LOW-TEMPERATURE AQUEOUS PREPARATION OF BARIUM METATITANATE POWDERS

Submicron BaTiO3 powders have been prepared at 85-degrees-C under atmospheric pressure starting from TiCl4 and Ba(OH)2 in NaOH aqueous solution. Characterisation by BET, thermal analysis, differential dilatometry, X-ray diffraction and SEM/TEM microscopy has been performed. The powders, with high specific surface area, show a cubic lattice and a quasi-spherical morphology. A slight deviation from stoichiometry and a low level of residual carbonate have also been observed Sintering tests on isostatically pressed samples without binders have been carried out. A 15 h thermal treatment at 950-degrees-C upon firing results in improved final density (almost-equal-to 96% of the theoretical density) and in very fine grain size (1.1 mum). Washing with dilute (0.1 m) acetic or hydrochloric acid to eliminate BaCO3 is detrimental to a high final density and gives rise to polytitanate formation.