マガディアイトとケニヤアイトの水熱合成

概要

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In order to synthesize well-crystallized magadiite and kenyaite as a single phase in a short reaction time, amorphous silica was hydrothermally reacted with alkaline solutions in the temperature range from 150℃ to 200℃. From a suspension containing SiO_2 and NaOH with molar ratios of H_2O/SiO_2=18.5 and NaOH/SiO_2=0.23, magadiite was formed after a reaction time of 48 h at 150℃ or after 18 h at 170℃. The formation of Na-kenyaite, however, required 6 h at 200℃. Then, KOH and K_2CO_3 were used to lower the formation temperature of kenyaite. K-kenyaite was synthesized after 16 h at 185℃ from a suspension with molar ratios of H_2O/SiO_2=18.5 and KOH/SiO_2=0.23. Furthermore, (Na, K)-kenyaite was formed after 48 h at 150℃ or after 24 h at 170℃ from suspensions with molar ratios of H_2O/ SiO_2=18.5, NaOH/SiO_2=0.23 and NaOH/K_2CO_3=0.95-23. Magadiite and kenyaite were formed through a difinite induction period after dissolution of amorphous silica.
社団法人日本セラミックス協会の論文
1992-03-01