Materials Literature
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Quasicrystal growth remains an unsolved problem in condensed matter. The dynamics of the process is studied by means of synchrotron live imaging all along the solidification of icosahedral AlPdMn quasicrystals. The lateral motion of ledges driving faceted growth at the solid-melt interface is conclusively shown. When…
The electronic properties of Fe-doped Al0.31Ga0.69N/GaN heterostructures have been studied by Shubnikov-de Haas measurement. Two subbands of the two-dimensional electron gas in the hetero-interface were populated. After the low temperature illumination, the electron density increases from 11.99 x 1012 cm-2 to 13.40 x…
Abstract It is shown here that deviations from a prolate ellipsoidal shape have a significant effect on the optical properties of gold nanorods. Transitions from rods to ‘dumbbell'‐ or ‘phi'‐shaped particles lead to a shift in the longitudinal plasmon peak in the blue and red directions, respectively. Development of ‘…
Density functional calculations have been used to study the electronic structure, preferred sites in the lattice, formation energies and vibrational frequencies for hydrogen interstitials in different charge states in the cubic phase of perovskite-structured BaZrO3. By combining ab initio results with thermodynamic mo…
The adsorption of starch that had been hydrophobically modified with octenyl succinate anhydride (OSA) at the oil/water interface during emulsification was studied. The starch samples were of waxy barley origin and were varied in molar mass and degree of substitution (DS). The particle size of the emulsions was measur…
The effect of Co addition on the magnetocaloric effect of amorphous alloys with Nanoperm-type composition has been studied for temperatures above room temperature. Co addition produces an increase in the maximum magnetic entropy change and a shift of its associated temperature to higher temperatures. The maximum refri…
Monodisperse magnetite Fe3O4 nanoparticles of controlled size within 6 and 20 nm in diameter were synthesized by thermal decomposition of an iron organic precursor in an organic medium. Particles were coated with oleic acid. For all samples studied, saturation magnetization Ms reaches the expected value for bulk magne…
Magnetization (M) and magnetoresistance (MR) measurements on polycrystalline R2Mn3Si5 (R = Tb, Dy and Ho) compounds (tetragonal, space group P4/mnc) have been carried out in the temperature range of 2 K-300 K, in various applied fields. Both, the rare earth and the Mn, are found to carry magnetic moments in these comp…
We report the synthesis, (micro)structural, magneto-transport and magnetization of polycrystalline La2/3Ca1/3MnO3:Agx composites with x = 0.0, 0.1, 0.2, 0.3 and 0.4. The temperature coefficient of resistance (TCR) near ferromagnetic (FM) transition is increased significantly with addition of Ag. The FM transition temp…
We consider the electrical current through a magnetic point contact in the limit of a strong inelastic scattering of electrons. In this limit local Joule heating of the contact region plays a decisive role in determining the transport properties of the point contact. We show that if an applied constant bias voltage ex…
The present controversy over the origin of glasslike thermal conductivity observed in certain crystalline materials is addressed by studies on single-crystal x-ray diffraction, thermal conductivity $\ensuremath{\kappa}(T)$, and specific heat ${C}_{p}(T)$ of carrier-tuned ${\mathrm{Ba}}_{8}{\mathrm{Ga}}_{16}{X}_{30}$ $…
Magnetization and Mössbauer studies have been performed on the polymer coated magnetite nanoparticles with particle size from 5.1 to 14.7 nm. The maximum in the temperature dependence of magnetization ( T M ) is found to be inconsistent with the particle size ( D TEM ). The effective magnetic anisotropy ( K an ) is fo…
Magnetism of a very thin antiferromagnetic (AFM) surface CuO has been investigated with partially oxidized nanocomposites of Cu–CuCl, ∼200 nm. The samples are characterized by x-ray diffraction, x-ray photoelectron spectroscopy, x-ray-excited Auger electron spectroscopy, transmission electron microscopy and magnetic m…
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…