Materials Literature
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Nanoparticles of iron were prepared in distilled water using very thin iron wires and sheets, by the electro-exploding wire technique. Transmission electron microscopy reveals the size of the nanoparticles to be in the range 10 to 50 nm. However, particles of different sizes can be segregated by using ultrahigh centri…
The observation of intense visible fluorescence from silver and iron nanoparticles in different solution phases and surface capping is reported here. Metallic silver and iron nanoparticles were obtained by exploding pure silver and iron wires in pure water. Bovine serum albumin protein adsorption on the silver nanopar…
In this work, an analytical formula that gives the reach-through breakdown voltage of bipolar transistors, asymmetric thyristors, Punch Through-IGBTs and other devices with similar structure is deduced for the first time.
Anisotropies of Young's modulus E, the shear modulus G, and Poisson's ratio of all 2D symmetry systems are studied. Simple necessary and sufficient conditions on their elastic compliances are derived to identify if any of these crystals are completely auxetic, non-auxetic and auxetic. Particular attention is paid to 2…
The tuning of CdSe quantum dot (QDs) sizes, and consequently their corresponding two-photon absorption (TPA) cross section, has been systematically investigated. As the size (diameter) of the quantum dots increases, the TPA cross section is found to be empirically related via a power-law proportionality of 3.5+/-0.5 a…
We propose an elastic-anisotropy measure. Zener’s familiar anisotropy index A=2C44∕(C11−C12) applies only to cubic symmetry [Elasticity and Anelasticity of Metals (University of Chicago Press, Chicago, 1948), p. 16]. Its extension to hexagonal symmetry creates ambiguities. Extension to orthorhombic (or lower) symmetri…
Despite the significant amount of research on carbon nanotubes, the thermal conductivity of individual single-wall carbon nanotubes has not been well established. To date only a few groups have reported experimental data for these molecules. Existing molecular dynamics simulation results range from several hundred to…
We calculate the nature of magnetic interactions in transition-metal doped ZnO using the local spin density approximation and (LSDA) the $\mathrm{LSDA}+U$ (Coulomb interaction) method of density functional theory. We investigate the following four cases: (i) single-transition-metal-ion types (Cr, Mn, Fe, Co, Ni and Cu…
We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (Tc) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are not only ferroelectric (with Tc as high as 250 kelvin) but als…
Superhydrophobic surfaces have considerable technological potential for various applications due to their extreme water-repellent properties. A number of studies have been carried out to produce artificial biomimetic roughness-induced hydrophobic surfaces. It is not clear whether microstructures or nanostructures or t…
A new model for the bending of a Bernoulli–Euler beam is developed using a modified couple stress theory. A variational formulation based on the principle of minimum total potential energy is employed. The new model contains an internal material length scale parameter and can capture the size effect, unlike the classi…
Understanding and controlling the complex environment of solid-state quantum bits is a central challenge in spintronics and quantum information science. Coherent manipulation of an individual electron spin associated with a nitrogen-vacancy center in diamond was used to gain insight into its local environment. We show…
Abstract We present two‐photon excitation luminescence experiments on carbon nanotubes which show the excitonic origin of the optical excitations. The two‐photon allowed exciton state, which has even parity under rotation about the U ‐axis, is roughly 300 meV above the one‐photon active, odd‐parity state. This indicat…
Abstract Because subtle changes in physical structure (chirality) can cause the electronic structure of carbon nanotubes to vary from metallic to semiconducting, the goal of fully controlled nanotube device fabrication has proved elusive. Using a mechanical transfer technique in parallel with optical characterization,…
We numerically analyze the statistics of the heat flow between an aging system and its thermal bath, following a method proposed and tested for a spin-glass model in a recent paper [P. Sibani and H. J. Jensen, Europhys. Lett. 69, 563 (2005)]. The present system, which lacks quenched randomness, consists of Ising spins…
Abstract Raman spectroscopy (RS) was used for the characterization of well‐aligned IrO 2 nanocrystals (NCs) grown on sapphire substrates with different orientations via reactive magnetron sputtering. Three Raman‐active modes, E g , B 2 g and A 1 g , were observed in the range 500–800 cm −1 . The intensity of certain m…
Abstract The temperature‐induced changes in Raman spectra of two BN‐based materials: a hexagonal boron nitride and soot with single‐wall BN nanotubes, have been measured in temperature range 77–600 K in course of heating in the oven/cryostat cell. A nonlinear temperature dependence of the tangential Raman mode positio…
We present a novel method for the accurate numerical determination of the phase behavior of fluid mixtures having large particle-size asymmetries. By incorporating the recently developed geometric cluster algorithm within a restricted Gibbs ensemble, we are able to probe directly the density and concentration fluctuat…
Taking advantage of the surface modification that a selective solvent can induce in a glassy polystyrene–poly(2-vinylpyridine) binary brush layer, a methodology is demonstrated for reversibly tuning the tackiness of a hydrophilic, pressure-sensitive adhesive against that surface. The significant and fully reversible a…
Calculations of the electron-acoustic phonon interaction, and Raman scattering efficiency, in matrix embedded Ge quantum dots (QDs) are presented. The work is focused on the understanding of the inelastic light scattering process excited close to resonance with the confined ${E}_{1}$ transitions. Due to the large join…