MEASUREMENT OF ACTIVITY OF GALLIUM IN LIQUID GA-SB-SN ALLOYS BY EMF METHOD WITH ZIRCONIA AS SOLID-ELECTROLYTE

The emf of galvanic cells with zirconia solid electrolytes was measure d to determine the activity of gallium in liquid Ga-Sb-Sn alloys in th e 1050-1150 K temperature range along three lines of constant antimony -to-tin mole ratio. A mixture of Ga and Ga2O3 was used as a reference electrode. The activity curves of Ga show negative to positive deviati ons from the ideal behavior with increasing Sn concentrations in the l ower concentration range of Ga; whereas in the concentration range X(G a)greater than or equal to 0.6, the activity of Ga in the ternary allo ys shows positive deviations from the ideal behavior. Isoactivity curv es at 1073 K, in the ternary Ga-Sb-Sn alloys, were derived by combinin g the activity data for Ga-Sb and Ga-Sn alloys. The shape of the curve s is simple in the Ga-poor region, but shows a wavy form with increasi ng Ga concentration. Isovalue curves in the excess free energies of mi xing in the ternary alloys are derived by the Darken method. The resul ts are in agreement with values derived by using the Chou method on th e Sb-poor side, but the agreement is not good in the Sb-rich region. ( C) 1998 Elsevier Science B.V.