The structural evolution of siderite (s), FeCO3, through decarbonation at elevated temperatures has been investigated by the in-situ single-crystal X-ray diffraction technique using an area detector. When the crystal was heated above 255 °C, the transparent crystal turned colour in faint black from surface, indicating that the decarbonation commenced. The spinel-type magnetite (m), Fe3O4, first appeared in coexistence with the FeCO3 parent crystal. The orientation relationship between the rhombohedral FeCO3 and the cubic Fe 3O4 can be described as m //  s, and [2-1-1]m // s. On further heating, additional diffraction spots appeared at 411 °C. They were indexed on the basis of the corundum-type hematite (h), (α-Fe2O3). The rhombohedral α-Fe2O3 unit cell had the same orientation relationship with the parent rhombohedral FeCO3 one, i.e., h // s, and h // s. On further heating the parent FeCO3 phase disappeared completely at 464 °C. The formation of iron oxides in FeCO 3 depended on not only temperature but also the holding time. The structural relationships among FeCO3, Fe3O4, and α-Fe2O3 are discussed.
|Journal||IOP Conference Series: Materials Science and Engineering|
|Issue number||SYMPOSIUM 1|
|Publication status||Published - 2011|
|Event||3rd International Congress on Ceramics, ICC3 - Osaka, Japan|
Duration: 2010 Nov 14 → 2010 Nov 18
ASJC Scopus subject areas
- Materials Science(all)