• Resources Recycling
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• v.17 no.6
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• pp.10-16
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• 2008

In this study, the crystallization of cerium carbonate from cerium chloride solution by addition of ammonium bicarbonate was investigated. The concentration of reactants such as cerium chloride(0.5-2M) and ammonium bicarbonate, and reaction temperature($20-60^{\circ}C$) have a great effect on the crystal types of cerium carbonate such as lanthanite-type cerium carbonate[$Ce_2(CO_3)_3{\cdot}8H_2O$] and tengerite-type cerium carbonate[$Ce_2(CO_3)_3{\cdot}2.5H_2O$]. The crystallinity of cerium carbonate changed from lanthanite to tengerite as the concentration of reactants and reaction temperature increased. Transformation of cerium carbonate hydrate was transformed to cerium hydroxy carbonate depended on the drying conditions. Cerium carbonate of lanthanite and tengerite has the shape of aggregates with plate type crystal, and the size of lanthanite and tengerite crystal was $3{\mu}m$ and $5{\mu}m$, respectively. Cerium hydroxy carbonate has the shape of aggregates with needle type crystal, and the crystal size was about $7{\mu}m$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.2
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• pp.101-107
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• 2013

Cerium compounds such as Cerium hydroxide ($Ce(OH)_3$), Cerium chloride ($CeCl_3{\cdot}nH_2O$), Cerium carbonate hydrate ($Ce_2(CO_3)_3{\cdot}8H_2O$), Cerium oxide ($CeO_2$) were synthesized using recycled Ce precursor. Cerium(IV) oxide of nanoparticles were obtained by Ultra-sonication. Cerium-sodium- sulfate compound was synthesized through acid-leaching and addition of sodium sulfate from 99 wt% purity of Ce precursor as a starting material that was recycled from the waste polishing slurry. Moreover Cerium hydroxide was obtained from Cerium-sodium-sulfate compound by adding to sodium hydroxide solution. Then Cerium chloride was synthesized by adding of hydrochloric acid to Cerium hydroxide. Needle-shaped Cerium carbonate hydrate was synthesized in the continuous process and Cerium(IV) oxide with 30~40 nm size was subsequently obtained by the calcinations and dispersion.