BaTiO₃ SYNTHESIS PARAMETER DETERMINATION VIA X-RAY POWDER DIFFRACTION ANALYSIS. C. Thompson¹, G.J.Kruger¹ and J.D. van Wyk², ¹Department of Chemistry and Biochemistry, ²Research Group for Industrial Electronic Technology, Rand Afrikaans University, Johannesburg-Auckland Park 2006, South Africa.

X-ray powder diffraction was used to study the effects of certain parameters in a revised sol-gel synthesis of barium titanate. This method involved the formation of a sol consisting of barium acetate and titanium isopropoxide dissolved in glacial acetic acid. Gelation was obtained by the addition of water to the sol. In order to determine the influence of certain parameters within the procedure, these were each individually adjusted. The gel products were dried and calcined at 900deg.C to yield the final products and analysed for composition by x-ray powder diffraction. The effect of the parameters were determined by studying the composition of the product. For instance, addition of an organic base DBU (diazabycycloundecene) instead of water to obtain gelation yielded a final product consisting of several undesirable phases, instead of the required tetragonal BaTiO₃. Further, if no addition of water was made to institute gelation, the formation of a colloidal precipitate still occurred, although from the XRD analysis it was seen to contain several unwanted phases. However, if water was subsequently added to the colloidal gel, the calcined product was shown to be pure tetragonal barium titanate. Increasing dilution of the acetic acid by water before the addition of titanium isopropoxide was found to correspond with an increase in contaminating phases in the final product, as determined by x-ray diffraction. These and other facts obtained made it possible to determine the parameters necessary to obtain pure tetragonal barium titanate via the revised sol-gel process.