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Journal of Supercritical Fluids, Vol.105, 201-208, 2015
Synthesis of fine-crystalline tetragonal barium titanate in low-density water fluid
Submicron crystals of BaTiO3 were synthesized in mild conditions of low-density water fluid media at T=230 degrees C, P-H2O = 2.94 MPa during 20 h. The crystals showed narrow size distribution with the average sizes of 165 and 168 nm. As-synthesized samples of BaTiO3 were annealed in air at 500 degrees C and washed in acid. It was found that this procedure contributed to the formation of tetragonal BaTiO3. Final BaTiO3 powder contained 0.884 wt.% of water and hydroxyl groups. Ceramics prepared from BaTiO3 powder by SPS technique showed grain-size effect and had dielectric permittivity at room temperature being up to 2320 at I MHz. The sequence of annealing and washing of product after synthesis influenced on the phase content of BaTiO3 crystals, but did not affect the properties of sintered ceramics. (C) 2015 Elsevier B.V. All rights reserved.
Keywords:Barium titanate;Low-density water fluid;Crystal growth;Ferroelectric ceramics;Dielectric;permittivity