Materials Literature
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Quadratic-response theory is shown to provide a conceptually simple but accurate approximation for the self-consistent one-electron potential of semiconductor nanostructures. Numerical examples are presented for GaAs/AlAs and InGaAs/InP (001) superlattices using the local-density approximation to density-functional th…
X-ray absorption spectroscopy was used to study the microscopic origin of conductance and resistive switching in chromium doped strontium titanate (Cr:SrTiO3). Differences in the x-ray absorption near edge spectroscopy (XANES) at the Cr K-edge indicate that the valence of Cr changes from 3+ to 4+ underneath the anode…
The influence of ordered regions (micro crystallites and aggregates) in the other wise disordered polymer host matrix on field and temperature dependence of mobility (μ) has been simulated. Increase in concentration of ordered regions leads to increase in magnitude of mobility and in high field regime the saturation o…
Transition-metal oxides exhibiting a bistable resistance state are attractive for non-volatile memory applications. The relevance of oxygen vacancies (VO) for the resistance-change memory was investigated with x-ray fluorescence, infrared microscopy, and x-ray absorption spectroscopy using Cr-doped SrTiO3 as example.…
In this Account, we discuss the usefulness of the sol-gel process in the synthesis of materials comprising nanoscale architectures. We describe the processing of semiconducting, metallic, ferroelectric, or scintillating nanoparticles in various oxide matrices. We also discuss the synthesis of some nanoporous oxides an…
X-ray diffraction data on liquids and disordered solids often provide useful complementary structural information to neutron diffraction data. Interpretation of the x-ray diffraction pattern, which is produced by scattering from the atomic electrons rather than from the atomic nuclei as in the case of neutron diffract…
A new approach to the reverse Monte Carlo analysis of total scattering data from polycrystalline materials is presented. The essential new feature is the incorporation of an explicit analysis of the Bragg peaks using a profile refinement, taking account of the instrument resolution function. Other new features includi…
PDFfit2 is a program as well as a library for real-space refinement of crystal structures. It is capable of fitting a theoretical three-dimensional (3D) structure to atomic pair distribution function data and is ideal for nanoscale investigations. The fit system accounts for lattice constants, atomic positions and ani…
New Aurivillius phases in the Bi–Ag–Ti–O system were investigated by means of a solid‐state reaction and X‐ray diffraction. We found that the oxygen partial pressure has a significant influence on the synthesis of the Aurivillius phases. The mixed‐layer Aurivillius phase Ag 0.5 Bi 8.5 Ti 7 O 27 was observed after firi…
Abstract Blend of ethylene‐vinyl acetate copolymer (EVA), ethylene‐propylene‐diene terpolymer rubber (EPDM), and chlorinated polyethylene (CPE) filled with talc was cross‐linked with dicumyl peroxide and blown simultaneously with azodicarbonamide for preparation of high elasticity material by injecting, cross‐linking,…
The unsymmetrical pi donor dimethyl(ethylenedioxy)tetraselenafulvalene (DMEDO-TSeF) has provided six new organic superconductors with a monovalent square-planar [Au(CN)(4)](-) ion and cyclic ethers as solvent of crystallization. The six new organic superconductors kappa-(DMEDO-TSeF)(2)[Au(CN)(4)](solv.) [solv.=1,3-dio…
Abstract A comprehensive study of the structure and properties has been performed for copolymers of propylene‐1‐hexene, CiPH, and propylene‐ethylene, CiPE, synthesized by an isotactic metallocene catalyst system. The comonomer content constitutes the most important factor affecting the structure and properties of thes…
Abstract The random end linking of different amounts of trifunctional crosslinkers with 3 000 prepolymer linear chains, with length varying from 10 to 30 monomers, to form networks at different system number densities was dynamically simulated by the molecular dynamics method. Investigation of the crosslinking kinetic…
Abstract A family of erbium alkoxides [Er(OR) 3 ] was prepared from the reaction of Er[N(SiMe 3 ) 2 ] 3 with a series of alcohols (HOR) in selected solvents and crystallographically characterized as: [Er(μ‐Onep) 2 (Onep)] 4 , ( 1 ), [Er 4 (μ 4 ‐O)(μ 3 ‐Onep)(μ‐Onep) 5 (Onep) 4 (py) 3 ] ( 3 ), Er 3 (μ 3 ‐O t Bu) 2 (μ‐O…
Abstract Linear isotactic metallocene based polypropylene ( M w = 125,000 g/mol, M n = 61,000 g/mol) was lightly crosslinked by small amounts of 1,3‐benzenedisulfonyl azide to form long chain branches (LCB). Crosslinking was carried out by reactive extrusion at 200°C in a small scale extruder. At the processing temper…
Eingefangen: Die Selbstorganisation von Bakterien gelang durch Kombination von Escherichia coli mit dem synthetischen Zeolith L. Der Organisationsprozess lässt sich so steuern, dass die Gebilde Bakterien und poröse Nanobehälter im Verhältnis 1:1 oder 2:1 enthalten (siehe schematische Darstellung).
Abstract We propose simple expressions $\Pi /\Pi _0 = 1 + (\varphi /\varphi _{{\rm ex}} )^{3\alpha - 1}$ and $(\delta _0 /\delta )^2 = 1 + (\varphi /\varphi _{{\rm ex}} )^{2\alpha }$ for the osmotic pressure Π and the depletion thickness δ as a function of the polymer concentration φ . Here, Π 0 and δ 0 correspond to…
Two unusual mixed-valent {MnIII6MnII} bitetrahedra display frustrated magnetic exchange, leading to S = 13/2 +/- 1 and 11/2 +/- 1 ground states and slow magnetization relaxation.
3,4-Dicyanophenyl O- and S-glycosides in the gluco, galacto, lacto, and cellobiose series were prepared in virtually quantitative yield through nucleophilic aromatic substitution of 4-nitrophthalonitrile with acetyl-protected glycoses and 1-thio-glycoses. Similarly, 2-(3,4-dicyanophenoxy)ethyl 2,3,4,6-tetra-O-acetyl-β…
An algebraic method to calculate the optical constants for a weakly absorbing thin film from the spectrum of normal reflectance is described. The calculation of the refractive index of the thin film is simplified by constructing a midpoint envelope through the reflection spectrum. If a portion of the spectrum includes…