Phase Equilibria and Chemical Reactions in the Mn₂O₃–ZnO–SiO₂, Mn₃О₄–ZnO–SiO₂ и MnO–ZnO–SiO₂ Systems

The subject matter of this work was the triangulation of the Mn2O3–ZnO–SiO2, Mn3O4–ZnO–SiO2, and MnO–ZnO–SiO2 systems and the determination of phase transformations to yield Zn2 – 2хMn2хSiO4 solid solution. Equilibrium phase diagrams have been plotted taking into account the existence temperatures of each of the manganese oxides, phase compositions of the constituent binary systems, and checkup points, whose phase compositions helped us to determine the positions of secondary triangles. The phase compositions of reaction products of the terminal oxides and the phase transformation sequence during Zn2 – 2хMn2хSiO4 synthesis were monitored by X-ray powder diffraction and thermal analysis. Phase ratios in the MnOх–ZnO–SiO2 system are caused by the charge states of manganese ions changing in response to rising temperature. The triangulation of the Mn2O3–ZnO–SiO2 system at 800°С is determined by the ZnMn2O4–Zn2SiO4 tie-line and partitions the system to the ZnO–Zn2SiO4–ZnMn2O4, Zn2SiO4–ZnMn2O4–SiO2, and ZnMn2O4–SiO2–Mn2O3 simplex triangles. The Zn2 – 2хMn2хSiO4 solid solution with an extent limited to Zn1.6Mn0.4SiO4 is formed at temperatures above 1000°С. The triangulation of the MnO–ZnO–SiO2 ternary system is determined by the Zn1.6Mn0.4SiO4–ZnO–MnSiO3 simplex triangle.

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