The crystal structure of PuNi₃and CeNi₃

Abstract

The structure of 1)u_Ni 3 and the structure and composition of CeNi 3 have been determined by single crystal X-ray methods. Pul~i 3 has three formula units in a rhombohedral unit cell with a = 6.22 A and a = 33 44', probable space group R3m. CeNi 3 has six formula units in a hexagonal cell with a=4.98 and c=16.54 A, probable space group P63/mmc. These structures are both derived from stacking single layers of the MNi 5 structure (CaCus-type) and double layers of the MNi~ structure (Cu~Mg-type).