Phase equilibria and thermodynamics of coexisting phases in rare-earth element--iron--oxygen systems. II. The praseodymium--iron--oxygen system

The phase equilibria and the thermodynamics of coexisting phases in the Pr--Fe--O system were studied using static and dynamic methods for attaining equilibrium with subsequent annealing and identification of the condensed phases by x-ray analysis. Equilibrium phase diagrams were constructed to define the changes that take place in the Pr--Fe--O system on variation of the partial oxygen pressure, the temperature, and the composition of the initial mixture of oxides. An isothermal cross section at 13000K and equilibrium diagrams of the type Po2 = f(composition) with T = constant, Po2 = f(1/T) with one composition parameter fixed and T = f(composition) with P o2 = constant have been constructed. It was shown in the Pr--Fe--O system that only one ternary compound with perovskite structure, PrFeO3, is formed, and furthermore, it is stable no matter how high the partial oxygen pressure