Phase relation studies in the CeO2-La2O3-Ho2O3 system at temperature of 1500 °С

Abstract

The phase equilibria in the ternary CeO2–La2O3–Ho2O3 and binary La2O3–Ho2O3 and CeO2–Ho2O3 systems at a temperature of 1500 °С in the whole concentration range were studied. No new phases have been identified in these systems. An isothermal cross section of the state diagram of the CeO2–LaO2–Ho2O3 system at a temperature of 1500 °С is constructed. It was found that the following solid solutions are formed in the studied systems: cubic solid solutions with a structure of fluorite type F-CeO2, as well as solid solutions based on monoclinic (B), hexagonal (A) and cubic (C) modifications of Ln2O3. It was found that cubic solid solutions of the fluorite type F-CeO2 are in equilibrium with all phases formed in the ternary system CeO2– La2O3–Ho2O3 at a temperature of 1500 °С. The boundaries of phase fields and lattice parameters of the formed phases for all investigated systems are determined. A brief description of the structure of isothermal cross sections of ternary state diagrams of systems of the CeO2–La2O3–Ln2O3 series at a temperature of 1500 °С is given. It is established that the systems of this series have a similar structure, although they are characterized by some differences due to the polymorphism of the original components.