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·xH2O and Ba(OH)2 at 250 °C and the following crystallization of this hydrothermal product at 330 °C. The peptisation of the SnO2·xH2O gel is dependent on the pH value. Through peptisation the mean particle size of SnO2·xH2O 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 °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 °C. This sol-prepared powder is more sinter-reactive than the gel-prepared powder and can be sintered to a ceramic with 90.7% of the theoretic density.