THE TIN-RICH SIDE OF THE RARE EARTH-TIN SYSTEMS (R = GD, TB, DY, HO, ER, TM, LU AND Y)

The tin-rich side of the rare earth-tin systems (R = Gd, Th, Dy, Ho, E r, Tm, Lu and Y) has been investigated using differential thermal anal ysis, microscopic analysis, X-ray diffraction and electron microscopy. A complex situation has been found which can be summarized by the pre sence of compounds with four types of stoichiometry that can be consid ered as members of the structural series R(n)Sn3n-2: RSn2, R3Sn7, R2Sn 5 and RSn3, two of which have structural modifications depending on te mperature. The main problem in studying these systems has been the dif ficulty of attaining equilibrium in these alloys, which had prevented till now the discovery of the existence of these compounds.