Synthesis and crystal chemical evolution of fresnoite powders
Wong, Chui L.
White, Timothy John
Date of Issue2012
School of Materials Science and Engineering
(Ba,Sr)2TiSi2O8 fresnoite powders were prepared via a Pechini process in which citric acid and ethylene glycol were used as complexing agents. The resulting gel contained a homogeneous distribution of the metal ions that suppressed the formation of (Ba,Sr)TiO3 perovskite as a secondary phase during calcination. Phase development was examined as by isochronal and isothermal reaction analysis. A combination of thermo- and differential gravimetric analysis (TGA–DGA), quantitative X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) confirmed that calcination at 900 °C/12 h yielded finely crystalline (∼70 nm) Ba2TiSi2O8 (BTS) and Sr2TiSi2O8 (STS). The endmembers and compositional intermediates crystallized directly from the Pechini resin and indirectly through reaction of (Ba,Sr)CO3, (Ba,Sr)TiO3 and a silica-rich glass intermediates. This new method for preparing fresnoite yields materials suitable for consolidation as dense monolithic dielectrics or for use as high surface area catalytic powders.
Journal of solid state chemistry
© 2012 Elsevier Inc.