Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Materials multifunctionality for optical sensing of adsorbates has obvious advantages-in addition to the potential for greater sensitivity, the different length scales associated with a variety of optical phenomena allow a greater variety of adsorption characteristics to be examined. Here, we show that ultrathin (appr…
The risk assessment of carbon materials, an important topic in nanomaterials research, has been hampered by the lack of characterizable samples. Transition-metal-free carbon nanohorn aggregates have been prepared that are covalently bonded aggregates of single-walled nanotubes. They were functionalized to give water-s…
Bi2ZnTiO6, a lead-free analogue of PbTiO3, has been prepared by high-pressure solid-state synthesis methods. Structural analysis reveals that the tetragonal distortion (c/a ratio = 1.21) of Bi2ZnTiO6 is the largest reported for any d0 B site Pb or Bi based perovskite. Significant cation displacements result in a point…
We calculate the diameter and chirality dependences of the binding energies, sizes, and bright-dark splittings of excitons in semiconducting single-wall carbon nanotubes. Using results and insights from ab initio calculations, we employ a symmetry-based variational method within the effective-mass and envelope-functio…
We present Monte Carlo simulations of the reversible transverse susceptibility (RTS) for a hexagonal array of dipolar interacting magnetic nanoparticles with random anisotropy. RTS curves with the bias-field in-plane and out-of-plane are compared. With increasing temperature the RTS curves evolve from a three-peak str…
Graphitization of the 6H-SiC(0001) surface as a function of annealing temperature has been studied by ARPES, high resolution XPS, and LEED. For the initial stage of graphitization - the 6root3 reconstructed surface - we observe sigma-bands characteristic of graphitic sp2-bonded carbon. The pi-bands are modified by the…
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,…