Microreaction mechanism in reduction of magnetite to wustite
Microreaction mechanism in reduction of magnetite to wustite
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DOI：
10.1007/s11663-004-0052-2
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发表时间：
2004-06
期刊：
影响因子：
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通讯作者：
Xing-Min Guo;Y. Sasaki;Y. Kashiwaya;K. Ishii
中科院分区：
文献类型：
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作者：
Xing-Min Guo;Y. Sasaki;Y. Kashiwaya;K. Ishii
为了解磁铁矿还原为浮氏体的微观反应机理，采用离子加速器在室温下对磁铁矿进行氢离子注入。利用选区电子衍射花样研究了还原过程中的晶型转变。实验结果表明，磁铁矿表面的{220}面首先发生变化，因为{220}面上的氧离子浓度高于其他面，从而使氧离子与氢离子发生反应，离开{220}面，导致离子重排。另一方面，在磁铁矿中，氧离子比铁离子更难迁移，因此，块体中的{220}面比其他面更稳定。根据实验事实，提出了磁铁矿还原为浮氏体的两种微观反应机理。结果表明：（1）在[001]晶向的磁铁矿上形成了[001]晶向的浮氏体;（2）在母相和新相之间，浮氏体的（220）和（200）晶面分别与磁铁矿的（220）和（400）晶面平行;（3）在还原过程中，部分{220}晶面形成较早。这些结果可以认为是由于磁铁矿和浮氏体之间氧离子的几何分布相似。
In order to understand the microreaction mechanism of the reduction of magnetite to wustite, hydrogen ions were implanted into magnetite at room temperature by an ion accelerator. The crystalloid transformation during the reduction process was investigated by using selected-area electron diffraction patterns. The experimental results showed that {220} planes on the surface of magnetite were changed first because the concentration of oxygen ions on the {220} planes is higher than other planes to follow the reaction of oxygen ions with hydrogen ions, leaving the {220} planes and resulting in rearrangement of ions. On the other hand, oxygen ions migrate more difficulty than iron ions in magnetite; therefore, {220} planes in the bulk are more stable than other planes. Based on the experimental facts, two kinds of microreaction mechanisms in reduction of magnetite to wustite are suggested. It was found that (1) wustite with [001] direction was formed on the magnetite with [001] direction, (2) (220) and (200) planes of wustite were parallel with (220) and (400) planes of magnetite, respectively, in crystal structure between parent phase and new phase, (3) some {220} planes were formed earlier than other ones in wustite during the reduction process. These results can be considered as due to the similar geometric distribution of oxygen ions between magnetite and wustite.