Solid electrolyte cell studies of solid nickel-gallium alloys

Abstract

Reversible galvanic cells employing ZrO2-CaO solid electrolytes and either Pt/O2 (air) or Ni/NiO reference electrodes were used to measure thermodynamic properties of solid Ni-Ga alloys at temperatures between 873 and 1100 K. Activities, partial Gibbs energies, and integral Gibbs energies, entropies, and enthalpies have been obtained for the a (fcc) solid solution and for the intermediate phases—Ni3Ga, Ni5Ga3, Ni3Ga2, Ni13Ga9, NiGa, and Ni2Ga3. The system is characterized by negative deviations from ideality, exothermic enthalpies, and negative entropies of formation. An analysis of the latter in terms of configurational, electronic, vibrational, dilatational, and magnetic contributions is suggested.