Recent thermochemical studies of the binary alloys of Er with group IVB elements by high temperature direct synthesis calorimetry

The standard enthalpies of formation for some Erbium alloys in the binary systems Er-X (where X=C,Si,Ge,Sn,B) have been determined by direct synthesis calorimetry at 1473 +/- 2 K. The following values of Delta H-f(o) in kJ/mole of atoms are reported: ErC2:(-28.8 +/- 1.6); ErSi:(-84.9 +/- 2.5); ErSi2:(-62.6 +/- 1.8); Er5Si3:(-0.7 +/- 3.1); Er5Ce3:(-95.6 +/- 2.0); Er5Sn3:(-72.3 +/- 2.1); ErB2:(-27.3 +/- 2.2). The results are compared with some earlier experimental values derived from mass spectrometric and thermal reduction measurements, with available calorimetric data for the corresponding compounds of some early lanthanide elements and with predicted values from the semi-empirical model of Miedema and coworkers. We will also rest the possible correlation between the enthalpies of formation, the relative molar volumes and the reduced temperatures of the compounds as suggested by Gschneidner.