SOL-GEL PROCESS FOR THE PREPARATION OF BA2TI9O20 AND BATI5O11

Barium titanate precursors with Ba/Ti ratio 2:9 and 1:5 were prepared by first hydrolyzing titanium alkoxide and then mixing the resulting titania sol with a barium alkoxide-methanol solution. After drying, the xerogels of the precursors of barium titanates were sintered at temperatures from 700-degrees-C (4 h) to 1200-degrees-C (110 h or longer). Characterization of the product was performed using X-ray diffraction and laser Raman spectroscopy. At 700-degrees-C, BaTi5O11 was formed from the 1:5 precursor and a two-phase mixture of BaTi2O5 and BaTi5O11 was formed from the 2:9 precursor. After prolonged heating at 1200-degrees-C, the latter mixture converted to a single-phase material, Ba2Ti9O20.