Standard enthalpies of formation for some samarium alloys, Sm + Me (Me = Ni, Rh, Pd, Pt), determined by high-temperature direct synthesis calorimetry

The standard enthalpies of formation of eight samarium alloys with late transition metals have been determined by direct synthesis calorimetry at 1273±2 K. The following values of ΔHf0, in kJ·(mole atom)−, are reported: SmNi5, −27.4±0.5; Sm5Rh4, −66.5±1.0; SmRh2, −65.5±1.2; SmPd, −82.4±2.0; Sm3Pd4, −87.2±2.5; SmPd3, −82.9±2.5; SmPt, −108.7±3.5; and SmPt2, −100.2±2.6. The results are compared with predicted values from the Miedema model, with available literature data for SmNi5, SmPd, and SmPt, and with earlier values for similar compounds formed by other lanthanide metals reported by this laboratory. The observed relationships between the enthalpies of formation and the number of f-electrons in the considered binary alloys REnMem (RE=lanthanide elements; and Me=Group VIII elements) are discussed.