Kornienko O. Phase equilibria in systems of oxides d-elements of group IV and lanthanides.

Korniienko О.А. Phase equilibria in systems of oxides d-elements of group IV and lanthanides. Manuscript. The Doctor of Science thesis by speciality 02.00.04 – physical chemistry. I. N. Franceviсh Institute for Problems of Material Science, NAS of Ukraine, Kyiv, 2021. Firstly the comprehensive study of phase equilibria in ternary systems CeO2(ZrO2)–La2O3–Ln2O3 (Ln=Sm, Eu, Gd, Er) and ZrO2–CeO2–Ln2O3 (Ln=Eu, Gd, Yb) has been carried out in the whole concentrtion range using conventional XRD techniqaue, petrography, SEM and X-ray microprobe analyses. The isothermal sections for the systems ZrO2–La2O3–Sm2O3 at 1100, 1500 °С and ZrO2–La2O3–Eu2O3 at 1250, 1500 °С, ZrO2–La2O3–Gd2O3 at 1500 and 1600 °С, CeO2–La2O3–Ln2O3 (Ln=Sm, Eu, Gd, Er) at 1250, 1500 °С and ZrO2–CeO2–Eu2O3 at 1500 °С, ZrO2–CeO2–Dy2O3(Yb2O3) at 1500, 1100 °С were constructed. The phase equilibria in the boundary binary systems La2O3–Ln2O3 and CeO2–Ln2O3 have been studied for the first time in the temperature range 600–1500 °С. The fragments of the 5 binary phase diagrams of the CeO2–Eu2O3 (Dy2O3, Er2O3, Yb2O3), ZrO2–Yb2O3 systems and complete phase diagrams of the La2O3–Sm2O3 (Eu2O3, Gd2O3, Er2O3,), ZrO2–Dy2O3 systems were developed. The main reguliarities of the phase reactions in the solid state have been revealed depending on lantanide ionic radius. The topology of isothermal sections were forecasted the unknown ternary systems CeO2–La2O3–Ln2O3 (Ln = Nd, Dy, Yb, Lu) at 1500 °С and HfO2–La2O3–Ln2O3 (Ln = Nd, Sm, Eu, Gd, Dy, Yb) at 2100, 1900, 1600, 1250 °С grounding on the aforementioned reguliarities of the binary systems studied in this research. Presented data are scientific background for desing of novel prospective ceramic materials of both structural and functional applications in energy engineering, medicine, nuclar power engineering, thermal barrier coatings and solid oxide fuel cells. Keywords: ZrO2, CeO2, Ln2O3, isothermal sections, pyrochlore-type ordered phase, phase equilibria, phase diagrams.