Materials Literature
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The conductivity of gas-free thin films of amorphous germanium was measured as a function of temperature and film thickness. Existing theories of hopping conduction have been modified to apply to very thin films. The results are consistent with experiment, indicating that hopping conduction near the Fermi energy is th…
A review is presented of the status of problems involving the interaction of matter and optical-band electromagnetic radiation of intensity such that any medium becomes a fully ionized plasma. The following are considered within the framework of the single-electron approximation in the case of nonrelativistic energies…
The alimentary and vascular systems are discussed. The "alimentary prosopon" of polymerid trilobites is thought to show the course of the superficial dorsal vascular system. The arrangement of segments in the cephalon and thorax is investigated. Evidence of six cephalic segments is found. The articulation and enrollme…
The ferroelectric and antiferromagnetic orthoferrite BiFeO 3 has been studied extensively using the Mossbauer effect technique. The sublattice magnetization data are not in agreement with those previously published but do agree with data for other orthoferrites and for iron oxides in general. The several phase transit…
Abstract When hydroxide ions are added to a solution of Cr(H 2 O) 6 3+ ions at low temperature a well crystallized chromium hydroxide hydrate is formed, corresponding to the formula [Cr(OH) 3 ‐(H 2 O) 3 ] ∞ . Its structure is the inverse of bayerite type, two thirds of the octahedral M 3+ positions being vacant. It lo…
A model is solved for a fluid of biaxial particles within a type of mean-field approximation. The results suggest that the phase diagram of such a fluid exhibits a special critical point where two second-order critical lines meet a first-order phase boundary in a sharp cusp. The features of the phase diagram suggest a…
First-principles calculations of the electronic band structure for the layer-type compounds $2H\ensuremath{-}\mathrm{Nb}{\mathrm{Se}}_{2}$ and $2H\ensuremath{-}\mathrm{Mo}{\mathrm{S}}_{2}$ predict a 1-eV hybridization gap within the ${d}_{{z}^{2}}$ and ${d}_{\mathrm{xy}}$, ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ manifold…
The model of a large-scale potential relief is used to explain the most striking effects typical for the amorphous semiconductor, the switching and the memory. The potential relief was produced experimentally in a classical crystal semiconductor, n-germanium, by compensation with fast neutrons. This results in the app…
Les structures magnétiques de TMn2O5 (T = Lu, Er, Y, Ho, Tb, Nd) ont été étudiées par diffraction neutronique. Pour toutes ces terres rares, l'ordre des spins des Mn3+ et Mn4+ est hélimagnétique, avec un vecteur de propagation κ = ½ 0 τ: la maille chimique est donc doublée suivant a, et les spins d'une maille à l'autr…
The anisotropic viscoelastic and heat-conductivity properties of nematic liquid crystals offer the possibility of obtaining thermal convection with very low thresholds in homeotropic films heated from above. We present experiments on $p\ensuremath{-}\mathrm{m}\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{o}\mathrm{x}\mathrm{y…
An initial oxidation process is studied on 5.59 at. % Si–Fe alloy (100) and iron (100) single crystals by the photoelectric work function combined with Auger electron spectroscopy in the low-pressure range of oxygen (10−8−10−6 Torr). A 46-V Auger peak of iron is split into two peaks (41 and 49 V) followed by an oxygen…
The thermal conductivity of cerium magnesium nitrate has been measured over the temperature range 0.2-1.5\ifmmode^\circ\else\textdegree\fi{}K. When an assumption is made that the surface of the crystal is damaged to a depth of 150 \ensuremath{\mu}m by sandblasting, the conductivity measurements are entirely described…
The specific heat of titanium sesquioxide, ${\mathrm{Ti}}_{2}$${\mathrm{O}}_{3}$, and the mixed system, ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}+x%$ ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$, with $x$ ranging from 1.9 to 10.3 wt% has been measured between 0.4 and 20 K. The Debye temperature at 0 K for pure ${\mathrm{Ti}}_{2}$${\…
A modified form of the Mitchell---Makinson time-dependent perturbative calculation of the surface photoelectric effect has been carried out based on a significantly improved treatment of surface-polarization charge-density variations. The approach taken allows calculation of the excitation current back into the metal…
For $T>{T}_{t}\ensuremath{\simeq}68$ \ifmmode^\circ\else\textdegree\fi{} C, V${\mathrm{O}}_{2}$ is a metal with the rutile structure. For $T<{T}_{t}$, V${\mathrm{O}}_{2}$ is a semiconductor with a monoclinic structure. We have found semiconducting energy bands for the low-temperature structure from a parametrize…
The interaction of CO with a (110) nickel surface has been investigated using a number of techniques. Auger electron spectroscopy was used to follow the chemical composition of the surface. Using LEED, two ordered chemisorbed CO structures were found to form on the clean surface at room temperature. A (2 × 1) structur…
Fowler's hypothesis commonly used to interpret results of photoemission into the vacuum has been extended to deal with the problem of internal photoemission. This leads to the empirical relation $Y\ensuremath{\propto}{(E\ensuremath{-}{E}_{t})}^{2}$ between the quantum efficiency $Y$ and the photon energy $E$, currentl…
The theory is developed for thermally stimulated currents (TSC) that flow in optically or electrically excited insulators and semiconductors in which the field is sufficiently high and the (active) region in which the free carriers are generated is sufficiently thin (e.g., reverse-biased junctions, thin films, etc.) s…
The dispersion of the Raman cross sections of several phonon modes in CdS and ZnO using a wide range of laser energies has been measured. The ${E}_{1}(\mathrm{LO})$ and multi-LO (2-LO, 3-LO and 4-LO) modes in CdS have been studied over the energy range extending from $0.45{E}_{\mathrm{ex}}$ (exciton energy) to $1.1{E}…
Infrared-reflectivity spectra have been obtained for a large number of group-IV (Ti, Zr, Hf) and group-VI (Mo, W) transition-metal dichalcogenides. Three distinct types of spectra have been identified: In Zr${\mathrm{S}}_{2}$, Hf${\mathrm{S}}_{2}$, and Hf${\mathrm{Se}}_{2}$, very strong reststrahlen with effective cha…