Agglomerate-free BaTiO₃ particles by salt-assisted spray pyrolysis

Abstract

Optimum conditions for the synthesis of nonagglomerated BaTiO 3 particles by salt-assisted spray pyrolysis (SASP) were investigated. The effect of particle residence time in the reactor and salt concentration on the crystallinity and surface morphology of BaTiO 3 was examined by x-ray diffraction and scanning electron microscopy. Mixtures of a metal chloride or nitrate salt, dissolved in aqueous precursor solutions, were sprayed by an ultrasonic atomizer into a five-zone hot-wall reactor. By increasing the salt concentration or the particle residence time in the hot zone, the primary particle size was increased, and its surface texture was improved compared to BaTiO 3 particles prepared by conventional spray pyrolysis. The SASP-prepared BaTiO 3 crystal was transformed from cubic to tetragonal by simply increasing the salt concentration at constant temperature and residence time. Further thermal treatments such as calcination or annealing are not necessary to obtain nonagglomerated tetragonal BaTiO 3 (200-500 nm) particles with a narrow size distribution. Increasing the carrier gas flow rate and decreasing the residence time in the hot zone resulted in cubic BaTiO 3 particles about 20 nm in diameter.

Control of Particle Size in Flame Spray Pyrolysis of Tb–doped Y2O3 for Bio-Imaging

“…In general, these salts serve as a molten medium (called as molten salts) for solid reactants during high-temperature reactions, which enables a facile transport of reactants to attain their highly crystalline state within a relatively short time [ 22 ]. The molten salts also help in preventing the aggregation of reactant particles as they cover and stabilize the surface of the particles [ 22 , 25 ]. Several researchers have also added alkali salts in FSP to produce lanthanide–doped Y 2 O 3 phosphors [ 23 , 24 ]; however, they could not control the particle size to the submicron range, thus leaving scope for improvement.…”

Synthesis of Single Crystalline Titanium Oxide and Sodium Titanate Nanorods Via Salt-Assisted Ultrasonic Spray Pyrolysis

“…Recently, controlling their size, morphology and crystalline nature has been achieved by the incorporation or in situ generation of inert or reactive salts such as NaCl, NaNO 3 or KNO 3 during USP [13][14][15]. However, relatively little research has been carried out on nanoscale materials with both 1D structure and single-crystalline nature.…”

Synthesis of hollow cobalt oxide nanopowders by a salt-assisted spray pyrolysis process applying nanoscale Kirkendall diffusion and their electrochemical properties

“…Spray pyrolysis, which is a gas-phase reaction process, was applied to the preparation of metal oxide nanopowders. [34][35][36][37][38] Okuyama et al reported salt-assisted spray pyrolysis for the preparation of aggregation-free metal oxide nanopowders. [34][35][36][37] The composite of a washable metal salt and a metal oxide prepared by spray pyrolysis transformed into metal oxide nanopowders after washing with water.…”