Phase relationships in the system Y2O3-ZrO2

Russian Chemical Bulletin -     

Phase diagram and thermodynamic properties of compounds in the SrO-SrF2-Mn2O3-O2 system

Temperature dependences of the Gibbs energy of the formation of strontium manganite (SrMn₃O_{6 ? δ}, SrMnO₃, Sr₂MnO₄) and fluorine manganite (Sr_2.5Mn₆O_{12.5 ? δ}F₂) from simple oxides, oxygen, and SrF₂, respectively, are determined by EMF with fluorine- and oxygen-ion electrolytes in the 1000–1300 K range of temperatures. Phase relations in the SrO-SrF₂-Mn₂O₃-O₂ system at p(O₂) = 1 atm are calculated on the basis of the obtained data.     

Vaporization and thermodynamic properties of the PbO-V2O5 system

The vaporization of individual lead and vanadium oxides and a wide range of compositions of PbO-V₂O₅ melts has been studied. The thermodynamic characteristics of the PbO-V₂O₅ system have been determined, PbO-V₂O₅ melts show negative deviations from the ideal behavior because of the formation of thermally stable compounds in their condensed phase. For gaseous lead vanadate PbV₂O₆, the thermodynamic functions have been calculated and the standard enthalpies of formation and atomization have been determined.     

Thermal analysis of the Bi2O3-Y2O3-ZrO2 pigments

The synthesis of new compounds based on Bi₂O₃ is investigated because they can be used as new colour inorganic pigments. Chemical compounds of the Bi_2-xY_x/2Zr_3x/₈O₃ type were synthetised. The host lattice of these pigments is Bi₂O₃ that is doped by Y³⁺ and Zr⁴⁺ ions. The incorporation of doped ions provides interesting colours and contributes to a growth of the thermal stability of these compounds. The simultaneous TG-DTA measurements were used for determination of the temperature region of the pigment formation and thermal stability of pigments. This paper also contains the results of the pigment characterization by X-ray powder diffraction and their colour properties.     

Phase equilibria and solid solution relationships in the La2O3-TiO2-ZrO2 system

In the ternary La₂O₃-TiO₂-ZrO₂ system the subsolidus phase relations at 1350 °C were determined using X-ray diffraction, scanning electron microscopy end energy dispersive X-ray analysis. The collected results are presented in the form of a phase diagram. In the equilibrium state there are 7 ternary and 5 binary compatible subsystems. In the system TiO₂ss, ZrO₂ss, ZrTiO₄ss, La₂Zr₂O₇ss and La₂O₃ss solid solutions were confirmed and La₄Ti₉O₂ss and La₂Ti₂O₇ss solid solutions were identified. The addition of ZrO₂ does not stabilize the La_2/3TiO₃ perovskite compound, nor the addition of TiO₂ a highly temperature stable compound La_2/3ZrO₃.