抄録
The emf of the galvanic cells involving zirconia solid electrolytes has been measured in order to obtain the standard free energy of formation of In2O3(s) in the temperature range from 835 to 1272 K and the thermodynamic data of the liquid Pb–In system for NIn=0.10–0.90 in the temperature range from 859 to 1330 K . The standard free energy of formation of In2O3(s) was determined as the following equation:
ΔG(In2O3°⁄J·mol−1=−930802+337.94T between 835 and 1272 K.
The concentration dependence of activities of indium shows a positive moderate deviation from the Raoult’s law and agrees well with the results by Terpilowski et al. Activities of lead agree well with the law of ideality in the lead-rich region but exhibit slightly positive deviations in the indium-rich region. Our data for lead do not agree with the result by Sommer et al. but well with that by Shiu et al.
The difference in thermodynamic properties between the liquid alloys composed of lead and indium and those composed of IB metals (Cu, Ag, and Au) and indium has been discussed from the standpoint of the alloy solution theory of Engel. Namely, the activities and the heats of mixing for both kinds of liquid alloys seem to be consistently explained by assuming that the filling of d shell is incomplete for the IB metals as well as the transition metals, whereas it is complete for lead and indium.
The activities and the heats of mixing of liquid Cu–In and Ag–In alloys are quite different from those of the liquid Au-In system, in which the activities show considerably negative deviations and the heats of mixing are exothermic, in the whole concentration range, owing to the larger electronegativity factor in the gold alloys.
