Journal article
Charge disproportionation in (X0.6Sr0.4)0.99Fe0.8Co0.2O3-δ perovskites (X = La, Pr, Sm, Gd)
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 Mossbauer spectroscopy. The perovskites investigated are (X0.6Sr0.4)(0.99)Fe0.8Co0.2O3-delta, 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.
| Language: | English |
|---|---|
| Year: | 2005 |
| Pages: | 1555-1561 |
| ISSN: | 18727689 and 01672738 |
| Types: | Journal article |
| DOI: | 10.1016/j.ssi.2005.04.003 |
| ORCIDs: | Pedersen, Thomas and Kammer Hansen, Kent |
