Epitaxial Growth of ϵ-Fe2O3 on Mullite Found through Studies on a Traditional Japanese Stoneware

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• 作者：Yoshihiro Kusano ; Tatsuo Fujii ; Jun Takada ; Minoru Fukuhara ; Akira Doi ; Yasunori Ikeda ; Mikio Takano
• 刊名：Chemistry of Materials
• 出版年：2008
• 出版时间：January 8, 2008
• 年：2008
• 卷：20
• 期：1
• 页码：151 - 156
• 全文大小：1165K
• 年卷期：v.20,no.1(January 8, 2008)
• ISSN：1520-5002

文摘

In the course of our study on a Japanese traditional stoneware called “Bizen”, we have found that ε-Fe₂O₃, which has been classically known but recently limelighted for its magnetic potentiality, crystallizes epitaxially on needlelike crystals of mullite, 3(Al,Fe)₂O₃·2SiO₂. This interesting reaction occurred when a pellet of Bizen clay powder was covered with rice straw and then heated to 1250 °C in a stream of nitrogen containing 1−2 vol % of oxygen. It is known that mullite forms from the clay on heating and that the rice straw provides potassium to induce partial melting in the pellet surface to a depth of ~50 µm. The ε-Fe₂O₃-on-mullite particles formed in this molten region, changing their morphology with the oxygen partial pressure. Square-columnar single-crystalline particles with prismatic ends grew to ~0.1 × 0.1 × 0.5 µm³ at N₂/O₂ = 99/1, while dendritic finlike crystals of ~0.3 × 0.1 × 0.8 µm³, which was then the biggest size ever reported, grew at N₂/O₂ = 98/2. The relative ε-Fe₂O₃-to-mullite orientation also changed with the oxygen partial pressure. This discovery suggests morphological controllability of this metastable but magnetically interesting iron oxide as a function of the oxygen partial pressure.