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Twin formation in hematite during dehydration of goethite
Title: | Twin formation in hematite during dehydration of goethite |
Authors: | Saito, Genki Browse this author →KAKEN DB | Kunisada, Yuji Browse this author →KAKEN DB | Nomura, Takahiro Browse this author →KAKEN DB | Sakaguchi, Norihito Browse this author →KAKEN DB | Akiyama, Tomohiro Browse this author →KAKEN DB |
Keywords: | Dehydration | Twinning | Transformation | Goethite | Hematite | Thermal decomposition | Twin boundary |
Issue Date: | Nov-2016 |
Publisher: | Springer |
Journal Title: | Physics and chemistry of minerals |
Volume: | 43 |
Issue: | 10 |
Start Page: | 749 |
End Page: | 757 |
Publisher DOI: | 10.1007/s00269-016-0831-8 |
Abstract: | Twin formation in hematite during dehydration was investigated using X-ray diffraction, electron diffraction, and high-resolution transmission electron microscopy (TEM). When synthetic goethite was heated at different temperatures between 100 and 800 degrees C, a phase transformation occurred at temperatures above 250 degrees C. The electron diffraction patterns showed that the single-crystalline goethite with a growth direction of [001](G) was transformed into hematite with a growth direction of [100](H). Two non-equivalent structures emerged in hematite after dehydration, with twin boundaries at the interface between the two variants. As the temperature was increased, crystal growth occurred. At 800 degrees C, the majority of the twin boundaries disappeared; however, some hematite particles remained in the twinned variant. The electron diffraction patterns and high-resolution TEM observations indicated that the twin boundaries consisted of crystallographically equivalent prismatic (100) (010), and (10) planes. According to the total energy calculations based on spin-polarized density functional theory, the twin boundary of prismatic (100) screw had small interfacial energy (0.24 J/m(2)). Owing to this low interfacial energy, the prismatic (100) screw interface remained after higher-temperature treatment at 800 degrees C. |
Rights: | The final publication is available at link.springer.com |
Type: | article (author version) |
URI: | http://hdl.handle.net/2115/67493 |
Appears in Collections: | エネルギー・マテリアル融合領域研究センター (Center for Advanced Research of Energy and Material) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 齊藤 元貴
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