Synthesis and characterization of the new ternary uranium compound U1.2Fe4Si9.7

A single crystal of a new ternary silicide U1.2Fe4Si9.7 has been synthesized by the Czockralski method and characterized by X-ray diffraction, magnetization, specific heat and electrical resistivity measurements. It crystallizes in the hexagonal Er1.2Fe4Si9.8-type structure characterized by a disordered two-dimensional lager of U-atoms. The lattice parameters are a = 3.056(1) Angstrom and c = 15.055(2) Angstrom. Magnetic susceptibility follows the Curie-Weiss law down to 40 K with the effective magnetic moment of 2.4 mu(B)/U. The electronic specific heat coefficient, gamma of 180 mJ/K(2)mol.U was obtained. A large residual resistivity due to the disordered structure of the U-Si layer was observed.