Materials Literature
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We report on the development of conductive polymer-based cladding layers for use in multilayered electro-optic (EO) device structures. The waveguide claddings used in these studies were based on blends formed from the conductive polymer poly (ethylene dioxythiophene) with poly (vinylalcohol). Thin films of the blended…
Porous silicon (PS) with strong and nondegrading photoluminescence (PL) is prepared by iron-passivating hydrothermal etching. The PL peak intensity of freshly as-prepared PS is as ∼2 times strong as that of conventionally anodized PS. This peak intensity reaches a saturation after the samples are annealed at 120 °C fo…
The longitudinal magnetoresistance (LMR) of thin films of the putative half-metallic ferromagnet CrO2 deposited by chemical vapor deposition onto TiO2/Si(111) substrates has been measured in the temperature range 0.55 K<T<4.2 K in magnetic fields up to 7 T. The dependence of the LMR on small changes in t…
Experimental studies on the morphology and thermal and electrooptical behavior of PDLC films consisting droplets of nematic LC (6CB) up to a 40% weight fraction in a polyester resin matrix crosslinked by diacrylane are presented. The PDLC samples were prepared by LC separation from a solution in a UV-polymerizing olig…
It was shown that the uniaxial compressive stress applied perpendicular to the electric field strongly changes the dielectric and electromechanical properties of relaxor ferroelectric 0.9PMN:0.1PT at temperatures around its dielectric constant maximum, Tm. This includes: (i) a shift of the temperature of the electric…
The vitrification line for the ternary system of polysulfone (PSf)/N-methyl-2-pyrrolidinone (NMP)/water was determined by differential scanning calorimeter (DSC) measurements with varying compositions. Pure PSf showed both α- and β-transition temperatures (Tg,α = 187.5°C, Tg,β = −21.4°C). The Tg,α of PSf decreased wit…
Poly(butylene terephthalate) (PBT) crystallization behavior is modified by blending it with acrylonitrile-butadiene-styrene copolymers (ABS). The effects of ABS on melting and crystallization of PBT/ABS blends have been examined. Most ABS copolymers of different rubber content and styrene/acrylonitrile ratios studied…
We have studied growth condition dependence of magnetic and transport properties of magnetic semiconductor (GaMn)As grown by low-temperature molecular-beam epitaxy (LT-MBE). With increasing substrate temperature and decreasing As overpressure during the growth of (Ga1−xMnx)As with x=0.043, the hole concentration incre…
In this work, the compatibility of blends of plasticized poly(vinyl chloride) (p-PVC) and thermoplastic polyurethane (TPU) was investigated using a dynamic mechanical analyzer and scanning electron microscopy. Two kinds of TPU with different ratios of hard to soft segments, i.e., TPU90 and TPU70 were compared. p-PVC/T…
Several dialkyl and fluoro bis-tolane liquid crystals were synthesized and their physical properties evaluated. These highly conjugated liquid crystals exhibit a wide nematic range, small heat fusion enthalpy, high birefringence, and relatively low viscosity. Their excellent compatibility with commercial cyano mixture…
We show that for itinerant $3d$ transition metal systems the magnetocrystalline anisotropy energy is directly related to the anisotropic part of the spin-orbit interaction, rather than to the orbital part of the magnetic moment as was previously suggested. We further show how the spin-orbit anisotropy can be obtained…
We study vicinal crystal surfaces within the terrace-step-kink model on a discrete lattice. Including both a short-ranged attractive interaction and a long-ranged repulsive interaction arising from elastic forces, we discover a series of phases in which steps coalesce into bunches of $n_b$ steps each. The value of $n_…
Many studies have confirmed that cracks in brittle materials branch when the crack speed exceeds a certain threshold velocity, but the value of that threshold is not understood. Almost all theoretical calculations overestimate the threshold by factors of two or more. We show that thermal noise can reduce the threshold…
$\mathrm{NH}\ensuremath{\cdots}\mathrm{N}$ hydrogen bonded crystals of $[{\mathrm{C}}_{6}{\mathrm{H}}_{7}{\mathrm{N}}_{2}{]}^{+}\ifmmode \dot{}\else \.{}\fi{}{\mathrm{ClO}}_{4}^{\phantom{\rule{0ex}{0ex}}\ensuremath{-}}$ and $[{\mathrm{C}}_{6}{\mathrm{H}}_{7}{\mathrm{N}}_{2}{]}^{+}\ifmmode \dot{}\else \.{}\fi{}{\mathrm…
A series of titanium aluminophosphate molecular sieves with four different structure types including TAPO-5 (AFI topology), TAPO-11 (AEL topology), TAPO-31 (ATO topology), and TAPO-36 (ATS topology) have been studied to determine the titanium location in the aluminophosphate framework. Some Ti(IV) was reduced to param…
λ-(BETS) 2 GaBr x Cl 4 - x [BETS = bis(ethylenedithio)tetraselenafulvalene; 0 ≤ x ≤ 2] is a molecular superconductor with strongly correlated conduction electrons. The electrical transport properties of λ-(BETS) 2 GaBr x Cl 4 - x are drastically changed by varying the bromine content x or by applying pressure. At ambi…
The first study on the growth process of an array comprising colloidal semiconductor nanoparticles (quantum dots) is presented. Two types of particles, CdS and CdSe/CdS (core/shell), suspended in pyridine and water, respectively, have been used. A liquid drop containing the particles is placed on a solid substrate, an…
Polyphosphazene single-substituent polymers were synthesized with the general formula [NP(OCH 2 CH 2 OCH 2 CH 2 XCH 3 ) 2 ] where X = oxygen for polymer 5 or X = sulfur for polymer 6 . Characterization of these materials made use of 1 H, 13 C, 15 N, and 31 P nuclear magnetic resonance (NMR) spectroscopy, differential…
This paper describes the partial discharge (PD) characteristics and V-t characteristics of several insulating materials, such as liquid crystal polymer, epoxy resins, polyimide, and polyethylene-terephthalate (PET) with a needle-plane electrode system at elevated temperature. The life index n for an applied electric f…
The results of the structural determination of barium calcium tetragallium octaoxide, BaCaGa 4 O 8 , from X-ray (Cu Kα) powder diffraction data and refinement by the Rietveld technique are presented. In BaCaGa 4 O 8 , GaO 4 tetrahedra are arranged in a tridymite-like framework. The arrangement of GaO 4 tetrahedra has…