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Mixed conductivity and Mössbauer spectra of (La0.5Sr0.5)1− x Fe1− y Al y O3− δ (x=0–0.05, y=0–0.30)
- Source :
-
Journal of Solid State Chemistry . Apr2006, Vol. 179 Issue 4, p1273-1284. 12p. - Publication Year :
- 2006
-
Abstract
- Abstract: Aluminum incorporation in the rhombohedrally distorted perovskite lattice of (La0.5Sr0.5)1− x Fe1− y AlyO3− δ (, ) decreases the unit cell volume and partial ionic and p-type electronic conductivities, while the oxygen nonstoichiometry and thermal expansion at 900–1200K increase on doping. The creation of A-site cation vacancies has an opposite effect on the transport properties of Al-substituted ceramics. The maximum A-site deficiency tolerated by the (La,Sr)(Fe,Al)O3− δ structure is however limited, close to 3–4%. The Mössbauer spectroscopy revealed progressive localization of electron holes and a mixed charge-compensation mechanism, which results in higher average oxidation state of iron when Al3+ concentration increases. The average thermal expansion coefficients of (La0.5Sr0.5)1− x Fe1− y Al y O3− δ are (12.2–13.0)×10−6 K−1 at 300–900K and (20.1–30.0)×10−6 K−1 at 900–1200K in air. The steady-state oxygen permeability (OP) of dense Al-containing membranes is determined mainly by the bulk ionic conductivity. The ion transference numbers at 973–1223K in air, calculated from the oxygen permeation and faradaic efficiency (FE) data, vary in the range 1×10−4–3×10−3, increasing with temperature. [Copyright &y& Elsevier]
- Subjects :
- *ALUMINUM
*PEROVSKITE
*STOICHIOMETRY
*MOSSBAUER spectroscopy
Subjects
Details
- Language :
- English
- ISSN :
- 00224596
- Volume :
- 179
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Journal of Solid State Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 20180935
- Full Text :
- https://doi.org/10.1016/j.jssc.2006.01.037