MAGNETIC-BEHAVIOR OF UCO2P2

The compound UCo2P2 has been prepared and found to crystallize in a de fective tetragonal CaBe2Ge2-type structure (space group P4/nmm). The m agnetization of this ternary phosphide is linear up to 14 T at 4.2 K b ut its temperature dependence shows a rapid increase at 175 K and a su bsequent drop at 220 K. Neutron-diffraction results at 2 K allow us to propose a model of an antiferromagnetic structure with magnetic cell (a, a, 2c) and moments on uranium sites of 1.8(1)mu(B) along the c-axi s direction, while those on cobalt sites have a very small value, abou t 0.2(1)mu(B).