Stoichiometry of UAl4

Samples with atomic ratios U:Al of 1:3.5 (at.% U:Al=22.2:77.8) and 1:4.5 (at.% U:Al=18.2:81.2) were prepared by standard arc-melting techniques. Two samples were annealed at 600 °C followed by slow cooling to room temperature whereas two other samples were heat-treated at 700 °C over the same period and quenched in ice water. The samples were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray powder diffraction, and single crystal X-ray diffraction experiments. The results show that UAl4 forms as a fully stoichiometric compound without constitutional defect in the U sublattice.