The Ternary Uranium Transition Metal Phosphides UV₅P₃, UCr₅P₃, and UMn₅P₃

Abstract

The title compounds were prepared from prereacted samples of the elemental components by arc-melting. UCr 5 P 3 was also obtained from a tin flux. UV 5 P 3 and UCr 5 P 3 crystallize with a new structure type, which was determined from X -ray data of a twinned crystal of UCr 5 P 3 :P2 1 /m, a = 959.1(2), b = 370.95(6), c = 696.7(1) pm , β = 100.05(3)°, Z = 2, R = 0.030 for 827 structure factors and 29 variable parameters. UMn 5 P 3 is isotypic with YCo 5 P 3 . The structure was refined to a residual of R = 0.054 for 455 structure factors and 28 variables. UCr 5 P 3 has a relatively high, almost temperature independent paramagnetic susceptibility as is frequently observed for metallic uranium compounds. The crystal structures of these phosphides are discussed together with those of other phosphides and silicides of similar composition.