Materials Literature
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The crystal and magnetic structures of ${\mathrm{Tb}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ series have been studied by x-ray and neutron-diffraction techniques. Macroscopic magnetic properties have been characterized using ac magnetic susceptibility measurements. The relationships between structural…
Most cellular solids are random materials, while practically all theoretical results are for periodic models. To be able to generate theoretical results for random models, the finite element method (FEM) was used to study the elastic properties of solids with a closed-cell cellular structure. We have computed the dens…
Low-T Brillouin spectra of the incipient ferroelectric KTaO3 exhibit a broad central peak (CP), and additional Brillouin doublets (BD), that can both be related to phonon-density fluctuations. On the basis of new high-resolution neutron data obtained of low-lying phonon branches, we analysed the phonon-kinetics mechan…
The iron rust phase was analyzed by using the in-situ x-ray diffraction (XRD) and alternating current (AC) impedance methods after a wet/dry corrosion test using sodium chloride (NaCl) solution, which is the main composition of airborne saline particles. The corrosion content of the carbon steel depended on the concen…
Raman microscopy has been employed to investigate the nature of damage created when natural type-IIa diamond is irradiated with MeV alpha particles. Three features appear in the Raman spectrum due to damage, viz., (i) the first-order diamond Raman line is broadened and downshifted, (ii) broad features appear which are…
This article reviews recent developments in the polymerization of α-amino acid- N-carboxyanhydrides (NCAs) to form polypeptides. Traditional methods used to polymerize these monomers are described, and limitations in the utility of these systems for the preparation of polypeptides with controlled molecular weights and…
Several copper complexes used successfully as the catalysts for atom transfer radical polymerization (ATRP) were studied by cyclic voltammetry in acetonitrile. These complexes include CuBr or CuCl complexed by 2,2′-bipyridine (bpy), 4,4′-di(5-nonyl)-2,2′-bipyridine (dNbpy), 4,4′-di(n-nonyl)-2,2′-bipyridine (dnNbpy), N…
Preferential growth along the 〈110〉 axes occurs in the preparation of Pt nanowires by reduction of [Pt(NH3)4]+ ions in the mesopores of silica MCM-41. The nanowires, uniformly 3.0 nm in diameter and with lengths of tens to hundreds of nanometers, consist of single crystals and are stable up to 500°C. Unsupported nanow…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTTuning the Properties of Conjugated Polyelectrolytes through Surfactant ComplexationLiaohai Chen, Su Xu, Duncan McBranch, and David WhittenView Author Information Bioscience Division and Chemical Science and Technology Division Los Alamos National Laboratory Los Alamos…
A ZrB 2 –SiC composite was prepared from a mixture of zirconium, silicon, and B 4 C via reactive hot pressing. The three‐point bending strength was 506 ± 43 MPa, and the fracture toughness was 4.0 MPa·m 1/2 . The microstructure of the composite was observed via scanning electron microscopy; the in‐situ ‐formed ZrB 2 a…
The emission spectra and the lifetimes of the lasing transition ${}^{4}{I}_{13/2}{\ensuremath{-}}^{4}{I}_{15/2}$ in ${\mathrm{Er}}^{3+}$-doped ${\mathrm{TeO}}_{2}{\ensuremath{-}\mathrm{Z}\mathrm{n}\mathrm{O}\ensuremath{-}\mathrm{N}\mathrm{a}}_{2}\mathrm{O}$ ternary glasses have been studied. The investigation includes…
Experimental results show that a nanolayered composite structure made of two kinds of metals strengthens dramatically as the layer thickness is reduced. In epitaxial systems, this strengthening has been attributed to the modulus, lattice parameter, gamma surface and slip-plane mismatches between adjacent layers. The m…
To probe the one-dimensional nature of single-wall carbon nanotubes (SWNTs) in bulk samples, we have devised a simple method for generating fibers of aligned SWNTs. We measured polarization-dependent Raman spectra on the oriented fibers. Contrary to what is expected from their theoretically assigned vibration-mode sym…
Targeted three-dimensional networks with unprecedented porosity (nanoporosity) can be designed from first principles. The diversity of nodes and ligands available allows fine tuning of the molecular recognition features of these porous solids. The materials so far prepared, for example [{Cu(4,4′-bipy)2}n](SiF6)n (see…
A new approach to the characterization of the mechanical and electrical properties of individual nanowires and nanotubes is demonstrated by in-situ transmission electron microscopy (TEM). The technique allows a one-to-one correlation between the structure and properties of the nanowires. Recent developments include th…
ABSTRACT: Effects of formulation (lipid presence, type of starch, and plasticizer) on microstructure, water vapor (WVP) and gas (GP) permeabilities of films and coatings were analyzed. Plasticizer was necessary to maintain film and coating integrity and to avoid pores and cracks. Films made from high amylose starch sh…
A new electrodeposition method for making porous ZnO layers with highly oriented and columnar morphology is reported here. A monolayer of dye is adsorbed onto the ZnO followed by electrodeposition of p-type CuSCN to create a complete inner-surface electrical contact, resulting in a bicontinuous-network heterojunction…
Relaxor ferroelectric single crystals Pb((Mg 1/3 Nb 2/3 ) 1- x Ti x )O 3 (PMNT 100(1- x )/100 x ) were grown directly from melt by a modified Bridgman technique. The segregation during the growth of PMNT single crystals was studied by means of differential thermal analysis (TGA), thermogravimetric analysis (DTA), X-ra…
This paper presents a simulation study of the packing of uniform fine-spherical particles where the van der Waals force is dominant. It is shown that porosity increases with the decreases of particle size from about 100 to 1 &mgr;m and the simulated relationship can match the literature data well. The packing structur…
We observed photon antibunching in the fluorescent light emitted from a single nitrogen-vacancy center in diamond at room temperature. The possibility of generating triggerable single photons with such a solid-state system is discussed.