Physical properties
BaSnO
3 crystallizes in a cubic perovskite structure. The lattice constant of BaSnO
3 is a=4.1163 ?.
Uses
BaSnO3 with cubic perovskite structure exhibits good dielectric properties. Because of these characteristic properties, BaSnO
3 ceramic is becoming more and more important in material technology. It can be used to prepare thermally stable capacitors and to fabricate ceramic boundary layer capacitors.
In recent years, BaSnO
3 has been found to be a very promising sensor material and has therefore received the most attention. In pure as well as doped forms, stannates have been investigated as potential solid-state sensor materials for many gases, including CO, NO
x, H
2 and CO
2. BaSnO
3 has also been used in the preparation of multifunctional temperature–humidity–gas sensors by combining it with BaTiO
3. Detection of gas in BaSnO
3 sensors is achieved by measurement of the electrical properties changes such as resistance and conductivity. The changes are induced in the semiconducting oxide form of BaSnO
3 following adsorption of any given gases on the solid surface. The gas sensitivity of this semiconducting oxide is related to the surface reaction process.
Preparation
BaSnO
3 powder with a crystallite size of 27.6 nm was prepared through a hydrothermal reaction of a peptized SnO
2·xH
3O and Ba(OH)
3 at 250°C. This was followed by crystallization of this hydrothermal product at 330°C. The peptization of the SnO
3·xH
3O gel is dependent on the pH value. Through peptization, the mean particle size of SnO
3·xH
3O in the aqueous solution has been decreased by a factor of 100 to 8 nm. A limited agglomeration in the sol-prepared powder was observed under the microscope. The structure evolution and crystallization behaviors of the solprepared 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 BaSnO
3 particles nucleate and grow with an increase in temperature. The single-phase BaSnO
3 powder has been obtained at a temperature as low as 330°C. This sol-prepared powder is more sinterable than the gel-prepared powder and can be sintered to a ceramic at 340°C with 90.7% of the theoretic density.
