Interaction of the ceria with ytterbia at temperature 1100 °C

Abstract

Phase equilibria in the binary CeO2–Yb2O3 system at 1100 °C were studied by X-ray diffraction in the overall concentration range. The samples of different compositions have been prepared from nitrate acid solutions by evaporation, drying, and calcinations at 1100 °C. The solid solutions based on various polymorphous forms of constituent phases. The boundaries of mutual solubility and concentration dependences the lattice parameters for all phases have been determined. The study of solid state reaction of СeO2 (fluorite-type, F) and Yb2O3 (cubic modification of rare-earth oxides, type C) at 1100 °С showed that two types of solid solutions based on cubic modifications of F–CeO2 and С–Yb2O3 in the CeO2–Yb2O3 system. These solid solution regimes were separated from end to end with the two-phase field: (F+С). The solubility of Yb2O3 in F- modification of CeO2 is about 15 mol % at 1100 °C. The lattice parameter of the unit cell decreased from а = 0.5409 nm in pure CeO2 to а = 0.5385 nm for the solid solution of boundary composition. The solubility of CeO2 in cubic C- ytterbium oxide attains ~10 mol %. The lattice parameters of the unit cell C phase varies from а = 1.0425 nm in pure Yb2O3 to а = 1.0437 nm for in two-phase sample (C+F), containing 10 mol % CeO2.

Keywords

• phase equilibria
• phase diagram
• solid solutions
• lattice parameters of the unit cells
• functional materials