Ammonium Bicarbonate → Carbonic acid, samarium(3+) salt (3:2)

In the preparative method, 10 liters of a solution containing 19.8 g/l samarium in dilute nitric acid are charged to the vessel. The solution pH is adjusted to about 3 with ammonium bicarbonate, heat is applied to obtain a solution temperature of about 60° C., and about 200 grams of samarium carbonate are added. The impeller is started and a 2M solution of ammonium bicarbonate is pumped through the distributor, at a rate of about 49 ml/minute, until a pH of about 6 is obtained. The addition of ammonium bicarbonate is stopped and, under continued vessel agitation, the vessel is drained to leave a total slurry volume of about 5 liters. Agitation is stopped, the crystals are allowed to settle, and clear solution is decanted to leave a proper amount of crystals for the next batch preparation. After adjusting the pH of slurry in the vessel to a value less than about 5, samarium solution for the next batch is added. All batches after the first are precipitated at a temperature of 40° C.