GADOLINIUM - LEAD SYSTEM

The gadolinium-lead binary phase diagram has been determined by differential thermal analysis, metalloρaphie and X-ray methods. The addition of lead to gadolinium lowers the α-β transformation from 1258 to 1212 °C by an inverted peritectic transformation. Gadolinium additions to lead raise its melting temperature by a peritectic transformation from 327 to 328 °C. The room temperature solid solubility is negligible for the pure materials. A eutectic transformation occurs at 14.5 at % Pb and 1120 °C. There are six intermetallic compounds. Gd5Pb3 melts congruently at 1670 °C and Gd5Pb4, Gd11Pb103, Gd6Pb7, GdPb2 and GdPb3 all melt peritectically at 1460, 1225, 1160, 1010, and 969 °C, respectively. In addition there is a polymorphic transformation in Gd5Pb4 at 1410 °C. The crystal structures and lattice parameters for Gd5Pb3, Gd5Pb4 and GdPb3 are: Gd5Pb3, hexagonal Mn5Si3 (D88) type, a0 = 9.078 ± 0.004 Å and c0 = 6.644 ± 0.005 Å; Gd5Pb4, pseudo-tetragonal Sm5Ge4 (Pnma-D2h16) type, a=c=8.20 ± 0.01 Å and b = 15.62 ± 0.02 Å; and GdPb3, cubic AuCu3 (LI2) type, a0 = 4.8261 ± 0.0007 Å. The crystal structures for the other intermetallic compounds are not known. © 1969.