Materials Literature
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The authors study a two-parameter one-dimensional lattice model embedded in three-dimensional space at T=0, that has indirect oscillatory interactions between neighbours. It can describe succession of modulated structures separated by first-order phase transitions. Qualitative agreement with experimental data obtained…
The molecular ordering in the nematic and smectic-C phases of the liquid crystal p-n-nonyloxy benzoic acid (NOBA) is investigated. The phase transition from isotropic to nematic phase is of first order. In the nematic phase over a wide range of temperatures the order parameter remained constant. In the low temperature…
Photo-stimulated luminescence provides a method of radiation dosimetry in which repeated readouts from an irradiated sample are possible without erasing the initial dose information. It is found that in CaSO4:Dy, photo-stimulated luminescence as well as thermoluminescence processes are both originating from the same t…
The stability of planar faults on possible slip planes in the DO19 structure is investigated using crystal symmetry considerations and the restoring force calculated for these faults. It is found that the superlattice intrinsic stacking fault on the basal plane and the antiphase boundaries on prismatic {1010} and {112…
The complex piezoelectric constants, d 21 , d 22 and d 23 , of ferroelectric AgNa(NO 2 ) 2 have been measured by two quasi-static methods; one is the optical interferometric method and the other is based on a comparison with the piezo-electric constant of quartz. The measurement covered the temperature range from 40°C…
Band structure calculations based on the extended Hückel method order energetically the 36 arsenic-like structures having the NaCl size unit cell in a way which is compatible with the observed crystal structures. Black phosphorus is the most stable of the 36, and the arsenic layer type is number seven. Energy differen…
We present an evaluation of the electron-phonon coupling parameter $\ensuremath{\lambda}$, using the McMillan formalism, for several classes of stoichiometric mono- and dihydrides with a metallic underlying fcc structure. We calculate the electronic term $\ensuremath{\eta}$ and use experimental estimates for the phono…
The Ag-deposited Se80Ge20 (at. %) amorphous films are found to show a large chemical shift (∼1.2 eV) in the Se 3d level toward lower binding energies and to form a Ag2Se phase on the surface region. The chemical shift of the Se 3d level by Ag photodoping becomes large with increasing UV exposure (15 mW/cm2) and is sat…
For the first time, infrared integrated absorption intensities and extinction coefficients have been determined for both the linearly adsorbed (high frequency-HF) and the bridged-bonded (low frequency-LF) forms of CO on Pt. Platinum dispersed on η-Al2O3, SiO2, SiO2–Al2O3, and TiO2 was characterized by both hydrogen an…
Susceptibilities of single crystals of CsCuCl 3 are measured in 4.2 K< T <500 K for H ⊥ c and H // c . Behaviors characteristic to a one-dimensional Heisenberg ferromagnet with weak interchain interactions are observed. The behaviors are analyzed by the high temperature expansion approximation, and intrachain and inte…
The structures of arsenic and black phosphorus can be regarded as distortions of the simple cubic or NaCl structure. The presence of more than four electrons per site results in the breaking of three of the six linkages around each atom in the NaCl structure. A generalization of Pólya’s enumeration theorem is proven w…
A new class of organic quinoid systems possessing intrinsically large, nonlinear second-order optical susceptibilities has been developed based on theoretical calculations and dc-induced second-harmonic generation measurements of the molecular second-order optical susceptibilities β. For one example, 2-(4-dicyanomethy…
A metal-to-insulator transition is observed using angle-resolved photoemission at the $1{T}_{2}\ensuremath{\rightarrow}1{T}_{3}$ phase transition of Ta${\mathrm{S}}_{2}$ at $T\ensuremath{\sim}200$ K: a 0.125-eV band gap, $d$ subbands, and Fermi-surface modifications occur. High-resolution (0.15-eV) Ta $4f$ core-level…
A silica supported Ni catalyst has been investigated by electron magnetic resonance between 293 and 4.2 K. A relatively narrow absorption signal with linewidth ΔHpp?400 Oe is observed at temperatures ?150 K as a result of motional averaging of the magnetocrystalline anistropy field Ha of the Ni particles resulting fro…
Hartree-Fock calculations on a linear cluster, Ni${\mathrm{N}}_{2}$, have been performed. Self-consistent-field calculations on the ground and hole states of the cluster and the free ${\mathrm{N}}_{2}$ molecule have been used to determine the shifts in valence ionization potentials (IP) of ${\mathrm{N}}_{2}$ when it i…
With the use of angle-resolved photoemission with synchrotron radiation, surface states on the (2\ifmmode\times\else\texttimes\fi{}1)/(2\ifmmode\times\else\texttimes\fi{}2) reconstructed diamond (111) surface are characterized. These states cover an energy range of about 2 eV and exhibit maximum emission intensity at…
Valence-level and core-level photoemission results are presented for ${\mathrm{N}}_{2}$ molecularly adsorbed on a Ni(100) surface at 77 K. Comparison is made to the Ni(100)/CO system. Differences are interpreted in terms of differences in chemisorption bonding. The data are in agreement with theoretical calculations (…
The presence of a moving dislocation represents a significant perturbation of a crystalline lattice. Here we present a quantum-mechanical account of the phonon field created by a moving edge dislocation. It is shown that the phonon energy is locally concentrated about the crystalline slip planes, indicating the existe…
We report the results of a detailed theoretical investigation of electronic properties of unrelaxed and relaxed ZnO surfaces. The surface electronic structure is evaluated using the scattering theoretical method on the basis of an accurately fit empirical tight-binding Hamiltonian for bulk ZnO. Surface band structures…
Raman scattering measurements between 20 and 450 K are reported in ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}\mathrm{As}$ single crystals for the range $0\ensuremath{\le}x\ensuremath{\le}1$. Peak-frequency and linewidth variations versus temperature and composition of the first-order modes are studied in the l…