Hydrothermal synthesis of nanocrystalline BaSnO3 using a SnO2•xH2O sol

A BaSnO3 powder with a crystallite size of 27.6 nm has been prepared through a hydrothermal reaction of a peptised SnO2 center dot xH(2)O and Ba(OH)(2) at 250 degrees C and the following crystallization of this hydrothermal product at 330 degrees C. The peptisation of the SnO(2)center dot xH(2)O gel is dependent on the pH value. Through peptisation the mean particle size of SnO(2)center dot xH(2)O in the aqueous solution has been decreased by a factor of 100 to 8 nm. A limited agglomeration in the sol-prepared powder has been observed under the microscope. The structure evolution and crystallisation behaviours of the sol-prepared powders were investigated by TG-DTA, IR and XRD. The BaSn(OH)(6) phase in the as-prepared powder transforms into an amorphous phase at 260 degrees C, from which the BaSnO3 particles nucleate and grow with an increase in temperature. The single-phase BaSnO3 powder has been obtained at a temperature as low as 330 degrees C. This sol-prepared powder is more sinter-reactive than the get-prepared powder and can be sintered to a ceramic with 90.7% of the theoretic density. (c) 2004 Elsevier Ltd. All rights reserved.