Materials Literature
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The results of a recent neutron diffraction experiment on water confined in Vycor glass, reported in the preceding paper [F. Bruni, M. A. Ricci, and A. K. Soper, J. Chem. Phys. 109, 1478 (1998)], are analyzed by attempting to correct for the distortions brought into the site–site radial distribution functions by the p…
The synthesis of zirconium oxide with a mesostructured framework (Zr-TMS) has been achieved through the use of amphiphilic compounds with a variety of headgroups (anionic and nonionic) and tail group chain lengths (1−18 carbons). Anionic surfactants with phosphate, carboxylate, sulfate, and sulfonate headgroups led to…
Polarized laser Raman microscopy was employed in order to investigate the effects of side chain length on the orientability of uniaxially drawn films of a model hairy-rod polymer, as a function of draw ratio; an aromatic polyester containing terphenyl units in the main chain and aliphatic side chains (hexyl and dodecy…
We examined polymer conformations at a strongly adsorbing solid surface and their evolution with elapsed time during the adsorption process. Poly(dimethylsiloxane) (PDMS: M w = 118 000; M w / M n = 1.16) was allowed to adsorb onto oxidized germanium from dilute carbon tetrachloride solutions. The mean backbone orienta…
The properties of elastomeric polypropylene synthesized from an unbridged metallocene catalyst are investigated by mechanical rheometry, differential scanning calorimetry, and optical depolarization. The material is compositionally heterogeneous in tacticity, and its behavior is compared to that of its solvent fractio…
Free-standing polyaniline films are studied as pervaporation membranes for separating carboxylic acid/water mixtures. Changing polyaniline membranes from an undoped to a fully doped state has a dramatic effect on their selectivity. For example, with a 52 wt % acetic acid/48 wt % water feed, the undoped, base form of p…
Contrast in MRI relies on differences in the local environment of water and is often enhanced by using contrast agents. We present a simple model for evaluating the minimal contrast agent concentration required to produce "satisfactory" contrast enhancement in magnetic resonance images. Previous strategies have been b…
A comparison of the magnetic properties and deformation behaviour of Nd-Fe-B magnets made from melt-spun, mechanically alloyed and HDDR powders , A Kirchner, W Grünberger, O Gutfleisch, V Neu, K-H Müller, L Schultz
Nanostructured materials consist of crystalline and grain boundary components. In the simplest case, both components are chemically identical. Here, we present the results of a study of a system consisting of a crystalline component built by A atoms (tungsten) and a grain boundary component of B atoms (gallium). Withi…
We performed molecular statics calculations of energy barriers for adatom moves in the vicinity of steps on Pt(111) surface. We used the semi-empirical many-body Rosato--Guillope--Legrand potential and we systematically calculated barriers for descent of straight steps, steps with a kink and small islands as well as b…
This paper studies the effect of Ta addition on the martensitic transformation characteristics and the X-ray visibility of NiTi shape memory alloys. It was found that: (1) The transformation temperatures of the Ti<SUB>49</SUB>Ni<SUB>51</SUB> binary alloy increase drastically by an addition of 0 -- 4at%Ta, but only sli…
The irradiation at 514.5 nm of a ferroelectric liquid crystal (FLC) film doped with a photochromic chiral thioindigo dye causes a change in the birefringence of the FLC film under a constant dc voltage. This birefringence photomodulation is used to create electric field controlled dynamic holograms. The diffraction ef…
Properties of piezoelectric ceramics important for actuator applications have been measured as a function of grain size. Fine grain piezoelectrics (≤1 μm) have been found to exhibit improved machinability and increased mechanical strength over conventional materials. Actuators made from fine grain ceramic are, t…
The piezoelectric properties of relaxor based ferroelectric single crystals, such as Pb(Zn<SUB>1/3</SUB>Nb<SUB>2/3</SUB>)O<SUB>3</SUB> - PbTiO<SUB>3</SUB> (PZN-PT) and Pb(Mg<SUB>1/3</SUB>Nb<SUB>2/3</SUB>)O<SUB>3</SUB> - PbTiO<SUB>3</SUB> (PMN- PT) were investigated for electromechanical actuators. In contrast to polyc…
It has been found that reduction of perovskite in vacuum leads to collapse of the ferromagnetic state without changes of cubic symmetry. ( , Tb) oxygen deficit orthorhombic phases undergo phase transitions approximately at temperatures K, K and K. The first order antiferro-ferromagnet transition at is accompanied by a…
Statistical and ergodic properties of a simple model of N hard discs in a circular cavity are investigated by means of analytical considerations and molecular dynamics computer simulations. The model exhibits ergodicity breaking at different densities as well as a kinetic crossover from hydrodynamic relaxation to part…
We report an investigation of the wetting behavior of 5CB drops on silicon wafers. Nematic drops exhibit a characteristic mesoscopic thickness that diverges as the nematic-isotropic transition is approached. This divergence may be associated with the vanishing of the anchoring strength, or equivalently, to a wetting t…
We have proposed the use of RMnO3 (R: rare earth elements) films for metal–ferroelectric–semiconductor field effect transistor (MFSFET)-type ferroelectric random access memories (ferroelectric RAMs). This reports the production of YMnO3 films on Si substrates for MFSFET with confirmation of the distinct ferroelectrici…
The shape of the short light pulses emitted from a single air bubble trapped in a resonant sound field in degassed water has been measured directly for the first time with a streak camera. At low driving pressures the pulse shape is nearly Gaussian with a slightly slower decay. With increasing driving pressure the fal…
Indium–zinc oxide films (ZnxInyOx+1.5y), with x/y=0.08–12.0, are grown by low-pressure metal-organic chemical vapor deposition using the volatile metal–organic precursors In(TMHD)3 and Zn(TMHD)2 (TMHD=2,2,6,6–tetramethyl–3,5–heptanedionato). Films are smooth (rms roughness=40–50 Å) with complex microstructures which v…