Materials Literature
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Magnetic measurements were made on the cubic perovskite-type SrFe 1- x Co x O 3 (0≤ x ≤0.2). It was observed that with decreasing x the paramagnetic Curie temperature θ p and the Curie temperature T C decrease and the Néel temperature T N of the screw phase increases. It is argued from these results that the main magn…
The exponential-band-tail (Urbach-tail) problem for structurally disordered material is treated by a simple model in which quantum wells (used to model the effects of local disorder) trap states in the gap. The density of states in the gap is calculated and is shown to have approximately exponential behavior over a ra…
Experiments on the anomalies in surface-plasmon dispersion on periodically modulated single- and multilayered structures are analyzed. These anomalies arise if the dispersion curves intersect in the reduced Brillouin zone. Experiments on different types of gratings and for different excitation methods, e.g., excitatio…
An improved smoothing procedure is used to extract more information from x-ray-absorption spectra by second-derivative analysis. The true energy position of the maxima and full width at half maximum are measured for all features. The excitonic peak is present for all compositions and is well correlated with the 3d-ele…
We present high-resolution synchrotron-radiation core-level photoemission results which show that the room-temperature deposition of Co onto GaAs(110) induces limited substrate disruption, leading to Ga and As intermixing with the metal overlayer. High-energy Auger electron diffraction and low-energy electron diffract…
Magic-angle spinning nuclear magnetic resonance measurements have been performed on $^{29}\mathrm{Si}$ nuclei in amorphous silica before and after densification \ensuremath{\sim}16% by pressure compaction at 50 kbar and 600?deC. The pressure-induced shift in the Si---O---Si bond-angle distribution maximum from 143\ifm…
Segregation and transport coefficients of impurities at the Si/SiO2 interface have been studied. A brief model has been proposed which relates the two coefficients to the oxidation rate and the impurity concentrations at both sides of a Si/SiO2 interface. The model enables us to obtain the transport coefficients from…
The molecular dynamics method is used to study the liquid–vapor interface of the Stockmayer fluid. We compare our results for the singlet density-orientation distribution function and surface tension with the predictions of integral equation and perturbation theory. We find that at low temperature and high moment cond…
Mixed crystals of potassium dihydrogen phosphate and ammonium dihydrogen phosphate (K 1- x (NH 4 ) x H 2 PO 4 ) have been investigated. Dielectric constants ε 11 and ε 33 and elastic compliance ( s 45°- Z ) on the 45°– Z -cut bars were measured. The crystals with \(0{\leqq}x{\lesssim}0.17\) show temperature dependence…
It is demonstrated that electronic structure calculations using the local-density approximation with density-functional theory accounts for the distinctly different behaviors in the equilibrium phase diagrams among Cu-Ag, Cu-Au, and Ag-Au alloy systems. A detailed microscopic analysis is made based on the prescription…
The temperature dependence of the resistance and of the Seebeck coefficient of ${\mathrm{TaSe}}_{3}$ were measured between 80 and 430 K. The Seebeck coefficient changes sign around 220 K, suggesting two-carrier transport. The magnitude of this coefficient at the ends of the temperature range and the poor metallic cond…
Effects of grain size, hardness, and stress on the magnetic hysteresis loops of AISI 410 stainless steel and SAE 4340 steel specimens were investigated experimentally. It was observed that both hardness and stress significantly influenced the hysteresis loops, while the grain size had a minimal effect. For each materi…
The Raman spectrum of hexagonal BaTiO 3 has been investigated in the temperature range from 2 K to room temperature. Below the structural-phase-transition temperature of T a (∼222 K), we find the corresponding underdamped soft-phonon modes; the mode frequencies are proportional to ( T a - T ) β with β∼1/3 in a wide te…
Contrast ratio is an important measure of the performance of an electrooptic display. From measurements of film brightness and transmittance, we determined contrast ratios of thin polymer films containing microdroplets of liquid crystalline material. Contrast ratios based on brightness were typically ~3 for all sample…
Ultraviolet photoelectron spectroscopy (UPS) and electron spectroscopy by deexcitation of metastable noble gas atoms (MDS) were used to follow the continuous oxidation of Cs films. While UPS has a finite information depth, MDS probes only the properties of the outermost atomic layer. Small doses of O2 cause the format…
We report time-resolved measurements of photoluminescence in bulk a-${\mathrm{SiO}}_{2}$ using 7.9- and 6.4-eV excitation. Time-resolved spectra have been obtained at room temperature and 25 K, and the intensity and decay rates of various luminescence bands have been measured as a function of temperature. Bands at 1.9…
The electronic structure of amorphous carbon and hydrogenated amorphous carbon (a-C:H) has been investigated through calculations on a number of model structures containing different configurations of ${\mathrm{sp}}^{2}$ and ${\mathrm{sp}}^{3}$ sites. We find that the most stable arrangement of ${\mathrm{sp}}^{2}$ sit…
Two important factors that determine the mechanism and temperature of the alpha - beta phase transition in solid oxygen are analysed: the magneto-elastic coupling which increases the temperature of the transition, and the antiferromagnetic order in the beta -phase which stabilises this phase at low temperatures, thus…
Order parameters, as measured from N.M.R. experiments, are reported for a series of small rigid molecules dissolved in the liquid crystals N-(p-ethoxybenzylidene)-p′-n-butylaniline, Merck ZLI 1132, and a 55 wt per cent 1132 mixture of the two. Previous studies have shown that in this mixture the external electric fiel…
Neutron spin-echo measurements have been performed on the ionic system ${\mathrm{Ca}}_{0.4}$${\mathrm{K}}_{0.6}$(${\mathrm{NO}}_{3}$${)}_{1.4}$ around the glass transition temperature ${\mathrm{T}}_{0}$, in order to determine the time dependence of the density correlation function ${\mathrm{\ensuremath{\varphi}}}_{\ma…