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Composite oxide ionic conductors consisting of Zr0.85Y0.15O1.925 (YSZ) and La9.33Si6O26 (LSO) have been synthesized by a modified coprecipitation method. X-ray diffraction, electron microscope, and complex impedance were adopted to investigate the phase component, microstructures, and conductivities, respectively. The results show that the average grain sizes of the composite powders and as-sintered pellets are less than 20 nm and 200 nm, respectively. The conductivity of the composite materials composed of 94 wt% YSZ and 6 wt% LSO is 0.215 S/cm at 700 ℃. The conductivity of the composite is three times higher than that of the polycrystalline YSZ and has two orders in magnitude higher than that of the polycrystalline LSO at 700 ℃. By analyzing the impedance spectra and modulus spectra, the grain-boundary effect on the conductivity improvement is investigated and the conductive mechanisms of the composite materials are discussed.


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Synthesis and characterization of Zr0.85Y0.15O1.925-La9.33Si6O26 composite electrolyte for application in SOFCs

Show Author's information Chaofeng LIUaHong ZHANGaJunxiao XIAaZhicheng LIa,b,*( )
School of Materials Science and Engineering, Central South University, Changsha 410083, China
State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China

Abstract

Composite oxide ionic conductors consisting of Zr0.85Y0.15O1.925 (YSZ) and La9.33Si6O26 (LSO) have been synthesized by a modified coprecipitation method. X-ray diffraction, electron microscope, and complex impedance were adopted to investigate the phase component, microstructures, and conductivities, respectively. The results show that the average grain sizes of the composite powders and as-sintered pellets are less than 20 nm and 200 nm, respectively. The conductivity of the composite materials composed of 94 wt% YSZ and 6 wt% LSO is 0.215 S/cm at 700 ℃. The conductivity of the composite is three times higher than that of the polycrystalline YSZ and has two orders in magnitude higher than that of the polycrystalline LSO at 700 ℃. By analyzing the impedance spectra and modulus spectra, the grain-boundary effect on the conductivity improvement is investigated and the conductive mechanisms of the composite materials are discussed.

Keywords: Zr0.85Y0.15O1.925, La9.33Si6O26, composite materials, coprecipitation synthesis, oxygen ionic conductivity

References(21)

[1]
Steele BCH. Fuel-cell technology: Running on natural gas. Nature 1999, 400:619-621.
[2]
Zhang H, Zhang Z, Ma GQ, et al. Copercipitation synthesis and oxide onic conductivities of Ce0.8Sm0.2O1.9 based nanocomposite materials. J Inorg Mater 2009, 24:353-356
[3]
Sanna S, Esposito V, Tebano A, et al. Enhancement of ionic conductivity in Sm-doped ceria/yttria-stabilized zirconia heteroepitaxial structures. Small 2010, 6:1863-1867.
[4]
Azad SM, Wang OA, Saraf CM, et al. Nanoscale effects on ion conductance of layer-by-layer structures of gadolinia-doped ceria and zirconia. Appl Phys Lett 2005, 86:131906-131908.
[5]
Souza F. Sol-gel nonhydrolytic synthesis of a hybrid organic-inorganic electrolyte for application in lithium-ion devices. Solid State Ionics 2004, 166:83-88.
[6]
Garcia-Barriocanal J, Rivera-Calzada A, Varela M, et al. Colossal ionic conductivity at interfaces of epitaxial ZrO2:Y2O3/SrTiO3 heterostructures. Science 2008, 321:676-680.
[7]
Sillassen M, Eklund P, Pryds N, et al. Low-temperature superionic conductivity in strained yttria-stabilized zirconia. Adv Funct Mater 2010, 20:2071-2076
[8]
Reyren N, Thiel S, Caviglia AD, et al. Superconducting interfaces between insulating oxides. Science 2007, 317:1196-1199.
[9]
Li S, Li ZC, Bergman B. Lanthanum gallate and ceria composite as electrolyte for solid oxide fuel cells. J Alloy Compd 2010, 492:392-395.
[10]
Xu D, Liu XM, Wang DJ, et al. Fabrication and characterization of SDC-LSGM composite electrolytes material in IT-SOFCs. J Alloy Compd 2007, 429:292-295.
[11]
Chockalingam R, Chockalingam S, Amarakoon VRW. The electrical properties of microwave sintered gadolinia doped ceria-alumina nano-composite electrolyte. J Power Sources 2011, 196:1808-1817.
[12]
Mizutani Y, Tamura M, Kawai M. Development of high-performance electrolyte in SOFC. Solid State Ionics 1994, 72:271-275.
[13]
Wang Q, Peng R, Xia C, et al. Characteristics of YSZ synthesized with a glycine-nitrate process. Ceramics International 2008, 34:1773-1778.
[14]
Tolchard JR, Slater PR, Islam MS. Enhanced ionic conductivity in Ce0.8Sm0.2O1.9: Unique effect of calcium co-doping. Adv Funct Mater 2007, 17:2847-2854.
[15]
Guo C, Cai T, Zhang W, et al. Synthesis and characterization of Al3+-doped La9.33Ge6O26 intermediate temperature electrolyte for SOFCs. Mater Sci Eng B 2010, 171:50-55.
[16]
Zhang H, Li ZC, Bergman B, et al. Investigation of La9.33Si6O26 oxygen ionic conductor. J Mater Sci Tech 2007, 23:629-632.
[17]
Chefia S, Madani A, Boussetta H, et al. Electrical properties of Al-doped oxyapatites at intermediate temperature. J Power Sources 2008, 177:464-467.
[18]
Tian CG, Liu JL, Cai J, et al. Direct synthesis of La9.33Si6O26 ultrafine powder via sol-gel self-combustion method. J Alloys Compd 2008, 458:378-382.
[19]
Gerhardt R. Impedance and dielectric spectroscopy revisited: Distinguishing localized relaxation from long-range conductivity. J Phys Chem Solids 1994, 55:1491-1506.
[20]
Henn FEG, Buchanan RM, Jiang N, et al. Permittivity and AC conductivity in yttria-stabilized zirconia. Appl Phys A 1995, 60:515-519.
[21]
Copel M, Cartier E, Ross FE. Formation of a stratified lanthanum silicate dielectric by reaction with Si(001). Appl Phys Lett 2001, 78:1607-1069.
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Received: 16 November 2012
Revised: 09 December 2012
Accepted: 11 December 2012
Published: 09 January 2013
Issue date: December 2012

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© The author(s) 2012

Acknowledgements

The authors acknowledge the support of the National Nature Science Foundation of China (Nos. 50872155 and 51172287). Much thanks to Dr. Haitao ZHOU for his useful information about this work. The first author also acknowledges the close discussion with Mr. Kaiming ZHANG and Mr. Hui YU.

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