Study of the preparation process for BaO-Al2O3-SiO2 powders by a two-step method

BaO-SiO2 and Al2O3-SiO2 dried gel powders were prepared by the sol-gel process using TEOS, aluminium nitrate and barium acetate as raw materials. By using these starting materials, β-BaAl2Si2O8 (hexacelsian) powders with small particle size were obtained after calcining at 1000 °C. The effects of solvents and prehydrolysis of TEOS on the gelation were studied. The physical and chemical changes, and phase transformation of the gel powders for BaO (Al2O3)-SiO2 and BaO-Al2O3-SiO2 systems during heating were examined using differential thermal analysis, gas chromatography and X-ray diffraction. The particle sizes of the gel powders obtained were also observed by SEM and TEM.