Materials Literature
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This article reviews some of the recent progress in the simulation of liquid crystals across a range of length and time scales. Simulators now have an extensive range of models at their disposal, ranging from fully atomistic studies where each atom is represented in a simulation, via hard or soft anisotropic potential…
We investigate the hydrodynamic properties of a fluid simulated with a mesoscopic solvent model. Two distinct regimes are identified, the "particle regime" in which the dynamics is gaslike and the "collective regime" where the dynamics is fluidlike. This behavior can be characterized by the Schmidt number, which measu…
A size effect on crystal structure has been investigated for barium titanate (BaTiO3) nanoparticles of 40-, 140-, and 430-nm sizes, by means of neutron and high-resolution synchrotron x-ray powder-diffraction and Raman-scattering techniques. These samples were prepared by a modified two-step thermal decomposition meth…
A vectorial finite-difference time-domain (FDTD) method is used to present a numerical study of very narrow spatial solitons interacting with the surface of what has become known as a left-handed medium. After a comprehensive discussion of the background and the family of surface modes to be expected on a left-handed…
The concept of negative refraction is attracting a lot of attention. The initial ideas and the misconceptions that have arisen are discussed in sufficient detail to understand the conceptual structure that binds negative refraction to the existence of backward wave and forward wave phenomena. A presentation of the pro…
The structural, optical and magnetic properties of nanostructured ZnO films co-doped with cobalt and aluminium have been studied. The nanocrystalline films, with cluster sizes in range 50 - 100 nm, were deposited by pulsed laser ablation in a mixed atmosphere of oxygen and helium. The nanocrystallites have the wurtzit…
For materials which are incorrectly predicted by density functional theory to be metallic, an iterative procedure must be adopted in order to perform GW calculations. In this paper we test two iterative schemes based on the quasi-particle and pseudopotential approximations for a number of inorganic semiconductors whos…
The dielectric, ferroelectric and piezoelectric properties of bismuth potassium titanate, (Bi 1/2 K 1/2 )TiO 3 (BKT), ceramics were studied. Single-phase BKT ceramics with a high relative density of 97% were obtained by the hot pressing (HP) method. The resistivities of BKT ceramics hot-pressed at 1060 and 1080°C (her…
We study the effect of thiols on the emission efficiency of aqueous CdSe/ZnS core/shell nanocrystal quantum dots (NQDs). We observe that the impact of thiol addition on emission quantum yields (QYs) is time-, concentration-, and pH-dependent. Further, we use a combination of time-resolved spectroscopic methods to dete…
To better understand the relationship between atomic-scale structures and densities of aluminosilicate glasses and liquids, we used 27 Al MAS NMR to determine the speciation of aluminum ions in K 3 AlSi 3 O 9 , Na 3 AlSi 3 O 9 , and Ca 3 Al 2 Si 6 O 18 glasses quenched from melts at 3 to 10 GPa. These data are a first…
We show that spinoadal decomposition phase in dilute magnetic semiconductors (DMS) offers the possibility to have high Curie temperatures ( T C ) even if the magnetic exchange interaction is short ranged. The spinodal decomposition is simulated by applying the Monte Carlo method to the Ising model with realistic ( ab…
Abstract Molecular hybrid materials formed from polyoxometalates dispersed in conducting polymers represent an innovative concept in energy storage. This work reports in detail the first practical realization of electrodes based on these materials for energy storage in electrochemical supercapacitors. The molecular hy…
Abstract Films of liquid‐crystal networks with a splayed molecular alignment over their cross‐section display a well‐controlled deformation as a function of temperature. The deformation can be explained in terms of differences in thermal expansion depending on the average molecular orientation of the mesogenic centers…
In a previous work (Morgan and London 1996), we proposed an optimized procedure for electron microprobe analysis (EMPA) of rhyolitic glasses using a broad (20 μm diameter), low-current (2 nA) fixed beam. Some important applications for EMPA of glass, such as vitreous inclusions in minerals and experimental run product…
In microrheology, elastic and viscous moduli are obtained from measurements of the fluctuating thermal motion of embedded colloidal probes. In such experiments, the probe motion is passive and reflects the near-equilibrium (linear response) properties of the surrounding medium. By actively pulling the probe through th…
Vertically oriented single-crystalline Co3O4 nanowalls (see Figure) have been successfully fabricated by directly heating Co foil in air using a hot plate. The morphologies of the Co3O4 nanowalls can be controlled by varying the growth temperature and time. The Co3O4 nanowalls show promising field-emission performance…
Ultrafine-grained materials may be produced by applying severe plastic deformation, but these materials generally exhibit high strength and limited ductility. This report describes a technique for producing high strength and high ductility (see Figure) in precipitation-hardened alloys at ambient temperatures based on…
In the applications of single-walled carbon nanotubes (SWNTs), it is extremely important to separate semiconducting and metallic SWNTs. Although several methods have been reported for the separation, only low yields have been achieved at great expense. We show a separation method involving a dispersion-centrifugation…
Uniform and monodisperse CuO nanorods have been synthesized by directional aggregation and crystallization of tiny CuO nanoparticles generated from a solid-liquid arc discharge process under ambient conditions in the absence of any surfactants. Uniform CuO nanorods with sharp ends are formed from tiny nanoparticles vi…
PEDOT nanorods have been fabricated using reverse cylindrical micelle-mediated interfacial polymerization without any templates and applied as chemical sensors for the detection of HCl and NH3 vapor. The PEDOT nanorods, shown in the Figure, display very stable conductivity. The chemical sensors can detect low vapor co…