Materials Literature
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Monte Carlo calculations of the herring-bone ordering phase transition of N 2 adsorbed on graphite have been performed for a variety of boundary conditions. The model consists of a rigid lattice of two-dimensional quadrupoles and for a small infinitely periodic system (PBC), a first-order phase transition is found, in…
Abstract The synthesis and the liquid‐crystal temperatures of sixty 4‐cyano‐2‐fluorophenyl and 4‐cyano‐3‐fluorophylen 4‐substituted benzoates are described. The nematic‐isotropic liquid transition temperatures of the most of these novel esters are only marginally lower than those of the corresponding esters containing…
For pt.I see ibid., vol.17, p.4705 (1984). The authors have measured the inelastic neutron scattering spectra of three samples of molten SrCl 2 with different isotopic chlorine compositions using the IN6 time-of-flight spectrometer at the Institut-Langevin in Grenoble. de Gennes narrowing of the quasielastic peak is o…
We demonstrate the feasibility of x-ray scattering studies of freely suspended strands of discotic liquid crystals (of triphenylene hexa-$n$-dodecanoate). We are able to grow strands, which are stable for days, of diameter > 50 \ensuremath{\mu}m with a few single-crystal domains. Unexpectedly, we find that the quas…
The Hall effect in ${\mathrm{NbSe}}_{3}$ has been measured in the magnetic field range 0-200 kG at temperatures of 20 and 30 K. At high magnetic fields the Hall coefficient is positive and the Hall voltage shows a strong dependence on electric field. As the electric field is increased from 0 to 80 mV/cm the Hall resis…
Effects on point-defect drift diffusion in the strain fields of straight edge or screw dislocations, due to anisotropic diffusion arising from the anisotropy of the point defect in its saddle-point configuration, are investigated. Expressions for sink strength and bias that include the saddle-point shape effect are de…
We present a nonperturbative theory of second-harmonic generation in reflection from a metallic grating. $p$-polarized light of frequency $\ensuremath{\omega}$ is assumed to be incident on the grating surface from the vacuum side, with the plane of incidence perpendicular to the grooves of the grating. We employ the m…
Fe 3,005 O 4 (magnetite naturelle recuite a 1373K) cristallise dans Fd3m avec a=8,3969 A, Z=8; affinement jusqu'a R=0,015• Fe 2,96 Mg 0,04 O 4 (magnetite naturelle recuite a 1073 K) cristallise dans Fd3m avec a=8,3975 A, Z=8; affinement jusqu'a R=0,014. Dans les deux cas, structure spinelle inverse ideale. Pas d'obser…
Nuclear-reaction analysis was used to investigate the behavior of deuterium (D) in three austenitic stainless steels following ion implantation with D and He. The D was bound to irradiation defects with a binding enthalpy of 0.23±0.08 eV relative to solution sites. Helium bubbles of diameter ∼1 nm trapped D with a bin…
A theory of the major chemical trends of impurity and vacancy levels in ${\mathrm{SnO}}_{2}$ is presented, based on a tight-binding Green's-function calculation. Our results account for the shallowness of levels associated with substitutional ${\mathrm{Sb}}_{\mathrm{Sn}}$ and ${\mathrm{F}}_{\mathrm{O}}$ centers and th…
The electrical properties of semiconducting ferrite materials are investigated. A simplified model, consisting of bulk material separated by highly resistive grain boundary layers, is proposed. The nature of grain boundary on its electrical behavior is also discussed. Complex impedance technique is used to analyze the…
The adsorption, desorption, and decomposition of methanol on a clean Ru(001) surface at 85 K has been examined with electron energy loss spectroscopy, multiple mass thermal desorption spectroscopy, low energy electron diffraction, and a work function probe. Methanol adsorbs readily on Ru(001) and is found to decompose…
A structural model for the oxygen-related thermal donors produced at moderate temperatures (<500 °C) is presented, where electrical activity commences with clusters containing five or more oxygen atoms and arises from a silicon atom at the center of the cluster. The donor activity of a cluster is terminated upo…
In this paper, we consider the transmission-line model used to calculate the transmittance of thin metallic strip gratings (at wavelengths longer than the grating period) to resolve a conflict of published expressions for the effect of a thick dielectric substrate on the equivalent circuit capacitance of capacitive gr…
High concentration Fe 1- x Cu x alloys have been obtained by rf sputtering technique and investigated by X-ray diffraction and magnetization measurements. The bcc phase is extended over the region with x =0–0.4, while the fcc phase with x =0.6–1.0. For x =0.4–0.6, we have the mixed phase of bcc and fcc. The lattice co…
We have characterized the dielectric relaxation of the charge-density wave (CDW) in ${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_{3}$ at temperatures between 60 and 101 K through measurement of the complex conductivity between 5 Hz and 13 MHz. The dielectric response is described well by a general expression which allows for a…
The excitation energies of impurities in semiconductors, as well as their donor and acceptor ionization energies, represent a combination of one-electron and many-electron multiplet effects, where the latter contribution becomes increasingly significant as localized states are formed. Analysis of the absorption and io…
We report self-consistent density-functional calculations of the energy and enthalpy of silicon and carbon in the fully relaxed complex B-8 structure (bcc with 8 atoms per cell). We find B-8 to be unstable in Si, with enthalpy slightly higher than the diamond and $\ensuremath{\beta}$-tin phases. B-8 is found to be a s…
Films of pure and Sn-doped semiconducting ${\mathrm{In}}_{2}$${\mathrm{O}}_{3}$ were prepared by reactive $e$-beam evaporation. The spectral absorption coefficient was evaluated by spectrophotometry in the (2-6)-eV range. The extracted band gap increases with electron density (${n}_{e}$) approximately as ${n}_{e}^{\fr…
The description of polymer collapse is presented both in conformational space and field theoretic forms along the same lines as we have provided for treating the theta point (tricritical) region for polymers. This enables the problem to be considered in terms of the same measurable parameters which are used in the the…