Powder synthesis of barium titanate and barium orthotitanate via an ethylene glycol complex polymerization route

Pure and reactive barium titanate (BaTiO3,) and barium orthotitanate (Ba2TiO4) powders have been synthesized by an ethylene glycol (EG), polymerization-complexation route. The EG content affected the crystallization behavior and powder morphology. The BaTiO3, powder, which had a particle size of approximately 100 nm, crystallized from amorphous to tetragonal phase on calcining at 700 degrees C for 1 h. Ball-milled BaTiO3, powder sintered to 97% relative density at 1200 degrees C after 2 h, with a grain size of approximately 200 nm. Ba2TiO4 powder required longer holding times or higher temperatures to be crystallized from the amorphous phase than did BaTiO3. In Ba2TiO4, the phase transformation between low-temperature monoclinic symmetry to high-temperature orthorhombic symmetry was observed by dilatometry and differential scanning calorimetry. A volume decrease of similar to 0.5% accompanied the monoclinic-to-orthorhombic transformation on heating. The high-temperature orthorhombic phase could be retained down to room temperature by the addition of at least 6 wt% magnesia (MgO) stabilizer.