STANDARD ENTHALPIES OF FORMATION OF LANTHANUM ALLOYS, LA+ME (ME-EQUIVALENT-TO-RU, RH, PD, OS, IR, PT), BY HIGH-TEMPERATURE CALORIMETRY

The standard enthalpies of formation of lanthanum alloys, La + Me (Me = Ru, Rh, Pd, Os, Ir, Pt) were determined by direct synthesis calorimetry at 1473 +/- 2 K. The following values of DELTA(f)H(m)0 (in kJ g-1 atom-1) are reported: LaRu2 -(10.3 +/- 2.8); LaRh2 (57.5 +/- 1.7); LaRh -(56.3 +/- 2.3); LaPd -(76.2 +/- 1.8); LaPd3 (-77.1 +/- 2.2); LaOS2 -(9.0 +/- 1.1); LaIr2 -(62.9 +/- 2.2); LaIr3 (-49.7 +/- 2.2); LaPt2 -(90.0 +/- 2.9); LaPt -(92.1 +/- 4.6). The results are compared with predicted values from the models of Miedema et al., of Watson and Bennett, and of Colinet and Pasturel, and with earlier data for some of the corresponding yttrium and scandium alloys.