Materials Literature
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Strong negative-electron-affinity effects have been observed on the surface of as-grown chemical-vapor-deposited diamond using secondary-electron emission. The samples were randomly oriented polycrystalline diamond films terminated with hydrogen. The effect appears as an intensive peak in the low-energy part of the sp…
A Kohn-Sham (KS) scheme for solids treating exchange exactly is introduced. The scheme emerges from a recently introduced exact formal KS procedure [A. G\"orling and M. Levy, Phys. Rev. A 50, 196 (1994)]. The exact density-functional exchange potential is obtained in terms of its Fourier components. The method can eas…
Mn-activated Zn2SiO4 and Ce-activated Y2SiO5 multilayer thin film electroluminescent (EL) devices were prepared by rf magnetron sputtering. The EL response of the devices under different voltages, frequencies, and pulse widths, as well as the transferred charge and decay characteristics were studied. The EL device usi…
We study the electronic structure of copper oxide clusters, ${\mathrm{Cu}}_{2}$${\mathrm{O}}_{\mathit{x}}$ (x=1--4), using anion photoelectron spectroscopy and density-functional calculations. The experiment is used to successfully guide a computational search for the cluster geometries. The predicted electron affinit…
The electronic structures of the itinerant ferromagnets ${\mathrm{Cr}}_{1\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$Te (\ensuremath{\delta}=0.05, 0.25, and 0.375) have been studied by photoemission spectroscopy. The valence-band spectra are compared with the density of states given by band-structure calculat…
We present theoretical and experimental studies of the infrared (IR) spectroscopy, normal Raman spectroscopy (NRS), surface-enhanced Raman spectroscopy (SERS), and surface-enhanced hyper-Raman (SEHRS) spectroscopy of trans-1,2-bis(4-pyridyl)ethylene (BPE). This centrosymmetric molecule is expected to have no common Ra…
We present ab initio investigations of the structural and electronic properties of clean and hydrogen-covered diamond (100) surfaces within local-density-functional theory. Our calculations are based on a variational solution of the Kohn-Sham equations using a preconditioned conjugate-gradient approach and on the opti…
Using the LDA+U method (where LDA is local-density approximation) we show that a separate treatment of ${\mathit{t}}_{2\mathit{g}}$ and ${\mathit{e}}_{\mathit{g}}$ electrons on transition-metal sites as localized and itinerant, respectively, gives an appropriate description for the band structure of LaM${\mathrm{O}}_{…
Synchrotron x-radiation in a double-crystal geometry has been used for topography and rocking-curve measurements to study imperfections in single-crystal HP/HT synthetic diamonds grown from (111) seeds by the reconstitution technique. The influence that clusters of small opaque particles (sometimes called `pin-point-l…
In this paper we deal with a numerical model for the evaluation of the magnetic iron losses in one steel lamination. The magnetodynamic model for the magnetic field strength H is coupled with the Preisach model. The resulting boundary value problem for H is solved numerically by a modified finite element - finite diff…
Employing absorption, excitation and luminescence spectroscopy in a wide spectral range, the upconversion processes are investigated in at low temperature. From the detailed analysis of the spectroscopic data and the power dependence of the upconverted intensity, excited state absorption and energy transfer between ex…
The authors report the design, fabrication and characterisation of a planar gradient index (GRIN) PECVD lens. The PECVD-based heilcon plasma reactor was used to deposit graded layers onto a silicon wafer. Ray tracing and beam propagation methods were used to simulate the periodic refocussing of the nominally parabolic…
Zinc oxide ceramic varistors with simplified compositions show nonlinear current - voltage characteristics with in the range 45 - 130. Addition of enhances the nonlinearity tremendously and the concentration range of needed for high is around 3 mol%. Formation and involvement of a liquid phase during sintering is indi…
The reinforcement of a natural rubber compound by various surface-modified precipitated silicas was compared. Compound physical properties were determined for two silicas differing in surface area and were used as controls to evaluate these silicas after surface modification by using either a bifunctional organosilane…
A model of vertical dynamic penetration of projectiles in granular soils was developed based on known experiments and the theory of dimensions. The depth of penetration is derived as a function of initial velocity and material properties. Velocity and acceleration are obtained as functions of time and depth of penetra…
The partial discharge activity (the number of discharges per second) during electrical tree growth in the flexible epoxy resin CY1311 was measured using a phase-resolved synchronous counting system. The experimental conditions, voltage and pin - plane spacing were varied to produce a wide range of tree structures from…
The real AC electrical conductivity was studied as a function of frequency f, temperature T and composition x for a series of samples prepared using the double-sintering ceramic technique. The experimental results indicated that increases as the temperature and frequency increase and as the Ni ion substitution decreas…
Flame reactors have high potential for synthesis of inexpensive nanosize powders since submicron size particles are made this way on an industrial scale at a rate of 100 ton/day. Thus, the formation of nanosize titania and silica powders by oxidation of TiCl 4 and SiCl 4 in a diffusion flame reactor were investigated…
Epoxy-clay nanocomposites have been synthesized by exfoliation of organoclays during the epoxy thermosetting process. The extent of silicate layer separation is governed by the chain length of gallery cations, the clay layer charge density and the acidity of the gallery cations. By using different curing agents, we ob…
We investigate the elastic properties of small droplets under compression. The compression of a bubble by two parallel plates is solved exactly and it is shown that a lowest-order expansion of the solution reduces to a form similar to that obtained by Morse and Witten. Other systems are studied numerically and results…