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Título: | Oxygen Nonstoichiometry, Mixed Conductivity, and Mössbauer Spectra of Ln0.5A0.5FeO3−δ (Ln = La−Sm, A = Sr, Ba): Effects of Cation Size | Autor: | Kharton, Vladislav V. Kovalevsky, Andrei V. Patrakeev, Mikhail V. Tsipis, Ekaterina V. Viskup, Alexandre P. Kolotygin, Vladislav A. Yaremchenko, Aleksey A. Shaula, Aliaksandr L. Kiselev, Evgeny A. Waerenborgh, João C. |
Data: | 28-Out-2008 | Editora: | American Chemical Society | Citação: | Chemistry of Materials. 20:20 (2008) 6457-6467 | Resumo: | Increasing the difference of the Ln3+ and A2+ cation radii in perovskite-type Ln0.5A0.5FeO3−δ (Ln = La, Pr, Nd, Sm; A = Sr, Ba) results in higher oxygen deficiency and lower oxygen-ionic and p-type electronic conductivities, determined using the oxygen permeation and total conductivity measurements at 973−1223 K. The relationships between the anion transport and A-site cation size mismatch remain essentially similar in air and under reducing conditions when most iron cations become trivalent, thus confirming critical influence of oxygen-vacancy trapping processes induced by the lattice strain. At low temperatures, analogous correlation is also observed for quadrupole splittings derived from the Mssbauer spectra of oxygen-stoichiometric Ln0.5A0.5FeO3. Contrary to the ionic conductivity variations, the role of surface exchange kinetics as a permeation-limiting factor, evaluated from the membrane thickness dependence of oxygen fluxes, tends to decrease on Ba2+ doping and on decreasing Ln3+ size in Ln0.5Sr0.5FeO3−δ series. The n-type electronic conduction and low-p(O2) stability at 1223 K are substantially unaffected by the cation radius mismatch. | URI: | https://hdl.handle.net/10316/10571 | ISSN: | 0897-4756 | DOI: | 10.1021/cm801569j | Direitos: | openAccess |
Aparece nas coleções: | FCTUC Eng.Mecânica - Artigos em Revistas Internacionais |
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Oxygen Nonstoichiometry, Mixed Conductivity, and Mössbauer.pdf | 580.48 kB | Adobe PDF | Ver/Abrir |
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