Structure refinement, magnetic susceptibility, electrical conductivity and europium-151 Mossbauer spectroscopy of EuNiIn4

The title compound was prepared by a reaction of the elemental components at 970 K in a tantalum tube. EuNiIn4 adopts the orthorhombic YNiAl4-type structure. It was refined from single-crystal X-ray data: space group Cmcm, a = 447.31(4) pm, b = 1695.88(15) pm, c = 722.32(6) pm, V = 0.5479(1) nm(3), Z = 4, wR2 = 0.0461, 637 F-2 values and 24 variable parameters. Magnetic susceptibility measurements show Curie-Weiss behaviour above 50 K. At 16(1) K, a phase transition to the antiferromagnetic state is observed in the temperature dependence of the inverse magnetic susceptibility. The experimental magnetic moment mu(exp) = 7.86(5) mu(B)/Eu is close to that of the free Eu2+ ion of mu(eff) = 7.94 mu(B). EuNiIn4 is a good metallic conductor with a specific resistivity of 14 mu Omega cm at room temperature. Eu-151 Mossbauer measurements can be fit by a single Eu site with an isomer shift delta = -10.9mm s(-1) against EuF3 which is typical for divalent Eu. At T-N = 32(1) K magnetic order begins, which can be detected by Mossbauer spectroscopy when the fluctuation rate is smaller than the inverse half-life of the excited state of the Eu-151 nuclide, which occurs in parts of the present sample only at temperatures significantly lower than T-N.