Thermodynamic Stability of LaCrO3 and CaZrO3 Using a Solid-state Galvanic Cell Method

Thermodynamic stability of CaZrO 3 with respect to LaCrO 3 was investigated. The possible products of the reaction are La 2 Zr 2 O 7 and CaCr 2 O 4 . The standard Gibbs free energy change for this reaction at T = 1273 K was calculated. To this purpose the standard Gibbs free energy of formation (from oxides) of LaCrO 3 , CaZrO 3 , La 2 Zr 2 O 7 and CaCr 2 O 4 were obtained from the measurements of electromotive force (EMF) of respective solid-state galvanic cells. LaCrO 3 was confirmed to be able to react with CaZrO 3 spontaneously. However, the solid solutions based on LaCrO 3 , in which the activity of LaCrO 3 at T = 1273 K reached the values below 0.168, are thermodynamically stable with respect to CaZrO 3 .