Materials Literature
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We show experimentally that a layer of silicon nanocrystals, prepared by the Si-ion implantation (with the energy of 400 keV) into a synthetic silica slab and exhibiting room-temperature red photoluminescence, can serve simultaneously as a single-mode planar optical waveguide. The waveguide is shown to self-select gui…
I consider a brush of gradient polymers, with the chains anchored at their pure A ends with the chemical composition changing linearly along the chain up to the untethered chain tips whose composition is pure B. Demixing of the A and B monomers results in the creation of a thermally-controllable zone from which free e…
The relaxation dynamics of a rubbed polystyrene (PS) surface have been characterized using infrared-visible sum frequency generation spectroscopy (SFG). The SFG results were compared with previous relaxation of retardation measurements, and the results show that the rubbed PS surface has the same T(g) as the bulk wher…
Primary nucleation of poly(vinylidene fluoride) (pVDF) from bulk entangled amorphous polymer melts has been observed from molecular dynamics (MD) simulations. This is the first instance of spontaneous primary nucleation of an entangled bulk polymer in a MD simulation. The melt-to-crystal phase transition occurs via a…
Poly(L-lactic acid) samples of varying regio regularity were studied by static and dynamic laser light scattering in conjunction with Raman spectroscopy. Light scattering results allow an estimate of the characteristic ratio, C∞. Experimental values were compared to the characteristic ratio computed from structural pa…
We report Monte Carlo simulations of the melting of a single-polymer crystallite. We find that, unlike most atomic and molecular crystals, such crystallites can be heated appreciably above their melting temperature before they transform to the disordered “coil” state. The surface of the superheated crystallite is foun…
Blazed gratings have been fabricated using gray-scale X-ray lithography. The gratings have high efficiency, low parasitic light, and high groove quality. The fabrication technique and resist characterization are described. The gratings can be generated over a considerable range of distances from the X-ray mask, thus d…
Highly-ordered GaAs/AlGaAs quantum-dot arrays (QDA) were grown by molecular-beam epitaxy on GaAs (001) using masks of anodic nanochannel alumina (NCA). The QDA replicated the hexagonal lattice pattern of the NCA masks with period spacing of 100 nm. The circular disk-like dots were defined by the nanohole channels of N…
One of the long-standing problems to improve the resolution of organic electroluminescence devices has been related to the fabrication of very smooth, high-quality indium tin oxide (ITO) layers at room temperature. It seems that this problem could be solved by low-energy oxygen-ion-beam assisted electron-beam evaporat…
The structural (α-) relaxation in diglycidylether of bisphenol A (DGEBA) has been examined using three spectroscopic methods: dielectric spectroscopy (DS), dynamic light scattering–photon correlation spectroscopy (LS), and mechanical spectroscopy. The DS and LS measurements were carried out as a function of both tempe…
Through the analysis of the magnetic properties and of the nuclear magnetic resonance response of La2/3Ca1/3MnO3 ceramics with different grain sizes, we have found that poorly conducting regions, some ferromagnetic and some weakly magnetic, are located at the surface of the grains. We state that these regions constitu…
Diamond is a material which displays exceptional electronic, thermal, tribological, elastic and acoustic properties. These exceptional properties make diamond extremely difficult to characterize. In particular, diamond displays the highest acoustic velocities of any material making it an ideal candidate for acoustic w…
The highly conductive surface layer induced in diamond by hydrogen termination has been used to fabricate in-plane gate transistors. The conductive channel has been separated from the Ohmic gate contacts by insulating thin lines, obtained by using a combination of electron-beam lithography with surface oxidation. Oxid…
YAl 3 (BO 3 ) 4 crystals doped with Dy 3+ were grown from a potassium trimolybdate flux. Their absorption and visible emission spectra and decay curves were measured at temperatures ranging from 10 to 298 K. The complete energy level scheme has been deduced from the low temperature measurements and reproduced by theor…
Nearly any diamond electronic or sensor device needs at least one ohmic contact. These contacts play a key role in the overall device performance. This paper reviews the dependence of the Schottky barrier height on the surface termination and the impact of annealing of carbide-forming metals on the specific contact re…
Over the past few years a variety of diamond electron devices have been fabricated, analysed and simulated. This includes Schottky diodes on boron-doped p + diamond substrates, boron/nitrogen pn-junction diodes, bipolar transistors based on this pn-junction and field effect transistors (FETs) with boron delta-doped ch…
Material synthesis using unilamellar liposomes with a high sol-gel temperature transition phase as a template leads to a new silica material.
Glassy, supercooled, and molten ZnCl2 and ZnBr2 have been studied by Raman spectroscopy over the broad temperature range −196 to 800 °C in an effort to follow in detail the structural changes caused by temperature variation. A systematic study has also been undertaken for the corresponding crystalline polymorphs showi…
The phase behavior and concentration fluctuations in suspensions of hard sphere colloids and nonadsorbing polymers under nearly ideal solvent conditions is studied experimentally. A remarkably different qualitative behavior compared to the athermal solvent case is observed for the dependence on polymer/particle size a…
In-situ Atomic Resolution Transmission Electron Microscopy studies carried out on a Rh/Ce0.8Pr0.2O(2-x) catalyst, under hydrogen in the temperature range 298-1223 K, show the occurrence of consecutive reduction of Pr4+ and Ce4+ ions, and the formation of an oxygen-deficient Ln16O30 (Ln: Ce, Pr) ordered phase.