Self-Assembled Growth of PbTiO₃ Nanoparticles into Microspheres and Bur-like Structures

Abstract

Novel bur-like hierarchical nanostructures of PbTiO3 were prepared by hydrothermal synthesis. Surfactants containing phenyl-sulfonic groups resulted in self-assembly of nanocrystals. In absence of the surfactant, monodisperse PbTiO3 microspheres were formed. The microspheres were 1−5 μm in diameter, and consisted of ∼20 nm tetragonal PbTiO3 crystals. The microspheres were formed by primary nucleation of PbTiO3 nanocrystals followed by aggregation into microspheres. The hierarchical bur-like nanostructures exhibit a unique geometry consisting of a microsphere core with an outer shell of nanorods. The nanorods, which grow along the [001] direction, were ∼50−100 nm in diameter and from several hundreds of nanometers up to 2 μm in length. A mechanism for the growth of the bur-like nanostructures was proposed. First, agglomeration of PbTiO3 nanocrystals into microspheres occurs. PbTiO3 mesocrystals are formed at the surface of the microspheres by self-assembly of cube-shaped or facetted PbTiO3 nanocrystals, and the mesocrystals ripen and grow further into nanorods.

Mesocrystals—Ordered Nanoparticle Superstructures

“…This example very illustratively demonstrates the nanoparticle assembly process to a mesocrystal and its fusion to a single crystal as drawn in the corresponding schematics, [1,2] since in this example the building units are monodisperse. Other systems in which the time resolved mesocrystal to single crystal transition was observed include PbTiO 3 [128] or InOOH [129] where the transition to a single crystal is less documented and suggested to occur by dissolution-recrystallization of nanoparticle surfaces and/or removal of stabilizer molecules. [89,129] …”

Submicron-sized cube-like α-Fe2O3 agglomerates as an anode material for Li-ion batteries

“…Considering that the usually low initial coulombic efficiency (<70%) is one of the obstacles of commercialization of metal oxides, our results seem to give a way to solve this problem. Compared to other nanostructured iron oxides, the Fe 2 O 3 nanoparticle in our experiments are agglomerated into submicronparticles, which are significantly larger than the nanodomains and could result in reduction of the side effect with electrolyte [19]. On the other hand, loss of the active material during cycling may be also reduced by the relatively tight agglomerates.…”

“…However, it was reported that EG is very important for assembling the nanoparticles into aggregates. EG is expected to bind the nanoparticles together through eater bond formation after the aggregation has taken place [19]. The possible growth routine of submicron-size cube-like Fe 2 O 3 agglomerates is that nano-ellipses nucleate, grow and aggregate.…”

Ce Doped Germanium Dioxide Nanowires and Solar Light Photocatalytic Performance

“…SDS affects the diffusion rate of various faces of the germanium dioxide and Ce germanate. The selective adsorption of SDS molecules on the surface of the crystalline nuclei induces the formation of the Ce doped germanium dioxide nanowires [20].…”