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1/29/11

Barium Titanate Synthesis

Barium Titanate belongs to the family of complex oxide pervoskites possessing the ferroelectric property have far reaching applications in the electronics industry, as transducers and actuators having piezoelectric effect, high-K dielectric capacitors and in memory applications. Barium titanate is one of the most important dielectric materials widely used for multilayer ceramic capacitors (MLCCs) and future nano-electronics. Barium titanate/glass nanocomposite capacitors have great future in energy storage applications.
Properties
Barium titanate nanoparticles, nanopowder, nanodots or nanocrystals are spherical or faceted high surface area nanocrystalline alloy particles with magnetic properties. Nanoscale barium titanate particles are typically 20-40 nanometers (nm) with specific surface area (SSA) in the 30 – 50 m 2 /g range and also available in an average particle size of 100 nm range with a specific surface area of approximately 7 m 2 /g. Nano barium titanate particles are also available in ultra high purity and as coated and dispersed forms.
Preparation of BaTiO3
For the preparation of BaTiO3 nanocrystals, nanowires and nanotubes various synthesis methods are used. They include hydrothermal/ solvothermal synthesis, co precipitation and sol-gel processing, pyrolysis and decomposition of bimetallic alkoxide precursors in the presence of coordinating ligands, liquid-solid-solution (LSS) phase transfer, peptide templates assisted room temperature synthesis, low temperature aqueous synthesis with seed-mediated growth method, and sol-precipitation route. But sol-gel processing and other traditional methods of producing colloids of nanoscale barium titanate often produce particles with broad size distributions and high tendencies toward aggregation.
For BaTiO3 nanocrystal synthesis, a single bimetallic molecular precursor is used to ensure a correct stoichiometry of the product. The BaTi precursor barium titanium glycolate BaTiC2H4O234C2H6O2H2O is first prepared in a dry box by mixing BaO, ethylene glycol, 2-propanol, and TiOPr4. The resulting white powder is filtered, washed, dried at 60 °C and kept in dry box because of its hygroscopic property.
Improved method
Researcher Huang and others of Columbia University report an improved method. The improved method is done by the nucleation controlled thermal decomposition of BaTi molecular precursor in the presence of oleic acid followed by further crystallization at higher temperature. The resulting BaTi oxide nanoparticles can be redispersed in hexane and have uniform BaTiO3 nanocrystals in the form of isolated nanocrystals and continuous and micro patterned thin films can be produced by spin coating or soft lithography micro printing or micro molding.

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