CRYSTAL-STRUCTURES AND MAGNETIC-PROPERTIES OF THE LANTHANOID NICKEL ANTIMONIDES LNNISB (LN=LA-ND, SM, GD-TM, LU)

The structure of the new compound LaNiSb has been refined by the Rietv eld technique from X-ray powder data. It is isotypic with ZrBeSi and h as the hexagonal lattice constants a = 440.60(3) pm, c = 839.64(5) pm. The compounds LnNiSb (Ln = Ce, Pr, Nd, Sm) have the same structure. T he cubic MgAgAs-type structure of the antimonides LnNiSb (Ln = Gd-Tm, Lu) was confirmed. The magnetic properties of these compounds were inv estigated with a SQUID magnetometer between 2 and 300 K with magnetic flux densities of up to 5 T. The nickel atoms do not carry magnetic mo ments as is indicated by the Pauli paramagnetism of the lanthanum and lutetium compounds. SmNiSb is van Vleck paramagnetic, while the others show Curie-Weiss behaviour with magnetic ordering temperatures below 4 K. The magnetic moments correspond to those of the free Ln(3+) ions.