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Americium(III) oxide

## Summary

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.[1]

Names Identifiers Other names Americium sesquioxide CAS Number 12254-64-7 3D model (JSmol) Interactive image PubChem CID 22506319 InChI InChI=1S/2Am.3O/q2*+3;3*-2Key: HPWBMQLLXMZFDK-UHFFFAOYSA-N SMILES [O-2].[O-2].[O-2].[Am+3].[Am+3] Chemical formula Am2O3 Molar mass 534 g·mol−1 Density 11.77 Melting point 2,205 °C (4,001 °F; 2,478 K) 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). Infobox references

## Formation

Americium(III) oxide can be made by heating americium dioxide in hydrogen at 600°C.[2]

${\displaystyle {\ce {2 AmO2 + H2 -> Am2O3 + H2O}}}$

## Forms

The hexagonal form is coloured tan, and the cubic form is coloured red-brown the same as persimmon.[2] The cubic form converts to the hexagonal form on heating to 800°C.[2] The cubic form is non-stoichimetric with variable oxygen composition. It darkens with increasing oxygen.[2]

## References

1. ^ 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.
2. ^ 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.