Standard thermodynamic properties of Bi2O3 by a solid-oxide electrolyte EMF technique

•The EMF of galvanic oxygen concentration cells including solid zirconia electrolyte were measured accurately.•An improved experimental apparatus and data analysis method have been applied.•△fG∘, ΔfH298∘ and S298∘ values for Bi2O3 have been determined using the measured EMF data.

The standard Gibbs free energies of formation of Bi2O3 were determined by the EMF technique using the following galvanic cell over the temperature range from (1012 to 1235) K:(-)Pt,Cr2O3,Bi(l),Bi2O3(s,l)|YSZ|O2,Pt(+),(-)Pt,Cr2O3,Bi(l),Bi2O3(s,l)|YSZ|O2,Pt(+),where YSZ denotes stabilized ZrO2 with 0.085 mass fraction of Y2O3. The standard Gibbs free energy of formation of Bi2O3 was derived from the cell above is described as linear functions of temperature as:ΔfG∘/(kJ·mol-1)=-591.511+0.2934T/K±0.492(1012≤T/K≤1098)Bi-liquid;Bi2O3-solid,ΔfG∘/(kJ·mol-1)=-582.682+0.2853T/K±0.481(1098≤T/K≤1235)Both phases in liquid.The ΔfH298∘ and S298∘ values of α-Bi2O3 were calculated to be −567.31 kJ ⋅ mol-1and 148.77 J ⋅ K−1 ⋅ mol−1 using the cp functions presented in the literature and the measured data. The results were compared to the corresponding values of the literature.