Thermogravimetric study of the Ln2O 3CoCO 2O 3 system . III. Ln = Pr, Sm, Eu, and Tb
Abstract
Phase equilibria in the system Ln2O 3CoCo 2O 3 ( Ln = Pr, Sm, Eu, and Tb) at 1200°C were studied at oxygen partial pressure ranging from 1 to 10 -12 atm O 2. "Pr 2CoO 4," PrCoO 3, and Pr 4Co 3O 10, are stable ternary compounds in the Pr 2O 3CoCo 2O 3 system, while only LnCoO 3-type compound is stable in the other systems. The standard Gibbs energies ( ΔG°) of reactions appearing in the systems were also determined from the oxygen partial pressures in equilibrium with three solid phases. ΔG° values for a reaction {1}/{2}Ln 2O 3 + CoO + {1}/{4}O 2 = Ln CoO3 fit well with the linear ΔG° vs ionic radius relation reported previously.
- Publication:
-
Journal of Solid State Chemistry France
- Pub Date:
- December 1988
- DOI:
- 10.1016/0022-4596(88)90260-5
- Bibcode:
- 1988JSSCh..77..366K