Materials Literature
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Six polylactides, polymerized with Salen−Al−OCH 3 initiator and having optical purities between 43% and 100%, were analyzed by differential scanning calorimetry, X-ray diffraction, and optical microscopy, following various crystallization conditions. It was found that each of those polylactides can crystallize, even t…
An ab initio study on three hypothetical nitrogen−oxygen clusters is presented. The investigated systems are N 2 O 3, N 4 O 6, and N 8 O 12 with highly symmetric geometries, D 3 h, T d, and O h symmetry, respectively. Calculations were performed at SCF and MP2 level (MP2, for the two smallest clusters only). Several b…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTLinear Ferrocenylene−Siloxyl−Diacetylene Polymers and Their Conversion to Ceramics with High Thermal and Oxidative StabilitiesEric J. Houser and Teddy M. KellerView Author Information Materials Chemistry Branch, CODE 6127, Chemistry…
Traditionally it was thought that the unidirectional strength in the fiber direction of fiber dominated composites was not influenced by the matrix material. As long as the fiber was not affected then the strength would remain. However this thesis will challange that belief. The unidirectional strength in the fiber di…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTDetermination of Order−Order and Order−Disorder Transition Temperatures of SIS Block Copolymers by Differential Scanning Calorimetry and RheologyJin Kon Kim, Hee Hyun Lee, Qi-Jiang Gu, Taihyun Chang, and Yoon Hee JeongView Author In…
The universal form for the average scattering intensity from systems undergoing order-disorder transitions is found by numerical integration of the Langevin dynamics. The result is nearly identical for simulations involving two different forms of the local contribution to the free energy, supporting the idea that the…
Precise microwave measurements of sample conductivity, dielectric, and magnetic properties are routinely performed with cavity perturbation measurements. These methods require the accurate determination of quality factor and resonant frequency of microwave resonators. Seven different methods to determine the resonant…
We present an ab initio exploration of the phenomena which will become important for freestanding structures of silicon as they are realized on the nanoscale. We find that not only surface but also edge effects are important considerations in structures of dimensions on the order of 3 nm. Specifically, for long nanosc…
Multiresolution analyses based upon interpolets, interpolating scaling functions introduced by Deslauriers and Dubuc, are particularly well-suited to physical applications because they allow exact recovery of the multiresolution representation of a function from its sample values on a finite set of points in space. We…
The lattice instability related to ferroelectric phase transitions of and its family has been studied by Raman scattering in the temperature range between 293 K and 958 K. The lowest optical mode of of at room temperature shows remarkable temperature variation towards . Its mode frequency decreases markedly and the da…
An x-ray photoelectron spectroscopy system with a laser-plasma x-ray source is shown to have energy resolution high enough to observe chemical shifts of Si 2p electrons in SiO2, Si3N4, and pure Si. A boron nitride (BN) plasma x-ray source is produced by irradiation of 100 mJ Q-switched YAG laser pulses. A single line…
A detailed investigation of with a very small radius of the A-site cations reveals the occurrence of a charge-ordering transition in the paramagnetic state, at a relatively high temperature of 260 K. The orthorhombic lattice distortion, as measured by the dimensionless index D , is large over the entire 300-100 K rang…
Thermal stability of fluorinated amorphous carbon (a-C:F) thin films with a low dielectric constant was investigated by electron spin resonance (ESR), infrared (IR) absorption, optical absorption, and x-ray photoelectron spectroscopy (XPS) as well as measurements of film thickness and dielectric constant. IR and XPS m…
A novel processing method is developed for preparing sol-gel derived Pb(Zr1−xTix)O3 (x=0.47) thin films on Pt/Ti/SiO2/Si substrates. Using a modified precursor solution and a rapid heat treatment without pyrolysis, it was possible to obtain highly (111) oriented PZT thin films with high perovskite content at a low ann…
Electrically pumped light emission was observed from a smectic mesophase of liquid-crystalline oxadiazole; 2,5-hexyloxybiphenyl–hexyloxyphenyl–oxadiazole (HOBP-OXD), which exhibits high electron transport capability. The light-emitting diode consisted of the HOBP-OXD film, a copper phthalocyanine vacuum deposited film…
Phosphor thermography, relying on the temperature dependence of the decay time of photoluminescence from suitable phosphors, provides remote measurement of the temperature of components. Such a phosphor is yttrium oxide doped with europium (Y2O3:Eu). Associated with this phosphor is also a rise time. Demonstrated is t…
The pressure and entropy of the face-centred cubic and hexagonal close-packed hard-sphere crystals were measured. At the melting density, the hcp crystal has a higher pressure. A precise equation of state is reported for the crystals. The equation extrapolates to a spinodal instability in the metastable low-density cr…
${}\left(222\right)$ MgO/Cu interfaces produced by internal oxidation are studied by electron energy loss spectroscopy (EELS) using an atomic sized electron beam. We determine interfacial chemistry of this interface with subnanometer spatial resolution and use EELS to measure directly the electronic states pertaining…
${}^{13}\mathrm{C}\ensuremath{-}\mathrm{NMR}$ measurements have been performed to investigate the nature of the insulating state of a quasi-one-dimensional conductor, $(\mathrm{DI}\ensuremath{-}\mathrm{DCNQI}{)}_{2}\mathrm{Ag}$, with a quarter-filled band. The ${4k}_{F}$ charge-density wave has been evidenced below ab…
The size, shape, and polarization orientation of fatigued areas formed during the suppression of the switchable polarization (Prs) (fatigue) in Pt–PZT–Pt ferroelectric capacitors (FECAPs), were observed by means of atomic force microscopy and by imaging the phase of the piezoelectric vibration induced by a low ac fiel…