HEATS OF FORMATION OF LANTHANUM-ANTIMONY ALLOYS

Heats of formation in the LaSb system have been measured using a small furnace isoperibol calorimeter. The compositions and states of the alloys prepared in the calorimeter were checked by metallographic and X-ray analyses. The following values of ΔHform (kcal (g atom)-1 ± 0.5) were obtained for the various compounds, for reaction in the solid state at 300 K: La2Sb, -23.4; La5Sb3, -25.5; La4Sb3, -28.4; LaSb, -31.2; LaSb2, -22.0. The experimental data are discussed briefly and found to be in good agreement with those computed according to Miedema's model and, for the La-rich alloys, also with those calculated according to Kubaschewski's suggestion based on the effective coordination number. © 1979.