Materials Literature
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Pinning phenomena in an incommensurate two-chain model of friction are studied numerically. The pinning effect due to the breaking of analyticity exists in the present model. The pinning behavior is, however, quite different from that for the breaking of analyticity state of the Frenkel-Kontorova model. When the elast…
We predict an extreme sensitivity to the dissipative losses of the resonant interaction of bulk phonons with a 2D defect in a solid. We show that the total resonant reflection of the transverse phonon at the 2D defect, described earlier without an account for dissipation, occurs only in the limit of extremely weak dis…
CrN is observed to undergo a paramagnetic to antiferromagnetic transition accompanied by a shear distortion from cubic NaCl-type to orthorhombic structure. Our first-principle plane wave and ultrasoft pseudopotential calculations confirm that the distorted antiferromagnetic phase with spin configuration arranged in do…
We found anomalies in the temperature dependence of the dielectric and the magnetic susceptibiliy of NaV_2O_5 in the microwave and far infrared frequency ranges. The anomalies occur at the phase transition temperature T_c, at which the spin gap opens. The real parts of the dielectric constants epsilon_a and epsilon_c…
The photophysical properties of a series of ethynyl-bridged (porphinato)zinc(II) oligomers have been investigated over the femtosecond and picosecond time scales using ultrafast magic angle and polarized pump−probe spectroscopy. Bis[(2,2‘,-5,10,15,20-tetraphenylporphinato)zinc(II)]ethyne, bis[(5,5‘,-10,20-diphenylporp…
Cu 2 O is an efficient catalyst in the partial oxidation of propylene to acrolein, while propylene oxidation on CuO leads to complete combustion. The interaction of propylene at elevated temperature ( > 300 K) and elevated pressure (5 Torr) with cuprous and cupric oxide has been investigated with core level XPS, reson…
We examine the dependence of the deformation obtained by bending quasi-Fuchsian structures on the bending lamination. We show that when we consider bending quasi-Fuchsian structures on a closed surface, the conditions obtained by Epstein and Marden to relate weak convergence of arbitrary laminations to the convergence…
Photoacoustic absorption measurements at room temperature are reported for Se1−xTex alloys in both crystalline and amorphous states for 0<x⩽0.3. The optical energy gap thus measured shows two features: (a) the gap decreases linearly as x increases with a change of slope at x=0.1 for both crystalline and amorpho…
Recent research into black powder problems experienced by natural-gas transmission pipelines indicates steps that can be taken to control the material in gas pipelines, gathering systems, and storage facilities. Black powder (the common term for various forms of iron sulfide mixed with contaminants) is the least under…
This work investigates the charge-transfer spectra of and complexes formed in anisotropic (X = Cl, Br) crystals. Attention is paid to the variations of the charge-transfer transition energies induced by chemical pressure effects when substituting along the crystal series. A salient feature of this study is the weak se…
The local atomic and magnetic structure of a powder crystalline sample of MnO has been modelled for a wide range of temperatures (10-1100 K) by fitting neutron powder diffraction data using the reverse Monte Carlo technique (RMC). This method allows simultaneous and self-consistent fitting of Bragg and diffuse scatter…
Carbon nanotubes can flatten into collapsed tubes with bulbs along either edge. The strong anisotropy in the graphitic radiation damage threshold both explains the rapid destruction of face-on flattened nanotubes and can be exploited to selectively modify the structure of edge-on flattened nanotubes, thereby creating…
Low molecular symmetry with regard to the conjugation path of the delocalized electrons was found to be a good guideline towards linearly conjugated molecules with large second-order hyperpolarizabilities γ. We show that this guideline is also valid for two-dimensionally conjugated systems. We experimentally demonstra…
Diamondlike carbon (DLC) was deposited on silicon using a plasma immersion ion deposition (PIID) method. Inductive radio-frequency plasma sources were used to generate Ar and C2H2 plasmas at low gas pressures ranging from 0.04 to 0.93 Pa. The film stress and hardness were sharply dependent upon bias voltage at an oper…
A long lasting green phosphorescence was found in -doped calcium aluminate glasses prepared under a strongly reducing atmosphere. An electron-trapped centre giving an EPR signal at g = 1.999, an analogue of the centre in CaO, was induced by illumination with ultraviolet (uv) radiation and decayed slowly after the illu…
Measurements of the spin-lattice relaxation rate are reported for muons and protons as a function of temperature for different values of the applied magnetic field in the ${\mathrm{Mn}}_{12}{\mathrm{O}}_{12}$ molecular cluster. Strongly field dependent maxima in the relaxation rate versus temperature are observed belo…
Electronic applications of diamond-like carbon have been limited by its relatively high disorder and defect density. We find that the density of paramagnetic defects in hydrogenated tetrahedral amorphous carbon and the Urbach slope of the optical absorption edge can be reduced by annealing at 300 °C, with little effec…
A combination of atomic-resolution $Z$-contrast imaging and first-principles density-functional calculations are used to establish that Ca impurities segregating to particular atomic columns in MgO grain boundaries induce a structural transformation. The presence of Ca in the boundary structure is independently confir…
La 0.6 Sr 0.4 MnO 3 thin films were fabricated on SrTiO3 (001) substrates using pulsed laser deposition with observing persistent intensity oscillation of reflection high-energy electron diffraction. By atomic force microscopy, the surface of resulting films was confirmed to be extremely flat, showing atomically smoot…
We present a new type of basis set which is local, compact, and orthogonal. The basis functions, called orthlets, are centered at the sites of a lattice and are specifically adapted to represent the system being studied. The adaptability includes the ability to have singular behavior within an orthlet, allowing a sing…