Magnetic structure and Pu ground state in β-Pu2O3

Neutron diffraction from a polycrystalline sample of 242Pu2O3 (La2O3 structure) has been used to solve the magnetic structure below T/sub N/ = 19 K. The magnetic unit cell requires a doubling in all three crystallographic directions of the chemical unit cell. Below 4 K the magnetic and chemical unit cells become identical. The moments point along the unique c axis at all temperatures below T/sub N/. The magnetic moment is 0.60(2)μ/sub B/ per Pu ion and the C2 coefficient in the Pu3+ form factor is 4.5(3). The value of the moment, its direction within the unit cell, and the C2 coefficients are all consistent with the +- 3/2> Kramers doublet being the ground state of the Pu3+ ion