Materials Literature
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Carbon nanotube field-effect transistors often exhibit a hysteresis effect in the gate-voltage dependence. We report devices fabricated with small hysteresis, and demonstrate a method to introduce this effect controllably by coating nanotube devices with charged polymers. In addition, the hysteresis is sensitive to hu…
An iron constitution: Dark superparamagnetic iron oxide nanoparticles are present within the walls of a hexagonal mesoporous aluminosilicate (as shown by the associated bright-field TEM image). The simple block-copolymer-based “one-pot” self-assembly approach enables potential applications in magnetic separation and c…
Star-shaped polylactide was synthesized by bulk polymerization of lactide with poly(amidoamine) (PAMAM) dendrimer as initiator, which was marked as PAMAM-g-PLA for simplicity. The nonlinear architecture of PAMAM-g-PLA was confirmed by gel permeation chromatograph, nuclear magnetic resonance, and differential scanning…
Combining high-resolution core-level spectroscopy (HRCLS), scanning tunneling microscopy (STM) and density-functional theory (DFT) calculations we reanalyze the Pd(100)-(SQRT(5) x SQRT(5) R27^o)-O surface oxide phase. We find that the prevalent structural model, a rumpled PdO(001) film suggested by previous low energy…
The stereochemistry of the 1,2-cyclohexanediol intermediate plays an important role with regard to both the rate and selectivity of the production of adipic acid from cyclohexene in the absence of an organic solvent. A titanium-containing aluminophosphate molecular sieve (TAPO-5) is shown to serve as a good heterogene…
We consider the effect of the Rashba spin-orbital interaction and space charge in a ferromagnet-insulator/semiconductor/insulator-ferromagnet junction where the spin current is severely affected by the doping, band structure and charge screening in the semiconductor. In diffusion region, if the the resistance of the t…
We study the effect of doping in the suppression of tunneling observed in multi-walled nanotubes, incorporating as well the influence of the finite dimensions of the system. A scaling approach allows us to encompass the different values of the critical exponent $α$ measured for the tunneling density of states in carbo…
We demonstrate the growth of GaN/AlN quantum well structures by plasma-assisted molecular-beam epitaxy by taking advantage of the surfactant effect of Ga. The GaN/AlN quantum wells show photoluminescence emission with photon energies in the range between 4.2 and 2.3 eV for well widths between 0.7 and 2.6 nm, respectiv…
A well-known connection between the magnetic susceptibility and the effective exchange parameter is analyzed. It is shown that all current computational schemes use a long-wave approximation which is suitable only for localized moments systems. A corresponding smallness parameter is derived in real and recipical space…
We perform ab initio calculations of charged graphene and single-wall carbon nanotubes (CNTs). A wealth of electromechanical behaviors is obtained. (1) Both nanotubes and graphene expand upon electron injection. (2) Upon hole injection, metallic nanotubes and graphene display a nonmonotonic behavior. Upon increasing h…
Large spin systems as given by magnetic macromolecules or two-dimensional spin arrays rule out an exact diagonalization of the Hamiltonian. Nevertheless, it is possible to derive upper and lower bounds of the minimal energies, i.e. the smallest energies for a given total spin S. The energy bounds are derived under add…
A polyhedral oligomeric silsesquioxane (POSS) containing one epoxy group and seven isobutyl groups per molecule was incorporated into an epoxy network following a two-stage process. In the first stage, POSS was reacted with an aromatic diamine, employing a 1:1 molar ratio of both reactants. The distribution of species…
We describe a scheme for first-principles calculations of the static, paramagnetic, spin susceptibility of metals with relativistic effects such as spin-orbit coupling included. This gives the direction for an applied modulated magnetic field to maximise its response. This easy axis depends on the modulation's wave-ve…
Two-dimensional metal oxide sheets in HTiNbO(5) and HSr(2)Nb(3)O(10), cation-exchangeable layered metal oxides, were examined as solid acid catalysts. Exfoliation of HTiNbO(5) and HSr(2)Nb(3)O(10) in aqueous solutions formed colloidal single-crystal TiNbO(5)(-) and Sr(2)Nb(3)O(10)(-) nanosheets, which precipitated und…
Slow paramagnetic relaxation was observed at low temperatures from ac susceptibility measurements in the form of a frequency-dependent out-of-phase (χ) signal for the title complex (see picture). This provides compelling evidence that this cluster is a rare example of a cyanide-bridged single-molecule magnet.
The Ising on the cake: The cyanide-bridged low-spin FeIII–high-spin CoII compounds of formula [{FeL(CN)4}2Co(H2O)2]⋅4 H2O with L=2,2′-bipyridine (bpy; see picture; Ow=water O-atom) or 1,10-phenanthroline are 1D Ising systems and the first examples of ferromagnetically coupled bimetallic chains which show slow magnetic…
The kinetics of intermediate phase formation in (20 nm) Cu/(80 nm) Mg multilayers is analyzed using differential scanning calorimetry (DSC) and in situ x-ray diffraction. The as-prepared Mg layers are polycrystalline with large grain sizes and a columnar structure which gives a preferred orientation along the (0002) d…
Abstract An attempt was made on the modification of the tetraglycidyl‐4,4′‐diaminodiphenyl methane/diaminodiphenyl sulfone (TGDDM/DDS) system to improve properties for several industrial applications. Epoxy resins [TGDDM and 1‐glycidyloxy‐4‐methoxy phenol (GMP)] were synthesized in the laboratory. Also, a new cyanate…
The aim of this work is to show that ReflEXAFS can be used as a tool for investigating the initial stages of solid state reactions, when local chemical equilibrium is not yet attained at the interfaces. A very classical solid state reaction, i.e. the formation of Ni–Al spinel starting from the parent oxides (NiO + Al2…
Zn 2 Si 0.5 Ge 0.5 O 4 : Mn was investigated as a green-emitting oxide phosphor for thin-film electroluminescent (EL) display applications. Detailed electro-optical characteristics of thin-film EL devices with SrTiO3 dielectrics on a glass substrate (TFEL) and EL devices with a single ceramic insulator (CIEL) have bee…