Microstructural characterization of grain-oriented glass-ceramics in the system Ba2 TiSi2O8-SiO2

摘要: In polycrystalline fresnoite, advantage of the piezo- and pyroelectric properties can be taken only if texturing along its polar [0 0 1]-axis achieved. We report on a novel technique to prepare grain-oriented glass-ceramics in system fresnoite-SiO2 by electrochemically induced nucleation. Optimum conditions for grain orientation were determined characterizing microstructure prepared at 1150, 1200 1350 °C using electron microscopy X-ray texture goniometry. At 1150 °C—due smallest crystal growth rate highest nucleation rate—the most distinct is obtained. The solidification glass-ceramic consist three subsequent steps. First, dendritic fresnoite crystallizes rapidly with [1 1 0] facet planes. Due selection, {c}-axes become oriented. Secondly, within interdendritic areas, pseudo-binary eutectic fresnoite-silica solidifies lamellarly. Finally, middle interspaces, crystalline barium silicate coexisting glassy silica formed °C. °C, however, glass composition melt solidifies.