Materials Literature
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Abstract Isophoron diisocyanate (IPDI) ‐based polyester polyurethane (PU) dispersion in water was prepared in a prepolymer mixing process. Dimethylol propionic acid (DMPA), triethylamine (TEA), and triethyl tetramine (TETA) were used, respectively, as potential anionic center, neutralizing agent, and chain extender in…
Dislocations in SrTiO3 deformed plastically by indentation at 900 and 1100 °C are studied by comprehensive transmission electron microscopy. At both 900 and 1100°C all the dislocations studied have Burgers vectors of either 〈100〉 or 〈110〉 type. At 900 °C both types of dislocation are in the glide configuration. On the…
Spatial correlation between the activator ion ${\mathrm{Eu}}^{2+}$ and electron and hole traps generated by x irradiation is thought to play a decisive role in the photostimulated emission process of the storage phosphor BaFBr:${\mathrm{Eu}}^{2+}$. We report the first direct experimental evidence for correlations amon…
We have studied the spreading of liquid drops on a solid surface by molecular-dynamics simulations of Lennard-Jones systems of liquid, vapor, and solid. As the attraction between liquid and solid increases we observe a smooth transition from partial wetting to terraced wetting, with distinct molecular layers spreading…
Basic thermoelectric p-type materials for the medium temperature range (600 to 900 K) are GeTe-based materials. Hot-pressed samples of (GeTe)1−x[(Ag2Te)1-y(Sb2Te3)y]x solid solutions with y = 0.6, y = 0.75 are prepared. Their thermoelectric properties (thermoelectric power S, electric conductivity σ and thermal conduc…
The dynamical properties of randomly cross-linked polymer melts, far above the vulcanization threshold, are studied using molecular-dynamics simulations. The mean-square displacements of the middle and end monomers of the chains as well as the cross-links are considered. The dynamics scattering function S(q,t) as meas…
Pressure-induced amorphization in \ensuremath{\alpha}-quartz has been investigated using constant-pressure molecular-dynamics calculations with the two-body potential of van Beest, Kramer, and van Santen. Both the static properties and the crystalline-to-amorphous phase transition were very well reproduced. Through an…
We have determined the Curie temperature ${\mathit{T}}_{\mathit{c}}$ of ferrimagnetic ${\mathrm{MnFe}}_{2}$${\mathrm{O}}_{4}$ nanoscale particles by means of direct measurement of the magnetization. A considerable enhancement in ${\mathit{T}}_{\mathit{c}}$ compared to the bulk was observed for particles in the size ra…
The temperature dependence of phase mode relaxation frequencies in the SmC A * phase (antiferroelectric phase), SmC γ * phase (ferrielecric phase) and SmC * phase (ferroelectric phase), and the dispersion of the phase mode in the SmC γ * phase were measured by photon correlation technique in R-MHPOBC (C 8 H 17 – –COO–…
The dynamic Mohr–Coulomb behavior of silicon carbide (SiC) was inferred from symmetric pressure/shear plate-impact experiments which entail planar impact of two SiC plates inclined at 15° to the impact direction. The transverse velocity of the free rear surface of the target plate was recorded using a laser Doppler ve…
The performance of a recently proposed two-body potential model for SiO2 [van Beest et al., Phys. Rev. Lett. 64, 1995 (1990)] was critically evaluated through the calculation of the static and dynamical properties of several polymorphs of SiO2 using molecular dynamics methods. It was found that the calculated static s…
The bcc phase of Fe-Mn alloys was studied by means of the Mössbauer effect, x-ray diffraction, thermogravimetry analysis, and magnetization measurements for Mn concent- rations up to 17.5 at.%. These alloys are disordered over this composition range and both the average hyperfine field and critical temperature (Tc) de…
The Cs/GaAs(100) system is studied by Auger electron spectroscopy, electron energy-loss spectroscopy, work function change measurements, low-energy electron diffraction, and thermal desorption spectroscopy at 200 K and at room temperature. At room temperature the Cs layer is nonmetallic; at low temperature there is cl…
The influence of temperature on the morphology of both the homogeneous and the inhomogeneous Cu(311) surfaces is investigated by high-resolution low-energy electron diffraction. Analyzing the spot profile of the diffracted electron beam under various scattering conditions provides information about both the surface ro…
We describe a computational method, based on scattering-matrix techniques, for calculating the electromagnetic response of multilayer systems that may include both anisotropic dielectric media and periodically inhomogeneous grating structures. The method calculates the transmission and reflection coefficients of the s…
We have determined the surface-plasmon modes of interacting spherical particles as a function of the particle radii, the separation R, and the dielectric constant of the surrounding medium. The coupling between the two particles produces a shift of all surface-plasmon eigenfrequencies leading, in the case of Al partic…
An upper bound of the diffraction efficiency of diffractive elements that only influence the phase of the illumination wave is derived. The derivation only utilizes the specification of the desired diffraction pattern. It is independent of the technique to design and fabricate the diffractive element. The theory is ba…
In order to probe into the growth mechanism of sprayed SnO2 films, the films were deposited with different Sn concentrations in the precursor solution. The orientational properties were determined using grazing incidence x-ray diffraction. The preferred growth changed from [110] to [200] direction as the Sn incorporat…
Abstract Sequences of high Bragg-angle (0B = 74°) double-crystal X-ray topographs taken at the SRS (Daresbury, U.K.) have yielded precise measurements of lattice parameter differences between growth sectors of different crystallographic forms in a large undoped synthetic diamond whose type Ib infrared absorption spect…
Steady-state photoluminescence, time-resolved photoluminescence, and x-ray photoelectron spectroscopy have been used to study the electrical and chemical properties of GaAs surfaces exposed to inorganic and organic sulfur donors. Despite a wide variation in S2−(aq) concentration, variation of the pH of aqueous HS−solu…