Materials Literature
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Unambiguous observation of the reorientation of azobenzene chromophores toward the propagation direction of the actinic light has been performed. Prolonged irradiation of a spin-coated film of liquid crystalline poly[6-{4-(4‘-methoxyphenyl)azophenyloxy}hexyl methacrylate] ( C6MeO ) with 436 nm light for n−π* excitatio…
A switchable diffuse reflective film with high color purity is demonstrated using holographic-polymer dispersed liquid crystals (HPDLC). By recording a diffuse hologram directly into the LC/polymer film, the diffuse mode HPDLC exhibit viewing angles an order of magnitude larger than the conventional mode. A simple phe…
Hard and smooth nanocrystalline diamond films are grown on mirror polished silicon substrates by biased enhanced growth (BEG) in microwave plasma chemical vapor deposition at lower temperatures. Hardness of the films varies with deposition condition and can be defined by the relative concentration of nanocrystalline d…
Magnetic second-harmonic generation is used for imaging of the orientation of the spins in antiferromagnetic ScMnO3 and HoMnO3 with 10 μm resolution and an accuracy of about 1°. This allows the observation of sample inhomogeneities and the coexistence of magnetic phases. The method is based on simple geometric argumen…
Based on experiments of both transport and paramagnetic resonance for (La1−xYx)2/3Ca1/3MnO3, the ground state above Tc and possible origins of both insulator–metal transition and colossal magnetoresistance near Tc are discussed. Modeling the system as a network of junctions, each consisting of a paramagnetic region sa…
A series of BaTiO3−x (x=0, 0.07, 0.18, and 0.48) thin films with c-axis oriented tetragonal perovskite structures were epitaxially grown on SrTiO3 (100) and MgO (100) substrates by laser molecular-beam epitaxy under various oxygen pressures. The electrical conductivity of the deposited thin films increases with decrea…
We measured the temperature dependence of the interfacial tension between free melt and end-grafted chemically identical polymers. The excess interfacial entropy (Delta S(MB)) was found to be extremely small and negative. This is in sharp contrast to the case of liquid surfaces and interfaces between different liquids…
Submicron thick ferroelectric AgTa0.38Nb0.62O3 (ATN) films have been prepared by pulsed laser deposition technique onto Pt80Ir20 polycrystalline and La0.7Sr0.3CoO3/LaAlO3 single crystal substrates. ATN/Pt80Ir20 films have been found to be (001) preferentially oriented, while the epitaxial quality of ATN/La0.7Sr0.3CoO3…
The optical response of Au/SiO2 nanocomposite films at temperatures spanning the transition to the liquid state has been measured. The change in the optical constants of gold from those corresponding to the crystalline material to those of the liquid occurs gradually and at temperatures below the bulk melting point. T…
The Preisach approach is applied to model ferroelectric pinched (or constricted) loops. Starting from the existence of distributed switchable dipolar defects in the material and a corresponding distribution function, an analytical expression for the resulting ferroelectric loop is obtained. The corresponding hysteresi…
Recently, a new class of reversible electrochemical energy storage systems have been developed that use: (a) the capacitance associated with charging and discharging of the electrical doublelayer at the electrode–electrolyte interface and are hence called electrical double-layer capacitors (EDLCs), and (b) the pseudoc…
A molecular dynamics simulation study of hydrogen bonding in poly(ethylene oxide) (PEO)/water solutions was performed. PEO-water and water-water hydrogen bonding manifested complex dependence on both composition and temperature. Strong water clustering in concentrated solutions was seen. Saturation of hydrogen bonding…
The mechanism of ultraviolet stimulated emission was investigated in ZnO/ZnMgO multiquantum wells. Stimulated emission induced by exciton–exciton scattering occurred throughout a range of temperatures from 5 K to room temperature. At temperatures higher than 160 K, stimulated emission due to electron-hole plasma recom…
We have designed and batch-fabricated thin-film thermocouple cantilever probes for scanning thermal microscopy (SThM). Here, we report the use of these probes for imaging the phonon temperature distribution of electrically heated carbon-nanotube (CN) circuits. The SThM images reveal possible heat dissipation mechanism…
A random walk model in a one dimensional disordered medium with an oscillatory input current is presented as a generic model of boundary perturbation methods to investigate properties of a transport process in a disordered medium. It is rigorously shown that an admittance which is equal to the Fourier-Laplace transfor…
We report the synthesis of porphyrazines (pzs), or tetraazaporphyrins, of the form H2[pz(An;B4-n)], where A is [S(CH2)3COOR]2 (R = n-Pr,H) and B is a fused beta,beta'-diisopropyloxybenzo group, including the compounds with n = 4 (6), n = 3 (7) and the trans compound with n = 2 (8) (Scheme 1). The synthesis employs Lin…
Highly conductive new aniline copolymers containing butylthio substituent have been first prepared from unsubstituted polyaniline, utilizing a concurrent reduction and substitution reaction performed in the solid-state matrix of polyaniline. The resultant copolymer film after one reaction treatment cycle was found to…
Here we describe the detection of live Pseudomonas aeruginosa using a sensing film containing a fourth-generation hydroxy-terminated polyamidoamine (PAMAM) dendrimer (i.e., G4-OH) and SYTOX Green fluorescent nucleic acid stain. The films are configured on simple, disposable plastic coupons or optical fibers and are in…
A hybrid density functional theory method previously developed for heterogeneous silica surfaces has been used to calculate model isotherms over a wide range of pore widths for the adsorption of nitrogen at 77 K within cylindrical pores having a clay-like surface. Using these models and the experimental isotherm data,…
Carbon black (CB) filled polymers display mechanical and electrical properties that depend not only on the volume fraction φ of the filler particles but also on their structure and on their distribution. Recently it has been shown that ultra-small-angle X-ray scattering measurements (USAXS) yield information on the ar…