Eur. Phys. J. AP
Volume 12, Number 1, October 2000
|Page(s)||37 - 46|
|Published online||15 October 2000|
Microstructural and magnetic properties of Fe/Cr-substituted ferrite composites
Institut de Physique et Chimie des Matériaux de Strasbourg, Groupe des Matériaux Inorganiques (UMR 7504),
23 rue du Loess, 67037 Strasbourg Cedex, France
2 Laboratoire de Physique de l'État Condensé (UPRESA 6087), Université du Maine, avenue O. Messiaen, BP 535, 72085 Le Mans Cedex 9, France
3 Institute of Inorganic Chemistry AS CR, Rez near Prague, Czech Republic
4 Institut de Physique et Chimie des Matériaux de Strasbourg, Groupe Surfaces Interfaces (UMR 7504), 23 rue du Loess, 67037 Strasbourg Cedex, France
Corresponding author: email@example.com
Revised: 10 September 2000
Accepted: 11 September 2000
Published online: 15 October 2000
Composites made of iron and Cr doped magnetite are obtained by precipitation from the metallic chlorides salts into a KOH solution heated under reflux. A KOH concentration of 14 mol l−1 is required. The composition of the samples is determined by X-ray diffraction, TG measurements, chemical analysis and Mössbauer spectrometry. The higher the chromium content, the smaller the lattice parameter and the lower the metal ratio. For Cr/Fe ≤ 0.1, the chemical formula of the composites can be written FeA/(FeCrO, . We show that only in-field Mössbauer spectrometry at low temperature is suitable to estimate unambiguously both the proportions of octahedral and tetrahedral iron sites in spinel and the valence of delocalised iron state, if any. A peculiar A-site occupation by either vacancies or Cr3+ ions is observed. This is probably due to the low temperature synthesis. The two phases, metal and spinel are found to be intimately mixed within the nanometer sized particles. For Cr/Fe ratios higher than 0.1, hydroxide phase is also present.
PACS: 77.84.Lf – Composite materials / 81.20.Fw – Sol–gel processing, precipitation / 81.20.Ka – Chemical synthesis; combustion synthesis
© EDP Sciences, 2000
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