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Title: Investigation into the effect of Si doping on the cell symmetry and performance of Sr{sub 1−y}Ca{sub y}FeO{sub 3−δ} SOFC cathode materials

In this paper we report the successful incorporation of silicon into Sr{sub 1−y}Ca{sub y}FeO{sub 3−δ} perovskite materials for potential applications as electrode materials for Solid Oxide Fuel Cells. It is observed that Si doping leads to a change from a tetragonal or orthorhombic structure (with partial ordering of oxygen vacancies) to a cubic one (with the oxygen vacancies disordered). The structures of the phases, SrFe{sub 0.85}Si{sub 0.15}O{sub 3−δ}, Sr{sub 0.75}Ca{sub 0.25}Fe{sub 0.85}Si{sub 0.15}O{sub 3−δ} and Sr{sub 0.5}Ca{sub 0.5}Fe{sub 0.85}Si{sub 0.15}O{sub 3−δ}, were analysed using neutron powder diffraction. The data confirmed the cubic unit cell, with no long range oxygen vacancy ordering. Conductivity measurements showed an improvement in the conductivity on Si doping, especially for samples with high Ca content. Composite electrodes comprising 50% Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} and 50% Sr{sub 1−y}Ca{sub y}(Fe/Si)O{sub 3−δ} on dense Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} pellets were therefore examined in air. An improvement in the area specific resistances (ASR) values is observed for the Si-doped samples with respect to the undoped samples. Thus the results show that silicon can be incorporated into Sr{sub 1−y}Ca{sub y}FeO{sub 3−δ}-based materials and can have a beneficial effect on the performance, making them potentially suitable for use as cathode material inmore » Solid Oxide Fuel Cells (SOFC). - Graphical abstract: X-ray diffraction patterns for: (left) Sr{sub 0.75}Ca{sub 0.25}Fe{sub 1−x}Si{sub x}O{sub 3−δ} (x=0, 0.05, 0.10 and 0.15) and (right) Sr{sub 0.25}Ca{sub 0.75}Fe{sub 1−x}Si{sub x}O{sub 3−δ} (x=0, 0.05, 0.10 and 0.15), showing the stabilization of the cubic form of these series through silicon doping. For the latter Sr{sub 0.25}Ca{sub 0.75}Fe{sub 1−x}Si{sub x}O{sub 3−δ} phase, the stabilisation is not quite complete at 15% Si doping. - Highlights: • In Sr{sub 1−y}Ca{sub y}Fe{sub 1−x}Si{sub x}O{sub 3−δ} materials Si doping results in a change from tetragonal or orthorhombic symmetry. • An improvement in the conductivity is observed on Si doping. • An improvement in the area specific resistances (ASR) values is observed on Si doping. • Silicon can have a beneficial effect on the performance in perovskite materials.« less
Authors:
 [1] ;  [2] ;  [1]
  1. School of Chemistry, University of Birmingham, Birmingham, B15 2TT (United Kingdom)
  2. ISIS Facility, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX (United Kingdom)
Publication Date:
OSTI Identifier:
22334211
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 213; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; CATHODES; DOPED MATERIALS; FERRITE; FERRITES; ORTHORHOMBIC LATTICES; OXYGEN; PEROVSKITE; SILICON; X-RAY DIFFRACTION