Orientated crystallization of fresnoite glass-ceramics by using a thermal gradient

The glass with chemical composition (mol%) 33.33 BaO, 16.66 TiO2, 50.00 SiO2 was prepared by a conventional melt-quenching method. The glass-ceramics with a Ba2TiSi2O8 crystal was prepared by crystallization of the glasses using a hot stage. The crystals are shown highly orientated along the c-axis perpendicular to the hot surface of the sample. Crystallization was controlled by a diffusion process with surface nucleation. The activation energy for crystallization was about 518 kJ/mol. The mechanism of oriented crystallization was considered in the present paper.