Correlation Between the Reactivity Towards Oxygen and the Coercitivity in Submicron Vanadium Ferrite Spinels

V. Nivoix; B. Gillot; D. Aymes; P. Perriat; N. Millot; S. Rousseau; M. Guyot

doi:doi:10.1051/jp4:1997190

Numéro		J. Phys. IV France Volume 07, Numéro C1, Mars 1997 7th INTERNATIONAL CONFERENCE ON FERRITES


Page(s)		C1-237 - C1-238
DOI		https://doi.org/10.1051/jp4:1997190

7th INTERNATIONAL CONFERENCE ON FERRITES

J. Phys. IV France 07 (1997) C1-237-C1-238
DOI: 10.1051/jp4:1997190

Correlation Between the Reactivity Towards Oxygen and the Coercitivity in Submicron Vanadium Ferrite Spinels

V. Nivoix¹, B. Gillot¹, D. Aymes¹, P. Perriat¹, N. Millot¹, S. Rousseau¹ and M. Guyot²

¹ Laboratoire de Recherche sur la Réactivité des Solides, UMR 5613, BP. 138, 21004 Dijon cedex, France
² Laboratoire de Magnétisme et d'Optique de Versailles, 78035 Versailles, France

Abstract
Nanometric powders of Fe₂VO₄ and Fe_1.84V_0.92Co_0.23O₄ have been synthetised by "chimie douce" process. The cations in the spinel structure can oxidize at low temperatures without any phase transformation leading to cationdeficient spinel with formula Fe₂VO_4+δ and Fe_1.84V_0.92Co_0.23O_4+δ, where δ is the deviation from stoichiometry, due to a change of the anion-cation ratio, consecutive to formation of vacancies. The oxidation, investigated by thermogravimetry, involves several stages, each stage corresponding to the oxidation of one oxidizable cation, Fe²⁺, V²⁺, V³⁺ on B (octahedral) or A (tetrahedral) sites. Coercivity has also been studied, revealing that the coercive field increases with the rate of oxidation.