Structural and physical properties of the U 9Fe 7Ge 24 uranium germanide

Abstract

A new ternary compound, U 9Fe 7Ge 24, was synthesized by arc-melting the elements, followed by annealing at 900 °C. This compound was characterized by single crystal and powder X-ray diffraction, magnetization, specific heat and electrical transport measurements. It crystallizes in an original tetragonal structure type (space group I4/mmm), with lattice parameters a = 12.3789(2) Å and c = 18.2881(3) Å. Three uranium, eighth germanium, and three iron crystallographic sites exist in this structure, with the atoms making a stacking of infinite chains along the a and b axis. From their interatomic distances strong interactions between the uranium and germanium atoms can be predicted. The magnetic and specific heat measurements down to 2 K do not show any magnetic transition. The Curie–Weiss behaviour with a negative paramagnetic Curie temperature θp = −94 K and reduced effective magnetic moment of μ eff = 2.13 μ B/U indicate that the compound is rather far from onset of magnetism, presumably due to a strong hybridisation of the 5 f and ligand states. The electrical transport measurements show a metallic behaviour.