CHARACTERIZATION OF BARIUM TITANYL OXALATE TETRAHYDRATE

The XRD pattern and the thermal behavior of barium titanyl oxalate tetrahydrate (BTOT) were investigated. BTOT crystallizes in the monoclinic system, 2/m, with unit cell dimensions of a= 14.954 Å, b= 19.332 Å, c= 13.947 Å, and β= 106.43°. Unit cell content (Z) is 12 and the Bravais lattice is P. Theoretical density is 2.31 g/cm3. At a relatively low temperature (∼60°C), BTOT starts to dehydrate, resulting in a less‐than‐calculated weight loss of ignition. Barium titanate powder obtained by calcining the oxalate exists as the cubic perovskite phase, instead of the tetragonal phase at low temperatures. This happens when the particle size of the crystals is smaller than ∼ 30 nm. As the crystal coarsens, barium titanate powder transforms to the tetragonal state. Copyright © 1990, Wiley Blackwell. All rights reserved