Materials Literature
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Phonon-phonon coupling strengths have been derived from first-principles total energy calculations for bcc Zr. It is shown that the instability leading to the bcc-hcp first-order phase transition in Zr is overcome at high temperatures by the strong interactions between the ${\mathrm{T}}_{1}$ N-point phonon and other l…
One-sixth of the value of all goods manufactured in the United States involves catalytic processes. However, in spite of this dramatic economic impact, little is known about this broad subject at the molecular level. In the last two decades a variety of techniques have been developed for studying at the atomic level t…
The extract (200 ml of 50 g/L) of common garden herb (in Sri Lanka) Aerua lanata (S. Polpala, T. Thengapookeerai) induced diuresis, consistent ovet four repetitions in 70% of the subjects. The rest of the subjects needed higher concentration of the solution (100 g/L), to induce diuresis. The urine output observed with…
Two-dimensional quasiperiodic lattices with 12-fold rotational symmetry are constructed by projecting a four-dimensional hyperhexagonal lattice onto a two-dimensional subspace. The projection method in the present case is greatly simplified by representing the four-dimensional lattice as a complex two-dimensional latt…
The reaction of oxygen on Si(100) surfaces from 700 to 950\ifmmode^\circ\else\textdegree\fi{}C has been studied in real time with about 10-\ensuremath{\mu}s resolution, by use of pulsed molecular-beam reactive scattering. The oxygen reaction probability is roughly proportional to the normal component of the incident v…
The growth of dendritic crystals of ${\mathrm{NH}}_{4}$Br from supersaturated solution has been studied in a way that allows high-resolution measurements of the early stages of side branching. The branches are found to be nonperiodic at any distance from the tip, with apparently random variations in both phase and amp…
The authors study the coexistence of ferromagnetism, charge-density waves and spin-density waves in the ground state of a simple two-dimensional system. They solve a model Hamiltonian that contains, in addition to the one-electron term, a Frolich electron-phonon term, a Hubbard-like local electron-electron interaction…
We report scanning tunneling microscope images of isolated oxygen atoms adsorbed on the GaAs(110) surface. The images display a dramatic voltage dependence, which arises from the energy dependence of the local state density, and provides a signature of an adsorbed electronegative atoms. At low oxygen coverages, a long…
Using molecular-dynamics calculations, we show that at 80 K, ice Ih undergoes a transition to a high-density amorphous (hda) form at about 13 kbar. At higher pressures, the calculated oxygen atom radial distribution function shows strong resemblance to that of ice VIII. The most characteristic feature of hda ice, name…
The formation of metal-containing amorphous hydrogenated carbon films (a-C:H) in a reactive sputtering process is reported. The layers were prepared at room temperature using various metals of different concentrations. According to tribological measurements the layers exhibit small friction values and an extremely low…
High-intensity femtosecond laser pulses are used to induce non- equilibrium electron heating in gold metal. The thermal relaxation of the electronic distribution is studied through pump and continuum probe measurements of transient reflectivity. Measurements are performed for different heating-pulse fluences and probe…
The systems Ba(PO3)2-BaF2/ZnF2-AlF3 and Zn(PO3)2-ZnF2-AlF3 are investigated in order to find the glass-forming regions and structure-property relationships. 19F and 31P nuclear magnetic resonance of the glassy material are measured using a breadline spectrometer. The second moments of the measured line shapes and the…
The crystal structures of [NH3(CH2)5NH3]CdCl4 are determined by X-ray diffraction at 293 K (phase I) and 353 K (phase II) in order to obtain a structural description of the second-order phase transition occurring at 337 K. This continuous transition is mainly of order-disorder type and can be associated to the reorien…
The far-infrared spectrum of MnFe2O4 reveals two prominent bands v1 and v2 and two weak bands v3 and v4 in the range 600 to 200 cm−1. The high frequency band (v1) and the low frequency band (v2) are assigned to tetrahedral and octahedral metal complexes, respectively. The spectra of the mixed Mn1–xMgxFe2O4, with x ran…
We examine the effects that strong electron-phonon coupling has on the electronic density of states and the phonon spectrum of the mixed valent phase. We examine the dependence of the polaronic properties on the position of the f level relative to the Fermi level.
The magnetic susceptibilities of five trinuclear pseudoplanar bibridged copper(II) chloride species have been measured from approximately 5 to 300 K. The compounds all show antiferromagnetic intratrimer and generally weaker ferromagnetic intertrimer spin coupling. These compounds show systematic deviations from the su…
The domain structure of cast NdFeB magnets has been observed using the Kerr effect, both at room temperature and at temperatures up to the Curie point. The domain structure is typical of strongly uniaxial materials, and no substantial changes in domain size or domain structure are found up to the Curie point. The valu…
The magnetic phase transition in the (NiAs-type) system Mn0.5Te0.5−xSbx was investigated by electrical resistivity and x-ray powder diffraction techniques. Crystallographically, the lattice parameter (a) was found to decrease smoothly with x, while (c) behaved in a steplike manner with the changeover taking place at 0…
A well-known model for the rate of heterogeneous nucleation and growth of a second-phase precipitate in a solid matrix has successfully been applied to electromigration rate studies in metallic thin-film interconnects. The application of these rate equations is based on the analogy between the nucleation and growth of…
We have prepared thin (50–1500 Å) polycrystalline films of Cr by vacuum (10−8 Torr) evaporation methods using the deposition rate on Corning glass 7059 and its temperature as experimental parameters. Electrical resistivity (ρ) of these films has been studied in situ as a function of temperature (T), film thickness (t)…