Influence of the temperature and the oxygen partial pressure on the phase formation in the system Cu – Fe – O
2004; Wiley; Volume: 39; Issue: 12 Linguagem: Inglês
10.1002/crat.200410292
ISSN1521-4079
Autores Tópico(s)Copper-based nanomaterials and applications
ResumoAbstract Copper iron oxides, Cu 1‐x Fe 2+x O 4 (0 ≤ x ≤ 0.5), have been synthesized by thermal oxidation of copper ‐ iron mixtures. In this process, the phase formation and the phase stability were investigated as function of the temperature (800°C – 1200°C) and the oxygen partial pressure (1.013 x 10 1 – 1.013 x 10 5 Pa). The phase formation starts with the reaction of the metallic components to simple oxides (Fe 3 O 4 , Fe 2 O 3 , CuO). From these simple oxides, the formation of complex oxides requires a minimum temperature of 800°C. The synthesis of single phase spinel compounds Cu 2+ 1‐2x Cu 1+ x Fe 2+x O 4±δ is realized for 0.1 ≤ x ≤ 0.5, using specific temperature – p(O 2 ) – conditions for a given value of x. Remarkably, to achieve our goal, we found that the increase of x implies that of the reaction temperature and/or a decrease of the p(O 2 ) in the reaction gas stream. Besides, a single phase spinel CuFe 2 O 4 does not exist in the temperature / p(O 2 )‐field investigated. Using the results of XRD ‐ phase analysis, T ‐ p(O 2 ) – x – diagrams were constructed. These diagrams allow the prediction of phase compositions expected for different synthesis conditions. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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