Electrospray Deposition of {200} Oriented Regular-Assembly BaTiO3 Nanocrystal Films under an Electric Field

Highly oriented, regularly assembled nanocrystalline films have recently emerged as attractive new functional materials. In this study, we deposited a BaTiO₃ (BT) nanocube dispersion on a Si substrate by electrospraying, resulting in a dense, regularly assembled BT nanocrystalline film. X-ray diffraction analysis revealed that applying a voltage between the electrospray nozzle and the Si substrate during electrospraying caused the BT nanocubes to form a regular array in the 200 plane aligned perpendicularly to the substrate. The volume fraction of BT nanocubes in the 200 plane in the assembly was estimated by the orientation distribution function analysis to be about 50%. The formation of this regularly assembled layer was determined to be linked to the interaction between the vaporized solvent and the substrate, enabled by the enhanced wettability under the electric field. Electrospray deposition has potential applications in the manufacture of nanocrystalline assembled films for nanofunctional devices.

Manifestation of dipole-induced disorder in self-assembly of ferroelectric and ferromagnetic nanocubes

The colloidal processing of nearly monodisperse and highly crystalline single-domain ferroelectric or ferromagnetic nanocubes is a promising route to produce superlattice structures for integration into next-generation devices, whereas controlling the local behaviour of nanocrystals is imperative for fabricating highly-ordered assemblies. The current picture of nanoscale polarization in individual nanocrystals suggests a potential presence of a significant dipolar interaction, but its role in the condensation of nanocubes is unknown. We simulate the self-assembly of colloidal dipolar nanocubes under osmotic compression and perform the microstructural characterization of their densified ensembles. Our results indicate that the long-range positional and orientational correlations of perovskite nanocubes are highly sensitive to the presence of dipoles.

Phase transformations, anisotropic pyroelectric energy harvesting and electrocaloric properties of (Pb,La)(Zr,Sn,Ti)O3 single crystals

(Pb,La)(Zr,Sn,Ti)O₃ single crystals are grown via the flux method. The structural phase transition, thermal–electrical energy harvesting and electrocaloric properties of the PLZST crystals with [100], [110], and [111] crystallographic directions are studied systematically.