Emf measurements of the following galvanic cells with the solid oxide electrolytes (ZrO₂+Y₂O₃ or ZrO₂+CaO) were carried out to determine the standard molar Gibbs energies of formation of ZnO (wurtz) and ZnGa₂O₄ (spinel):
(−)W,Re⁄Zn,ZnO⁄ZrO₂+Y₂O₃⁄In,In₂O₃⁄Re,W(+)
(−)Pt,Re⁄Zn,ZnO⁄ZrO₂+Y₂O₃⁄air,Pt(+)
(−)Pt,Re⁄Cu–10 at%Zn,Ga₂O₃,ZnGa₂O₄⁄ZrO₂+CaO⁄Fe,Fe_xO⁄Pt(+)
(−)Pt,Re⁄Cu–10 at%Zn,ZnO⁄ZrO₂+CaO⁄Fe,Fe₂O⁄Pt(+)
The results were represented by the following equations:
ΔG_f^°⁄J±280=−354560+107.8T⁄K, (843–1067 K)
for Zn(1)+1⁄2O₂(g)→ZnO(wurtz)
and ΔG_f^°⁄J±370=−8640+0.463T⁄K, (988–1172 K)
for ZnO (wurtz)+Ga₂O₃(β)→ZnGa₂O₄ (spinel).