Materials Literature
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The new titanatranes (Ar = 2,6-di- i -Pr-phenoxy; Ar‘ = 2,4-di-MeC 6 H 2; x = 0, 5; x = 1, 6; x = 2, 7; x = 3, 8 ) featuring three six-membered chelating rings ( 5 ) to three five-membered chelating rings ( 8 ) in a stepwise fashion through 6 and 7 were synthesized from the corresponding trihydroxy chelating ligands 1…
Electronic transport properties of bismuth nanocontacts are analyzed by means of a low temperature scanning tunneling microscope. The subquantum steps observed in the conductance versus elongation curves give evidence of atomic rearrangements in the contact. The underlying quantum nature of the conductance reveals its…
The method of iterated conformal maps is developed for quasi-static fracture of brittle materials, for all modes of fracture. Previous theory, that was relevant for mode III only, is extended here to mode I and II. The latter require solution of the bi-Laplace rather than the Laplace equation. For all cases we can con…
We propose and study a simplified model for the surface and bulk structures of crosslinked polymer gels, into which voids are introduced through templating by surfactant micelles. Such systems were recently studied by Atomic Force Microscopy [M. Chakrapani et al., e-print cond-mat/0112255]. The gel is represented by a…
The intersection between dislocations and a Ag(111) surface has been studied using an interplay of scanning tunneling microscopy (STM) and molecular dynamics (MD). Whereas the STM provides atomically resolved information about the surface structure and Burgers vectors of the dislocations, the simulations can be used t…
We present a first-principles comparison of ${\mathrm{BaTiO}}_{3},{\mathrm{CaMnO}}_{3},$ and ${\mathrm{YMnO}}_{3}$ which reveals the fundamental role of the d electron occupation in preventing or favoring the simultaneous presence of magnetic and electric polarization. The ferroelectric compounds are distinguished fro…
Density (or state) dependent pair potentials arise naturally from coarse-graining procedures in many areas of condensed matter science. However, correctly using them to calculate physical properties of interest is subtle and cannot be uncoupled from the route by which they were derived. Furthermore, there is usually n…
Excitonic absorption, reflection and photoluminescence spectra of mixed Zn(P_{1-x}As_{x})_{2}crystals over the full range of x (0 < x < 1) and Zn_{1-x}Cd_{x}P_{2} crystals at 0 < x < 0.05 have been studied at low temperatures (1.8 K). The decrease of the energy gap in Zn(P_{1-x}As_{x})_{2} at the increase of x occurs…
Because of the increase in the electronic density of states in low-dimensional systems, semiconductor quantum wires constitute a most promising thermoelectric material. We report here the first experimental observation of a very large enhancement of the thermoelectric power of composites containing bismuth nanowires w…
Abstract Nanoscale poly(vinyl alcohol) (PVA) fiber (100–500 nm) aggregates were prepared with an electrospinning technique. Additionally, a chemical crosslinking method was used to crosslink the nanoscale PVA fiber aggregates. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and scanning electron micro…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPlastic Optical Fiber Lasers and Amplifiers Containing Lanthanide ComplexesKen Kuriki, Yasuhiro Koike, and Yoshi OkamotoView Author Information Faculty of Science and Technology, Keio University, Yokohama, Kanagawa 223-8522, Japan, JST ERATO, Koike Photonics Polymer Project,…
Biochemical, crystallographic, and computational data support the hypothesis that electrostatic interactions are among the dominant forces in stabilizing hyperthermophilic proteins. The thermostable beta-glycosidase from the hyperthermophile Sulfolobus solfataricus (Ssbeta-gly) is an interesting model system for the s…
Generation of equilibrium configurations is the major obstacle for numerical investigation of the slow dynamics in supercooled liquid states. The parallel tempering (PT) technique, originally proposed for the numerical equilibration of discrete spin-glass model configurations, has recently been applied in the study of…
0.5 Pb[Yb1/2Nb1/2]O3–0.5 PbTiO3 thin films were deposited on (111) Pt/Ti/SiO2/Si substrates by sol–gel processing using a thin Pb(Zr0.52Ti0.48)O3 seed layer. X-ray diffraction analysis and scanning electron microscopy revealed that the films were strongly (111) oriented, mimicking the orientation of the (111) Pt/Ti/Si…
An approach is proposed to develop recording materials for high speed phase change optical data storage. It utilizes a thin film alloy mixture between a stoichiometric GeSbTe alloy and an additive ternary telluride alloy. Selection rules for an additive alloy are suggested. For a test, (Ge1Sb2Te4)1−x(Sn1Bi2Te4)x thin…
We have heteroepitaxially deposited compositionally graded (Ba1−xSrx)TiO3 (BST) thin films with increasing x from 0.0 to 0.25 on (100)-oriented MgO substrates using pulsed-laser deposition. The compositional gradients along the depth in the graded films were characterized by Rutherford backscattering spectroscopy. By…
<div class="htmlview paragraph">Exhaust stream from automotives and trucks will be subjected to new and more stringent emissions standards. In the case of Diesel engine the lowering of carbon particulates emission (soot) is based on a filtration system in which trapped soot is periodically removed by controlled…
<div class="htmlview paragraph">Advanced flow-reactor capabilities created at Cummins were applied to the study of the diesel particulate matter (soot) oxidation process. This approach complemented the on-engine studies with a number of important features, including accurate control of gas composition and soot l…
The magnetic anisotropy of (001) oriented La0.7Sr0.3MnO3 films of thickness t=7–156 nm, deposited on LaAlO3 substrates, was measured by torque magnetometry in the temperature range T=10–300 K. For t⩾50 nm and H rotating out of plane the anisotropy Ku agrees well with shape anisotropy. For thinner films, Ku is reduced…
Based on a generalization of a capillary equation for solids, we develop a method for measuring the absolute value of grain-boundary stress in polycrystalline samples having a large interface-to-volume ratio. The grain-boundary stress in nanocrystalline Pd is calculated from x-ray diffraction measurements of the avera…