水熱法によるFe(II)含有酸化物結晶の合成

Abstract

Fe(II) bearing oxide single crystals of magnetite, fayalite, ilmenite and their related oxides were by drothermally synthesized under controlled reduced conditions. The reduced condition was controlled by hydrogen gas formed from the hydrothermal reaction of the starting metallic powder with the hydrothermal solution. It was found that single crystals of fayalite and ilmenite free from Fe (III) were effectively synthesized at temperatures below 650°C under pressures lower than 1500 kg/cm2. The oxygen fugacity influenced remarkably the morphologies of the grown single crystals of magnetite and fayalite. By the hydrothermal alternation of ilmenite with 10 M KOH solution, the fibrous K2Ti6O13 crystals useful as the thermal insulator could be synthesized above 650°C under 300 kg/cm2. The single crystal of Na0.56Fe0.28Ti1.72O2 which shows the high ionic conductiviy along b-axis at room temperature was grown by the hydrothermal reaction of metallic titanium and iron powders with 10 M NaOH solution above 650°C under 1000kg/cm2. This hydrothermal growth method under controlled reduced condition is applicable for the crystal synthesis of the mineral of which cation valences should be controlled.