| Summary: | 碩士 === 國立中央大學 === 化學工程研究所 === 89 === Barium titanate fine particles were prepared by hydrothermal synthesis. The synthesis was preformed at temperature between 75 ℃ and 180 ℃ and for 10 min-96 h. The reactions were carried out in a strong alkaline solution. Ba(OH)2‧8H2O was used as the Ba-precursor material. The various Ti-precursors were used to investigate their effects on the properties of BaTiO3. The as-synthesized of BaTiO3 powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption measurement, and differential scanning calorimetry (DSC). XRD showed that the as-synthesized of BaTiO3 powders have the BaTiO3 structure. SEM and TEM showed the particle size and morphology of BaTiO3. The average particle size of BaTiO3 was calculated from BET surface area. The type of precursor has strong influence on the size and the morphology of barium titanate. The particle size of BaTiO3 was the largest when synthesized at 120 ℃ for 24 h by using anataseTiO2 (Merck) precursor. The particle size was about 0.1 μm when using TiO2 (70 % anatase and 30 % rutile, Degussa P25) or Ti(OH)4 as the precursor. The morphology of powder was the porous structure when using Ti(OH)4 Ti-precursor. In addition, the particle size and morphology was dependent on synthesis temperature. At 85 ℃, the morphology of powder was small crystal and agglomerate of clusters. At 180 ℃, the morphology of powder was large (~130 nm), uniform and nearly monodisperse particles. The extending synthesis time has no significant influence on size and morphology.
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