MAGNETISM OF A NEW U-SB PHASE - U5SB4

The synthesis of a new U-Sb phase of composition U5Sb4 is reported. The crystal structure was determined by single crystal X-ray diffraction and found to be isotypic to Ti5Ga4 (space group P6(3)mcm). The U atoms occupy two distinct crystallographic sites with a short U-U distance of 3.10 Angstrom present in the U-II coordination polyhedron. The magnetism of this compound was studied by Mossbauer spectroscopy, magnetization and susceptibility measurements, resistivity, specific heat and neutron scattering. From these measurements it was concluded that U5Sb4 is a highly anisotropic ferromagnet with a Curie temperature of 86 K and a magnetic moment of 1.7(mu B)/U atom.