Earth Planets Space, Vol. 62 (No. 1), pp. 29-31, 2010
Chihiro Kaito, Akihito Kumamoto, Yoshio Saito, and Ryoichi Ono
Laboratory for Nano-Structure Science, Department of Physics, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu-shi, Shiga 525-8577, Japan
(Received July 31, 2008; Revised October 2, 2008; Accepted October 6, 2008; Online published February 12, 2010)
The crystallization of an amorphous SiO layer covering Fe crystal grains has been clarified by high-resolution transmission electron microscopic (HRTEM) observation. Cristobalite crystals were produced preferentially on the (110) surface of Fe particles by the oxidation of silicon crystallites in the SiO layer, i.e. the oxidation energy of the silicon crystallites resulted in the epitaxial growth of the oxide layer on the Fe surface. The chemical reaction energy due to the oxidation of silicon crystallites in the SiO layer was concentrated at the interface of the crystal and the amorphous layer. Crystal growth took place from the Fe grain surface.
Key words: Low-temperature crystallization, silicate layer, crystalline dust, crystobalite, oxidation energy.