Chudinovych O. Phase equilibria in the systems La2O3-Y2O3-Ln2O3, where Ln = Nd, Sm, Eu, Gd, Yb

Using the methods of physicochemical analysis (XRD, petrography, SEM, X-ray microprobe analysis) phase equilibria were firstly investigated in the ternary systems La2O3-Y2O3-Ln2O3, where Ln = Nd, Sm, Eu, Gd, Yb. The isothermal sections for these systems at 1500 and 1600 °C were developed. Phase equilibria in the boundary binary system La2O3-Yb2O3 were studied for the first time in the temperature range 1100-1600 °C. Phase boundaries were refined fields in the binary system Nd2O3-Y2O3 at 1500-1600 °C. The main regularities of the phase reactions in the solid state have been revealed depending on lanthanide ionic radius. Basing on the established feature of phase diagram constitution of the ternary systems La2O3-Y2O3-Ln2O3 it was found that with decreasing ionic radius of lanthanide the homogeneity range of R-phase decreases. The obtained data are of scientific basis for the development of new materials for structural and functional applications in energy, medicine, ceramics, glass production and others.