Neodymium(III) oxide or neodymium sesquioxide is the chemical compound composed of neodymium and oxygen with the formula Nd2O3. It forms very light grayish-blue hexagonal crystals.
Molar mass： 336.48 g/mol
Appearance： light bluish gray hexagonal crystals
Density： 7.24 g/cm3
Melting point： 2,233 °C (4,051 °F; 2,506 K)
Boiling point： 3,760 °C (6,800 °F; 4,030 K)
Solubility in water：.0003 g/100 mL (75 °C)
Magnetic susceptibility (χ)：+10,200.0·10−6 cm3/mol
Crystal structure：Hexagonal, hP5
Neodymium(III) oxide is used to dope glass, including sunglasses, to make solid-state lasers, and to color glasses and enamels. Neodymium-doped glass turns purple due to the absorbance of yellow and green light, and is used in welding goggles. Some neodymium-doped glass is dichroic; that is, it changes color depending on the lighting. One kind of glass named for the mineral alexandrite appears blue in sunlight and red in artificial light. About 7000 tonnes of neodymium(III) oxide are produced worldwide each year. Neodymium(III) oxide is also used as a polymerization catalyst.