Uniform distribution of TiO2 nanocrystals on reduced graphene oxide sheets by the chelating ligands

Reduced graphene oxide-TiO(2) hybrids were successfully prepared by the hydrothermal approach using triethanolamine and acetylacetone as the chelating agents. Without any additive, large aggregated TiO(2) clusters were randomly distributed dominantly at the edge and less on the basil plane of coagulated reduced graphene oxide (RGO) layers. The presence of chelating ligands remarkably facilitated the selective growth and regular spread of TiO(2) nanocrystals onto individually exfoliated RGO sheet. Such sandwich-like structure with stronger coupling and chemical interaction resulted in the surface area increase, the rearrangement of energy level, the enhanced concentration of oxygen vacancies, leading to much higher adsorbability and photocatalytic degradation of Rhodamine B under both UV and visible irradiations. These RGO-TiO(2) hybrid systems are potentially beneficial for widely practical applications in air/water purification, electronic devices, batteries, solar cells or supercapacitors.     

Photoisomerization-induced stable liquid crystalline cubic blue phase

We have succeeded in obtaining a photoinduced liquid crystalline cubic BP in a mixture of photoinactive and photoresponsive bent-core mesogens. The UV stimulus can convert N* to cubic BP through photoisomerization of the azobenzene linkages included in the photoresponsive bent-core molecule.     

Immobilization of gold nanoparticles on poly(methyl methacrylate) electrospun fibers exhibiting solid‐state surface plasmon effect

In this study, the surface plasmon effect of Au nanoparticles was successfully realized in the solid state by embedding the Au nanoparticles on the surface of the transparent polymer fibers for the first time. Electrospinning a poly(methyl methacrylate) (PMMA) and HAuCl₄ mixture followed by a wet chemical reduction, the gold nanoparticles were formed on the PMMA nanocomposite electrospun fibers in a well‐distributed manner to give photostable purple color. The Au nanoparticles were all sphere shaped with an average diameter of 12 nm. Specifically, simply adjusting HAuCl₄ salt concentration in the electrospinning solution, it is able to control the electrospun fiber diameter and gold nanoparticle content in the resulting PMMA/Au nanocomposite fibers. Therefore, the developed method described herein is simple and effective for the large volume production of PMMA/Au nanocomposite fibers. Copyright © 2011 John Wiley & Sons, Ltd.     

Localization-delocalization transition in a system of quantum kicked rotors

The quantum dynamics of atoms subjected to pairs of closely spaced delta kicks from optical potentials are shown to be quite different from the well-known paradigm of quantum chaos, the single delta-kick system. We find the unitary matrix has a new oscillating band structure corresponding to a cellular structure of phase space and observe a spectral signature of a localization-delocalization transition from one cell to several. We find that the eigenstates have localization lengths which scale with a fractional power L approximately h(-0.75) and obtain a regime of near-linear spectral variances which approximate the "critical statistics" relation summation2(L) approximately or equal to chi(L) approximately 1/2 (1-nu)L, where nu approximately 0.75 is related to the fractal classical phase-space structure. The origin of the nu approximately 0.75 exponent is analyzed.     

Magnetic and transport properties of lanthanum perovskites with B-site half doping

We have synthesized various half doped lanthanum perovskites (BB′=MnV, MnCr, MnCo, MnNi, FeCr, FeMn, FeCo, FeNi) by solid state reaction method. The crystal structure was orthorhombic in all samples, but the magnetic and transport properties showed a large variation with the composition. A ferromagnetic feature was quite strong in the Mn-based perovskites but weak or non-existent in the Fe-based ones. The resistivity of Ni-doped ones was much smaller than those of the others. For all half doped perovskits, remarkably, the temperature dependent transport was well explained by variable range hopping model with different localization lengths.     

Growth of FePt nanocrystals by a single bimetallic precursor [(CO)3Fe(mu-dppm)(mu-CO)PtCl2

A new single source approach was developed to synthesize face-centered tetragonal (fct) FePt nanoparticles using bimetallic compound (CO)3Fe(mu-dppm)(mu-CO)PtCl2, which has been characterized by single crystal X-ray diffraction and was used as the precursor to ensure the accurate stoichiometry of the final FePt product; the ability of the molecular complex to act as a single source precursor for the formation of fct FePt nanocrystals with an average diameter of 3.2 nm has been demonstrated.     

Enhanced photocatalytic activity in composites of TiO2 nanotubes and CdS nanoparticles

A new composite consisting of TiO(2) nanotubes and CdS nanoparticles, where CdS particles bind covalently to the titania surface through a bifunctional organic linker, was successfully fabricated; this titania nanotube-based composite shows enhanced photocatalytic activity under visible-light irradiation.     

Layered titanate-zinc oxide nanohybrids with mesoporosity

Zinc oxide-layered titanate nanohybrids with a 1 ratio 1 ordered heterostructure have been successfully synthesized by reassembling exfoliated titanate nanosheets in the sol solution of zinc acetate under hydrothermal conditions.