FORMATION OF LANTHANIDE-PLATINUM ALLOYS BY REACTION OF PLATINUM WITH LANTHANIDE IODIDES .2. STRUCTURAL AND MAGNETOCHEMICAL INVESTIGATIONS INTO THE SYSTEMS WITH LN EQUALS OVER-CAPND, GD, TB, DY, TM

The synthesis of Ln-Pt alloys (Ln (=) over cap Nd, Gd, Tb, Dy, Tm) at 800 degrees C in the presence of iodine is described. In the case of N d and Gd the phases LnPt(5), LnPt(3) and LnPt(2) are produced dependin g on the residual ratio n(I)/n(Ln) (Ln amount less the alloying propor tion). Using the same conditions for the systems with Tb, Dy, and Tm, only LnPt(5) and LnPt(3) are obtained. The single-phase and two-phase intermetallic reaction products with Ln (=) over cap Nd, Gd, and Tb ar e magnetochemically analysed on the basis of the Curie-Weiss law (Gd, Tb) and the crystal field/molecular field model (Nd). The thermodynami c interpretation of the reactions shows that besides the heats of form ation of the lanthanide diiodides, further factors have to be consider ed.