Synthesis and characterization of BaSn(OH)₆ and BaSnO₃ acicular particles

Abstract

The synthesis of BaSn(OH)6 acicular crystals by precipitation at 100 °C from aqueous solutions and their transformation in the perovskitelike compound BaSnO3 was investigated. Single acicular crystals 100–200 μm in length were obtained from a 0.05M solution, whereas bundlelike aggregates of 20–40 μm were precipitated from 0.2–0.6 M solutions. The x-ray diffraction pattern of barium hexahydroxostannate was indexed according to monoclinic symmetry with cell parameters a = 11.029 ± 0.002 Å, b = 6.340 ± 0.001 Å, c = 10.563 ± 0.001 Å = 128.51 ± 0.01°, α = γ = 90°. The BaSn(OH)6 particles decomposed to BaSnO3 and water at approximately 270 °C and the original morphology was retained. The resulting product had specific surface area up to 30–40 m2/g and consisted of 10–20 nm crystallites. The larger unit cell edge in comparison to the reference value and the continuous weight loss up to 1200 °C indicate that water is not completely released during decomposition and a substantial amount of proton defects (up to 0.4 mol per mole of BaSnO3) is incorporated in the perovskite lattice as OH− groups. Normal crystallographic properties of BaSnO3 are restored only after calcination at 1300 °C.

Structural and optical characterization of BaSnO3 nanopowder synthesized through a novel combustion technique

“…In the last few years many preparation procedures have been reported to obtain fine-grained BaSnO 3 powders at relatively low temperatures. Different hydrothermal methods or sol-gel processes have been developed and reported in literatures [15][16][17][18][19][20]. Recently, a lyothermal synthesis at 250 • C has been reported by Lu and Schmidt [21].…”

Low temperature synthesis of Ba1−x Sr x SnO3 (x = 0–1) from molten alkali hydroxide flux

“…Presence of carbonates has been reported even at a calcination temperature of 1000°C during the synthesis of SrSnO 3 and BaSnO 3 by polymeric complex method (Udawatte et al 2000). In hydrothermal synthesis of these stannates (Buscaglia et al 2003;Lu and Schmidt 2005) at low temperature, the product contains OH -ions in lattice even at a calcination temperature of 1200°C.…”

Nano-sized BaSnO3 powder via a precursor route: Comparative study of sintering behaviour and mechanism of fine and coarse-grained powders

“…It can be seen a thermal treatment above 1000 • C leads to parameters which do not significantly change with increasing temperature. Buscaglia et al 23 investigated the decomposition of BaSn(OH) 6 to BaSnO 3 and observed a decreasing cell parameter with increasing annealing temperature, too. By Raman spectroscopy they found that the powders, calcined at very low temperatures, retain a lot of hydroxyl groups inside the lattice, which cause the larger cell parameter.…”

“…[19][20][21][22][23] A peroxide method was reported by Pfaff 24 to synthesise phase pure BaSnO 3 . Recently, a lyothermal synthesis at 250 • C has been reported by Lu and Schmidt.…”