Materials Literature
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Drei strukturell diverse Polymere mit intrinsischer Mikroporosität (PIMs) adsorbieren erhebliche Mengen Wasserstoff (1.4–1.7 Gew.-% bei 77 K). Sie bilden eine neue Klasse von organischen Wasserstoffspeichermaterialien, die an spezifische Anforderungen für die Wasserstoffphysisorption angepasst werden können.
Surface functionalization of ZnO nanoparticles with a quaternary ammonium organosilane leads to ionically modified nanoparticles. Upon exchange with a poly(ethylene glycol)-tailed sulfonate anion (A−), strongly photoluminescent nanoparticles result, which exhibit liquidlike behavior in the absence of solvents.
Mn ion doping of CdSe and other semimagnetic quantum dot (QDs) alloys has been an area of active speculation for over a decade. We report evidence of Mn(II) doping of CdSe grown from a cubic single source precursor that is superparamagnetic (SPM) with a blocking temperature of 40 K following thermal annealing. Prior t…
Transition metal containing ZnO powders (Zn1−xMxO, 0≤x≤0.30; M = Ni, Mn, Co) have been synthesized by a sol–gel process using zinc acetate dihydrate, respective acetate and oxalic acid as precursors with ethanol as a solvent. The process essentially involves gel formation, drying at 80 °C for 24 h to provide the oxala…
The radial breathing and $G$-band vibrational modes of all 300 single-walled carbon nanotubes in the radius range from $2\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}12\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$ were calculated within a symmetry-adapted nonorthogonal tight-binding model. The dynamical…
Tensile properties of microcoupons of polyelectrolyte complex, formed by the multilayering method, were determined using a micromechanical analysis system. The degree of internal ion-pair ("electrostatic") cross-linking was reversibly controlled by exposure to salt solution of varying concentration, which "doped" coun…
We report that entirely end-bonded multiwalled carbon nanotubes (MWNTs) can exhibit superconductivity with a transition temperature (T(c)) as high as 12 K, which is approximately 30 times greater than T(c) reported for ropes of single-walled nanotubes. We find that the emergence of this superconductivity is highly sen…
We explore the possibility that hyperfine interaction causes the recently discovered organic magnetoresistance (OMAR) effect. Our study employs both experiment and theoretical modelling. An excitonic pair mechanism model based on hyperfine interaction, previously suggested by others to explain magnetic field effects i…
β-Cyclodextrin (β-CD)-modified CdSe (β-CD/CdSe) and CdSe−CdS core−shell structured (β-CD/CdSe−CdS) quantum dots (QDs) were synthesized by a single-phase approach in aqueous solutions. These receptor-modified QDs are very soluble and stable in water over a wide range of pH values and ionic strengths. Coating a CdS shel…
Carbon nanotubes (CNTs) are known to possess extraordinary strength, stiffness and ductility properties. Their fracture resistance is an important issue from the perspective of durability and reliability of CNT-based materials and devices. According to existing studies, brittle fracture is one of the important failure…
An investigation of the pressure induced phase transition from the scheelite phase ( I 4 1 / a , Z = 4) to the fergusonite-like phase ( I 2/ a , Z = 4) and to the LaTaO 4 phase ( P 2 1 / c , Z = 4) of LiYF 4 is presented. Employing density functional theory (DFT) within the generalized gradient approximation, the stru…
Copper oxide (CuO) thin films were deposited using a reactive DC sputtering method for gas sensor applications. The structure of the films determined by means of an x-ray diffraction method indicates that the phase of copper oxide can be synthesized in the total pressure and temperature ranges of 6–8.5 mbar and 151–19…
A fluid flow in a simple dense liquid, passing an obstacle in a two-dimensional thin film geometry, is simulated by Molecular Dynamics (MD) computer simulation and compared to results of Lattice Boltzmann (LB) simulations. By the appropriate mapping of length and time units from LB to MD, the velocity field as obtaine…
Vortex dynamics in a restricted geometry is considered for a magnetic system consisting of ferromagnetic cylindrical dots. To describe the vortex dynamic susceptibility and relaxation the equation of motion for the vortex center position is applied. The dependencies of the vortex dynamic susceptibility and resonance l…
Electronic and magnetic properties of the fcc Americium (001) surface have been investigated via full-potential all-electron density-functional electronic structure calculations at both scalar and fully relativistic levels. Effects of various theoretical approximations on the fcc Am (001) surface properties have been…
We grow Fe film on (4 by 2)-GaAs(100) at low temperature, (~ 130 K) and study their chemical structure by photoelectron spectroscopy using synchrotron radiation. We observe the effective suppression of As segregation and remarkable reduction of alloy formation near the interface between Fe and substrate. Hence, this s…
The combination of density functional theory with other approaches to the many-electron problem through the separation of the electron-electron interaction into a short-range and a long-range contribution is a promising method, which is raising more and more interest in recent years. In this work some properties of th…
The atomic and electronic structure, formation energy, and the energy barriers for migration have been calculated for the neutral O vacancy point defect ($F$ center) in cubic $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$ employing various implementations of density functional theory (DFT). Both bulk and $\mathrm{Ti}{\mathr…
Cores and effect: Using different temperature-sensitive polymers a core–shell microgel is prepared, which at intermediate temperatures has a shell with a higher segment density Φ than the core (see radial density profiles: core (red), shell (blue)). More detailed information is obtained from small-angle neutron scatte…
The extinction spectra of spherical gold nanoparticles suspended in a homogeneous media were measured and the results were adjusted with Mie's theory together with an appropriate modification of the optical properties of bulk material considering the limitation that introduces the size of nanoparticles on the dielectr…