Materials Literature
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Dilute fixed fiber beds provide a model system for studying drop dynamics in disordered flows. Fluctuations about the mean uniform velocity are generated by fiber elements within the media, and the disturbance velocities far from any single fiber (at distances on the order of the pore size) have been predicted to be s…
The 4f11 energy levels of Er3+ in LiYF4 in the spectral region 39000–65000 cm−1 have been studied. The agreement between experimental energy levels, obtained from luminescence excitation spectra, and calculated energy levels is good. Luminescence originating from high-lying energy levels has been investigated. Emissio…
Room temperature optical absorption measurements of Nd3+ in NaBi(WO4)2 single crystals grown by the Czochralski method have been used to calculate the following Judd-Ofelt intensity parameters Ω2 = 30.9 × 10−20, cm2, Ω4 = 12.0 × 10-20 cm2 and Ω6 = 9.3 × 10−20 cm2. Using these parameters the emission properties of Nd3+…
A novel photoresponsive azobenzene-containing organosilane was synthesized via an isocyanato-amino coupling reaction, and its crystal structure was determined by X-ray crystallography.
The tensile yielding of multiwall carbon nanotubes (MWCNTs) has been studied using molecular-dynamics simulations and a transition state theory based model. We find a strong dependence of the yielding on the strain rate. A critical strain rate has been predicted above/below which yielding strain of a MWCNT is larger/s…
Nanometer metal particles of tailored size (3−5 nm) and composition prepared via inverse microemulsion were encapsulated by ultrathin coatings (<2.5 nm) of inorganic porous aerogels covered with surface −OH groups. These composite materials formed metastable colloids in solvent(s), and the organic surfactant molecules…
Ordering and quantum fluctuations of orbital degrees of freedom are studied theoretically for LaVO3 in the spin-C-type antiferromagnetic state. The effective Hamiltonian for the orbital pseudospin shows strong one-dimensional anisotropy due to the negative interference among various exchange processes. This significan…
Fabrication of field emitters by the radio-frequency plasma-enhanced chemical vapor deposition of vertically aligned carbon nanotubes (CNT) on soda-lime glass is reported. CNT was produced at 400 °C by the control of the collision energy of carbonic cations to a substrate through a dc bias voltage. The CNTs produced i…
In the structure of graphite, graphene hexagon sheets are stacked in an AB stacking mode as shown in Figure 1.3. Such as mode is characterized by strong in-plane C-C bonds and weak interlayer interaction. This structural feature imparts two-dimensionality to its electronic structure. In the in-plane hexagon carbon net…
The characteristics of mechanical behavior are investigated for Ti-6Al-4V alloy. Four kinds of specimens are prepared under different heat treatments in order to produce different microstructures. In the present investigations, impact, tensile and fatigue crack growth tests are performed for each test specimen. The re…
A theory of multiphonon relaxation for rare-earth ions in ionic crystals and glasses is presented. The theory is based on the static coupling scheme. The electron-vibration coupling is assumed to be linear with respect to the relative ligand rare-earth displacements. The multiphonon transitions are induced by higher-o…
Electronic absorption spectra of crystals and solutions of praseodymium and thulium acetates and dipicolinates are reported. The influence of spectral properties of both ligands on intensities of the f—f transitions in the crystals studied is discussed. In the near-IR region, overtone vibrations of ligands are strongl…
Welding of C f / SiC to Ni-based superalloy has been realized using Cu/W/Cu/W/Cu multiple interlayers. The bending strength of the joints has been improved by using the active metallic filler contacted with C f / SiC . The strength of the joints is remarkably affected by the welding temperature. The maximum value 102.…
The accuracy of the Judd-Ofelt theory is investigated in several rare earth doped glasses. Using a normalized method to fit the experimental data, we show that an average accuracy of 5 to 15% is often obtained. However, large errors (up to 35%) can be found on some transitions, even in the case of ions usually conside…
Auf der Basis des Multichromophor-Ansatzes wurde der hier gezeigte Ruthenium(II)-Komplex erhalten, der die längste bisher bekannte Lumineszenzlebensdauer aufweist (1.8 μs). Beim Multichromophor-Ansatz nutzt man eine nur geringe Wechselwirkung zwischen den vorhandenen Chromophoren, sodass deren individuelle Eigenschaft…
The phonon spectra of zinc-blende CuCl are studied as a function of pressure using density functional linear-response theory. A pressure-induced soft transverse-acoustic-phonon mode is identified. At 2.6 GPa, the TA phonon mode softens at the X point, initiating the phase transition from the zinc-blende structure CuCl…
We demonstrate the applicability of continuous electropolishing for the preparation of metal tapes for ion-beam assisted deposition of MgO for the fabrication of in-plane textured template layers. These templates are used for the fabrication of second generation high temperature superconducting wires utilizing YBa 2 C…
We report on the electrical properties of thermally oxidized p-GaN metal–oxide–semiconductor (MOS) diodes with n+ source regions fabricated on sapphire substrates. The n+ regions were selectively produced in Mg-doped GaN by Si+N coimplantation and subsequent annealing at 1300 °C, and then 100-nm-thick β-Ga2O3 was grow…
Vom einen Spin zum andern: Bei dem durch Eintopfreaktion erhältlichen [FeIIH3L][FeIIIL](NO3)2 (H3L=sechszähniger Tripod-Ligand mit drei Imidazolgruppen) handelt es sich um eine homochirale gemischtvalente Spin-Crossover-Verbindung bestehend aus zweidimensionalen geordneten Schichten, die durch Imidazol-Imidazolat-Wass…
The theory of multiphonon vibronic coupling to electronic transitions is applied in analysing fluorescence spectra of Eu2+ in BaFCI, which consist of the 4f7(6P7/2,) → 4f7(8S7/2) and 4f65d → 4f7 transitions, and the 4f7-4f65d excitation spectrum of Ce3+ in YPO4. The 4f electrons are weakly coupled to lattice vibration…