Einsteinium(III) oxide

Einsteinium(III) oxide
	__ Es3+ __ O2−
Names
	IUPAC names Einsteinium sesquioxide; Dieinsteinium trioxide; Einsteinium(III) oxide
Identifiers
CAS Number	37362-94-0;
3D model (JSmol)	Interactive image;
ChemSpider	154325 deprecated;
PubChem CID	177221 charge imbalance;
	InChI InChI=1S/2Es.3O/q2+3;3-2 Key: DMBKIFBGDPVPRA-UHFFFAOYSA-N;
	SMILES [Es+3].[Es+3].[O-2].[O-2].[O-2];
Properties
Chemical formula	Es2O3
Molar mass	554 g/mol (253Es)
Appearance	colourless solid
Structure
Crystal structure	Hexagonal
Space group	Ia3
Lattice constant	a = 370 pm, c = 600 pm
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Einsteinium(III) oxide is an oxide of the synthetic actinide einsteinium which has the molecular formula Es₂O₃. It is a colourless solid.

Three modifications are known. The body-centered cubic form has lattice parameter a = 1076.6 ± 0.6 pm; this allows the ionic radius of the Es³⁺ ion to be calculated as 92.8 pm. The other two forms are monoclinic and hexagonal: the hexagonal form has the lanthanum(III) oxide structure.

Einsteinium(III) oxide can be obtained by annealing einsteinium(III) nitrate in sub-microgram quantities.