zhang, M. Robertson, C. Deĉes-Petit, W. Qu, O. Kesler, R. Maric, and D.
Ghosh, “Internal shorting and fuel loss of a low temperature solid oxide fuel cell with SDC electrolyte,” J. Power Sources, 164, 668-77 (2007)
¾ K. Zhou, X. Wang, X. Sun, Q. Peng, and Y. Li, “Enhanced catalytic activity of ceria nanorods from well-defined reactive crystal planes,” J. catal., 229, 206-12 (2005)