Materials Literature
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We present the quasiparticle band structure and the optical excitation spectrum of bulk LiF and the LiF(001)-(1\ifmmode\times\else\texttimes\fi{}1) surface. First, we calculate the ground-state geometry of the bulk and the surface using density-functional theory within the local-density approximation. Next, applying t…
Strong polarization-sensitive anisotropy of the optical absorption in the visible and infrared spectral range is observed in porous silicon (PSi) layers formed from bulk (110) Si wafers. It is shown that the anisotropy of the absorption via band-to-band and intraband (Drude-like) electronic transitions is consistent w…
The growth or dissolution of small gas bubbles (R0<15 microm) by rectified diffusion in nearly saturated liquids, subject to low frequencies (20 kHz<f<100 kHz) and high driving acoustic fields (1 bar<p<5 bars), is investigated theoretically. It is shown that, in such conditions, the rectified diffusion threshold radiu…
Coupled mechanical and electronic behaviours of single walled open carbon nanotubes (CNTs) under applied electric field and tensile loading are investigated by the use of quantum mechanics as well as quantum-molecular dynamics techniques based on the Roothaan–Hall equations and the Newton motion laws. Different failur…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTFourier Transform Infrared Investigation of the Deformation Behavior of Montmorillonite in Nylon-6/Nanoclay NanocompositeLeslie S. Loo and Karen K. GleasonView Author Information Department of Chemical Engineering, Massachusetts Ins…
Ab Initio molecular dynamics simulations have been performed to study the hydration of a sodium smectite clay. Water molecules are intercalated as a double layer in the interlayer spacing of this swelling clay mineral. The solvent structure was found to be very similar to predictions by a previous Monte Carlo study ba…
Er 3+ doped Na 2 O–Nb 2 O 5 –TeO 2 (NNT) glasses suitable for making optical waveguide devices has been fabricated and characterized. Intense 1.53 μm infrared fluorescence and green upconversion luminescence were observed under 975 nm diode laser and 798 nm laser excitation. The optical absorption, the Judd–Ofelt para…
We show that granular media, consisting of metallic microparticles immersed in a poorly conducting liquid in a strong dc electric field, self-assemble into a rich variety of novel phases. These phases include static precipitates: honeycombs and Wigner crystals; and novel dynamic condensates: toroidal vortices and puls…
Organo-functionalised MCM-41 nanoparticles have been prepared by a dilution/neutralisation method involving the surfactant-templated co-condensation of 3-aminopropyltriethoxysilane, allyltriethoxysilane or 3-mercaptopropyltriethoxysilane with tetraethoxysilane under alkaline conditions. The presence of covalently coup…
Soda-lime silicate glass is the fundamental base glass for many technologically important oxide glasses, and it has been used as window glass since the Roman Empire. Mixed-cation silicates also are useful models of the structure and dynamics of basaltic magmas and mantle melts. The diffusivity of Na + in silicate melt…
Abstract An overview of heterogeneous epoxidation catalysts is given, with an emphasis on practical parameters such as catalyst productivity, turnover numbers and stereoselectivity. Special focus is directed towards catalysts that have resulted from research in the authors' group.
During the chemical vapor deposition of multiwalled carbon nanotubes using the vapor phase delivery of a metal-organic (ferrocene) catalyst precursor, a strong selectivity for growth on patterned SiO 2 /Si substrates has been observed. A mechanism for this selective growth is described here. Delivered metal particles…
We compare the phase behavior of a series of lithium perchlorate-doped poly(isoprene- b -styrene- b -ethylene oxide) (ISO) and poly(styrene- b -isoprene- b -ethylene oxide) (SIO) triblock copolymers. Complete phase diagram isopleths ( f I = f S ) are described for the lithium-doped ISO system and the previously report…
The optimized effective potential (OEP) is the exact Kohn-Sham potential for explicitly orbital-dependent energy functionals, e.g., the exact exchange energy. We give a proof for the OEP equation which does not depend on the chain rule for functional derivatives and directly yields the equation in its simplest form: a…
Structural and electronic properties of amorphous and single-phase polycrystalline films of gamma- and kappa-In2Se3 have been measured. The stable gamma phase nucleates homogeneously in the film bulk and has a high resistivity, while the metastable kappa phase nucleates at the film surface and has a moderate resistivi…
We suggest a general rule for the shift quantum numbers k of the relative ground states of antiferromagnetic Heisenberg spin rings. This rule generalizes well-known results of Marshall, Peierls, Lieb, Schultz, and Mattis for even rings. Our rule is confirmed by numerical investigations and rigorous proofs for special…
Powder of magnesium diboride was hot isostatically pressed using three qualitatively different cycles: cooling under pressure (DMCUP), "standard" cycle with pressure and temperature reduced simultaneously and isothermal presure release. Elastic properties of dense material were measured at normal conditions using reso…
The synthesis and spectroscopic characterization of the mononuclear uranium complex [((ArO)(3)tacn)U(III)(NCCH(3))] is reported. The uranium(III) complex reacts with organic azides to yield uranium(IV) azido as well as uranium(V) imido complexes, [((ArO)(3)tacn)U(IV)(N(3))] and [((ArO)(3)tacn)U(V)(NSi(CH(3))(3))]. Sin…
We report molecular dynamics simulations showing that a DNA molecule could be spontaneously inserted into carbon nanotube (CNT) in a water solute environment. The van der Waals and hydrophobic forces were found to be important for the insertion process, with the former playing a more dominant role in the DNA−CNT inter…
Positron energy levels and distributions in the ${\mathrm{C}}_{60}$ crystal have been calculated based on the self-consistent electronic structure obtained with an ab initio plane-wave pseudopotential calculation. For the correlation energy between electrons and a positron, we used both the local-density approximation…