| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing ammonium cerium (IV) nitrate where crystals having a small particle size account for a small portion. SOLUTION: A seed crystal is added to an aqueous solution of ammonium cerium (IV) nitrate at a temperature ranging from the saturated temperature of ammonium cerium (IV) nitrate (T1) to (T1-10 deg.C) (e.g. 80 deg.C to 100 deg.C). The aqueous solution is cooled to 30 deg.C or below at an average cooling rate 25 deg.C, so that the crystal of ammonium cerium (IV) nitrate is deposited. The aqueous solution of ammonium cerium (IV) nitrate can be obtained e.g. by dissolving cerium (IV) oxide hydrate or cerium (IV) hydroxide in an aqueous solution of nitric acid and then mixing the resultant with ammonium nitrate. After the seed crystal is added, the solution may be held 30 min or more at the temperature within±5 deg.C of the temperature ranging from 50 deg.C to 90 deg.C, and succeedingly be cooled to 30 deg.C or below.
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