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J. Korean Ceram. Soc. > Volume 40(12); 2003 > Article
Journal of the Korean Ceramic Society 2003;40(12): 1208.
doi: https://doi.org/10.4191/kcers.2003.40.12.1208
침전법에 의한 구형 Vaterite분말의 합성
윤봉구, 신대용, 한상목
강원대학교 신소재공학과
Synthesis of Vaterite Powders with a Spherical Shape by the Precipitation Method
CaCO$_3$ powders were synthesized by aqueous solution reaction of CaC1$_2$ㆍ2$H_2O$-(NH$_4$)$_2$CO$_3$ system with NH$_4$OH at 45$^{circ}C$ and pHs 8, 9, 10, and 11 and in the concentration range of 0.1∼5 M and its polymorphism, morphology and size were investigated. In order to investigate the influence of pH on nucleation, pH was adjusted before and after reaction respectively. When pH was adjusted after reaction a formation ratio of vaterite was increased with increasing pH and concentration but vaterite was formed with calcite. But, when pH was adjusted before reaction, the formation rate of vaterite was increased with increasing pH and concentration. resulting in a phase-pure vaterite with a spherical shape and 2∼5 $mutextrm{m}$ in size. It was found that solubility of alkaline vaterite was decreased with increasing OH- ions in the high pH solution. When pH was adjusted before nucleation in the high concentration range, in particular, decreasing of solubility disturbed transformation of initially formed numerous vaterite to calcite.
Key words: $CaCO_3$, calcite, Vaterite, $CaC1_2$-O-($NH_4$)$_2$$CO_3$-$NH_4$OH aqueous system
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