Investigation on the Sr-doped ceria Ce1-xSrO2-delta (x=0.05-0.2) as an electrolyte for intermediate temperature SOFC

The effect of Sr doping in CeO2 for its use as solid electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been explored here. Ce1-xSrxO2-delta (x = 0.05-0.2) are successfully synthesized by citrate-complexation method. XRD, Raman, FT-IR, FE-SEM/EDX and electrochemical impedance spectra are used for structural and electrical characterizations. The formation of well crystalline cubic fluorite structured solid solution is observed for x = 0.05 based on XRD and Raman spectra. For compositions i.e., x > 0.05, however, a secondary phase of SrCeO3 is confirmed by the peak at 342 cm(-1) in Raman spectra. Although the oxygen ion conductivity was found to decrease with increase in x, based on ac-impedance studies, conductivity of Ce0.95Sr0.05O2-delta was found to be higher than of Ce0.95Gd0.1O2-delta and Ce0.8Gd0.2O2-delta. The decrease in conductivity of Ce1-xSrxO2-delta with increasing dopant concentration is ascribed to formation of impurity phase SrCeO3 as well as the formation of neutral associated pairs, Se `' Ce V-o. The activation energies are found to be 0.77, 0.83, 0.85 and 0.90 eV for x = 0.05, 0.1, 0.15 and 0.20, respectively. (C) 2014 Elsevier B.V. All rights reserved.

Citrate-complexation synthesized Ce0.85Gd0.15O2-delta (GDC15) as solid electrolyte for intermediate temperature SOFC

A typical Ce0.85Gd0.15O2-delta (CDC15) composition of CeO2-Gd2O3 system is synthesized by modified sol - gel technique known as citrate-complexation. TG-DTA, XRD, FT-IR, Raman, FE-SEM/EDX and ac impedance analysis are carried out for structural and electrical characterization. XRD pattern confirmed the well crystalline cubic fluorite structure of CDC15 after calcining at 873 K. Raman spectral bands at 463, 550 and 600 cm(-1) are also in agreement with these structural features. FE-SEM image shows well-defined grains separated from grain boundary and good densification. Ac impedance studies reveal that GDC15 has oxide ionic conductivity similar to that reported for Ce0.9Gd0.1O2-delta (GDC10) and Ce0.8Gd0.2O2-delta (GDC20). Ionic and electronic transference numbers at 673 K are found to be 0.95 and 0.05, respectively. This indicates the possible application of GDC15 as a potential electrolyte for IT-SOFCs. (C) 2014 Elsevier B.V. All rights reserved.

Desarrollo de capas de contacto para su aplicación en SOFC

256 p.+anexos

Influence of synthetic method on the properties of La0.5Ba0.5FeO3 SOFC cathode

Power Point presentado en The Energy and Materials Research Conference - EMR2015 celebrado en Madrid (España) entre el 25-27 de febrero de 2015

Stabilization of a complex perovskite superstructure under ambient conditions: Influence of cation composition and ordering, and evaluation as an SOFC cathode

Ba1.6Ca2.3Y1.1Fe5O13 is an Fe3+ oxide adopting a complex perovskite superstructure, which is an ordered intergrowth between the Ca2Fe2O5 and YBa2Fe3O8 structures featuring octahedral, square pyramidal, and tetrahedral B sites and three distinct A site environments. The distribution of A site cations was evaluated by combined neutron and X-ray powder diffraction. Consistent with the Fe3+ charge state, the material is an antiferromagnetic insulator with a Néel temperature of 480-485 °C and has a relatively low d.c. conductivity of 2.06 S cm-1 at 700 °C. The observed area specific resistance in symmetrical cell cathodes with the samarium-doped ceria electrolyte is 0.87 Ω cm2 at 700 °C, consistent with the square pyramidal Fe3+ layer favoring oxide ion formation and mobility in the oxygen reduction reaction. Density functional theory calculations reveal factors favoring the observed cation ordering and its influence on the electronic structure, in particular the frontier occupied and unoccupied electronic states. © 2010 American Chemical Society.