Materials Literature
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We describe a defect in pentacene single crystals that is created by bias stress and persists at room temperature for an hour in the dark but only seconds with 420nm illumination. The defect gives rise to a hole trap at Ev + 0.38eV and causes metastable transport effects at room temperature. Creation and decay rates o…
Optical orientation in the strained semiconductor superlattices is investigated theoretically. The dependence of the features in spin-polarization spectra on the structure parameters is clarified. The value of polarization in the first polarization maximum in the SL structures is shown to grow with the splitting betwe…
We show that optical and electrical measurements on pentacene single crystals can be used to extract the density of states in the HOMO-LUMO bandgap. It is found that these highly purified crystals possess band tails broader than those typically observed in inorganic amorphous solids. Results on field effect transistor…
We present here an efficient method which systematically reduces the rank of the augmented space and thereby helps to implement augmented space recursion for any real calculation. Our method is based on the symmetry of the Hamiltonian in the augmented space and keeping recursion basis vectors in the irreducible subspa…
We have investigated electronic structures and magnetic properties of ZnO-based potential diluted magnetic semiconductors codoped with transition metals: ${\mathrm{Zn}}_{1\ensuremath{-}x}(\mathrm{FeCo}{)}_{x}\mathrm{O}$ and ${\mathrm{Zn}}_{1\ensuremath{-}x}(\mathrm{FeCu}{)}_{x}\mathrm{O}.$ We have found that the origi…
We combine ab initio, tight-binding methods and analytical theory to study piezoelectric effect of boron nitride nanotubes. We find that piezoelectricity of a heteropolar nanotube depends on its chirality and diameter and can be understood starting from the piezoelectric response of an isolated planar sheet, along wit…
This paper reports a novel preparation of highly ordered monolithic super-microporous lamellar silica with a series of ionic liquids (ILs), 1-alkyl-3-methylimidazolium chloride, as templates via a nanocasting technique. The results show that the silica walls of the formed ordered, super-microporous, lamellar mesostruc…
We report the first successful synthesis and characterization of single-crystal wurtzite CdSe nanoribbons through a simple thermal evaporation process. Asymmetric growth of the nanoribbons occurs, yielding a sawlike shape with sharp teeth on one side. This asymmetric growth is suggested to be induced by the polarizati…
Multiple scattering of light in colloidal suspensions can be suppressed by suspending the particles in a liquid with matching refractive index. We minimize the multiple scattering of light in charged silica suspensions by dispersing them in a mixed solvent of ethylene glycol/water (EGW). We report here the static and…
The detonation of carbon- or nitrogen-containing explosives not only produces powerful shock waves but also provides elemental building blocks and a unique high-pressure and high-temperature physical environment for the construction of various nanostructures. This review highlights the situation and key progresses in…
Four new pregnane glycosides, named marstenacissides A (1), B (2), C (3), and D (4), have been isolated from the stems of Marsdenia tenacissima. Their structures were established on the basis of chemical and spectral methods.
We study a model of carbon nanotube with a half filled conduction band. At this filling the system is a Mott insulator. The Coulomb interaction is assumed to be unscreened. It is shown that this allows to develop the adiabatic approximation which leads to considerable simplifications in calculations of the excitation…
For NiTi shape memory alloys, powder metallurgical (PM) processes are pioneering production routes. One promising route for the PM fabrication of NiTi compacts is Hot Isostatic Pressing (HIP). For the present investigation, cost‐effective elemental powder mixtures as well as high‐purity prealloyed NiTi powders were us…
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Despite of their successes, the results of first-principles quantum mechanical calculations contain inherent numerical errors that are caused by inadequate treatment of electron correlation, incompleteness of basis sets, relativistic effects or approximated exchange-correlation functionals. In this work, we develop a…
Materials exhibiting gas permeable porosity are of particular interest for a number of functional applications. Here, the authors show a new nanoporous superalloy membrane, far surpassing existing gas permeable porous metals in fineness and regularity of the porosity. This may not only open the path for new medical ap…
Simulations of nanocrystalline materials reveal that the pressure gradient present within the structure can play a key role in the movement of self-interstitial atoms (SIA's) to surrounding grain boundaries and therefore in the resulting defect structure formed during displacement cascades. Initially SIA's sense the g…
Here, we introduce the synthesis, characterization, and surface orientation properties of a new generation of biodegradable and biomimetic polymers. These phospholipid-mimetic, biodegradable polymers are synthesized by combining poly ε-caprolactone (PCL) with various functional polar end-groups, including zwitterionic…
Multiple-walled carbon nanotubes (MWNTs) were chemically modified by a ligand-exchange reaction of ferrocene (Cp-Fe-Cp). The modified MWNTs (Cp-Fe-MWNTs) were next monolithiated by tert -butyllithium and terminated by p -chloromethylstyrene ( p MS). The p MS - terminated species ( p MS-Cp-Fe-MWNTs) were then functiona…
Scanning tunneling microscopy studies of vanadium oxides grown on Pd(111) show interesting structures especially in the low-coverage region. Evaporation of V in an oxygen background at elevated sample temperature $(250\ifmmode^\circ\else\textdegree\fi{}\mathrm{C})$ results in the formation of a nonperiodic honeycomb-l…