Neodymium oxide

Production Methods

Neodymium oxide is produced from the two principal rare earth minerals, monazite, and bastnasite. The oxide is obtained as an intermediate in the recovery of neodymium metal (See Neodymium).The oxide also may be formed by thermal dissociation of neodymium oxalate, hydroxide or carbonate:Nd2(C2O4)3 → Nd2O3 + 6CO22Nd(OH)3 → Nd2O3 + 3H2ONd2(CO3)3 → Nd2O3 + 3CO2.

Reactions

The anhydrous oxide absorbs moisture from the air at ambient temperatures forming hydrated oxide. The oxide also absorbs carbon dioxide from air, forming neodymium carbonate. Neodymium oxide dissolves in strong mineral acids forming corresponding neodymium salts: Nd2O3 + 3H2SO4 → Nd2(SO4)3 + 3H2O Reactions with acetic and other organic acids produce corresponding salts. When heated with ammonium chloride at 300 to 400°C, the oxide converts to chloride liberating ammonia and water: Nd2O3 + 6NH4Cl → 2NdCl3 + 6NH3 + 3H2O When heated with hydrogen fluoride, the product is neodymium fluoride: Nd2O3 + 6HF → 2NdF3 + 3H2O The oxide is reduced to neodymium metal when heated with hydrogen, carbon monoxide, or other reducing agents.

Flammability and Explosibility

Nonflammable

Safety Profile

Low toxicity by ingestion.

Purification Methods

Dissolve it in HClO4, precipitate it as the oxalate with doubly recrystallised oxalic acid, wash it free of soluble impurities, dry it at room temperature and ignite it in a platinum crucible at higher than 850o in a stream of oxygen. It is a blue powder. [Tobias & Garrett J Am Chem Soc 80 3532 1958.]

Physical properties

Blue powder; hexagonal crystals; fluoresces red; density 7.24 g/cm3; melts around 1,900°C; practically insoluble in water, 30 mg/L at 75°C; dissolves in acids.