含硫酸ジルコニア微結晶の生成プロセスと結晶成長

概要

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Zirconium sulfate solutions were hydrothermally treated at temperatures from 200° to 250℃ for various periods of time. Crystalline phases, morphology and amount of solid products were investigated to study, especially, the formation process of zirconium oxide sulfate (ZOS) , being submicron thin hexagonal crystals with a chemical composition of Zr_3O_5SO_4・nH_2O. Crystalline phases of the solid products varied with H_2SO_4 concentration of the solution ; at 240℃ for 3 days, m- ZrO_2 and t-ZrO_2, ZOS and/or a pseudo ZOS phase (PZOS) and ZrOSO_4・H_2O at H_2SO_4 concentrations below 0.2 mol/l, in the range of 0.2-2.0 mol/ l and above 2.5 mol/l respectively. PZOS formed generally at lower temperature or at the early stage of the hydrothermal process, and its amount decreased with increasing H_2SO_4 concentration. Since the PZOS phase was metastable at higher temperature or higher H_2SO_4 concentration, it gradually changed to ZOS with a prolonged hydrothermal treatment time. The ZOS crystals were considered to be formed by a neucleation and crystal growth process. The crystal size of the ZOS increased with increasing H_2SO_4 concentration but was almost independent of Zr concentration. Effect of seeding and repeated treating on the crystal growth of ZOS was confirmed in a solution containing 1.6 mol/l H_2SO_4 at 250℃.
社団法人日本セラミックス協会の論文
1989-02-01