Solid solutions based on oxides of zirconium, yttrium, and rare earth elements as a basis for creating the latest functional materials for optical and medical purposes

Work number - M 8 AWARDED

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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