Materials Literature
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The acid−base properties of oxides are well described by the surface complexation model, which superposes a thermodynamic description of acid−base reactions at the oxide surface with a double-layer model of the electrostatics at the solid−solution interface. So far, however, this model has not been extended to include…
Recent reports have shown that cyclic peptides composed of an even number of alternating d - and l -amino acids can adopt flat, disklike conformations and stack through backbone−backbone hydrogen-bonding to form extended nanotubular structures. The present work details a general strategy for limiting this self-assembl…
The coarsening dynamics of three-dimensional islands on a growing film is discussed. It is assumed that the origin of the initial instability of a planar surface is the Ehrlich-Schwoebel step-edge barrier for adatom diffusion. Two mechanisms of coarsening are identified: (i) surface diffusion driven by an uneven distr…
We study the evolution of solidification microstructures using a phase-field model computed on an adaptive, finite element grid. We discuss the details of our algorithm and show that it greatly reduces the computational cost of solving the phase-field model at low undercooling. In particular we show that the computati…
We calculate the free energies of unstable stacking fault (USF) configurations on the glide and shuffle slip planes in silicon as a function of temperature, using the recently developed Environment Dependent Interatomic Potential (EDIP). We employ the molecular dynamics (MD) adiabatic switching method with appropriate…
We discuss how simulations of mechanical properties of materials require descriptions at many different length scales --- from the nanoscale where an atomic description is appropriate, through a mesoscale where dislocation based descriptions may be useful, to macroscopic length scales. In some materials, such as nanoc…
Individual dendrimer molecules of poly(amidoamine) (PAMAM) from generation 10 (G10) to G5 were imaged by conventional transmission electron microscopy (TEM) after staining with aqueous sodium phosphotungstate. The dendrimers were resolved as separate, beam-stable entities, and their sizes and distribution of sizes wer…
Various single layer reflective polarizers are introduced based on cholesteric liquid crystal materials containing one polymeric liquid crystal component and other non-reactive liquid crystals. A non-linear pitch gradient has been created during a process called polymerization induced molecular re-distribution. The po…
We report the results of a density-functional study of the diffusion of Pt dimers on the (111) surface of Pt. The calculated activation energy of 0.37 eV is in {\em exact} agreement with the recent experiment of Kyuno {\em et al.} \protect{[}Surf. Sci. {\bf 397}, 191 (1998)\protect{]}. Our calculations establish that…
This is a response to a recent paper by van Dongen, Uhrig, and E. Müller-Hartmann. We clarify the issues, which the above authors apparently did not fully appreciate, by referring to the microscopic foundations of Landau's Fermi Liquid Theory, its general application to the theory of metals and the theory of local Fer…
The low-temperature DC-transport properties of doped conducting polymers on the metallic side of the metal-insulator transition are analysed with modern localization-interaction theories. The DC conductivity at the lowest temperatures is governed by the 3D electron-electron interaction formula , while the magnetocondu…
Vacancy ordering was directly observed by high resolution transmission electron microscopy (HRTEM) at the heterointerface of GaSe/GaAs(100) grown by molecular beam epitaxy. Ga2Se3 crystalline film forms immediately to the GaAs (100) substrate, acting as an intermediate layer with thickness of 1.6–3.2 nm between the Ga…
We report that the thermally activated conductivity in several fullerene systems obeys the Meyer–Nelder (MN) rule, σ=σ00eΔE/kT0e−ΔE/kT. We found that the MN conductivity σ00 and the characteristic energy kT0 have a strong correlation, which is in good agreement with the prediction of the model proposed by Crandall [R.…
We studied the vibrational modes of H-doped nanocrystalline Pd $\mathrm{H}/\mathrm{Pd}\ensuremath{\le}0.04)$ by neutron spectroscopy, using the small H content as a probe for a separate determination of the vibrations of Pd atoms at surfaces and/or grain boundaries. We find that these atoms are responsible for the add…
Thin film trilayer junction of La0.67Sr0.33MnO3-SrTiO3-La0.67Sr0.33MnO3 shows a factor of 9.7 change in resistance, in a magnetic field around 100 Oe at 14 K. The junction magnetoresistance is bias and temperature dependent. The energy scales associated with bias and temperature dependence are an order of magnitude ap…
Conducting polymers under pressure: synchrotron x-ray determined structure and structure related properties of two forms of poly(octyl-thiophene) , J Mårdalen, E J Samuelsen, O R Konestabo, M Hanfland, M Lorenzen
Polycondensation of molecular adamantanoid [Ge4S10]4− precursors at a remarkably low temperature (50°C) affords the crystalline binary dichalcogenide δ-GeS2. Its crystal structure contains two interpenetrating cristobalite-like frameworks composed of adamantanoid [Ge4S6S4/2] building blocks. Rings containing 24 atoms…
When a film of poly[2-(4-phenylazophenyloxy)ethyl methacrylate] is subjected to irradiation with nonpolarized 436 nm light for n-π* excitation at an oblique incident angle with respect to a film surface, dichroism is induced as a result of the reorientation of azobenzene chromophores. The orientational direction is de…
We report a new stress-induced kinetically driven morphological instability for driven systems. The effect of stress on the interfacial mobility couples to stress variations along a perturbed planar growth front. Comparison of theory and experiment for solid phase epitaxy at a corrugated Si(001) interface, with no fre…
Carbon nitride (CN) thin films were prepared at 600 °C by rf plasma pulsed laser deposition. As we increased the magnitude of the negative dc bias voltage, the CN bonds were transformed from a mixture of sp2 C–N and sp3 C–N states into a CN phase predominated by tetrahedral CN bonds. A biasing threshold of this transf…