Solid solution phases from thermally crystallized lithia manganese magnesia silicate glasses

Abstract

The crystallization characteristics and phase analysis of some thermally crystallized glasses related to the Li 2OMnOMgOSiO 2 system have been followed by X-ray, DTA and petrography. A series of synthesized Mg and/or Mn-Silicate solid solution phases are mostly formed in the glasses under reducing melting conditions. Clinoenstatite-MgSiO 3 transformed into rhodonite phase MnSiO 3 by MnO MgO replacement, passing through a solid solution series of variable MgSiO 3MnSiO 3 compositions. At low MnO MgO ratio, clinoenstatite ss of the probable formula (Mg 0.75Mn 0.25)SiO 3 was formed. On increasing the MnO MgO ratio up to unity, Mn-containing pyroxene-(MgMn) 2Si 2O 6 was detected at low temperature (>800). However, for prolonged heating or at higher temperature, rhodonite ss. (MnMg)SiO 3 Phase was formed instead. Rhodonite ss. of the probable formula (Mn 0.75Mg 0.25)SiO 3, was also detected at higher MnO MgO ratio. Rhodonite-MnSiO 3 and braunite-Mn 7SiO 12 were formed in the glass based on Li 2OMnOSiO 2 melted at normal atmospheric conditions. In all cases, both lithium-disilicate and quartz were also encountered. The conditions at which these crystallized phase assemblages were formed are discussed.