Materials Literature
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The dielectric behavior and the main features of the diffuse phase transition of nondoped and rare earth (La, Nd, or Gd) doped Sr0.61Ba0.39Nb2O6 relaxor ferroelectric ceramics were carefully investigated. The dopant incorporation gives rise to one continuous decrease of the temperatures of maximum dielectric permittiv…
The correspondence between the Stokes and anti-Stokes Raman D band of graphitic materials in general, and bundles of single-wall carbon nanotubes (SWCNT's) in particular is investigated using the double resonance theory. The D band of bundles of SWCNT's is determined by the Van Hove singularity enhanced double-resonan…
The effects of chemical, plasma, and reactive ion etching (RIE) treatments on the adhesion of Cu and Cr/Cu to the multifunctional polymer were investigated. The adhesion was measured with the newly developed pull test. The polymer surfaces were characterized by the x-ray photoelectron spectroscopy, atomic force micros…
The magnetocaloric effect of a La2/3(Ca,Pb)1/3MnO3 single crystal was examined. From the measurements of isothermal magnetization and heat capacity around the Curie temperature, we have calculated the maximum isothermal magnetic entropy change as ∼7.5 J/kg K and the adiabatic temperature changes as ∼5.6 K, near room t…
The thermodynamic interactions in anionically synthesized poly(styrene- block -ferrocenyldimethylsilane) (SF) copolymers were examined using birefringence, small-angle X-ray and neutron scattering (SAXS and SANS). We show that birefringence detection of the order−disorder transition is possible in colored samples prov…
Abstract Two unsymmetrical and kink non‐coplanar heterocyclic diamines, 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)phenyl](2 H )phthalazin‐1‐one and 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐3,5‐dimethylphenyl](2 H ) phthalazin‐1‐one, were successfully synthesized by readily available heterocyclic bi…
Unusual copolymers were prepared by Candida antarctica Lipase B (Novozyme-435) catalyzed copolymerization of ω-pentadecalactone (PDL) with trimethylene carbonate (TMC). Atypical solid-state properties were revealed by thermogravimetric analysis, differential scanning calorimetry (DSC), and X-ray diffraction analyses.…
The polycondensation of 1a in the presence of 2 as an initiator and 18-crown-6 proceeded in a chain-polymerization manner in sulfolane at 120 °C to yield poly(ether sulfone) having defined molecular weights and low polydispersities.
The response of alloys based on the intermetallic compound NiTi to high-strain-rate and shock loading conditions has recently attracted attention. In particular, similarities between it, and other shape memory materials such as the alloy U–6%Nb in the propagation of the plastic wave in Taylor cylinders are of signific…
Dendron rod−coil molecules are a novel supramolecular building block, comprising a dendritic unit, a rodlike unit, and a coil unit ( J. Am. Chem. Soc. 2001, 123, 4105). It was proposed that in solution these molecules assemble into ribbonlike aggregates of high aspect ratio. We report here on the self-assembly of DRC-…
Small-angle neutron scattering (SANS) experiments were conducted on a 25 vol % blend of a poly(ethylene- block -head-to-head propylene) copolymer (PE−PP) in polyisobutylene (PIB). PE/PIB and PE/PP chains are incompatible (the Flory−Huggins interaction parameter χ > 0), while PIB and PP are compatible (χ < 0) at low te…
We study the layer-by-layer assembly and properties of polyelectrolyte multilayers containing anionic and cationic poly(alkoxythiophene) derivatives, poly(3-(3‘-thienyloxy)propanesulfonate) (P3TOPS) and poly(3-(3‘-thienyloxy)propyltriethylammonium) (P3TOPA), together with poly(diallyldimethylammonium chloride) (PDADMA…
We present a pair of nonorthogonal tight-binding (TB) models for germanium within the NRL-TB approach. One uses an ${\mathrm{sp}}^{3}$ basis, and is optimized for total-energy calculations by fitting to the total energy and band structures of several high-symmetry lattice structures. The other uses an ${\mathrm{sp}}^{…
Two asymmetrically substituted porphyrins (5,15-bis(4-nitrophenyl)-10,20-bis(3,4-bis(2-ethylhexyloxy)phenyl)-21 H,23 H -porphine, CAH3; 5,15-bis(4-aminophenyl)-10,20-bis(3,4-bis(2-ethylhexyloxy)phenyl)-21 H,23 H -porphine, CAH4) have been used in this work. Good Langmuir monolayers of these compounds have been prepare…
Water expands upon freezing, has minima in its volume, heat capacity, and isothermal compressibility with temperature, and shows signs of a first-order phase transition when supercooled. We present an analytical molecular theory that can account for these behaviors. It suggests that local network formation and hydroge…
Slow oscillations of the interlayer magnetoresistance observed in the layered organic metal $\ensuremath{\beta}\mathrm{\text{\ensuremath{-}}}(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\mathrm{\text{\ensuremath{-}}}\mathrm{T}\mathrm{T}\mathrm{F}{)}_{2}{\mathrm{I}\mathrm{B}\mathrm{r}}_{2}$ are shown to originate from the…
It is argued that the vacancy–oxygen (VO) complex (A center) in Ge has three charge states: double negative, single negative, and neutral. Corresponding energy levels are located at Ec−0.21 eV (VO−−/−) and Ev+0.27 eV (VO−/0). An absorption line at 716 cm−1 has been assigned to the asymmetrical stretching vibration mod…
BaMgAl 10 O 17 : Eu 2+ (BAM) phosphors used for plasma display panels (PDP) are compelled to be exposed to an oxidizing environment at about 500 °C, which is currently unavoidable in the actual manufacturing process of PDP. We investigated the mechanism of the luminance degradation of BAM caused by the annealing at 50…
Polydispersity is believed to have important effects on the formation of liquid crystal phases in suspensions of rodlike particles. To understand such effects, we analyze the phase behavior of thin hard rods with length polydispersity. Our treatment is based on a simplified Onsager theory, obtained by truncating the s…
Microstructural features evolving in crystalline solids from diffusion-reaction kinetics of mobile components depend crucially on the dimension of the underlying diffusion process which is commonly assumed to be three-dimensional (3D). In metals, irradiation-induced displacement cascades produce clusters of self-inter…