Thermal Stability of a Metal Alloy—Spinel Ferrite Composite Prepared by Disproportionation in a Liquid Medium
✍ Scribed by A. Malats i Riera; G. Pourroy; P. Poix
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 229 KB
- Volume
- 108
- Category
- Article
- ISSN
- 0022-4596
No coin nor oath required. For personal study only.
✦ Synopsis
An original method for obtaining a composite made up of cobalt-iron alloy and cobalt doped magnetite is described. This method is based on a disproportionation reaction in a liquid me. dium at (110^{\circ} \mathrm{C}). Chemical analysis and crystallographic measurements allow a schematic chemical formula for the composite (\left(\mathrm{Fe}{0.2} \mathrm{Co}{0.8}\right){0.8}\left[\mathrm{Fe}{2.38} \mathrm{Co}{0.62} \mathrm{O}{4}\right]) to be given. The crystallographic parameter of the cobalt doped magnetite of spinel structure is (a=) 8.396(1) (\AA). Cobalt-iron alloy presents BCC and FCC structures and does not oxidize up to (320^{\circ} \mathrm{C}). At room temperature this composite is characterized by a saturation magnetization of 90 (\mathrm{cmu} / \mathrm{g}) and a cocreive fied of 1700()\left(\mathrm{O}\right.). (\Lambda) further heating at (200^{\circ} \mathrm{C}) increases the concentration of metalic phase of the BCC structure and the saturation magnetization, decreases the crystallographic parameter of spinel phase and the coercive field. Above (320^{\circ} \mathrm{C}), the alloy oxidizes; the spinel (\mathrm{CoFe}{2} \mathrm{O}{4}) crystallizes at (900^{\circ} \mathrm{C}). O 1994 Academic Press, Inc.