Formation Process of Crystalline Ammonium Yttrium Carbonate Double Salt

摘要

The research was mainly based on the formation condition of crystalline ammoniu yttrium carbonate and the variation characteristics of PH value during the crystallization in which NH4HCO3 was used to precipitate yttrium ion. It is found that the crystallization process is always associated with the descent of pH. The pH of solution is controlled by the crystallization reaction of ammonium yttrium carbonate and the hydrolysis of NH4HCO3. Based on the pH variation, it can be judged whether the crystallization reaction occurs or not and the speed and the degree of crystallinity can be deterolfned. The precipitates were characterized by X- ray powder diffraction and differential thermal -thermogravimetric analysis. The results show that the crystallization is the process of NH4Y(CO3)2 formation and it is effected by feed ratio and feed method.