Crystalline titanium dioxide (TiO 2) semiconductor nanorods (NRs) feature several optical properties, such as birefringence combined with high refractive indexes and a wide bandgap precluding optical absorption in visible-light spectrum, making them attractive for many applications such as optoelectronics. Dispersing these NRs in suitable solvents creates inorganic liquid crystals (LCs) offering enhanced collective and orientation-dependent properties, which can additionally be utilized to manipulate optical behavior. Herein, a synthetic procedure from literature is scaled up and coupled with an important post-synthesis-treatment step such that self-assembled NRs dried onto a liquid interface and in bulk can be investigated. Comprehensive characterizations confirm the vital role of surface ligand density of the NRs in reducing the effects of attractions between them and thus increasing the range of volume fractions in which these dispersions can be exploited. Various symmetries (hexagonal or tetragonal) can be achieved in the smectic layers of NRs by tuning the aspect ratios of the NRs from 4.8 to 8.5. Experiments show that external fields such as shear flow or electric fields can easily either induce a reversible nematic order in isotropic dispersions or order existing LC phases over much longer regions, opening many opportunities to manipulate light for optical applications.

Nanoparticles of Co3O4 and CoO are of paramount importance because of their chemical properties propelling their applications in catalysis and battery materials, and because of their intriguing magnetic properties. Here...

Anatase TiO 2 nanocrystals (NCs) play a vital role in photocatalytic applications due to their high catalytic activity and in gas-sensing applications due to their high chemical sensitivity. Here, we report the transformation at elevated temperature of anatase nanorods (NRs) with a length of 25 nm into rock-salt TiO nanoparticles with an average size of 9.2 ± 2.1 nm investigated by means of in situ heating in the transmission electron microscope. The NRs were completely transformed to titanium monoxide NCs after heating to a temperature of 1200 °C. We also identified an intermediate stage in the temperature range of 950–1200 °C, during which not only the anatase and rock-salt phases were found but also the brookite phase. Understanding of the phase and morphology evolution at high temperatures is of essence to the functionality of the NRs in various applications, as discussed in this work. Moreover, the high-temperature transformation to titanium monoxide is of interest as rock-salt TiO (γ-TiO) is known to exhibit superconducting properties. We propose the heating-induced transformation as a physical route to synthesize TiO NCs of very small size.

No abstract