Surfactant Effect on the Electrorheological Performance and Colloidal Stability

The impact of two nonionic surfactants, namely Span 20 and Span 85, on the electrorheological response and colloidal stability of urea-coated barium titanyl oxalate (BTRU)/silicone oil suspensions is investigated. We...

Preparation and Characterization of Highly-Dispersed and Highly-Crystalline Barium Titanate Nanoparticles

Highly dispersed barium titanate (BaTiO3, BT) nanoparticles were prepared by the new 2-step thermal decomposition method of barium titanyl oxalate of 30 nm in size. The nanoparticles were heated at 450 °C for 5 hours in air to yield intermediate product: Ba2Ti2O5CO3. Highly dispersed BaTiO3 nanoparticles were prepared by rotationally stirring it at the reduced pressure of 0.2 Pa at various temperatures between 800 °C and 900 °C. The particle size and morphology of the BaTiO3 nanoparticles were investigated by X-ray diffraction and scanning electron microscopy. These measurements showed that the BT nanoparticles were highly dispersed and well-crystallized.

Synthesis of Barium Titanate Nanoparticles from Decomposition of Barium Titanyl Oxalate Tetrahydrate with Aid of Supercritical Water

A novel process of BaTiO3 manufacture was conducted by using supercritical water. Preparation of BaTiO3 nanoparticles was investigated from decomposition of BaTiO(C2O4)2•4H2O (BTOT) with aid of supercritical water for the first time. When BTOT was exposed to supercritical water around 673 K and 30 MPa, it decomposed quickly in 5-22 seconds. The products formed strongly reply on environmental conditions. BaCO3 and TiO2 were always observed as the products in the absence of alkaline additives. BaTiO3 nanoparticles with specific surface area as high as 12~14 m2/g were able to be obtained under strong alkaline conditions, such as NaOH/COSubscript text2=2/1. It was found that environment of supercritical water was better than sub-critical conditions to obtain high quality BaTiO3 particles with fewer defects. Employment of supercritical water significantly reduced the reaction time and temperature compared to other BaTiO3 manufacture processes utilizing BTOT as precursor.