Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9761609 | Solid State Ionics | 2005 | 7 Pages |
Abstract
The change in crystal structure and the oxidation state in iron of iron-cobalt-based perovskites with different A-site cations is investigated by the use of powder XRD and Mössbauer spectroscopy. The perovskites investigated are (X0.6Sr0.4)0.99Fe0.8Co0.2O3âδ, where X is La, Pr, Sm or Gd. It is shown that the crystal structure changes from hexagonal to orthorhombic when the size of the A-site cation is lowered. At room temperature, the oxidation state of iron increases when the size of the A-site cation is lowered. This is explained by a crystal packing effect. At lower temperatures, charge disproportionation of Fe(IV) occurs to Fe(III) and Fe(V). The transition temperature depends on the type of the A-site cation. Some of the Fe is reduced to Fe(III) by transference of electrons from Co upon cooling below room temperature.
Related Topics
Physical Sciences and Engineering
Chemistry
Electrochemistry
Authors
T. Pedersen, S. Saadi, K.H. Nielsen, S. Mørup, K. Kammer,