Page "Promethium" Paragraph 8

Unlike the nitrate, the oxide is similar to the corresponding samarium salt and not the neodymium salt.

As-synthesized, e. g. by heating the oxalate, it is a white or lavender-colored powder with disordered structure.

This powder crystallizes in a cubic lattice upon heating to 600 ° C.

Further annealing at 800 ° C and then at 1750 ° C irreversibly transforms it to a monoclinic and hexagonal phases, respectively, and the last two phases can be interconverted by adjusting the annealing time and temperature.