A THERMODYNAMIC STUDY OF TIN OXIDES BY COULOMETRIC TITRATION

The nonstoichiometries of tin oxides have been studied by coulometric titration, using solid state electrolytes (YSZ) between 694 K and 990 K. The nonstoichiometry (X) and the oxygen partial pressure (P(O2) vary as x is-proportional-to P(O)2(1/6) mean 900 k. A phase Sn3O4 between the Sn and SnO2 in the range of 969-732 k. The Gibbs free energy change of formation of Sn3O4 is given by DELTAG-degree(Sn3O4) = -1,163,960 + 417.36 T (J/mol). (C) 1994 Academic Press, Inc.