The Crystal Structures of U2Cu9Al and UCu3,5Al1,5

Abstract

Two new ternary phases were found by substituting copper with aluminium in the binary phase UCu5. Their compositions were determined as U2Cu9Al and UCu3,5Al1,5. X-ray powder diffraction investigations showed that the first one is hexagonal (S. G. P63/mmc, No. 194, MgZn2 type) with a = 4.998 = 0.005 A, c = 9.040 ∓ 0.005 Å and c/a = 1.809, Z = 1. UCu3,5Al1,5 is also hexagonal but it belongs to the space group P6/mmm (No. 191, CaCu5 type). The lattice parameters are a = 5.083 ∓ 0.005 Å, c = 4.155 ∓ 0.005 A and c/a = 0.817, Z = 1. In both structures atomic positions were determined by the trial and error method.