Reverse uptake of oxygen from La1-xSrx (Fe3+/Fe4+)O-3 +/-delta perovskite-type mixed oxides (x=0.00, 0.15, 0.30, 0.40, 0.60, 0.70, 0.80, 0.90)

 
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2003 (EN)
Reverse uptake of oxygen from La1-xSrx (Fe3+/Fe4+)O-3 +/-delta perovskite-type mixed oxides (x=0.00, 0.15, 0.30, 0.40, 0.60, 0.70, 0.80, 0.90) (EN)

Leontiou, A. A. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Leontiou, A. A. (EN)

Substituted perovskite-type mixed oxides of the general formula La1-xSrx(Fe3+/Fe4+)O3+/-6 were prepared for x = 0.00, 0.15, 0.30, 0.40, 0.60, 0.70, 0.80, and 0.90 by the ceramic method and heating at 1000degreesC. The prepared solids were examined by X-ray diffractogram (XRD) for their crystal structure and by Mossbauer spectroscopy at RT for the kind and the exact amount of iron containing crystal phases. The gradual substitution of La3+ by Sr2+ results in a quantitative development of the crystal phase SrFe4+O3 and the corresponding diminution of the rest phases containing iron, i.e. LaFeO3 and Fe2O3 (traces). Detailed thermogravimetric O-2/temperature-programmed desorption (TPD) experiments showed that the solids release oxygen when heated in a He atmosphere which is strictly proportional to the amount of Fe4+ in the samples. Quantitative calculations showed that exactly one atom of oxygen is released per unit cell of Sr-Fe-O perovskite, which contains four Sr(Fe4+/Fe3+)O3+/-delta units. The phenomenon is reversible and the solids re-adsorb fast and quantitatively the lost lattice oxygen when gaseous oxygen is admitted back to the system. (C) 2002 Elsevier Science B.V. All rights reserved. (EN)

la1-xsrx(fe+3/fe+4)o-3 +/-delta (EN)

Πανεπιστήμιο Ιωαννίνων (EL)
University of Ioannina (EN)

Applied Catalysis a-General (EN)

English

2003

<Go to ISI>://000181260400012

Elsevier (EN)



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