Materials Literature
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Using in situ small-angle X-ray scattering, the electric field induced orientation in a block copolymer having a cylindrical microdomain morphology was investigated. Studies were performed with the copolymer in different initial states. Beginning with a disordered copolymer, composition fluctuations are oriented by th…
Many transition metal compounds show saturation of the resistivity at high temperatures, T, while the alkali-doped fullerenes and the high-Tc cuprates are usually considered to show no saturation. We present a model of transition metal compounds, showing saturation, and a model of alkali-doped fullerenes, showing no s…
Scanning tunneling spectroscopy images of Bi$_2$Se$_3$ doped with excess Bi reveal electronic defect states with a striking shape resembling clover leaves. With a simple tight-binding model we show that the geometry of the defect states in Bi$_2$Se$_3$ can be directly related to the position of the originating impurit…
The magnetic order resulting from an indirect exchange between magnetic moments in the metallic phase of a Ga(1-x)Mn(x)As bilayered structure is studied "via" Monte Carlo simulation. The coupling mechanism involves a perturbative calculation in second order of the interaction between the magnetic moments and carriers…
We calculate magnetic anisotropy energy of Fe and Ni by taking into account the effects of strong electronic correlations, spin-orbit coupling, and non-collinearity of intra-atomic magnetization. The LDA+U method is used and its equivalence to dynamical mean-field theory in the static limit is derived. The effects of…
The high-pressure behaviour of alpha-PbF2 has been investigated by angular-dispersive synchrotron X-ray powder diffraction up to 6.55(8) GPa. The fit of a 3rd-order Birch-Murnaghan equation-of-state gave the volume at zero pressure V0=194.14(4)Å$^3 and the bulk modulus b_0=47.0(6)GPa with the pressure derivative b'=7.…
The classic Lifshitz-Slezov-Wagner theory of ripening assumes that within a closed system, the total volume of the phase undergoing ripening remains constant while the total surface area of the phase decreases. We present here the ripening behavior in an open system in which the total surface area of the phase undergo…
Vesicles prepared in water from a series of diblock copolymers “polymersomes” are physically characterized. With increasing molecular weight M̄ n, the hydrophobic core thickness for self-assembled bilayers of poly(ethylene oxide)−polybutadiene increases up to ∼20 nm, which is considerably greater than any previously s…
Very rough surfaces can suspend small water drops, prevent wetting, and cause contact angles to approach 180°. A criterion based on contact line density is proposed for predicting the conditions that produce these ultrahydrophobic surfaces, where, above a critical value, drops are suspended by asperities. Critical val…
Polyesters such as poly(3-hydroxybutyrate) (PHB) or other polyhydroxyalkanoates (PHA) have attracted commercial and academic interest as new biodegradable materials. The ability to degrade PHA is widely distributed among bacteria and fungi and depends on the secretion of specific extracellular PHA depolymerases (e-PHA…
Systematic studies of binding energies for the electron excitation of core levels for atoms, molecules, and solids have been calculated with various density functional theories. The generalized gradient approximation provides the most accurate description of the absolute binding energies when spin polarization is incl…
A theoretical model is proposed for describing the polar biaxial and uniaxial nematic phases observed in thermotropic liquid crystals formed from rodlike polyester molecules. The polarity and biaxiality are shown to result from the same molecular mechanism, i.e., they are associated with the same critical order parame…
A simple and completely non-lithographic route to free-standing nanostructured polymeric films with a close-packed hexagonal array of nanoembossments or nanorods is presented in which electrochemically prepared textured aluminum sheets or nanoporous anodic alumimum oxide are used. The Figure shows an polystyrene/PMMA…
Using a geometry-based density functional theory we investigate the free interface between demixed bulk fluid phases of a colloidal mixture of hard spheres and vanishingly thin needles. Results are presented for the spatial and orientational density distributions of the particles, as well as for the interface tension.…
The pressure dependences of the elastic constants and the sound velocities are calculated from first principles for $3C\ensuremath{-}\mathrm{SiC}$ in the range 0--100 GPa. The sound velocities are found to decrease with increasing pressure for the lowest transverse acoustic (TA) branches for the [110] and [111] sound…
An ordered mesoporous silica with novel cubic structure (space group Fd3m) has been synthesized by using tri-head group quaternary ammonium surfactants [CmH2m + 1N+(CH3)2CH2CH2N+(CH3)2CH2CH2CH2N+(-)(CH3)(3).3Br-] (Cm-2-3-1, m = 14, 16, 18) as the structure-directing agents under basic conditions at low temperature.
Isothermal magnetization curves up to 23 T have been measured in ${\mathrm{Gd}}_{5}{\mathrm{Si}}_{1.8}{\mathrm{Ge}}_{2.2}.$ We show that the values of the entropy change at the first-order magnetostructural transition, obtained from the Clausius-Clapeyron equation and the Maxwell relation, are coincident, provided the…
The existence of spin polarized sub-bands, a half-semiconducting state in which the electron spins in “valence” and “conduction” bands are oppositely polarized, has been derived for the vanadium-organyl-based “soft” ferrimagnet V(TCNE)x by measurements of its electrical and magnetic resistance at different temperature…
The formation of Ni(OH)2 nanorods within an anodic oxide template via hydrothermal synthesis, followed by their subsequent liberation to form discrete NiO nanorods, is presented. The carbon can effectively be removed to form this uniform rod-like product. The Figure shows a schematic illustration of the synthesis.
From in situ stress measurements, we have observed that a large component of the precoalescence compressive stress that develops during Volmer-Weber growth of polycrystalline Cu films relaxes reversibly. This phenomenon is similar to the reversible stress relaxation previously observed in the postcoalescence regime. W…