|Molar mass||554 g/mol (253Es)|
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).
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.