Materials Literature
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We use classical molecular dynamics simulations to study the motion of sodium atoms in amorphous Na 2 O – 4SiO 2 over a wide range of temperatures below and above the glass transition temperature T g . We find that the region of space most visited by the sodium atoms forms a network of connected pockets that we call c…
We report on the photo-response behavior of n-ZnO/p-Si photodiodes. Semiconducting n-ZnO films have been deposited on p-Si substrate by RF sputtering at 300, 480 and 550°C. An optimum static photo-response was achieved from the photodiode prepared at 480°C as characterized by photocurrent measurements using a continuo…
A decrease in tilt angle generation for a nematic liquid crystal (NLC) with negative dielectric anisotropy on a blended homeotropic polyimide (PI) surface containing trifluoromethyl moieties was investigated. The decrease in tilt angle (below 90°) of NLC on the blended PI surface containing a homogeneous PI structure…
A different class of layered systems derived from ${\mathrm{ThCr}}_{2}{\mathrm{Si}}_{2}$-type materials is introduced and studied. We present preparation, x-ray analysis, band-structure, and total-energy calculations of ${\mathrm{KCu}}_{2}{\mathrm{Se}}_{2},$ a semimetallic representative of this class. The crystal has…
Inductively coupled plasma chemical vapor deposition combined with substrate biasing using pure methane was applied to low-temperature synthesis of carbon nanotubes. We found that the resultant carbon nanotubes were crystalline even at a growth temperature of 500°C. The growth mechanism of the crystallized carbon nano…
The conductivity dispersion in several alkali phosphate glasses is examined as the glass structure changes from an interconnected 'mesh' network to one of phosphate chains cross-linked by alkali ions. For metaphosphate glasses the dispersion varies in response to the size of the mobile ion relative to the mean spacing…
This study examined the solid-state structure and oxygen transport properties of smectic poly(diethylene glycol 4,4‘-bibenzoate) (PDEGBB). The polymer was quenched from the isotropic melt to the smectic liquid crystalline glass and subsequently isothermally crystallized by heating above the glass transition temperatur…
A single crystal of perovskite bilayer manganite La 1.2 Sr 1.8 Mn 2 O 7 has been studied by the 55 Mn NMR technique. The observed spectra at 4.2 K in zero external magnetic field are broad and spread in the frequency range 310–480 MHz. The shape of the spectrum depends strongly on the rf radiation field for exciting a…
Abstract The porosity‐dependent Young's modulus for PEEK membranes was determined and the data compared to several empirical and semiempirical equations often applied to porous systems. The Spriggs equation, Wang's approximation, Sudduth's equation, and the foam modulus‐density relationship were all tested against the…
The HH and HV Raman spectra of vitreous silica are calculated from first principles for a model structure consisting of a disordered network of corner-sharing tetrahedra, for which the vibrational properties were obtained previously. We analyse the contribution of specific atomic motions to the Raman spectra and perfo…
The effect of synchrotron radiation (SR) irradiation of a polytetrafluoroethylene (PTFE) surface was investigated using X-ray photoelectron spectroscopy (XPS). After the SR irradiation, the relative intensity of the F 1 s peak to the C 1 s peak decreased markedly. The chemical composition ratio of the F atoms to C ato…
Selective H/D kinetic isotope effects (KIEs) have been determined for the various routes by which • OH radicals react with ethanol (CH 3 CH 2 OH and CD 3 CD 2 OH) and methylamine (CH 3 NH 2 and CD 3 NH 2 ) in H 2 O solutions. The KIEs have been evaluated from overall rate constants and the yields in which the individu…
Copolymers containing nonhomopolymerizable γ-butyrolactone (BL) and ε-caprolactone (CL) units of different compositions were synthesized by the ring-opening polymerization method using the SmI 2 /Sm initiator system. A maximum of 33 mol % of BL was incorporated into polycaprolactone (PCL) backbone. The microstructure…
The paper presents the results of measurements of the linear dielectric properties of the compounds from the homologous series of alkylcyanobiphenyls (C(n)H(2n+1)PhPhCN, nCB) in the vicinity of the first order transition (from the isotropic liquid to the crystalline phase) of nonmesogenic nCB's (n=2-4) and the weakly…
Temperature modulated differential scanning calorimetry measurements on Ag y (Ge x Se 1− x ) 1− y glasses provide evidence for bimodal glass transition temperatures in Se-rich glasses ( x < 1/3). At x = 0.20 and 0.25, thermal measurements performed as a function of Ag content in the 0 ≤ y ≤ 0.25 range reveal that the…
Using photoluminescence and Raman scattering, we have studied the optical properties of Mn-doped ZnS nanocrystallites prepared by a microemulsion-hydrothermal method. The PL spectrum shows two distinct peaks in the blue-green region. The PL peak from the nanoparticles, in the region 400–480 nm (3.1–2.6 eV), shifts tow…
Vibrational properties of Ba doped Si clathrate are investigated at high pressures up to 20 GPa by Raman spectroscopy. Vibrations related with Ba encaged in the Si cages are observed below $100\text{ }\text{ }{\mathrm{c}\mathrm{m}}^{\ensuremath{-}1}$ by low-frequency Raman measurements of ${\mathrm{B}\mathrm{a}}_{8}{\…
We report on the nature of photothermally patterned regions inside self-assembled hydrogel nanoparticle materials containing coassembled colloidal Au. These composite materials are prepared from approximately 226-nm diameter particles composed of the environmentally responsive polymer, poly(N-isopropylacrylamide) (pNI…
This paper presents a unified theoretical picture of quasi-two-dimensional organic conductors in a new minimal model based on an anisotropic triangular lattice. These materials exhibit abundance of low-temperature physics, where the systematic understanding was lagging behind respective studies. This is ascribed to a…
The concept of matrix-mediated coupling assumes that coupling between movements of unlike cations in glass occurs in order to dissipate mechanical stresses created by small cations entering sites which are too large (e.g. Li+ ions entering empty sodium, ā, sites) and large cations entering sites which are too small (e…