Structural transition at 360 K in the CaFe₅O₇ ferrite: toward a new charge ordering distribution

C Delacotte; F Hüe; Y Bréard; S Hébert; O Pérez; V Caignaert; J M Greneche; D Pelloquin

doi:10.1021/ic5011456

Structural transition at 360 K in the CaFe₅O₇ ferrite: toward a new charge ordering distribution

Inorg Chem. 2014 Oct 6;53(19):10171-7. doi: 10.1021/ic5011456. Epub 2014 Sep 9.

Authors

C Delacotte¹, F Hüe, Y Bréard, S Hébert, O Pérez, V Caignaert, J M Greneche, D Pelloquin

Affiliation

¹ Laboratoire CRISMAT ENSICAEN UMR CNRS 6508 , 6 Boulevard du Maréchal Juin, 14050 Caen Cedex 04, France.

PMID: 25203604
DOI: 10.1021/ic5011456

Abstract

An efficient synthesis route is proposed to obtain single phase powder ceramic of CaFe5O7. This complex structure can be described as an intergrowth between one CaFe2O4 unit and n = 3 slices of FeO Wüstite-type structure. A detailed structural study has been carried out at room temperature combining transmission electron microscopy (TEM) observations (ED, HREM), scanning transmission electron microscopy (STEM-HAADF), and X-ray diffraction data. The analysis of these data has revealed an unexpected supercell with a monoclinic symmetry. From the hkl conditions deduced from the electron diffraction study and the analysis of X-ray diffraction data by simulated annealing, a structural model considering the centrosymmetric P2₁/m setting can be proposed. In addition the first magnetic and electrical transport measurements are reported showing a sharp peak in magnetic susceptibility and a strong localization around 360 K, associated to a structural change from monoclinic setting to orthorhombic one.