Manufacture of BaTiO3 Powders by Gel-hydrothermal Method
In this study, spherical pre-BaTiO3 particles are prepared by gelation and aging process in autoclave without catalysts. The (Ba-Ti) gel used as a starting material was prepared by aging mixtures of titanyl acylate with barium acetate aqueous solution([glacial acetic acid (AcOH)]/[titanium isopropoxide (TIP)] 4, [barium acetate]/[TIP] 1) at 45℃ for 48hrs. XRD and SEM results for the (Ba-Ti) gel sample at aging process showed that the gel was formed via aggregation of the fine particles. It seems to be the primary particles of bulk (Ba-Ti) gel amorphous, but the spatial arrangement of barium and titanium in the (Ba-Ti) gel is similar to that in crystalline BaTiO3 particles. From XRD and FT-IR. spectroscopy analysis it was found that the crystal structure of the prepared particles continuously transformed from amorphous to tetragonal as the calcination temperature increased, and crystallized spherical cubic and tetragonal BaTiO3 powder obtained at the very low calcination temperature between 500℃ and 900℃ after 1hrs of heat treatment respectively. According to BET analysis result, final particle have pore structure of ink bottle shape which is produced by aggregation of fine spherical particles with surface area of 280m2/g and average pore size of 130nm.