Materials Literature
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We study in this article the mathematical properties of a class of orbital-free kinetic energy functionals. We prove that these models are linearly stable but nonlinearly unstable, in the sense that the corresponding kinetic energy functionals are not bounded from below. As a matter of illustration, we provide an exam…
Control of intramolecular spin alignment is studied theoretically in a model of polyene-based molecular magnets in which delocalized $π$ electrons are coupled with localized radical spins. In a previous paper [Phys. Rev. Lett. 90 (2003) 207203], we have demonstrated that charge doping is an effective way to realize co…
We summarize our recent findings on how current-driven magnetization switching and magnetoresistance in nanofabricated magnetic multilayers are affected by varying the spin-scattering properties of the non-magnetic spacers, the relative orientations of the magnetic layers, and spin-dependent scattering properties of t…
A simple method combining photolithography and shadow (or angle) evaporation is developed to fabricate single-walled carbon nanotube (SWCNT) devices with tube lengths of approximately 10-50 nm between metal contacts. Large numbers of such short devices are obtained without the need of complex tools such as electron be…
From a macroscopic viewpoint phase transitions as surface melting or growth mode can be described in term of Gibbs excess quantity duly amended by size effect. The aim of this study is to consider such amended quantities to describe surface melting and Stranski Krastanov transition of epitaxial layers. The size effect…
The non-linear response of infinite periodic solids to homogenous electric fields and collective atomic displacements is discussed in the framework of density functional perturbation theory. The approach is based on the 2n + 1 theorem applied to an electric-field-dependent energy functional. We report the expressions…
Raman microspectroscopy has been used for the first time to determine quantitatively the orientation of the beta-sheets in silk monofilaments from Bombyx mori and Samia cynthia ricini silkworms, and from the spider Nephila edulis. It is shown that, for systems with uniaxial symmetry such as silk, it is possible to det…
Abstract Since the first report on the synthesis of inorganic WS 2 nanotubes in 1992, the number of articles on the successful growth of different inorganic nanotubes has increased rapidly, emphasizing the importance of this field for nanotechnology. Although there are some geometrical similarities to carbon nanotubes…
We have investigated the detailed magnetic field dependence of the electric polarization and dielectric constant in $(\mathrm{T}\mathrm{b},\mathrm{D}\mathrm{y},\mathrm{H}\mathrm{o}){\mathrm{M}\mathrm{n}}_{2}{\mathrm{O}}_{5}$ where magnetic and ferroelectric transitions are intimately coupled. Our fundamental discovery…
Ordered mesoporous carbon and nitrogen-doped (CNx) materials with graphitic pore walls have been prepared via chemical vapor deposition (CVD) using mesoporous silica (SBA-15) as a solid template and styrene or acetonitrile as carbon source. CVD temperatures above 850 °C were found to be most suitable for the fabricati…
Gold nanoparticles were prepared by reducing gold salt with a polysaccharide, chitosan, in the absence/presence of tripolyphosphate (TPP). Here, chitosan acted as a reducing/stabilizing agent. The obtained gold nanoparticles were characterized with UV--vis spectroscopy and transmission electron microscopy. The results…
Ternary imides of Li–Mg and Li–Ca were synthesized and tested for hydrogen storage. Li2MgN2H2, as an example, reversibly stores 5.5 wt.-% hydrogen at temperatures below 180 °C (see Figure) with relatively high desorption plateau pressures. The present work also reveals the significance of chemical reactions between am…
Guided modes in a vertical strip line embedded in a non-radiative dielectric (NRD) guide were analysed based on the two-dimensional finite-element method. The dominant mode in this guiding structure is the TEM wave, and furthermore, it is evident that a quasi-LSM11 odd mode occurs when a wide metal strip is used, wher…
Using plane-wave pseudopotential density functional theory calculations, we have investigated the behaviors of neutral interstitials and vacancies at the amorphous-crystalline (a–c)Si interface. A continuous random network model is employed in the construction of defect-free a-c interface structure. We find that both…
Nickel microspheres were produced by the spark erosion technique under both liquid nitrogen and water conditions. Density measurements and Scanning electron microscope analysis revealed that a significant portion of the Ni particles produced under the liquid nitrogen conditions are hollow spheres with a density of 6.6…
Carbon nanofibers have been grown at room temperature using a combination of radio frequency and microwave assisted plasma-enhanced chemical vapor deposition. The nanofibers were grown, using Ni powder catalyst, onto substrates kept at room temperature by using a purposely designed water-cooled sample holder. Branched…
A mathematical model is presented to analyze the kinetics of solid-state polymerization of bisphenol A polycarbonate. The reaction kinetic model incorporated in the solid-state polymerization model is a hybrid of a molecular species model and a functional group model derived from the original model developed by Flory.…
We present neutron and synchrotron powder-diffraction investigations as well as ab initio calculations to elucidate delicate structural features in doped skutterudites. Samples with assumed Fe doping were investigated (FeyCo4Sb12, y=0.4, 0.8, 1.0, and 1.6), as well as samples with formal Ni substitution (Co4−xNixSb12,…
The chainlike silicon nanowires SiNWs have been synthesized by fluctuating the pressure of the carrier gas in the growth process. The chainlike SiNWs comprise crystalline Si nanoparticles interconnected by amorphous silicon oxide wires. In addition to the sphere, other interesting shapes such as rectangular and triang…
Domain structure changes in (1-x)Pb(Mg1∕3Nb2∕3)O3-xPbTiO3 have been studied by polarized optical microscopy. In the zero-field-cooled condition, increasing the x revealed systematic changes in the domain morphology from polar nanodomains for x<0.25, to fine crosshatched domains near the morphotrophic phase boun…