Work number - M 8 ALLOWED TO PARTICIPATE
Presented Frantsevich Institute for Problems of Materials Science NAS of Ukraine
Authors:
Olga Chudinovych, Iryna Marek
The purpose of the work is to construct the diagrams of the state of the three-component systems La2O3–Y2O3–Ln2O3, where Ln = Nd, Sm, Eu, Gd, Yb in the temperature range 1500 and 1600 °C, where the intermediate phase is organized/disordered throughout the concentration range for the creation of physically-chemical bases for the development of new ceramic materials of functional purpose. The aim of the work is to determine the effect of the composition of the ZrO2-based solid solution on the physical and chemical properties of nanodisperse and nanocrystalline powders of the ZrO2−Y2O3−CeO2 system. Investigate the low-temperature phase stability of materials from the obtained powders.
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 of 1100–1600 °C. Phase boundaries for the fields in the binary system Nd2O3–Y2O3 at 1500–1600 °C were refined.
The isothermal sections for the ternary La2O3–Y2O3–Ln2O3 (Ln = Nd, Sm, Eu, Gd, Yb) systems at 1500 and 1600 °C were developed. The solid solutions based on various polymorphous forms of constituent phases and ordered phase with a structure of the perovskite-type of LaYO3, LaYbO3 were revealed in the systems. The main regularities of the phase diagrams for the ternary La2O3–Y2O3–Ln2O3 (Ln = Nd, Sm, Eu, Gd) systems at 1500 and 1600 °C are shown. The solid solutions are formed by the mechanism of the isovalent substitution. The stability of ordered phases and solid solutions are determined by the dimensional factor: in the LaYO3, the large size Nd3+ ions replace La3+ ions, the smaller ions of the cerium series Sm3+, Eu3+, Gd3+ substitute both Y3+ and La3+, whereas all the mentioned rare earth ions maybe replaced by Y3+ ions. The solubility of Ln2O3 in the solid solutions based on cubic modification of C-Y2O3 (Yb2O3) in the ternary La2O3−Y2O3−Ln2O3 (Ln = Nd, Sm, Eu, Gd) systems at 1500 and 1600 °C decreases with a decrease in the Ln3+ ionic radius: from 14 mоl % for the case of Nd3+ to 8 mol % for Gd3+ and to 7 mol % for Yb3+.
Number of publications: 18 articles in magazines included in category "A" (including 3 foreign editions) and 17 articles in magazines included in category "B", 40 abstracts of reports. The total number of references to authors' publications/h-index by work according to databases is, respectively: Scopus 41/5, Google Scholar 54/6.
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