Experimental Study of Phase Equilibria in the MnO-SiO₂-“TiO₂”-“Ti₂O₃” System

Abstract

Phase equilibria and liquidus surface in the system MnO-SiO₂-“TiO₂”-“Ti₂O₃” under controlled atmosphere have been investigated in the temperature range from 1200 to 1500°C and in the range of log pO₂ from -7.6 (pCO/pCO₂=1) to -16.6 (C-CO equilibration). High-temperature equilibration, quenching and electron probe microanalysis (EPMA) were employed to obtain equilibrium compositions of liquid and several solid solutions. The following primary phases have been observed; molten oxide, manganosite (MnO), rutile (TiO_2-δ), tridymite and cristobalite (SiO₂), tephroite (Mn₂SiO₄), rhodonite (MnSiO₃), spinel (Mn₂TiO₄-MnTi₂O₄), pyrophanite (MnTiO₃-Ti₂O₃) and pseudobrookite (“MnTi₂O₅”-Ti₃O₅) solid solutions. By decreasing oxygen partial pressure, homogeneous liquid oxide area becomes smaller. No ternary compounds or ternary solid solutions were observed.