Abstract: The processes of the phase-separation, nucleation and crystallization of the MgO-Al₂O₃-SiO₂ glass containing TiO₂ and ZrO₂ were studied by the
methods of infrared spectra, differential thermal analysis, X-ray powder diffraction, and electric microscopy. Phase-separation was found first during the heat treatment
of the glass. The phase like drops contained more Ti element and surrounded by other phases. The analogous structure was remained during the nucleation process.
Titanium ions were found to be of six-coordination, which accounted for the crystallization of the crystals containing titanium element.

Key words: TiO₂, ZrO₂, glass-ceramic, phase-separation, nucleation, crystallization