INTERACTION OF THE LANTHANA, YTTRIA WITH NEODYMIA AT TEMPERATURE 1600 °C

First, the phase equilibria in the ternary La2О3–Y2O3–Nd2О3 system at 1600 °C were studied by X–ray diffraction and petrography in the overall concentration range. The samples of different compositions have been prepared from nitrate acid solutions by evaporation, drying, and calcinations at 1100, 1500 and 1600 °C. It was established that in the system there exist fields of solid solutions based on cubic (C) modification of Y2O3, hexagonal (А) and monoclinic (В) modifications of La2O3 and Nd2O3. The isothermal section has been developed. The systematic study that covered whole composition range excluded formation of new phases. The isothermal section of the La2О3–Y2O3–Nd2О3 system at 1600 °С is characterized by three homogeneity fields (А, B, С) and two two-phase (A + B, B + С ) fields. The lattice parameters of the unit cells and the boundaries of the homogeneity fields for solid solutions were determined. The homogeneity field of solid solutions based on В-phase extends from 33 tо 44 mol.% Y2O3 along the section Y2О3 – (90 mol % La2О3 – 10 mol% Nd2O3) and from 33 tо 43 mol% Y2O3 along the section Y2О3 – (50 mol % La2О3 – 50 mol % Nd2O3). The homogeneity field of A-phase was revealed to extend from 0 tо 19 mol % Y2O3 along the section Y2О3 – (90 mol% La2О3 – 10 mol % Nd2O3)