Crystal structure and magnetic properties of the binary uranium–nickel alloy UNi4

The crystal structure of binary UNi4 was studied from single crystal X-ray diffraction data. This compound crystallises with CaCu5 structure type (space group p6/mmm), with the unit-cell dimension: a=4.8457(2) Å, c=4.0451(2) Å. This phase belongs to the limited solid solution U1+xNi5−x with 0.20<x<0.33, where U atoms substitute partially Ni on its two crystallographic sites. UNi4 is paramagnetic down to 4.2 K.