ISOTHERMAL SECTION FOR THE TERNARY CeO₂-La₂O₃-Dy₂O₃ SYSTEM AT 1100 C

Using recently published scientific literature, been being provided that scientists around the world have grown increasingly interested in materials based on cerium oxide doped with rare earth metal oxides. The undeniable fact of that the study of phase equilibria of multicomponent oxide systems is both the physical and chemical basis for novel improved materials design. Among the important tasks in the study of phase equilibria of multicomponent systems is to determine the stability limits of solid solutions in a certain temperature and concentration range as well as to confirm the existence of ordered phases. In the present work, the phase equilibria of the ternary system CeO2-La2O3-Dy2O3 were investigated in the whole concentration range. The performed work was to construct an isothermal cross-section of the phase diagram CeO2-La2O3-Dy2O3 ternary system at 1100 & DEG;C. The obtained results indicate the absence of the formation of new phases in the studied system under the used technological conditions. By the method of XRD, it was determined that the formation of solid solutions based on the (F) modification of CeO2 with a fluorite -type structure, as well as monoclinic (B) and hexagonal (A) modifications of rare earth oxides, is observed in the studied system. The values of the lattice unit cell parameters of solid solutions formed in the ternary CeO2-La2O3-Dy2O3 system at a temperature of 1100 & DEG;C were analyzed. From the obtained data, it can be concluded that the lattice unit cell parameters of cubic solid solutions formed in the studied system change linearly following Wegard's law. The formation of a cubic solid solution with a fluorite-type structure F-CeO2 results in the replacement of tetravalent Ce4+ ions with trivalent Ln3+ ions. As a result, there is an increase in the unit cell parameter for cubic solid solutions with a fluorite-type structure, since the replacement occurs with ions with a larger ionic radius.