フォルステライト前駆体の熱的挙動における表面近傍局所構造変化のXANES分光法による研究

抄録

Forsterite (Mg₂SiO₄) precursor was synthesized from heterogeneous alkoxide solution containing MgO powder (mean particle size: 10nm). In order to examine thermal behavior of the precursor, DTA was carried out. The precursor was calcined at temperatures before and after each exothermic and endothermic reaction. The calcined powders were examined by XRD analysis and FT-IR spectroscopy to clarify the reactions. It was found that C₂H₅OH adsorbed on the surface of the powder evaporates at 82°C, Mg(OH)₂ decomposes at 390°C and that forsterite phase is formed at 796°C. The changes in near-surface crystal structure involving these reactions were evaluated by Si and Mg K-edge XANES spectroscopy. The forsterite precursor was found to have a metastable structure before crystallizing as forsterite crystal, resulting from the dehydration around 400°C. The phase was identified as amorphous and the electronic structure was close to Mg₂Si₃O₈.