Materials Literature
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We propose that localized defects in magnetic semiconductors act as deep impurities and can be described by the Anderson model. Within this model, hybridization of d-orbitals and p-orbitals gives rise to a non-RKKY indirect exchange mechanism, when the localized d-electrons are exchanged through both conduction and va…
Semiconductor quantum wires constitute a promising thermoelectric material because of the increase of the electronic density of states in low-dimensional materials. We studied the magnetic-field-dependent resistance and Seebeck coefficient of a high-density network of 6-nm-diameter wires of Bi and of Bi(1-x)Te(x), x=0…
In dynamic Monte Carlo simulations, using for example the Metropolis dynamic, it is often required to simulate for long times and to simulate large systems. We present an overview of advanced algorithms to simulate for larger times and to simulate larger systems. The longer-time algorithm focused on is the Monte Carlo…
Compressed copper powder has a very large electrical resistance (1MOhm), due to the oxide layer on grains (100 micro m). We observe that its voltage-current U-I characteristics are nonlinear, and undergo an instability, from an insulating to a conductive state at relatively small applied voltages. Current through the…
In this paper, we elucidate the vibrational response of cylindrical nanorods to ultrafast laser-induced heating. A theoretical analysis of the expected behavior is first presented. This analysis predicts that both extensional and breathing vibrational modes of the rods should be excited by laser-induced heating. Analy…
We present results of the preparation (by precursor decomposition), characterization (with x-ray diffraction, transmission electron microscopy, and dc magnetization measurements), and detailed computation (using density functional theory) of polycrystalline ZnO with up to 15% substitution of the zinc sites by divalent…
Supramolekulare Chirogenese: Die supramolekulare Wechselwirkung von achiralem Bis(zinkporphyrin) mit enantiomerenreinen Aminosäure-Derivaten führt zur Induktion von Chiralität. Vorzeichen und Größe des Circulardichroismus werden durch die Polarität des Lösungsmittels bestimmt (siehe Bild).
In a RF induction thermal plasma chemical vapour deposition system the substrate is used as an electrical probe to monitor the diamond film evolution in situ . The evolving electron emission current allows us to identify the transition from the initial nucleation stage to the diamond growth stage. A direct-current bia…
Quasi‐amorphous BaTiO 3 thin films (see Figure) represent a polar ionic solid without spatial periodicity. Most probably, polarity of the quasi‐amorphous BaTiO 3 is associated with directional ordering of crystal motifs formed in the steep temperature gradient and stabilized by high in‐plane mechanical stress. A remar…
We present exact results on the thermal conductivity of the one-dimensional spin-1/2 XXZ model in the massive antiferromagnetic and ferromagnetic regimes. The thermal Drude weight is calculated by a lattice path integral formulation. Numerical results for wide ranges of temperature and anisotropy as well as analytical…
p-Chlorophenol (4-CP) is a recalcitrant organic pollutant that is biologically toxic in industrial wastewater. A high-frequency ultrasonic device operated at 1.7 MHz was designed and used successfully to degrade 4-CP. Iodine liberation in the KI aqueous solution confirmed that effective cavitation occurred under the h…
Super Structures: By thermally evaporating elemental layers onto substrates at ambient temperature, structural precursors are constructed with appropriate composition and modulation lengths to kinetically favor the formation of the desired superstructure. On annealing, these modulated elemental reactants form metastab…
Abstract Bis(2,6‐bis(pyrazol‐3‐yl)pyridine)iron( II ) thiocyanate dihydrate undergoes a two‐step singlet ( 1 A 1 ) ⇄ quintet ( 5 T 2 ) transition in which both steps are associated with thermal hysteresis. Thermal cycling of the sample results in its conversion to a second phase which displays a single‐step transition…
Einfach zu Nanomaterialien! Die Oxidation von [Zn(c-C6H11)2] bei Raumtemperatur in einem organischen Solvens, das langkettige Aminliganden enthält, liefert in Größe und Form definierte kristalline ZnO-Nanopartikel (siehe Bild). Diese sind als Nanoscheiben und -stäbchen mit geringer Größendispersion (3–10 nm) vollständ…
Carbon is one of the elements most abundant in nature. It is essential for living organisms and, as an element, occurs in several morphologies. Nowadays, carbon is encountered widely in our daily lives in its various forms and compounds, such as graphite, diamond, hydrocarbons, fibres, soot, oil, complex molecules, et…
Gamma irradiation sterilization (gamma-irradiation) fragments and denatures collagen, drastically decreasing critical physical properties. Our goal was to maintain strength and stability of gamma-irradiated collagen by adding glucose, which in theory can initiate crosslink formation in collagen during exposure to gamm…
A carboxy-substituted alkylammonium salt, namely, (4-carboxybenzyl)tributylammonium hexafluorophosphate, ZHPF(6), was prepared and used as incoming carboxylate ligand in a ligand-exchange reaction with [Mn(12)O(12)(O(2)CCH(3))(16)(H(2)O)(4)] (1) to afford a new Mn(12) single-molecule magnet (SMM), [Mn(12)O(12)(Z)(16)(…
Abstract A method is presented for dispersing ropes or bundles of single‐walled carbon nanotubes (RCNTs) in a polycarbonate (PC) matrix. Films of PC/RCNT composites are produced, with thicknesses ranging from 10 to 60 μm, and containing small concentrations (0.06–0.25 wt.‐%) of RCNT. Our process is based on a unique m…
Metal clusters deposited on a substrate and positioned at a nanometric distance from a wave-reflecting layer act as nanoresonators able to receive, store and transmit energy within the visible and infrared range of the spectrum. Among the unique effects of these metal nanocluster assemblies are high local field enhanc…
CaCO3-Komposite mit regelmäßigen Mustern auf der Oberfläche wurden hergestellt (siehe Bild). Diese submikrometergroßen Strukturen scheiden sich aus einer wässrigen Lösung, die ein saures Polymer enthält, spontan auf einer dünnen Matrix aus einem modifizierten Polysaccharid ab.