Materials Literature
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Using quasi-in-situ scanning force microscopy we study the details of nanopattern alignment in ABC terblock copolymer thin films in the presence of an in-plane electric field. Because of the surface interactions and electric field the lamellae are oriented both perpendicular to the plane of the film and parallel to th…
The existence of a neutron scattering resonance at a wave vector ${q}^{\ensuremath{\ast}}$ implies a sign change of the gap between two Fermi-surface regions separated by wave vector ${q}^{\ensuremath{\ast}}$. For the Fe pnictides, a resonance has been observed for a wave vector ${q}^{\ensuremath{\ast}}$ which connect…
We discuss the emergence of a spontaneous temperature and critical current spatial modulation in current-carrying high temperature superconducting wire. The modulation of the critical current along the wire on a scale of 3 - 10 mm forces a fraction of the transport current to crisscross the resistive interface between…
CeB6, a typical Gamma_8-quartet system, exhibits a mysterious antiferroquadrupolar ordered phase in magnetic fields, which is considered as originating from the T_{xyz}-type magnetic octupole moment induced by the field. By resonant x-ray diffraction in magnetic fields, we have verified that the T_{xyz}-type octupole…
We report Auger recombination rates for wurtzite InGaN calculated from first principles density-functional and many-body-perturbation theory. Two different mechanisms are examined -- inter- and intra-band recombination -- that affect different parts of the emission spectrum. In the blue to green spectral region and at…
We report a detailed study of a model Hamiltonian which exhibits a rich interplay of geometrical spin frustration, strong electronic correlations, and charge ordering. The character of the insulating phase depends on the magnitude of Delta/|t| and on the sign of t. We find a Mott insulator for Delta >> U >> |t|; a cha…
Carbon nitride nanotubes were produced by using porous anodic aluminum oxide membranes as the template through a polymerization reaction between ethylenediamine and carbon tetrachloride. The synthesized nanotubes were systematically studied by scan electron microscopy (SEM), transmission electron microscopy (TEM), X-r…
We study theoretically the effects of spatial confinement on the phoretic motion of a dissolved particle driven by composition gradients generated by chemical reactions of its solvent, which are active only on certain parts of the particle surface. We show that the presence of confining walls increases in a similar wa…
For the study of molecular spin junctions, we take into account two types of couplings between the molecule and the metal leads: (i) electron transfer that gives rise to net current in the biased junction and (ii) energy transfer between the molecule and the leads. Using a rotating wave approximation in the Heisenberg…
We present the results of ab initio calculations describing the adsorption of certain small organic molecules on clean and oxidized Al(111) surfaces as well as on the α- Al(2)O(3)(0001) surface. Our results show that adsorption of benzene on the clean and oxidized Al(111) surfaces is generally weak, the adsorption ene…
We report about investigations of time-dependent structural modifications in single-crystal graphene due to laser irradiation even at moderate power levels of 1 mW in a diffraction-limited spot. The modifications have been characterized by in situ scanning confocal Raman spectroscopy, atomic force height microscopy, a…
Rattle-type Fe 3 O 4 @SiO 2 hollow mesoporous spheres with large cavities have been successfully prepared by using the colloidal carbon spheres as the templates. The spheres are well monodisperse and nearly uniform in dimension with particle size of ca. 900 nm. The thickness of the mesoporous silica shell is about 100…
Abstract Kohlenstoff leuchtet auf : Ein einfacher chemischer Weg zu mehrfarbig photolumineszierenden Kohlenstoffpunkten, die sich von Polymer/Silica‐Nanokompositen ableiten, nutzt tensidmodifizierte Silicakugeln als Träger und Resole (Phenol/Formaldehydharze) als Kohlenstoffvorstufe (siehe Bild). Die oberflächenpassiv…
Multilayer VO_{2}/TiO_{2} nanostructures (d;{1}-d;{0} interfaces with no polar discontinuity) are studied with first-principles density functional methods including structural relaxation. Quantum confinement of the half-metallic VO2 slab within insulating TiO2 produces an unexpected and unprecedented two-dimensional n…
In the spirit of Germain the most general objective stored elastic energy for a second gradient material is deduced using a literature result of Fortuné & Vallée. Linear isotropic constitutive relations for stress and hyperstress in terms of strain and strain-gradient are then obtained proving that these materials…
We have performed first-principles calculations of graphene edge stresses, which display two interesting quantum manifestations absent from the classical interpretation: the armchair edge stress oscillates with a nanoribbon width, and the zigzag edge stress is noticeably reduced by spin polarization. Such quantum stre…
Abstract Halloysite particles are aluminum‐silicate hollow cylinders with a length of 0.5–1 µm, an outer diameter of ca. 50 nm and a lumen of 15 nm. These nanotubes are used for loading and sustained release of corrosion inhibitors. The inhibitor is kept inside the particles infinitely long under dry conditions. Here,…
We have synthesized a series of new alkali-metal or Tl(+) titanium iodates, A(2)Ti(IO(3))(6) (A = Li, Na, K, Rb, Cs, Tl). Interestingly the Li and Na phases are noncentrosymmetric (NCS) and polar, whereas the K, Rb, Cs, and Tl analogues are centrosymmetric (CS) and nonpolar. We are able to explain the change from NCS…
Abstract Owing to their promising applications in electronic and optoelectronic devices, conducting polymers have been continuously studied during the past few decades. Nevertheless, only limited progress had been made in conducting‐polymer‐based sensors until nanostructured conducting polymers were demonstrated for h…
Carbon lights up: A facile chemical method yields multicolor photoluminescent carbon dots derived from polymer/silica nanocomposites, which were prepared using surfactant-modified silica spheres as carriers and resols (phenol/formaldehyde resins) as carbon precursor (see picture). The surface-passivated carbon dots sh…