Mössbauer characterisations and magnetic properties of iron cobaltites CoxFe3−xO4 (1 ≤ x ≤ 2.46) before and after spinodal decomposition

Hoa Le Trong (1, 2) , Lionel Presmanes (1) , Eddy de Grave (3) , Antoine Barnabé (1) , Corine Bonningue (1) , Philippe Tailhades (1)

1 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux
2 VNU - Vietnam National University [Hanoï]
3 Nuclear Material Physics - NUMAT (Ghent, Belgium)

Iron cobaltite powders CoxFe3_xO4 (1 ≤ x ≤ 2.46) were synthesized with compositions in between the cobalt errite CoFe2 O4 and Co2.46Fe0.54O4. The cationic distribution of pure spinel phases was determined by Mossbauer spectroscopy: as Co content increases in the spinel oxide, Co3+ cations replace Fe3+ cations in the octahedral sites and Co2+ cations migrate from octahedral to tetrahedral sites. Saturation magnetizations MS measured at 5 K by a SQUID magnetometer were consistent with the values calculated from the cationic distribution. MS decreases as diamagnetic Co3+ cations replace strongly magnetic Fe3+ cations. Two spinel phases were formed by spinodal decomposition of Co1.73Fe1.27O4 phase submitted to a subsequent thermal treatment, one with a high amount of iron Co1.16Fe1.84O4 and one other containing mostly cobalt Co2.69Fe0.31O4. Increase of the experimental MS value obtained after the spinodal decomposition is in accordance with the calculated value deduced from the cationic distribution of the two phases.

Mots clés: Spinel oxide; Cobaltite; Mössbauer; Spinodal decomposition

Domaines: Matériaux

Hoa Le Trong, Lionel Presmanes, Eddy de Grave, Antoine Barnabé, Corine Bonningue, et al.. Mössbauer characterisations and magnetic properties of iron cobaltites CoxFe3−xO4 (1 ≤ x ≤ 2.46) before and after spinodal decomposition. Journal of Magnetism and Magnetic Materials, 2013, vol. 334, pp.66-73. ⟨10.1016/j.jmmm.2013.01.007⟩. ⟨hal-00844442⟩