Phase Relation of the ZrO2–HfO2–La2O3 System at 1500-1100 °C

DOI: 10.62564/M4-OK9460

Yuriy Yurchenko¹, Oksana Korniienko¹, Sergey Korichev¹, Anatoliy Sameljuk¹, Hanna Barchevska¹, Irina Subbota<sup>2

1</sup>Institute for Problems in Material Science, NAS of Ukraine
²National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute»


Complex oxides such as the rare-earth zirconate and hafnate ceramic materials in the fluorite-type (space group Fm3m) and/or pyrochlore-type structure (space group Fd-3m) display a variety of interesting and promising physical, chemical, thermal and magnetic properties which render them excellent candidates in applications such as thermal barrier coatings, solid electrolytes, materials for nuclear industry, and are of interest as luminescent materials, scintillators for applications in radiation detectors and others. The phase diagrams of multicomponent systems are the theoretical basis for the creation of new functional and structural materials. In the presented work, for the first time phase equilibria and physicochemical properties of phases formed in the ZrO2–HfO2–La2O3 ternary system at a temperature of 1500, 1250 and 1100 °C (in the air) in the entire concentration range were researched using powder X-ray diffraction and microstructural analysis. The samples were prepared with a concentration step of 1-5 mol.%. X-ray diffraction analysis (XRD) of the samples was performed by the powder method on the DRON-3 device at room temperature. The scanning step was 0.05-0.1 degrees, the exposure was 4 sec. in the 2 angles range from 10 ° to 100°. In the present work, phase equilibria in the ZrO2–HfO2–La2O3 ternary system have been studied, and isothermal sections of this system at temperatures of 1500 1250 and 1100 °С were constructed. It was found that, at these temperatures, the formation of new compounds in the studied system is not observed. The studied isothermal sections are characterized by the formation of a continuous series of solid solutions based on an ordered phase with a pyrochlore-type structure. It was found that the isothermal sections of the state diagram of the ZrO2–HfO2–La2O3 system at 1500 and 1250 °C are characterized by the existence of four two-phase regions (A+Py, Py+T, Py+M, T+M) and one three-phase region (Py+T+M).

Keywords
phase diagram, solid solutions, unit cell parameters

Acknowledgments
Not provided

References
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