Enhanced production of celsian barium aluminosilicates by a three-step firing technique

Synthesis of monoclinic celsian barium aluminosilicate by a three-step firing technique with or without the addition of Li2O was studied using X-ray powder diffraction (XRD). Prefiring BaCO3 and SiO2 at 1150°C to yield BaSi2O5 prevents the reaction path to hexacelsian via the formation of BaAl2O4. Reacting BaSi2O8 with Al2O3 at 1200°C to yield hexacelsian BaAl2Si2O5 (BAS) would encourages the formation of monoclinic celsian nucleus. Finally, the ground hexacelsian powder is annealed at temperatures between 1200 and 1530°C to promote the transformation of hexacelsian-to-celsian. With the presence of 0.4 wt.% Li2O, complete transformation to celsian occurs at temperature as low as 900°C in 4 h.