R2: Crystal structure, crystal chemistry, physical properties of minerals, crystal growth and applied mineralogy

[R2P-06] Study on magnetite-maghemite-hematite transformation

*Ibuki Kinebuchi¹, Yoshinari Sano¹, Atsushi Kyono¹ (1. Univ Tsukuba. Life.)

Keywords:Magnetite, Maghemite, Hematite, phase transformation

In the study, the phase transition mechanism from magnetite to hematite through maghemite was investigated by using, thermal analysis (TG・DTA), powder XRD measurement, and high-temperature ex-situ and in-situ XAFS measurement. From the results, it is found that in the case of magnetite, Fe²⁺ in the octahedral site first diffuses due to heating, and part of the octahedral site becomes vacancy and phase transition to maghemite. After that, it is thought that octahedral site that became maghemite vacancy forms octahedral coordination of Fe again and phase transition to hematite.