Characterisation of the reduction properties of La0.5Sr0.5Fe0.5Co0.5O3

摘要

We report here on the characterisation by temperature programmed reduction, Fe-57 Mossbauer spectroscopy and X-ray absorption spectroscopy of the phases resulting from treatment of the perovskite-related material La0.5Sr0.5Fe0.5Co0.5O3 in a flowing 90 hydrogen/10 nitrogen atmosphere. The results show that treatment of La0.5Sr0.5Fe0.5Co0.5O3 (which contains approximately 50 Fe4+ and 50 Fe3+) in the flowing 90 hydrogen/10 nitrogen atmosphere at 600 degrees C does not result in the reduction of any of the constituent elements of the material and that the perovskite structure is still retained. The Mossbauer spectrum recorded following heating in the gaseous reducing environment at 1,000 degrees C shows the presence of metallic iron, an Fe3+-containing phase with parameters compatible with the presence of SrLaFeO4 which has a K2NiF4-type structure, and a paramagnetic Fe3+ phase. The X-ray absorption spectroscopy results show the presence of metallic cobalt. The Mossbauer spectrum recorded following heating at 1,200 degrees C continues to show the Fe3+-containing components plus a larger contribution from metallic iron. The X-ray absorption spectroscopy results show the presence of metallic cobalt, SrLaFeO4, La2O3 and SrO.