Materials Literature
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The dielectric properties of semicrystalline nylon 11 (mixture of γ and α phase, degree of crystallinity 62%) were investigated in wide ranges of frequency and temperature by broadband dielectric relaxation spectroscopy, thermally stimulated depolarization current techniques and triangular voltage measurements. The ma…
In order to investigate the origin of the often invoked nanoheterogeneities in miscible polymer blends, we have performed quasielastic neutron scattering experiments on the component dynamics within the miscible polymer blend polyisoprene/polyvinyl ether including the pure components as a reference. We find that the a…
We have investigated the optical and structural properties of high-quality ZnO films grown on epitaxial GaN (epi-GaN) by plasma-assisted molecular-beam epitaxy employing low-temperature buffer layers. High-resolution x-ray diffraction for both symmetric and asymmetric reflexes shows that crystalline defects in ZnO fil…
Electroluminescence (EL) studies of AlN:Er alternating-current thin-film electroluminescent (ACTFEL) devices were performed at 300 K. Thin films of Er-doped AlN, ∼200 nm thick, were grown on indium–tin–oxide/aluminum–titanium–oxide/glass substrates using rf magnetron sputtering in a nitrogen atmosphere. The turn-on vo…
A new mechanism for electron emission from planar cathodes is described. The theoretical analysis shows that, with an ultrathin wide band-gap semiconductor layer (UTSC) on a metal, the surface barrier is lowered to approximately 0.1 eV due to the creation of a space charge induced by the electrons injected from the me…
We have investigated the alignment properties of liquid crystals induced by multiple rubbing of the surfaces in different directions. Experiments were carried out using homeotropic and hybrid-aligned samples. It is experimentally found that the alignment of the liquid crystals is along neither of the rubbing direction…
A capacitance-type humidity sensor in which a porous silicon layer is used as a humidity-sensing material was developed. This sensor was fabricated monolithically to be compatible with the typical IC process technology except for the formation of porous silicon layer. As the sensor is made as a mesa structure, the cor…
Frequency upconversion of Er3+ in alkali bismuth gallate glasses have been investigated. The upconversion mechanisms are discussed, and the dominant mechanisms are excited state absorption for the H11/22→I15/24 and S3/24→I15/24 transitions, and energy transfer upconversion for the F9/24→I15/24 transition. Intense gree…
Brittle fracture usually proceeds at crack driving forces which are larger than those needed to create the new fracture surfaces. This surplus can lead to faster crack propagation or to the onset of additional dissipation mechanisms. Dynamic fracture experiments on silicon single crystals reported here show several di…
We investigate the vibration dynamics of ellipsoidal silver nanoparticles, using time-resolved optical pump-probe spectroscopy. When excited with femtosecond laser pulses, the particles execute anisotropic shape oscillations. We show that these vibrations are triggered by the thermal expansion of the optically heated…
The transient network model of Green-Tobolsky [1946], Yamamoto [1956] and Tanaka-Edwards [1992] is formulated within the frame of thermodynamics of irreversible processes, using as a fundamental quantity the chemical potential associated to the connection of strands to the network and treating these connections as che…
We derive a stochastic nonlinear continuum theory to describe the morphological evolution of amorphous surfaces eroded by ion bombardment. Starting from Sigmund's theory of sputter erosion, we calculate the coefficients appearing in the continuum equation in terms of the physical parameters characterizing the sputteri…
A sensitive tunnel diode oscillator (TDO) operating at 4MHz is used to probe the dynamic response of La_{1-x}Sr_{x}MnO_{3} single crystals for x=0.125,0.175,0.28 and 0.33 doping. Systematics of the measured change in reactance as a function of temperature (30K
The increasing information density in magnetic recording, the miniaturization in magnetic sensor technology, the trend towards nanocrystalline magnetic materials and the improved availability of large-scale computer power are the main reasons why micromagnetic modelling has been developing extremely rapidly. Computati…
"Tissue engineering" uses implanted cells, scaffolds, DNA, protein, and/or protein fragments to replace or repair injured or diseased tissues and organs. Despite its early success, tissue engineers have faced challenges in repairing or replacing tissues that serve a predominantly biomechanical function. An evolving di…
We demonstrate a novel method for measuring the microrheology of soft viscoelastic media, based on cross correlating the thermal motion of pairs of embedded tracer particles. The method does not depend on the exact nature of the coupling between the tracers and the medium, and yields accurate rheological data for high…
Simple, reactive amphiphilic molecules were prepared by condensation of perfluorooctylethyl alcohol with elaidic, oleic, and linoleic acids. The fluorinated, unsaturated esters were found to be surface active in polyester and urethane-modified alkyd coatings. In addition, they function much like typical drying oils us…
Microcontact printing is used to transfer an Fe(III)-containing gel-like catalyst precursor from a hydrophilized elastomeric stamp to a substrate. The catalytic pattern activates the growth of multiwall carbon nanotubes using chemical vapor deposition of acetylene. Our results show that the choice of the catalyst is o…
Fully relativistic density-functional calculations have been performed for group 7 oxychlorides MO3Cl, where M=Tc, Re, and element 107, Bh. The results have shown the Bh compound to be thermochemically stable and the most stable towards reduction. Due to increasing dipole moments and electric dipole polarizabilities i…
In this paper, we report the hydrolysis of Co 2+ ions absorbed in organized, multilayered polymer films to form cobalt hydroxide nanocrystals. Polymer films were prepared using the layer-by-layer deposition technique that consists of adsorbing polycations and polyanions alternately on a quartz substrate. By monitoring…