Particle-shape control and formation mechanisms of hydrothermally derived lead titanate

Abstract

Phase-pure perovskite lead titanate with various morphologies has been synthesized by a hydrothermal method at 150 °C. Particle shapes include cubic, tabular, and aggregated platelike shapes. The feedstock concentration greatly influences particle morphology of the hydrothermally derived PbTiO3. At a concentration of 0.05 M, the tabular particles form while cubic particles are produced at 0.1 M. Aggregated plateletlike particles are synthesized at 0.125 M. It was observed that both tabular and cubic particles directly precipitate from the coprecipitated precursor gel. In contrast, the plateletlike shaped intermediate phase appears during the initial stage of reaction at 0.125 M and in situ transforms into perovskite PbTiO3 during further hydrothermal treatment. The intermediate phase preserves its particle shape during transformation and, acting as a template, gives rise to the final tabular PbTiO3 particles. It is demonstrated that only base reagents such KOH and NaOH, which provide a highly basic condition (i.e., pH > 14), promote transformation of the coprecipitated gel into the perovskite PbTiO3. A Hancock and Sharp kinetic analysis in conjunction with microstructural evidence suggests that the formation mechanism is dissolution and recrystallization in which the degree of supersaturation plays an important role in dictating the crystallographic particle phase and morphology of the particles. An experimentally constructed solubility diagram indicates that an excess lead condition is necessary to compensate for loss of lead species and to increase supersaturation to expedite precipitation of PbTiO3 at highly alkaline conditions.

Synthesis and growth mechanism of donut-like lead titanate particles by hydrothermal method

“…3(a), which is same to the results of J. Moon [10]. And when the [Pb 2+ ]/[Ti 4+ ] ratio was adjusted to stoichiometric, the products was sphere-like PbTiO 3 aggregates, as shown in Fig.…”

“…471.4 nm (2.63 eV), which may be a promising candidate in future piezoelectric sensors, and optoelectric device. Moon J. et al [10] synthesized PbTiO 3 particles with Here, we report a simple synthesis approach to build a novel PbTiO 3 donut-like structure under hydrothermal conditions using lead nitrate (Pb(NO 3 ) 2 ) and TiCl 4 as the starting materials and NaOH as a mineralizer. Furthermore, donut-like PbTiO 3 particles formation mechanism was investigated in conjunction with micro-structural evolution of the particles during reaction.…”

Synthesis and characterization of novel nanorod superstructures and twin octahedral morphologies of WO3 by hydrothermal treatment

“…This concept is further strengthened by the explanation of Gu et al stating that the anisotropic growth of the particles occurs by way of the specific adsorption of ions to particular crystal surface, thereby inhibiting the growth of these faces by lowering their surface energy [13,16,17]. Furthermore, Moon et al [60] reported that the particle morphology of the hydrothermally derived oxides is influenced by the feedstock concentration; the particle shape was tubular at lower feedstock concentration. In our case, a similar result is obtained for pH ¼ 1.0 (at lower feedstock concentration) where a rod like morphology was observed.…”

Nucleation and growth of self-assembled nanofibre-structured rutile (TiO2) particles via controlled forced hydrolysis of titanium tetrachloride solution

“…Thus at 80 1C (Fig. 2B) The S-shaped kinetic curves can be described with the aid of the Avrami nucleation-growth model equation [27,28]:…”