Materials Literature
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The formulation of Fermat's principle for electromagnetic waves traveling in materials with a negative refractive index is refined. It is shown that a formulation in terms of the minimum (or extremum) of wave travel time between two points is not correct in general. The correct formulation involves the extremum of the…
BaPbO 3 (BPO)/PbZr0.53Ti0.47 (PZT)/BPO heterostructures were fabricated by combining the sol-gel and rf-magnetron sputtering techniques. Experimental results indicate that the BPO bottom electrodes effectively prevent the formation of the rosette structure of PZT, producing smooth surfaces. Additionally, ferroelectric…
Surface potential and the amount of charging on an insulator surface under electron beam irradiation have been quantitatively measured. For these measurements, a special sample holder was developed. The surface potential was measured using a secondary electron method. The measurement of the surface potential revealed…
This article reports on the interfacial behavior of large liquid-phase polycyclic aromatic hydrocarbons in pitches that are common precursors to carbon materials. Experiments were conducted to identify preferred angles of molecular orientation (“surface anchoring” states) and to measure contact angles on a variety of…
Bulk, single-crystal ZnO was etched in Cl2/Ar and CH4/H2/Ar inductively coupled plasmas as a function of ion impact energy. For CH4/H2/Ar, the etch rate (R) increases with ion energy (E) as predicted from a model of ion enhanced sputtering by a collision–cascade process, R∝(E0.5−ETH0.5), where the threshold energy, ET…
Conformations of isolated homo-dendrimers of G=1–7 generations with D=1–6 spacers have been studied in the good and poor solvents, as well as across the coil-to-globule transition, by means of a version of the Gaussian self-consistent method and Monte Carlo simulation in continuous space based on the same coarse-grain…
We comparatively study two conventional types of Si/SiO2 materials, Si/SiO2 superlattices (SLs) and Si-rich silica (SiOx) films, prepared with a molecular beam deposition method. Raman scattering, photoluminescence (PL), ultraviolet-visible-infrared absorption, and x-ray photoelectron spectroscopies are employed to ch…
Uncharged block copolymer micelles display thermoreversible transitions between close-packed and bcc lattices for a range of concentration, solvent selectivity, and copolymer composition. Using small-angle x-ray scattering on shear-oriented solutions, highly aligned fcc crystals are seen to transform epitaxially to bc…
Irradiation of proteins with intense X-ray radiation produced by third-generation synchrotron sources generates specific structural and chemical alterations, including breakage of disulfide bonds and decarboxylation. In this paper, disulfide bond lengths in irradiated crystals of the enzyme Torpedo californica acetylc…
The use of third-generation synchrotron sources has led to renewed interest in the effect that ionizing radiation has on crystalline biological materials. Simple criteria have been sought to study the effects systematically. The unit-cell volume of protein crystals shows a linear increase with absorbed dose and has th…
A flexible method of preparing and macroscopically aligning nanoparticles of crystalline silver into millimeter long fibers is presented. The approach utilizes the dual functionality of a reverse hexagonal liquid crystalline template containing a built-in reducing agent facing the aqueous domain. The method is advanta…
Competition between microsegregation and rigidity in bolaamphiphilic biphenyl derivatives bearing lateral semiperfluorinated alkyl chains leads to the formation of novel smectic liquid-crystalline phases, designated SmAb and LamA, in which the rigid rodlike segments are organized parallel to the planes of the layers.
Nanoporous shell or sphere-in-sphere structures have been constructed by consecutive alternating adsorption of polyelectrolytes and SiO2 on melamine formaldehyde particles, followed by removal of the cores with HCl and SiO2 with HF. The shells have been distinguished by confocal laser scanning microscopy imaging (see…
Building catalyst models for complex catalytic systems is still a challenging task. In the case of supported bimetallic catalysts, such models can be obtained by taking advantage of nucleation and growth processes during the metal vapor deposition of two metals onto a suitable support (see picture). In this way, the o…
The relationship between molecular structure and electronic properties of 18 N -arylbenzamides has been investigated. The secondary amides adopt extended trans-amide conformations, whereas the tertiary amides adopt folded cis-amide conformations in which the N- aryl group is approximately perpendicular to the benzoyl…
In a recent paper we used a phase-field model of solidification in deeply undercooled pure melts to show that a kinetic instability could result in dendrite tip splitting, and we speculated that such tip splitting could give rise to the phenomenon of spontaneous grain refinement. Here we present evidence, from the as-…
Low ionic sorption capacities and high hydraulic conductivities of sandy soils contribute to the potential for leaching of nutrients applied to these soils. Batch sorption experiments were used to examine NO3–, NH4+, and Psorption/desorption isotherms for Karrakatta sand and Kwinana fly ash. Column experiments assesse…
Three-dimensional micromagnetic simulations are used to study the effect of crystallographic textures on the magnetic properties of uniaxial nanocrystalline films of hard magnetic materials with arbitrary grain shapes and size distributions. The correlation lengths (effective ferromagnetic exchange interaction radius…
We demonstrated a deposition of nanometer-scale Zn dots using the selective photodissociation of adsorption-phase diethylzinc with a nonresonant optical near field, where the photon energy is lower than that of the absorption edge of gas-phase diethylzinc. We achieved nanometric prenucleation by dissociating diethylzi…
The piezoelectric properties of lead zirconate titanate (PZT)–polymer composites were studied as a function of composition and phase connectivity. PZT skeletal structures were fabricated by robotic deposition, densified at 1275 °C, and subsequently infiltrated with epoxy to produce the desired PZT–polymer composites.…