The stabilization of a single domain in free-standing ferroelectric nanocrystals.

High resolution electron microscopy, electron diffraction and electron holography were used to study individual free-standing ∼ 30 nm barium titanate nanocrystals. Large unidirectional variations in the tetragonal distortion were mapped across the smaller nanocrystals, peaking to anomalously large values of up to 4% at the centers of the nanocrystals. This indicated that the nanocrystals consist of highly strained single ferroelectric domains.

Size dependence of chiroptical activity in colloidal quantum dots.

The synthesis of chiral penicillamine-capped CdS and CdSe quantum dots (QDs) was adjusted to control the size of the nanoparticles. This, together with size separation, allowed for simultaneous tuning of absorption, circular dichroism (CD), and fluorescence on a wide wavelength range. Band edge transitions were accompanied by circular dichroism peaks which red-shifted together with the increase in particle size.

The size-dependent ferroelectric phase transition in BaTiO₃ nanocrystals probed by surface plasmons.

A new technique for probing the temperature dependence of the dielectric constant of ferroelectric nanocrystals (NCs) using shifts in the localized surface plasmon resonance (LSPR) wavelength of gold nanoparticles attached to the surface of the ferroelectric NCs is demonstrated. This technique can selectively probe the surface of the NCs and was used to study the ferroelectric-to-paraelectric phase transition of barium titanate (BTO) nanocubes in three size regimes of 16 ± 4, 47 ± 11, and 220 ± 140 nm. Temperature-dependent Raman spectroscopy was also applied to probe the whole volume of the NCs.

Growth of Au/Ag nanowires in thin surfactant solution films: an electron microscopy study.

The surfactant templated gold-silver nanowire growth process in a thin solution film was probed by cryo-transmission electron microscopy (cryo-TEM). The increasing surfactant concentration upon film drying appears to induce phase transformations in the film and form a liquid crystalline template for the nanowires growth. High-resolution transmission electron microscopy (HRTEM) and electron holography revealed that the nanowires were polycrystalline with some preferred crystallite orientations and had a roughly cylindrical cross-section.