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 piezoresistivity of polycrystalline p-type diamond films has been studied. The films were grown by microwave plasma assisted chemical vapor deposition and in situ doped with different concentrations of boron. A four-point electrical measurement was performed to evaluate the film resistivity change upon straining i…
Wide-angle x-ray diffraction studies were performed for as-spun wet poly(p-phenylene terephthalamide) fiber. The effects of sorbed water on the equatorial diffractions from the (110) and (200) crystal planes and on the meridional diffractions from the (002), (004), and (006) crystal planes were analyzed during desorpt…
Although polymeric crystallization processes heterogeneously induced by foreign surfaces have been the subject of an overwhelming amount of experimental investigations over the last 30 years, this topic suffers from the absence of theoretical or predictive tools describing the polymer–substrate interactions at work in…
Dielectric spectrometry experiments are performed on a series of polystyrene–glass bead composites with volume filler content from 0 to 50% and with three particle diameters (5 μm, 20 μm, and 90 μm) in order to study the Maxwell–Wagner–Sillars (MWS) relaxations and the percolation phenomena. In the high-temperature re…
FT–IR spectroscopy was used to study the specific interactions in polyacrylonitrile-silk fibroin (PAN–SF) and poly(acrylonitrile-co-methyl acrylate)-silk fibroin (PANMA–SF) blends. No specific interaction was found in PAN–SF blends. In PANMA–SF blends, however, a new 1703 cm−1 band, assigned to be hydrogen-bonded carb…
The crystal structure, thermal vibrations, and electron density of the charge-transfer complex bis(thiodimethylene)-tetrathiafulvalene tetracyanoquinodimethane (BTDMTTF-TCNQ, formally ${\mathrm{C}}_{10}{\mathrm{H}}_{8}{\mathrm{S}}_{6}^{+}{\mathrm{\ensuremath{\cdot}}\mathrm{C}}_{12}{\mathrm{H}}_{4}{\mathrm{N}}_{4}^{\ma…
Numerous polycarbonates were prepared by means of “diphosgene” in pyridine using hydroquinone 4-hydroxybenzoate (HQHB) as mesogenic diphenol. In addition to the homopolycarbonate, binary copolycarbonates of HQHB and 4,4′-dihydroxychalcone (DHC) with varying molar composition were prepared. A series of ternary copolyca…
We report that antiferromagnetic and antiferromagnetic (AF-AF) alternating Heisenberg chains with S =1/2 are formed in (CH 3 ) 2 CHNH 3 CuBr 3 , which is in contrast to the almost isomorphous compound (CH 3 ) 2 CHNH 3 CuCl 3 , because the Cl compound forms ferromagnetic-dominant ferromagnetic and antiferromagnetic (F-…
We report temperature-dependent infrared spectra of ${\mathrm{NdNiO}}_{3}$ prepared by synthesis under high oxygen pressure. Its room-temperature reflectivity is characteristic of a metal oxide with a Drude tail asymptotically extending to higher frequencies. The sharp metal-insulator transition is detected at about 2…
Faraday effect measurements have been carried out at room temperature for some sodium borate glasses containing Eu2+ ions prepared under a reducing atmosphere. The wavelength dependence of the Verdet constant is analyzed in terms of a theory derived by Van Vleck and Hebb to obtain effective transition wavelength of th…
The chemical state of sulfur on (NH${}_{4}{)}_{2}{\mathrm{S}}_{x}$-treated InAs(001) and thermal stability of the surface have been studied by high-resolution x-ray photoelectron spectroscopy and low-energy electron diffraction. We find sulfur bonded to In and As atoms but no elemental sulfur for the as-treated surfac…
The effect of monomer structure and catalyst on the synthesis of hyperbranched polyesters based on 4,4-(4′-hydroxyphenyl)pentanoic acid has been examined. The nature of the ester group and the catalyst have a significant effect on the molecular weight of the hyperbranched polyester but do not effect the degree of bran…
In the present work, the influence of the substitution of Al for Mn on the structure and magnetic properties of TbMn6−xAlxSn6 compounds was investigated. With increasing Al concentration the lattice constants a, c, and the unit-cell volume V decrease monotonically. The TbMn6−xAlxSn6 compounds exhibit ferrimagnetic ord…
Efficient near infrared to visible upconversion luminescence is reported in the low phonon-energy host material ${\mathrm{Ba}}_{2}{\mathrm{YCl}}_{7}:x%$ ${\mathrm{Er}}^{3+}$ ($x=1,$ 10, 100). The upconversion mechanisms upon ${}^{4}{I}_{9/2}$ excitation $(\ensuremath{\approx}800\mathrm{nm})$ are investigated by means…
We have studied the photoluminescence mechanism of freshly prepared and naturally oxidized porous silicon by fluorescence-line-narrowing spectroscopy. The surfaces of fresh and oxidized porous silicon are terminated by silicon hydrides and silicon dioxide, respectively. The TO-phonon-related structure in resonantly ex…
Intrinsic localized radiative surface states belonging to Si-Si dimers on the surface of silicon nanocrystallites have been recently predicted. We examine the various photoexcitation pathways involved in populating these molecular states. We include both direct excitation from the ground state and indirect excitation…
The energy dependence of the relaxation of photoexcited electrons in copper was measured using femtosecond time-resolved photoemission spectroscopy to within 0.3 eV above the Fermi level. By performing lifetime measurements under different surface conditions, several surface dynamical processes were investigated. In p…
The miscibility of blends of phenolphthalein poly(ether ether sulfone) (PES-C) and poly(ethylene oxide) (PEO) was established on the basis of the thermal analysis results. Differential scanning calorimetry (DSC) studies showed that the PES-C/PEO blends prepared by casting from N,N-dimethylformamide (DMF) possessed a s…
The effects of a long-range electronic potential on a one-dimensional commensurate charge-density-wave state are investigated. Using numerical techniques it is shown that a transition to a metallic ground state is reached as the range of the electron-electron repulsion increases. In this metallic state, the optical co…
Remarkable features of local density of states (LDOS) at a single $n$-membered ring defect $(n=4,5,7,8)$ in monolayered graphite are described. Based on the $n$-fold rotational symmetry at the center of the $n$-membered ring, the wave functions and the spectra of these systems are classified into $n$ kinds of componen…