Kresse G, Hafner J (1993) Ab initio molecular dynamics for liquid metals. Kresse G, Furthmüller J (1996b) Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Kresse G, Furthmüller J (1996a) Efficiency of ab initio total energy calculations for metals and semiconductors using a plane-wave basis set. Jia F, Ramirez-Muñiz K, Song S (2015) Mechanism of the formation of micropores in the thermal decomposition of goethite to hematite. Gualtieri AF, Venturelli P (1999) In situ study of the goethite–hematite phase transformation by real time synchrotron powder diffraction. Goss C (1987) The kinetics and reaction mechanism of the goethite to hematite transformation. Gialanella S, Girardi F, Ischia G, Lonardelli I, Mattarelli M, Montagna M (2010) On the goethite to hematite phase transformation. Phys Rev B 66:155415įrancombe M, Rooksby H (1959) Structure transformations effected by the dehydration of diaspore, goethite and delta ferric oxide. The electron diffraction patterns and high-resolution TEM observations indicated that the twin boundaries consisted of crystallographically equivalent prismatic (100) (010), and (1 \(\bar\) twin boundary in α-Al 2O 3 investigated by density functional theory and transmission electron microscopy. At 800 ☌, the majority of the twin boundaries disappeared however, some hematite particles remained in the twinned variant. As the temperature was increased, crystal growth occurred. Two non-equivalent structures emerged in hematite after dehydration, with twin boundaries at the interface between the two variants. The electron diffraction patterns showed that the single-crystalline goethite with a growth direction of G was transformed into hematite with a growth direction of H. When synthetic goethite was heated at different temperatures between 100 and 800 ☌, a phase transformation occurred at temperatures above 250 ☌. Twin formation in hematite during dehydration was investigated using X-ray diffraction, electron diffraction, and high-resolution transmission electron microscopy (TEM).
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