Americium(III) oxide

From Wikipedia, the free encyclopedia
Americium(III) oxide
Kristallstruktur Lanthanoid-C-Typ.png
Other names
Americium sesquioxide
3D model (JSmol)
  • InChI=1S/2Am.3O/q2*+3;3*-2
  • [O-2].[O-2].[O-2].[Am+3].[Am+3]
Molar mass 534 g·mol−1
Density 11.77
Melting point 2,205 °C (4,001 °F; 2,478 K)
Trigonal, hP5
P3m1, No. 164
a = 381.7 pm, c = 597.1 pm[1]
Related compounds
Other cations
Curium(III) oxide
Related compounds
Americium dioxide Americium(II) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Americium(III) oxide or americium sesquioxide is an oxide of the element americium. It has the empirical formula Am2O3. Since all isotopes of americium are only artificially produced, americium (III) oxide has no natural occurrence. The colour depends on the crystal structure, of which there are more than one. It is soluble in acids.[2]


Americium(III) oxide can be made by heating americium dioxide in hydrogen at 600°C.[3]


The hexagonal form is coloured tan, and the cubic form is coloured red-brown the same as persimmon.[3] The cubic form converts to the hexagonal form on heating to 800°C.[3] The cubic form is non-stoichimetric with variable oxygen composition. It darkens with increasing oxygen.[3]


  1. ^ Christine Guéneau; Alain Chartier; Paul Fossati; Laurent Van Brutzel; Philippe Martin (2020). "Thermodynamic and Thermophysical Properties of the Actinide Oxides". Comprehensive Nuclear Materials 2nd Ed. 7: 111–154. doi:10.1016/B978-0-12-803581-8.11786-2.
  2. ^ Lide, David R. (1995). CRC Handbook of Chemistry and Physics: A Ready-reference Book of Chemical and Physical Data. CRC Press. p. 4-38. ISBN 978-0-8493-0595-5.
  3. ^ a b c d Chikalla, T.D.; Eyring, L. (January 1968). "Phase relationships in the americium-oxygen system". Journal of Inorganic and Nuclear Chemistry. 30 (1): 133–145. doi:10.1016/0022-1902(68)80072-7.