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。
The OH stretch mode of hydrogen defect ensembles in cubic and tetragonal ${\mathrm{SrTiO}}_{3}$ and ${\mathrm{KTaO}}_{3}$:Li has been investigated with polarized Raman scattering. Introducing the Raman behavior type analysis to tetragonal crystals allows the determination of the local symmetry and proves for ${\mathrm…
Abstract Glassy polymers undergo relatively rapid physical aging just below their glass transition temperatures that can lead to embrittlement of normally tough materials like polycarbonate (PC). One approach for solving the embrittlement problem is to incorporate an impact modifier that can cause toughening when the…
The luminescence decay of excitons in disordered low-dimensional semiconductors with quantum confinement is shown experimentally to be characterized by a nonexponential profile and an absence of spectral diffusion. We are able to describe this luminescence as a hopping-assisted recombination using the correlation func…
Recently, it has been demonstrated that semiorganic materials have potential for very efficient nonlinear optical devices. Among many recently reported materials is zinc tris thiourea sulfate. We report measurements of the electro-optic, piezoelectric, and dielectric constants of this new material.
Blue upconversion laser operation in Tm:YLiF4 at 450.2 nm on the 1D2→3F4 transition, and at 483.0 nm on the 1G4→3H6 transition has been achieved using cw pumping with Ti Sapphire and DCM dye lasers. The 450.2-nm laser was excited by sequential two-photon absorption with 784.5-nm and 648-nm laser sources and was operat…
This highly illustrated monograph provides a comprehensive study of the structure and function of proteins, nucleic acids and viruses using synchrotron radiation and crystallography. Synchrotron radiation is intense, polychromatic and finely collimated, and is highly effective for probing the structure of macromolecul…
Reproduction in whole, or in part, is permitted for any purpose of the United States Government *This document has been approved for public release and sale; its distribution is unlimited
We report measurements of the phase-slip process by which charge-density-wave (CDW) current is converted to single-particle current at electrical contacts. An excess voltage ${\mathit{V}}_{\mathrm{ps}}$ produces a large static deformation of the CDW phase, which drives formation of dislocation loops. Measurements of t…
We report the preparation of silicon-based visible light-emitting diodes, configured as heterojunctions between porous silicon (formed by electrochemical etching of p-type silicon wafers), and n-type indium tin oxide (ITO). The transparent ITO film allows light emission through the top surface of the device, under a f…
A model for ion transport in glass is presented which is based on the experimental evidence that cations in glass create and maintain their own characteristic environments. By postulating the existence of a site memory effect, we are able to visualize the formation of conducting pathways. We develop a quantitative the…
Abstract The compatibility of epoxidized poly( cis ‐1,4‐butadiene) (EPB) with chlorinated polyvinylchloride (CPVC) was investigated. Blends studied covered the complete composition range using EPB at two degrees of epoxidation: 20 and 43 mol % oxirane units. Tensile properties of EPB (63)/CPVC were also studied at the…
We find that tetragonal B${}_{5}$${}_{0}$N${}_{2}$ is stable against decomposition into BN and B${}_{1}$${}_{2}$, that the calculated lattice constants are in excellent agreement with the x-ray data, and that the atomic positions within the unit cell agree in general with the x-ray data but differ in detail due to dis…
Diamond coatings were prepared on silicon substrates for fracture studies. Two thicknesses of coatings were evaluated: 6 and 12 μm. The diamond films increased the strength of the silicon for the same size fracture initiating crack and thus caused an apparent toughness increase from 1.2 MPam1/2 for the uncoated silico…
We consider a cylindrical waveguide consisting of an inhomogeneous anisotropic liquid-crystal core embedded in an infinite homogeneous isotropic cladding. The wave equations for the pure modes are uncoupled but may have complex coefficients owing to the inhomogeneity and anisotropy of the liquid crystal. A simple nume…
Measurements are reported for the real and imaginary parts of the ac conductivity of semiconducting tellurium molybdate glass in the frequency range ${10}^{2}$--${10}^{5}$ Hz and in the temperature range 80--350 K. The experimental results are interpreted in terms of the classical correlated-barrier hopping theory.
The structure factor for a system of end-grafted neutral polymers is computed self-consistently in a random phase approximation. Both single-end-grafted, brushes, and twice-grafted layer are considered. We find that the polymer brush collapses uniformly, density variations in the direction parallel to the grafting pla…
Zinc 2,3-naphthalocyanine (ZnNc) was vacuum evaporated onto glass, NaCl, and highly oriented pyrolytic graphite (HOPG) substrates, and the molecular orientation was investigated by x-ray-diffraction, Fourier-transform-infrared–reflection-absorption spectroscopy, electronic spectroscopy, transmission electron microscop…
Self-consistent particle-fluid hybrid simulations have been used to study the structure of hydrogen dc discharges between parallel plates. A Monte Carlo simulation is used to describe individual energetic electrons in the cathode sheath, while the electrons and ions in the low-field region of the discharge are modeled…
Abstract Aminoalkyl celluloses (AmACs) were prepared from 6‐chlorodeoxycellulose and aliphatic diamines H 2 N(CH 2 ) m NH 2 (m = 2, 4, 6, 8). Their adsorption and desorption of divalent heavy metal ions such as Cu 2+ , Mn 2+ , Co 2+ , Ni 2+ and their mixtures were also investigated in detail. Adsorption of metal ions…
A thin liquid ribbon deposited on a wettable surface and subjected to a horizontal thermal gradient develops periodic fingers towards the cold region. We present an observation of the exponential growth regime, expected at early times, but not accessible in other driven fingering patterns induced by gravitational flow…