STRUCTURAL ANOMALY IN GDNIAL - A CRYSTALLOGRAPHIC, ELECTRIC AND MAGNETIC INVESTIGATION

Low temperature electrical resistivity and X-ray powder diffraction me asurements showed a transformation paint at about 200 K, attributed to a transition between two slightly different crystallographic forms of the ZrNiAl type. A corresponding anomaly was observed in the thermal behaviour of the magnetic susceptibility, and the results were analyze d in the framework of the RKKY theory. Ferromagnetic ordering occurs a t 57 K, and two other transition temperatures, 30 and 14 K, were detec ted: these points, as already observed for TbNiAl, DyNiAl and HoNiAl m ay be imputed to order-order magnetic transitions. (C) 1998 Elsevier S cience S.A.