Materials Literature
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Europium impurities can be incorporated in two forms: divalent and trivalent. Phosphors activated by or find important applications. Exposure to ionizing radiations is known to cause conversion. This conversion is important in understanding thermoluminescence and radiophotoluminescence applications. However, there hav…
We show that the equilibrium shapes of small solid Pb inclusions embedded in an Al matrix are size dependent. Using high resolution electron microscopy we have observed that small inclusions a few nanometers in size adopt equilibrium shapes with smooth {111} facets. Inclusion dimensions follow preferred sizes shown to…
Dielectric superlattices of (Sr,Ca)TiO3/(Ba,Sr)TiO3 have been formed by a pulsed laser ablation technique. The crystal structure is controlled with atomic order accuracy and a large lattice stress of 0.5–1 GPa can be introduced periodically at the interfaces owing to the lattice mismatch of the constituent layers. The…
The atomic structure of the fivefold symmetric quasicrystal surface of A${\mathrm{l}}_{70}$P${\mathrm{d}}_{21}$M${\mathrm{n}}_{9}$ was investigated by means of a dynamical low energy electron-diffraction analysis. Approximations are developed to address the high structural complexity of quasicrystals, yielding average…
We study the cellular patterns of the white light granulation and of the chromospheric Ca II K supergranular network. We apply a gradient-based tessellation algorithm to define the cell outlines. The geometry of the patterns formed by the associated granular and supergranular flows are very similar, in spite of the su…
We have performed massively parallel 3D molecular dynamics simulations with up to 35 million atoms to investigate ductile failure, obtaining mechanistic information at the atomistic level inaccessible to experiment. We observe dislocation loops emitted from the crack front---the first time this has been seen in comput…
Surface x-ray diffraction has been used to determine the structural relaxations of ${\mathrm{TiO}}_{2}(110)\ensuremath{-}(1\ifmmode\times\else\texttimes\fi{}1)$. The magnitudes range from 0 to 0.27 \AA{}, leading to rumpling of the titanium planes. The data are compared to the results of three independent calculations…
Ground state properties of SiC, AlN, GaN and InN in the zinc-blende and wurtzite structures are determined using an ab initio scheme. For the self-consistent field part of the calculations, the Hartree-Fock program Crystal has been used. Correlation contributions are evaluated using the coupled-cluster approach with s…
Single crystalline ${\mathrm{Bi}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ ( $0.74\ensuremath{\le}x\ensuremath{\le}0.82$) were studied with neutron scattering, electron diffraction, and bulk magnetic measurement. We discovered dynamic ferromagnetic spin correlations at high temperatures, which are replac…
The total structure factor, $S(Q)$, and the corresponding radial distribution function, $G(r)$, for supercooled and stable liquid aluminum oxide have been measured with x-ray synchrotron radiation. The specimens were levitated in a conical nozzle and melted with a laser, achieving temperatures in the range of 2200--27…
The influence of wax on the viscoelasticity and peel adhesion of poly(ethylene-co-vinyl acetate) (EVA)-based hot melt adhesives was evaluated. Wax does not affect the glass transition temperature of a homogeneous EVA/rosin blend. However, for a heterogeneous EVA/rosin blend, wax addition increases the EVA-rich phase p…
A series of poly(ethylene-co-vinyl acetate) (EVA)-based hot melt adhesives containing either a rosin or a hydrocarbon (C5–C9) tackifier have been prepared to investigate viscoelastic properties and peel adhesion. Fracture energies were determined by the use of a T-Peel geometry (two polypropylene films bonded with mod…
Films of regenerated Bombyx mori silk are strongly affected by absorbed moisture, a phenomenon studied here by differential scanning calorimetry (DSC). Exposure of previously dried films to environments of controlled relative humidity produces test samples of well-defined equilibrium moisture content. Ultimate moistur…
Fluids such as liquids and glasses are not usually thought of as possessing distinct forms or phases. As Poole et al . discuss in their Perspective, recent results show that liquids can exhibit “polymorphism”—different phases characterized by different densities.
Ion bombardment is known to enhance surface diffusion and affect the surface morphology. To quantify this phenomenon we calculate the ion-induced diffusion constant and its dependence on the ion energy, flux and angle of incidence. We find that ion bombardment can both enhance and suppress diffusion and that the sign…
(001) oriented NiO/NiFe bilayers were grown on single crystal MgO (001) substrates by ion beam sputtering in order to determine the effect that the crystalline orientation of the NiO antiferromagnetic layer has on the magnetization curve of the NiFe ferromagnetic layer. Simple models predict no exchange anisotropy for…
Emphasizing the utility of copper-related compounds, this text illustrates the numerous current and potential uses from agricultural bactericides and wood preservatives to colourants and solar cells. It discusses the properties and behaviour of the copper ion, copper compounds' employment in organic polymerization and…
The structure of the title compound, sodium indium diarsenate(4−), consists of corner-sharing InO6 octahedra and layers of the diarsenate groups stack alternately parallel to [010]. The framework delimits cages where four Na+ cations per unit cell are located. The structure is closely related to that of NaFeP2O7-II, b…
We study transport properties of Fibonacci semiconductor superlattices in a uniform magnetic field (B) applied along the growth direction. Complicated magnetoresistance oscillations which do not vary periodically in 1/B are found. A field-dependent metal-insulator transition is predicted, and it is shown that the magn…
Novel densely crosslinked polycarbosiloxanes were obtained by using functional branched prepolymers. Two types of soluble prepolymers were prepared from di- and trifunctional alkoxysilane monomers via cohydrolysis/condensation and for both final crosslinking occurred via hydrosilylation. The prepolymers having only vi…