Neodymium(III) oxide
IUPAC name
Neodymium(III) oxide
Other names
Neodymium oxide, Neodymium sesquioxide
3D model (JSmol)
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EC Number
  • 215-214-1
  • InChI=1S/2Nd.3O
  • O=[Nd]O[Nd]=O
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)[1]
.0003 g/100 mL (75 °C)
+10,200.0·10−6 cm3/mol
Hexagonal, hP5
P-3m1, No. 164
111.3 J·mol−1·K−1[1]
158.6 J·mol−1·K−1
−1807.9 kJ·mol−1
Related compounds
Other anions
Neodymium(II) chloride
Neodymium(III) chloride
Other cations
Uranium(VI) oxide
Praseodymium(III) oxide
Promethium(III) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.[1] The rare-earth mixture didymium, previously believed to be an element, partially consists of neodymium(III) oxide.[2]


Neodymium(III) oxide is used to dope glass, including sunglasses, to make solid-state lasers, and to color glasses and enamels.[3] Neodymium-doped glass turns purple due to the absorbance of yellow and green light, and is used in welding goggles.[4] 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.[5] About 7000 tonnes of neodymium(III) oxide are produced worldwide each year. Neodymium(III) oxide is also used as a polymerization catalyst.[4]


Neodymium(III) oxide is formed when neodymium(III) nitride or neodymium(III) hydroxide is roasted in air.[6]


Neodymium(III) oxide has a low-temperature trigonal A form in space group P3m1.[7] This structure type is favoured by the early lanthanides.[8][9] At higher temperatures it adopts two other forms, the hexagonal H form in space group P63/mmc and the cubic X form in Im3m. The high-temperature forms exhibit crystallographic disorder.[10][11]

Crystal structure of the A form of neodymium(III) oxide
Packing Neodymium coordination Oxygen O1 coordination Oxygen O2 coordination
A-M2O3 structure type approximately capped octahedral octahedral approximately tetrahedral


  1. ^ a b c Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 471, 552, ISBN 0-8493-0594-2
  2. ^ Brady, George Stuart; Clauser, Henry R.; Vaccari, John A. (2002), Materials Handbook (15 ed.), New York: McGraw-Hill Professional, p. 779, ISBN 978-0-07-136076-0, retrieved 2009-03-18
  3. ^ Eagleson, Mary (1994), Concise Encyclopedia of Chemistry, Springer, p. 680, ISBN 978-3-11-011451-5, retrieved 2009-03-18
  4. ^ a b Emsley, John (2003), Nature's Building Blocks, Oxford University Press, pp. 268–9, ISBN 978-0-19-850340-8, retrieved 2009-03-18
  5. ^ Bray, Charles (2001), Dictionary of Glass (2 ed.), University of Pennsylvania Press, p. 103, ISBN 978-0-8122-3619-4, retrieved 2009-03-18
  6. ^ Spencer, James Frederick (1919), The Metals of the Rare Earths, London: Longmans, Green, and Co, p. 115, retrieved 2009-03-18
  7. ^ D. Taylor (1984). "Thermal Expansion Data: III Sesquioxides, U2N3, with the corundum and the A-, B- and C-M2O3 structures". Trans. J. Br. Ceram. Soc. 83: 92–98.
  8. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 1238-1239. ISBN 978-0-08-037941-8.
  9. ^ A. F. Wells (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. pp. 544–547.
  10. ^ Müller-Buschbaum, H. (1966). "Zur Struktur der A-Form der Sesquioxide der Seltenen Erden. II. Strukturuntersuchung an Nd2O3". Z. Anorg. Allg. Chem. 343 (1–2): 6–10. doi:10.1002/zaac.19663430103.
  11. ^ Aldebert, P.; Traverse, J. P. (1979). "Etude par diffraction neutronique des structures de haute temperature de La2O3 et Nd2O3". Mater. Res. Bull. 14 (3): 303–323. doi:10.1016/0025-5408(79)90095-3.