Particle size effects on the oxidation–reduction behavior of Mn₃O₄ hausmannite

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• 作者：Gillot ; B. ; El Guendouzi ; M. ; Laarj ; M.
• 关键词：Hausmannite ; Oxidation ; Particle size ; Thermogravimetric analysis ; Kinetics
• 刊名：Materials Chemistry and Physics
• 出版年：2001
• 期刊代码：58_02540584
• 类别：ms
• 出版时间：April 2, 2001
• 卷：70
• 期：1
• 页码：54-60
• 文件大小：236 K

摘要

The oxidation of hausmannite, Mn₃O₄, of different particle sizes has been studied by thermogravimetry with a large range of linear heating programs under an oxygen pressure of 10⁵Pa. For high heating rate (600°C/h) and whatever the particle size, Mn₃O₄ was converted to α-Mn₂O₃. For small particle size (32nm) and low heating rate (3°C/h) the oxidation shows the formation of two metastable manganese oxides, a cation deficient spinel of the formula Mn₂O_2.92 with Mn²⁺ ions oxidation and Mn₅O₈ associated to Mn³⁺ ions oxidation. The difference in the kinetic behavior of Mn²⁺ and Mn³⁺ ions is interpreted with regard to a structural change from the cation deficient spinel to Mn₅O₈ initiated by the oxidation temperature.