Materials Literature
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Percolation effects are studied in phase change materials used for optical and electrical nonvolatile memory applications. Simultaneous measurements of the electrical resistivity and optical reflectivity allow experimental assessment of the percolation behavior associated with the mixed amorphous and crystalline phase…
Abstract A novel composite material consisting of polypropylene (PP) fibers in a random poly(propylene‐ co ‐ethylene) (PPE) matrix was prepared and its properties were evaluated. The thermal and mechanical properties of PP–PPE composites were studied by dynamic mechanical analysis (DMA) and differential scanning calor…
We report the crystal structure and magnetic properties of the Zn1−xMnxO compounds synthesized by a combustion method. The Zn1−xMnxO compounds with x=0–0.1 crystallize in the wurtzite ZnO structure. The lattice parameters a and c of Zn1−xMnxO increase linearly with the Mn content, indicating that Mn2+ ions substitute…
Optical phonon confinement and efficient UV emission of ZnO nanowires were investigated in use of resonant Raman scattering (RRS) and photoluminescence (PL). The high-quality ZnO nanowires with diameters of 80-100 nm and lengths of several micrometers were epitaxially grown through a simple low-pressure vapor-phase de…
Abstract Summary: The wavelength‐dependent vacuum ultraviolet (VUV) photolysis of several polymers, low density polyethylene (LDPE), biaxially oriented poly(propylene) (BOPP), atactic polystyrene (PS), and poly(methyl methacrylate) (PMMA), was studied by irradiation in vacuum with the well‐characterized emissions from…
We present a combined double S-shaped metamaterial structure that exhibits a left-handed property over a wide frequency band of 6GHz. The transmission experiment, phase measurement, and prism refraction experiment from the structure confirm the presence of the negative index of refraction.
Efficient upconversion luminescence is observed from CdTe nanoparticles in solution and precipitated as solids. In the solids, the upconversion luminescence spectrum is significantly red shifted relative to the photoluminescence spectrum, whereas in solution, there is very little spectral shift. The upconversion lumin…
Single-wall carbon nanotubes (SWNTs) suspended in isopropyl alcohol are placed between two cross-structured electrodes using an ac dielectrophoresis technique. The SWNTs are found to attach to the electrodes along the direction of the ac external electric field. The SWNTs predominately bridge the shortest gap between…
A chiral supramolecular “sergeant” as the structure-directing agent affects the backbone stereochemistry during polymerization of the achiral “soldier” monomers. The polymer obtained shows preferred helical folding despite its mixed microstructure.
ZnO nanowires with diameters ranging from 20 to 60 nm and lengths in the range 5–15 μm were synthesized by metalorganic chemical vapor deposition, assisted by colloidal gold nanoparticles with a diameter of 20 nm dispersed on SiO2∕Si substrates. The ZnO nanowires were found to have a high-internal quantum efficiency a…
Adsorption of inorganic mercury(II) from an aqueous solution on mercaptopropyl-functionalized SBA-15 mesoporous silicas has been investigated. Adsorbents were prepared by the cocondensation method using tetraethoxysilane and different quantities of (mercaptopropyl)trimethoxysilane. Pluronic P123 was employed as a stru…
We calculate the electronic wave-function for a phosphorus donor in silicon by numerical diagonalisation of the donor Hamiltonian in the basis of the pure crystal Bloch functions. The Hamiltonian is calculated at discrete points localised around the conduction band minima in the reciprocal lattice space. Such a techni…
Current-induced switching from metallic to insulating state is observed in phase-separated states of (La_{1-y}Pr_y)_{0.7}Ca_{0.3}MnO_3 (y=0.7) and Nd_{0.5}Ca_{0.5}Mn_{1-z}Cr_zO_3 (z=0.03) crystals. Application of magnetic fields to this current-induced insulating state causes pronounced low-field negative magnetoresis…
The dispersion properties of rectangular metallic waveguides periodically loaded by uniaxial resonant scatterers are studied with help of an analytical theory based on the local field approach, the dipole approximation and the method of images. The cases of both magnetic and electric uniaxial scatterers with both long…
The current-induced magnetization dynamics of a spin valve are studied using a macrospin (single domain) approximation and numerical solutions of a generalized Landau-Lifshitz-Gilbert equation. For the purpose of quantitative comparison with experiment [Kiselev {\it et al.} Nature {\bf 425}, 380 (2003)], we calculate…
We study the double exchange in transition metal oxides with itinerant and localized electrons. We show that the charge transfer energy Delta and the oxygen-oxygen hopping amplitude t(pp) have a strong effect on magnetic ordering: while for Delta>0 the ground state is ferromagnetic, for negative Delta and large t(pp)…
The Berezinskii-Kosterlitz-Thouless (BKT) transition in two-dimensional planar rotator and XY models on a square lattice, diluted by randomly placed vacancies, is studied here using hybrid Monte Carlo simulations that combine single spin flip, cluster and over-relaxation techniques. The transition temperature $T_c$ is…
For solving the longstanding materials science problem of correlating elastic properties of a solid material to the formation of cracks we present a new general concept. This concept is applied to the technologically most important cracks of loading mode I for which we establish exact correlations by introducing a loc…
We analyze the modification of the intersubband absorption of electrons in quantum wells under intense THz irradiation. An expression for the induced current is obtained, based on the adiabatic approach and the resonant approximation. We predict the occurrence of a significant fine structure as well as the broadening…
Natural abundance, much higher strength per unit weight than most inorganic fillers, lower density and their biodegradable nature make natural fillers attractive as reinforcements of engineering polymer systems. However, certain drawbacks such as incompatibility with the hydrophobic polymer matrix, the tendency to for…