Thermodynamic stabilities of TeO2 and Sb2Te3 by a solid-oxide electrolyte e.m.f. technique

Article abstract of DOI:10.1016/0021-9614(86)90106-0

The thermodynamic stabilities of TeO2(s) and Sb2Te3(s) were determined by the solid-electrolyte technique using the following galvanic cells in the temperature ranges 588 to 722 K and 726 to 898 K for TeO2(s) and 645 to 712 K for Sb2Te3(s): Pt/C/Te(s)/TeO2(s)/YSZ/air0>/Pt, (I); Pt/C/Te(l)/TeO2(s)/YSZ/air0>/Pt, (II); Pt/C/Sb2Te3(s)/Te(s)/Sb2O3(s)/YSZ/air0>/Pt, (III); where p⁰ = 101325 Pa and YSZ denotes 15 mass per cent of Y2O3 stabilizing ZrO2.The standard molar Gibbs energies of formation calculated from the above cells are: Δ_fG⁰_m(TeO2,s)/(kJ/mol) = -(323.28 - 0.17600 T/K) +/- 1.21, (588 to 722 K); Δ_fG⁰_m(TeO2,s)/(kJ/mol) = -(339.31 - 0.19861 T/K) +/- 0.60, (726 to 898 K); Δ_fG⁰_m(Sb2Te3,s)/(kJ/mol) = -(91.57 - 0.04339 T/K) +/- 1.20, (645 to 712 K).From these results, values of -(321.11 +/- 1.29) kJ/mol, 71.51 J/K*mol, and 16.0 kJ/mol were computed for Δ_fH⁰_m(TeO2, s, 298.15 K), S⁰_m(TeO2, s, 298.15 K), and Δ_fusH⁰_m(Te, s), respectively, and were compared with literature values.