Promethium(III) hydroxidePromethium hydroxide is an inorganic compound with a chemical formula Pm3. It is a radioactive compound.ProductionPromethium hydroxide can be produced by reacting ammonia water with a solution of a promethium salt, from which promethium hydroxide precipitates as a purplish-pink amorphous solid. By heating with water, it can be forced to crystallize, giving hexagonal crystals isomorphous with other rare earth hydroxides: