Preparation of phase-separated textures and crystalline phases from two-liquid immiscible melts in the TiO2–SiO2 system

Phase-separation textures in two-liquid immiscible melts in the TiO2–SiO2 system were obtained by melting at 1800 °C and rapidly quenching TiO2–SiO2 samples of various compositions. The chemical compositions studied contained 40–90 mass% TiO2. The resultant samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystalline phases varied according to the melting conditions and the compositions. The anatase fraction in the samples decreased with increasing TiO2 content. The difference in the anatase fraction in these samples is attributed to the difference in their microtextures which change from a binodal texture containing a TiO2-rich phase dispersed in a SiO2-rich matrix to a spinodal texture, then to a binodal texture containing a SiO2-rich phase dispersed in a TiO2-rich matrix. The phase-separation textures coarsened on melting at higher temperatures, causing a change in the anatase fraction due to the change in the phase-separation texture.