Materials Literature
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Emission enhancement from BaTiO3:Pr3+ by addition of trivalent ion under excitation above the fundamental absorption edge of BaTiO3 host crystals has been investigated. In this system, energy transfer occurs from BaTiO3 to Pr3+. Emission of Pr3+ is intensified by addition of small trivalent ions, e.g., Yb3+ or Sc3+, w…
We performed local density approximation (LDA)-based ab initio calculations for isolated substitutional donor impurities (phosphorus single donor and sulfur double donor), hydrogen at various sites, and hydrogen-related complexes (phosphorus-hydrogen and sulfur-hydrogen) in diamond. Their stable atomic configurations…
Infrared and Raman spectra of vermiculite clay have been recorded, and an assignment of the observed features in the spectra is proposed on the basis of molecular dynamics calculations. For this purpose, a force field yielding a structure and vibrational spectra in good agreement with the experimental data was develop…
The demagnetizing problem should be studied numerically in nonellipsoids with nonzero susceptibility χ, except for a few limiting cases where analytical treatment turns out to be practical. In this work, for an infinitely long bar with rectangular cross section 2a×2b and χ=∞ and −1 in a uniform transverse applied fiel…
The image contrast of a single-walled carbon nanotube (SWCNT) is investigated via high resolution transmission electron microscopy (HRTEM) experiments and image simulations. It is found that the common practice of determining the tube diameter by measuring the two dark lines in the HRTEM image of a SWCNT is not very a…
Spectroscopic analysis of the unhydrogenated amorphous carbon nitride (a-CNx) films, prepared by ion beam sputtering, was done by ellipsometry, Raman scattering and x-ray photoelectron spectroscopic (XPS) studies. The optical gap of the films was estimated from the Tauc’s analysis of the (n,k) data obtained from spect…
Blue luminescence emission around 480 nm through cooperative upconversion from pairs of Yb3+ ions implanted into 60TeO2–10GeO2–10K2O–10Li2O–10Nb2O5 tellurite glasses and excited by a cw laser at 1.064 μm is demonstrated. Cooperative luminescence emission enhancement owing to the temperature dependent multiphonon-assis…
A photonic model for freshly anodized porous silicon multilayer structures is presented. The photonic structures are composed of alternating high and low dielectric function porous silicon layers. The model takes into account the presence of silicon dioxide and its lattice expansion in the porous structure. We work wi…
Highly oriented indium tin oxide (ITO) thin films were grown by pulsed-laser deposition (PLD) on glass and single-crystal yttria-stabilized zirconia (YSZ) substrates. The structural, electrical, and optical properties of these films were investigated as a function of oxygen partial pressure. Films were deposited at su…
The nonlinear optical properties of solid-solid phase transformation in vanadium dioxide are studied. It is found that the efficiency of the third-harmonic optical signal generated from the surface of the material increases by 1.5 orders of magnitude as a function of this phase transformation. Microscopy studies show…
An irreversible conductor-insulator transition has been observed when heating Mg2NiH4 in the temperature interval 110 to 570 K. The disappearance of the electric conductivity is concomitant with the appearance of stacking faults (or microtwinning) in the Mg2NiH4 structure, as observed by powder x-ray diffraction. Howe…
The formation dynamics of reflective holographic polymer dispersed liquid crystals (H-PDLCs) is investigated with in situ spectroscopy. A modified diffusion model is proposed to describe the time dependent shrinkage of the polymer matrix during formation. The relationship between polymer shrinkage and functionality in…
The Debye theory of dielectric relaxation of an assembly of polar molecules is reformulated using a fractional noninertial Fokker–Planck equation for the purpose of extending that theory to explain anomalous dielectric relaxation. The fractional Fourier–Planck equation in question is a generalization of the Smoluchows…
A theoretical analysis based on a perturbation method is used to elucidate the results of attenuated total reflection (ATR) measurements performed on silicon oxide layers of different thicknesses on silicon substrates. This analysis shows that the absorbance ATR spectrum in p polarization is the image of the layer ene…
1,3-Dibromo-2,4,6-trinitrobenzene (DBTNB), a two-dimensional charge transfer hyperpolarisable chromophore, crystallizes in the non-centrosymmetric space group C2 in perfect polar order leading to an intense powder SHG signal at 1.06 microns.
Energy increments for van der Waal effects are determined by bond-energy measurements on over 50 guest compounds (see diagram) and can be used for prediction. Hydrophobic effects can be discounted on the basis of comparison measurements with alkylated derivatives.
In einem einzigen Schritt erhält man ausgehend von Bipyrrol-Vorstufen in über 70 % Ausbeute Cyclo[8]pyrrole. Diese verkörpern eine neue Klasse von Porphyrin-Analoga und weisen die charakteristische scheibenartige Struktur der Porphyrine auf. Aus der Struktur eines solchen Cyclo[8]pyrrols im Kristall (siehe Bild) geht…
Abstract Colored fibers can be intimately blended in suitable proportions to achieve a specific color. This kind of formulation suffers from a lack of computer‐aided tool to assist the colorist attempting to find a good recipe to reproduce a target color. In this article a color‐matching system based on the theoretica…
Extremely thin titanium nitride (TiN) barrier layers for Cu based interconnects were deposited using metal organic chemical vapor deposition. The effect of the subsequently performed nitrogen/hydrogen plasma treatment on the microstructure, composition, and electrical properties of these films is studied using convent…
Fractal growth of nanofiber networks from a small-molecule organic gel has been identified and measured in situ for the first time by a new rheological method. The unique nucleation and growth mechanism promises the manipulation of the fractal structure and rheological properties of functional supramolecular materials…