Lanthanum orthophosphate, LaPO₄

Lanthanum orthophosphate, LaPO₄, is obtained as a white, amorphous precipitate by adding phosphoric acid or sodium orthophosphate to a solution of a lanthanum salt (Cleve). It may be obtained in the crystalline form by heating lanthana with molten potassium metaphosphate. The double salt 2LaPO₄.K₃PO₄ may be prepared by saturating molten potassium pyro- or ortho-phosphate with lanthana.