Papers by Author: Yoko Yamashita

Abstract: We synthesized barium titanate (BaTiO3) nanoparticles by sol-gel process and investigated their crystallization behavior using differential scanning calorimetry and X-ray diffraction. BaTiO3 nanoparticles with various degrees of crystallinity were obtained by adjusting synthesis conditions. Under aging conditions that do not allow dealcholization reaction to complete, many hydroxyl ligands remain in as-synthesized BaTiO3 nanoparticles, resulting in the formation of voids or defects in the nanoparticles after calcination. It is essential to use high concentration alkoxides precursor solutions for producing BaTiO3 nanoparticles with high crystallinity at low temperature.

Abstract: Barium titanate nanoparticle (BT-NP) suspensions were prepared by dispersing sol-gel-derived BT-NPs in ethylene glycol monomethyl ether (EGMME) under sonication. When an electric field was applied, a part of the BT-NPs in a suspension was deposited on the cathode by electrophoretically deposition and most of the rest of the BT-NPs settled down towards the bottom of a container. The concentration of BT-NPs in the lower part of the container (Cbottom) increased with time until the Cbottom reached a specific concentration (threshold concentration) at which sedimentation of BT-NPs start to occur. The threshold concentration of the nanoparticles sedimentation gave a significant influence upon the aspect of a BT-NPs deposit formed on the cathode.