Er and Gd Co-Doped Ceria-Based Electrolyte Materials for IT-SOFCs Prepared by the Cellulose-Templating Method
- PDF / 2,761,965 Bytes
- 11 Pages / 593.972 x 792 pts Page_size
- 72 Downloads / 174 Views
SOLID oxide fuel cells (SOFCs) are the most efficient devices that convert the chemical energy of a fuel into electrical energy in a clean and cost-effective route. The cells have a high efficiency and large fuel flexibility at high temperatures. In general, conventional SOFC systems that use, the conventional SOFC electrolyte, yttriastabilized zirconia (YSZ) as an electrolyte for their high conversion efficiency are operated at around 1273 K (1000 C).[1,2] Operating at high temperatures 1273 K (1000 C) has some difficulties such as interfacial reaction between the components, mechanical and thermal degradation, thermal expansion mismatch, and high cost materials. It is thus necessary to lower the operating temperature of the SOFCs. It is known that the replacement of YSZ electrolyte by the doped ceria which shows high ionic conductivity at low temperatures is one of the most promising methods for lowering the operating temperature.[3] The ionic conductivity of ceria increases significantly with the oxygen vacancies created by the doping of rare-earth cations into the ceria lattice. The ionic conductivity of doped ceria at 1023 K (750 C) is similar to that of YSZ at 1273 K (1000 C).[4] Among the various dopants used, Sm3+, Dy3+, and Gd3+ are favorable for increasing the ionic conductivity.[4,5] The literature reports show that GDC exhibits best of the high ALIYE ARABACI, Assistant Professor, is with the Department of Metallurgical Engineering, Faculty of Engineering, Istanbul University, Avcilar, 34320 Istanbul, Turkey. Contact e-mail: aliye@istanbul. edu.tr VEDAT SARIBOG˘A, Ph.D. Candidate, and M.A. FARUK O¨KSU¨ZO¨MER, Associate Professor, are with the Department of Chemical Engineering, Faculty of Engineering, Istanbul University. Manuscript submitted March 17, 2014. Article published online July 17, 2014 METALLURGICAL AND MATERIALS TRANSACTIONS A
ionic conductivity as SOFC electrolyte materials.[6,7] Furthermore, Kuharuangrong[4] reported that an increasing amount of Er from 10 to 20 mol pct reduces the conductivity of ceria and results in a separated phase of Er2O3 as detected by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Therefore, in the present work, the maximum amount of Er was selected to be 10 mol pct. In addition, Jamshidijam et al.[8] studied the characterization of some selected rare-earth (RE)doped ceria nanopowders such as Ce0.9Gd0.1O1.95, Ce0.9Sm0.1O1.95, Ce0.9Er0.1O1.95, Ce0.9Pr0.1O1.95, Ce0.9Nd0.1O1.95, and Ce0.9Y0.1O1.95 prepared via citric acid– nitrate combustion reaction. It is well known that co-doping is an effective way for improving the conductivity of ceria-based electrolyte. In addition, to further improve the ionic conductivity, codoped samples such as Ce0.85 Gd0.1Mg0.05O1.9, Ce0.8Gd0.2xPrxO1.9, Ce0.8 Ce1aGdaySmyO20.5a, Sm0.2xYxO1.9, Ce1xySmxLayO2z, and Ce0.8La0.1 Y0.1O1.9 have been studied.[9–14] However, to the best of our knowledge, there are no detailed studies in the literature about the Ce0.9xGd0.1ErxO1.95x/2. To obtain ceria-based electrolytes, various tech
Data Loading...
