Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Raman scattering spectra of single-wall nanotubes with mean radii 0.55, 0.65, and 1.0 nm show size-dependent multiple splittings of the optical phonon peak corresponding to the ${E}_{2g}$ mode in graphite. These splittings constitute the first experimental evidence for the unique feature of nanotubes that they exhibit…
The contribution from the irreversible displacement of non- domain walls to the direct longitudinal piezoelectric coefficient of and ceramics was determined quantitatively by using the Rayleigh law. Effects of the crystal structure and microstructure of the ceramics as well as the external d.c. pressure on the domain…
An extremely large magnetic entropy change has been discovered in $\mathrm{Gd}{}_{5}(\mathrm{Si}{}_{2}\mathrm{Ge}{}_{2})$ when subjected to a change in the magnetic field. It exceeds the reversible (with respect to an alternating magnetic field) magnetocaloric effect in any known magnetic material by at least a factor…
The resonance Raman spectrum of InP nanocrystals is characterized by features ascribable to both longitudinal (LO) and transverse (TO) optical modes. The intensity ratio of these modes exhibits a strong size dependence. To calculate the size dependence of the LO and TO Raman cross sections, we combine existing models…
The phase behavior of fluid mixtures of hard uniaxial ellipsoids with elongations e and 1/e, and equal molecular volume, has been studied using constant-pressure Gibbs ensemble Monte Carlo simulations for e=15 and e=20. Four distinct phases are observed: isotropic (I), uniaxial nematic (N+ and N−) and biaxial nematic…
This review concerns the experimental and theoretical publications devoted to the important problem of the large piezoelectric anisotropy in -based polarized ferroelectric ceramics.
The dielectric properties of biaxially stretched polyethylene terephthalate (PET) films of thickness and 68% degree of crystallinity were investigated by means of dielectric relaxation spectroscopy in the frequency range Hz and the temperature range C. Differencial scanning calorimetry (DSC), in the range C, was emplo…
A beam with piezoceramic elements bonded to the beam's top and bottom surfaces is investigated. Simple pin-force models allow the user to predict the deformation of the beam very well for the static case. As the pin-force models are simple they are well suited for active control algorithms of such structures. In exper…
A surface of thin square polytetrafluoroethylene (PTFE) samples (1 × 1 × 0.2 cm3) was irradiated with Ar+ at 1 keV with varying ion dose from 5 × 1014 to 1 × 1017 ions/cm2 with and without an oxygen environment. The irradiated surface of the samples was examined by scanning electron microscopy (SEM) for surface textur…
The performance of magnetostrictive Terfenol-D is highly dependent on the state of the material and in particular on the mechanical prestress. This paper presents an experimental investigation of the effect of prestress on the dynamic performance of a Terfenol-D transducer. The effects of both prestress and magnetic b…
Thermal characteristics of ethylene—vinylacetate (EVA) copolymers having vinylacetate contents ranging from 5 to 40 w/w % are studied by differential scanning calorimetry. It is first shown that EVA copolymers having a vinylacetate content lower than 30 w/w % obey the Flory and Burfield theories of copolymer crystalli…
Molecularly designed surfaces formed by chemisorption of alkanethiols on ultrathin films of gold permit control of both the azimuthal and polar orientations of supported nematic liquid crystals (LCs). These surfaces, when patterned, form simple and versatile templates for the fabrication of complex optical structures…
The electronic structures of Sr_{14-x}Ca_{x}Cu24O41 are calculated within the local density approximation. Around the Fermi energy there exist quasi-one-dimensional bands originated from the ladder and chain layers. The nearest-neighbor inter-ladder hoppings are estimated to be 5--20% of the intra-ladder ones. Possibl…
Environmentally benign chemical synthesis is a central thrust in the current U.S. research arena. Production of polymers contributes to pollution during synthesis and after use. Thus, the synthesis of a biodegradable plastic by “green” technology could have a real impact. Indeed, such a polymer produced by microorgani…
We studied interplay between kinetic roughening and phase ordering in 1+1 dimensional single-step solid-on-solid growth model with two kinds of particles and Ising-like interaction. Evolution of both geometrical and compositional properties was investigated by Monte Carlo simulations for various strengths of coupling.…
This paper describes recent results of AF-sponsored research in the thermal stability of high temperature fuels. At temperatures of 550 °C (1000 °F) and above, both thermal -oxidative and pyrolytic deposition are important. A brief discussion of deposition characteristics and mitigation measures is presented.
Results of quantum chemical calculations for the and F centres in cubic and orthorhombic phases of a perovskite ferroelectric are presented and analysed in the light of existing experimental literature. It is shown that one (two) electrons of the and F centres, respectively, are considerably delocalized, even in the g…
For a composite consisting of magnetostrictive particles dispersed in a nonmagnetostrictive matrix, a simple, approximate model for the effective magnetostriction, defined as the ratio of the magnetostriction of the composite to that of the magnetostrictive component, is described. The predictions of the model compare…
A team led by Solar Turbines Incorporated is conducting a three phase program under the sponsorship of the United States Department of Energy, Office of Industrial Technologies, to improve the performance of stationary gas turbines in cogeneration through the selective replacement of metallic hot section components wi…
A probabilistic design code is being developed for high energy disks and rotors used in aircraft gas turbine engines. This code is intended to augment, not replace, the current safe-life approach to the design of these critical components. While the code will ultimately be applicable to a range of disk alloys, initial…