[en] Short note

[en] The Ho₄Zr₃O₁₂ compound is synthesized fo the first time. The temperature interval of the compound existence is determined by means of high-temperature X-ray analysis. The crystal structure is studied by the power method. The partial ordering of cation sublattice is detected. The rest of Zr atoms and Ho atoms are arranged at general 18f positions chaotically and have the coordination oof oxygen 7

[en] Reaction in HfO₂-Y₂O₃-CaO and ZrO₂-Y₂O₃-CaO systems is studied. Isothermal cross sections of phase diagrams are plotted at 1600 and 1850 deg C. Ternary compounds are not formed within the investigated interval. Ranges of solid solutions on the basis of HfO₂, ZrO₂ monoclinic, cubic and tetragonal modifications, CaHfO₃ and CaZrO₃ rhombic form and CaO and Y₂O₃ C-form are determined

[en] Using the methods of thermal analysis, x-ray phase analysis, petrography, electron microscopy employed for molten and annealed samples, phase radios in the system ZrO₂-Y₂O₃-Er₂O₃ at high temperature >2000 C have been studied and liquidus of state diagram of the system ZrO₂-Er₂O₃ has been refined. Projections of the surfaces of liquidus, solidus, polythermal cross section in the range with a high content of erbium oxide, volumetric image of the state diagram of the ternary system mentioned have been plotted. At high temperatures in the system ZrO₂-Y₂O₃-Er₂O₃ a continuous series of solid solutions is formed. Refs. 28, figs. 6

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[en] High-temperature methods for investigating high-refractory oxide systems are reviewed. They are: high-temperature DTA, thermal analysis (TA), superacute quenching. The available phase diagrams are analyzed, new diagrams are studied. A conclusion is drawn that studying the phase equilibria in the medium with controlled partial oxygen pressure remains one of the main tasks; it is especially significant for the synthesis of phases of a definite stoichiometry. Many important directions are being insufficiently developed, such as investigating thermodynamic properties of oxide phases versus temperature and pressure, studying ternary and multicomponent systems, investigating the properties of metastable phases and estimating non-equilibrium states, studying the effect of high pressure and high cooling rates on substances, investigating the interaction of oxide melts with various gases. Many of known systems require revision, primarily, silicate, aluminate, zirconate, titanate, rare earth systems, etc

[en] Phase equilibria in the system HFO₂-Y₂O₃-La₂O₃ at 1250 C have been studied. State diagram of the system HFO₂-Y₂O₃-La₂O₃ at 1250 C has been plotted. The isothermal cross section is defined by specific features of phase equilibria in restricting binary systems: formation of solid solutions on the basis of ordered phases La₂Hf₂O₇(Py), LaYO₃(R) and different crystal modifications of the initial components. Refs. 33