Materials Literature
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The effect of high magnetic fields on the electronic structure of some quasi-one-dimensional systems with charge- or spin-density waves is examined. Because of the specific anisotropy of the system, small electron and hole pockets created by the density wave can be destroyed by the presence of a magnetic field. This p…
The surface-enhanced Raman scattering (SERS) from thin films formed by p-nitrobenzoic acid (PNBA) adsorbed onto silver island films has been investigated. SERS spectra obtained using low laser powers were very similar to the normal Raman spectra of the sodium salt of PNBA and were characterized by strong bands near 16…
We have investigated the dynamical behavior of twisted nematic crystals quenched from an isotropic phase into a nematic phase. In such a system the collective motion of an assembly of disclination can be observed and a dynamical scaling law was found. The u-field theory developed by Ohta, Jasnow and Kawasaki was appli…
Adsorption of CO and the coadsorption of CO with low coverages of K on Fe(111) at temperatures as low as 83 K have been studied with low energy electron diffraction (LEED), thermal desorption spectroscopy (TDS), and high resolution electron energy loss spectroscopy (HREELS). The results indicate that CO fills three di…
The experimental carbon Auger line shape for graphite has been obtained, corrected for the effects of the secondary-electron background and extrinsic losses, and placed on an absolute energy scale through the use of photoelectron measurements. The resulting line shape is compared to a model which consists of the self-…
We have examined the question of whether excess low-frequency (1/f) noise in metal films arises in the bulk or at the sample surface. We measured the noise in continuous Cr films with 80 A\r{}2600 A\r{}, where t is the film thickness. Establishing that the relative noise intensity ${S}_{\ensuremath{\rho}}$(f)/${\ensur…
Based upon a superlattice model for graphite intercalated compounds (GIC's), we present in this paper a detailed calculation of the lifetime of a conduction electron in a stage-1, acceptor-type GIC. Both intraband and interband processes, as well as intervalley processes, are included in this calculation. We find that…
Pyrrole-based conducting polymers have been investigated by high-resolution electron-energy-loss spectroscopy and by electron diffraction. The evolution of the \ensuremath{\pi}-electron band structure as a function of the oxidation can be explained in terms of a bipolaron model. Strongly oxidized polypyrrole is not a…
The structural features of three different graphite fibers were studied via small- and wide-angle x-ray techniques. The experimental evidence is consistent with a sheath/core fiber morphology. Graphitization, degree of orientation, crystallite size, and microporosity were analyzed. Samples included low (AS4) and high…
The solubility measurements of H, D, and T in Pd in a large temperature range are presented. Analytic expressions are given for the equilibrium constants which describe the equilibria between hydrogen isotopes in the gas phase and hydrogen isotopes dissolved in a metal at infinite dilution. These expressions are used…
A series of V–O alloy films were sputter deposited on glass substrates using a vanadium target and rf-excited Ar/O2 discharges containing 2%–8% O2. On the basis of x-ray results, the films were nominally identified as vanadium pentoxide. Optical transmission and reflection characteristics were measured by double-beam…
A new method for determining the total number of dislocations per unit area, as well as the fraction of screw and edge components, is presented. Single-crystal specimens which have been (a) bent over a mandrel, (b) cold rolled at room temperature, and (c) deformed in tension at 200 K have been studied. Etch pits were…
We report static magnetic susceptibility data, $\ensuremath{\chi}(T)$, for the $\ensuremath{\alpha}$ and $\ensuremath{\beta}$ phases of the organic conductor di[bis(ethylenediothiolo)tetrathiafulvalene] tri-iodide [${(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{F})}_{2}$${\mathrm{…
The path maintaining rhombohedral symmetry in the transition from graphite to diamond which minimizes the energy at each value of the bond length between layers is determined. The energy barrier for this path is found to be 0.33 eV. The total energy of the solid is calculated using local-density-functional theory with…
Packings of spheres placed on vertices of two- or three-dimensional Penrose tilings arise in various models of glassy or ``quasicrystal'' metals. Such packings are described, with particular attention to the packing fractions and coordination numbers: In particular, one of the three-dimensional packings attains a pack…
Results of a renormalization-group analysis augmented by numerical calculations are presented for the electronic and phonon properties of a one-dimensional quasiperiodic lattice. Qualitative differences in the electronic and phonon band structure are predicted analytically and confirmed numerically. An exactly evaluat…
Thermal expansion of the hexagonal (4H) polytype of SiC was measured from 20 to 1000 °C by the x-ray diffraction technique. The principal axial coefficients of thermal expansion are expressed by the second-order polynomials: α11=3.21×10−6+3.56×10−9T−1.62×10−12T2, and α33=3.09×10−6+2.63×10−9T−1.08×10−12T2 (°C−1). The α…
In this paper, we carefully study the dielectric function of stage-1, acceptor-type graphite intercalated compounds (GIC's). We model the system by a superlattice of an infinite number of graphite layers, each of which has the band structure described by the two-dimensional calculation of Blinowski et al. Tunneling be…
In this (second) paper, quasicrystalline configurations of unit cells are analyzed for the cases of pentagonal and icosahedral orientational symmetry. We illustrate how two ideal quasicrystal structures with the same orientational symmetry and unit cells can be composed from very different local configurations of the…
In a recent paper, we introduced the concept of quasicrystals [Phys. Rev. Lett. 53, 2477 (1984)], a new class of ordered atomic structures. Quasicrystals have long-range quasiperiodic translational order and long-range orientational order. In the present paper and the following one, we discuss the details of our analy…