THE OXIDATION OF MAGNETITE AND RELATED SPINELS - CONSTITUTION OF GAMMA FERRIC OXIDE
THE OXIDATION OF MAGNETITE AND RELATED SPINELS - CONSTITUTION OF GAMMA FERRIC OXIDE
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DOI：
10.1039/tf9565201642
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发表时间：
1956-01-01
影响因子：
--
通讯作者：
WELCH, AJE
中科院分区：
文献类型：
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作者：
DAVID, I;WELCH, AJE
本文详细研究了在各种控制条件下，用不同温度的氧气氧化制备的磁铁矿FenFein04的产物。在氧化条件下产生氧化铁的磁铁矿样品总是含有相当比例的水，而在干燥条件下制备的样品则很难氧化，永远不会产生氧化铁。还发现，氧化伽马本身含有少量的水，显然不能在不破坏尖晶石结构的情况下将其除去。认为目前对γ氧化铁缺陷结构的认识是不充分的，羟基离子的存在取代了尖晶石晶格中的部分氧离子，从而使结构稳定。本文报道了一种结构类似于磁铁矿的海尖铁矿FeA1204的氧化初步实验。γ -三氧化铁（y-Fe2O3）是一种相对不稳定的，铁磁性的，立方形式的氧化物，通常是由在中等温度下氧化磁铁矿（Fex1Fe2n* 04），或通过在溶液或悬浮液中氧化由某些铁化合物制备的相应的γ水合物（7-FeOOH, lepidococite）脱水而得。1 x射线检查显示，y-氧化物具有众所周知的尖晶石结构，尽管Fez03中金属阳离子与氧离子的比例（0.67）比尖晶石的特征（0-75）要小得多。因此，由Hagg 2和Verwey 3独立提出的y-氧化物的普遍接受结构是缺陷结构；单位胞含量用Fe21表示。33032.00, 21.33个Fe3+阳离子被认为统计分布在24个可能的正离子位置，2.67个正离子位点上
A detailed study has been made of products obtained by oxidizing magnetite FenFein04, prepared under a variety of controlled conditions, in oxygen at various temperatures. Specimens of magnetite which gave gamma ferric oxide on oxidation invariably contained appreciable percentages of water, while specimens prepared under dry conditions oxidized with great difficulty, never yielding the gamma oxide. It has also been found that the gamma oxide itself contains a small percentage of water, which apparently cannot be removed without destroying the characteristic spinel structure. It is suggested that current views on the defect structure of gamma ferric oxide are inadequate, and that the structure is stabilized by the presence of hydroxyl ions which replace some of the oxygen ions of the spinel lattice. Preliminary experiments on the oxidation of hercynite, FeA1204, a structural analogue of magnetite, are reported.Gamma ferric oxide (y-Fe2O3) is a relatively unstable, ferromagnetic, cubic form of the oxide, generally prepared by oxidation of magnetite (Fex1Fe2n* 04) at a moderate temperature, or by dehydration of a corresponding gamma hydrate (7-FeOOH, lepidocrocite) prepared from certain ferrous compounds by oxidation in solution or in suspension. 1 X-Ray examination shows the y-oxide to possess the well-known spinel structure, although the ratio of metal cations to oxygen ions in Fez03 is considerably smaller (0.67) than that characteristic of a spinel (0-75). The generally accepted structure of the y-oxide, proposed independently by Hagg 2 and by Verwey, 3 is accordingly a defect structure; the unit-cell content is formulated as Fe21. 33032.00, and the 21.33 Fe3+ cations are considered to be distributed statistically over the 24 possible cation positions, 2.67 cation sites