YB-PB INTERMETALLIC COMPOUNDS - DIFFRACTOMETRY AND HEAT-CAPACITY MEASUREMENTS

Structures and molar heat capacities of the Yb-Pb intermetallic compounds were determined at different temperatures by using differential scanning calorimetry, X-ray diffraction and metallographic analyses. Formulae and crystal structures of the different compounds (Yb2Pb, possibly Yb5Pb3, YbPb and YbPb3) were confirmed. For the YbPb compound, the crystal structure of the high temperature modification (cI2, W type) was determined. A value of DELTAH(trs) = + 1.35 +/- 0.1 kJ mol-1 for the transformation enthalpy was measured. Negligible or very small homogeneity ranges were observed for the Yb2Pb and YbPb3 compounds. A homogeneity range from 48 to 50 at.% Pb (at 300-550-degrees-C) was determined for YbPb.