Materials Literature
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It is generally believed that nature does not provide materials with negative refraction. Here we demonstrate experimentally that such materials do exist at least at GHz frequencies: ferromagnetic metals reveal a negative refraction index close to the frequency of the ferromagnetic resonance. The experimental realizat…
Nanoparticles of a Prussian blue (PB) analogue, copper hexacyanoferrate, were synthesized by using ultrasonic radiation and characterized by spectroscopic and electrochemical techniques. The nanoparticles (ca. 10 nm diameter) were immobilized onto transparent indium tin oxide electrodes by electrostatic layer-by-layer…
Nanoporous aluminum oxide membranes with high open porosity are prepared by anodic oxidation. Conventional self-supporting as well as mechanically stabilized nanoporous membranes are produced from aluminum plates and microimprinted aluminum foils, respectively. The mechanically stabilized membranes are characterized b…
Co-Authors: Michael Feuerbacher, Carsten Thomas, Julien P. A. Makongo, Stefan Hoffmann, Wilder Carrillo-Cabrera, Raul Cardoso, Yuri Grin, Guido Kreiner, Jean-Marc Joubert, Thomas Schenk, Joseph Gastaldi, Henri Nguyen-Thi, Nathalie Mangelinck-Noël, Bernard Billia, Patricia Donnadieu, Aleksandra Czyrska-Filemonowicz, An…
In this paper, we describe a unique strategy for preparing discrete composite nanoparticles consisting of a large gold core (60-150 nm in diameter) surrounded by a thermally responsive nontoxic hydrogel polymer derived from the polymerization of N-isopropylacrylamide (NIPAM) or a mixture of NIPAM and acrylic acid. We…
(1− x )(Na 0.5 K 0.5 )NbO 3 – x LiNbO 3 [(1− x )NKN– x LN] ceramics were produced by the conventional solid‐state sintering method, and their microstructure and piezoelectric properties were investigated. The formation of the liquid phase and K 6 Li 4 Nb 10 O 30 second phase that were observed in the (1− x )NKN– x LN…
Almost 25 years have passed since Shechtman discovered quasicrystals, and 15 years since the Commission on Aperiodic Crystals of the International Union of Crystallography put forth a provisional definition of the term crystal to mean “any solid having an essentially discrete diffraction diagram.” Have we learned enou…
How do carbon nanotubes behave in an external electric field? What will be the relation between the intensity of the electric field and the tube's deformation? What are the geometry effects on the response of carbon nanotubes to electric fields? To answer these questions, we have developed a computational technique co…
A method for the preparation of heterobifunctional biodegradable dendrimers is described involving the preparation of a symmetric aliphatic ester dendrimer derived from 2,2-bis(hydroxymethyl)propanoic acid bearing a cyclic carbonate periphery, followed by opening of the carbonate moieties with a functional amine. This…
I propose a path integral description of the Su-Schrieffer-Heeger Hamiltonian, both in one and two dimensions, after mapping the real space model onto the time scale. While the lattice degrees of freedom are classical functions of time and are integrated out exactly, the electron particle paths are treated quantum mec…
The authors present an efficient perturbative method to obtain both static and dynamic polarizabilities and hyperpolarizabilities of complex electronic systems. This approach is based on the solution of a frequency-dependent Sternheimer equation, within the formalism of time-dependent density functional theory, and al…
Ga interstitials in GaAs ($I_{Ga}$) are studied using the local-orbital {ab-initio} code SIESTA in a supercell of {216+1} atoms. Starting from eight different initial configurations, we find five metastable structures: the two tetrahedral sites in addition to the 110-split$\mathrm{_{[Ga-As]}}$, 111-split$\mathrm{_{[Ga…
Three-terminal devices with conduction channels formed by quasi-metallic carbon nanotubes (CNT) are shown to operate as nanotube-based field-effect transistors under strong magnetic fields. The off-state conductance of the devices varies exponentially with the magnetic flux intensity. We extract the quasi-metallic CNT…
In this paper we study magnetization excitations induced in a thin extended film by a spin-polarized dc-current injected through a point contact in the current-perpendicular-to-plane (CPP) geometry. Using full-scale micromagnetic simulations, we demonstrate that in addition to the oscillations of the propagating wave…
The interactions between biological substances and carbon nanotubes (CNTs) and their effect on the nanotubes are of significant importance in this emerging era of nanobiotechnology. Consequently, highly stable dispersions of debundled CNTs in aqueous solution are an important prerequisite for their applications and fo…
Raman and combined infrared transmission and reflectivity measurements were carried out at room temperature (RT) on monoclinic VO2 over the 0-19 GPa and 0-14 GPa pressure ranges. Both lattice dynamics and optical gap show a remarkable stability up to P* approximately 10 GPa whereas subtle modifications of V ion arrang…
Thin films of Co-TiO2 are deposited on silicon and quartz substrates using Pulse Laser Deposition (PLD) process at various oxygen partial pressures ranging from 6.6 x 10-3 Pascals (Pa) to 53 Pa. Crystal structure, transport and magnetic properties of reduced CoxTi(1-x)O2 (0
To simulate the transient enhanced diffusion near the surface or interface, a set of equations describing the impurity diffusion and quasichemical reactions of dopant atoms and point defects in ion-implanted layers is proposed and analyzed. The diffusion equations obtained take into account different charge states of…
Glutathione-capped ZnSe and Zn1–xCdxSe alloyed quantum dots (QDs) have been successfully synthesized in aqueous solution (see figure). Their fluorescence emissions are tunable between 360 and 500 nm. The as-prepared QDs have a quantum yield of up to 50 %, comparable to or better than most QDs prepared by an organometa…
Continuing on recent computational and experimental work on jammed packings of hard ellipsoids [Donev, Science 303, 990 (2004)] we consider jamming in packings of smooth strictly convex nonspherical hard particles. We explain why an isocounting conjecture, which states that for large disordered jammed packings the ave…