Effect of the A Cation Size Disorder on the Properties of an Iron Perovskite Series for Their Use as Cathodes for SOFCs
✍ Scribed by K. Vidal; L. M. Rodríguez-Martínez; L. Ortega-San-Martín; M. L. Nó; T. Rojo; M. I. Arriortua
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 392 KB
- Volume
- 11
- Category
- Article
- ISSN
- 1615-6846
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✦ Synopsis
Abstract
In order to develop a cathode that can be used in intermediate temperature solid oxide fuel cells, a family of iron perovskites with the general formula Ln~0.5~M~0.5~FeO~3–δ~ (A = Ln~1–~~x~M~x~; Ln = La, Nd and/or Pr; M = Sr, Ca or/and Ba) with fixed divalent dopant concentration x to 0.5, mean A cation radius 〈r~A~〉 to 1.25 Å but with different A cation size disorder σ^2^(r~A~) has been prepared by the conventional solid state reaction. These compounds have been characterised by power X‐ray diffraction (XRD), high‐resolution scanning electron microscopy (SEM), electrical conductivity, I–V measurements and AC impedance spectroscopy. All the samples have a rhombohedral crystal structure (space group: __R‐3__c). SEM images show that the average grain size increases with increasing σ^2^(r~A~) in the bulk samples. The DC four‐probe measurements indicate that electrical conductivity is strongly dependent on the σ^2^(r~A~). Electrochemical impedance spectra at 700 and 800 °C revealed that better electrochemical cathode performances are for samples with smaller values of σ^2^(r~A~).