High temperature thermodynamic stabilities of RCoO3 (R=Nd,Sm,Eu,Gd or Dy) using solid oxide-electrolyte emf technique

Solid oxide-electrolyte emf measurements were carried out on the test electrodes Pt, RCoO3, R2O3, CoO (R = Sm, Eu, Gd or Dy) as well as on Pt, Nd4CO3O10, NdCoO3, CoO and Pt, Nd4CO3O10, Nd2O3, CoO against air. Pt was used as the reference electrode by using a 15 mol% calcia stabilized zirconia tube as the electrolyte in a two compartment cell assembly. These emf values were used to derive the standard change for the reaction (ΔG R)1/2R2O3(s)+CoO(s)+1/4O2(g)→RCoO3(s)A systematic trend in the ΔGR0 values at 1100 K could be observed for the above reaction as a function of atomic number as well as σ, the distortion from perovskite structure. (orig.)