Materials Literature
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Abstract A series of a segmented copolymer, poly(4,4′‐dioxy‐2,2′‐dimethyl‐azoxybenzene dodecanedioyl)‐ co ‐polyoxyethylene 400 (PMABD‐ co ‐POE) was prepared; the average chain lengths n , of the PMABD studied are 8.1 to 20.6. The thermotropic properties and the mesophase texture of the segmented copolymers were elucid…
Abstract The effects of various catalysts on the reactive blending of poly(ethylene terephthalate) (PET) and bisphenol A polycarbonate (PC) was investigated. The various catalysts employed for PET syntheses, Ti(OBu)4, SmL 3 , EuL 3 , Ca + Sb, CeAc 3 , Er(NO 3 ) 3 ·B 12 C 4 and Tb (acac) 3 ·diPy (where L is o ‐formylph…
Theoretical vibrational spectra of polypyrrole are presented, based on a single-periodic-chain model and harmonic potential in-plane and out-of-plane parameters transferred from the pyrrole molecule. The infrared-absorption intensities were included in the calculations for the first time in polypyrrole. Experimental s…
Recent experiments in metallic solid solutions have revealed interesting correlations between static pair-displacements and the ordering behavior of these alloys. This paper discusses a simple theoretical model which successfully explains these observations and which provides a natural framework for analyzing experime…
A very short GaGa bond, stabilized by carborane moieties, is present in the digallane 1, which is air- and moisture-sensitive, and soluble in both polar and nonpolar organic solvents. The coordination of each Ga atom to the respective C2B3 carborane face is “slip distorted”. • = H, □ = SiMe3.
The MnIVO unit in the five-coordinate oxo(porphyrinato)manganese(IV) complex 2, which is formed by oxidation of the bromo(porphyrinato)manganese(III) complex 1 with potassium peroxycarbonate, was characterized by X-ray absorption spectroscopy. The relatively long MnO bond (1.69±0.03 Å) is probably attributable to th…
The reversible photoisomerization of the helical thioxanthenes 1 and 2 leads to photostationary states with large diastereomeric excesses. These compounds are promising starting materials for optical data storage devices.
The laminated ferroelectric 180 degrees domain structure optically observed in uniaxial ferroelectric KDP is periodic along the normal to the domain walls. Each half-period of the domain structure is characterized by the first four pre-fractals of the pentad Cantor sets. In order to investigate the thermodynamic stabi…
Capacitively coupled radio frequency (cc-rf) plasmas offer advantages over microwave (MW) induced plasmas for the growth of large area homogeneous thin films. However, conventionally designed cc-rf sources lead, at best, to extremely poor quality material when diamond growth is attempted. The first complete diamond ov…
Nonresonant third-order harmonic generation from CdS clusters encapsulated in zeolite A and X was observed at a fundamental wavelength of 1900 nm. To avoid scattering from the surfaces of the small zeolite crystals, the powder samples were dispersed in a liquid with nearly the same refractive index as that of the samp…
High-efficiency diffractive elements with a graded volume distribution of refractive index are proposed, designed, and fabricated using thermal ion exchange in glass. A deliberate use of isotropic diffusion of ions enables us to generate, even with a single binary mask, a structure that acts like a continuous surface-…
In this letter the observation by scanning tunneling microscopy of a Au(111) surface reconstruction induced by prolonged annealing of gold films in oxygen (pO2=1 bar) at high temperature (T=800 °C) is reported. At the atomic scale, the surface is characterized by a (√3×√3)R30° surface structure. In addition, the surfa…
Scanning tunneling microscopy observations reveal a new mechanism for Ni(100) surface oxidation. It is dominated by nucleation at steps and lateral growth of 2D oxide islands. At 300 K nucleation is facile and oxidation starts at rather low exposures. At higher temperatures the interaction between chemisorbed O and Ni…
The antiferroelectric-two ferroelectric (F R(LT )-F R(HT ))-paraelectric phase sequence was ascertained in PZT-95/5 ceramics. Unusual behaviour of the temperature characteristics of electric permittivity, tan delta , remanent polarization and pyroelectric current was observed in the range of diffuse transition between…
Glasses of the formula xPbCl2-(30-x)PbO-40B2O3-30P2O5 (0<or=x<or=30 mol%) were prepared and their physical properties have been studied. To enhance the conductivity of these glasses, the 'mixed former effect' and the halide salt (PbCl2) doping effect have been combined. The decrease in Tg and increase in both the ther…
The third-order nonlinear optical properties of multilayered films containing 23% by weight of an axially modified silicon phthalocyanine derivative have been measured by degenerate four-wave mixing at 532 nm with 70 ps full width at half maximum pulses. The average χ(3)of the films measured at (1.33±0.15) ×10−11 esu…
Correlation between growth mode transition and photoluminescence (PL) properties of Si1−xGex/Si quantum wells (QWs) with high Ge composition grown by gas-source molecular beam epitaxy is investigated. With increasing Ge composition in the QWs, significant deviation from the theoretical calculation is observed for x≳0.…
A new type of correlated disorder is shown to be responsible for the appearance of extended electronic states in one-dimensional aperiodic systems like the Thue-Morse lattice. Our analysis leads to an understanding of the underlying reason for the extended states in this system, for which only numerical evidence is av…
We show that the coupling between aggregation and sedimentation in colloidal suspensions gives rise to either cluster deposition or to settling of a gelled suspension, depending on the volume fraction of particles. In the latter case, we report novel settling properties which are interpreted in terms of the specific s…
A new silicon clathrate compound containing barium, (Na,Ba) ${}_{x}$S${\mathrm{i}}_{46}$, becomes a type-II superconductor with a critical temperature $({T}_{\mathrm{c}})$ of about 4 K. In the compound, the silicon atoms are bonded tetrahedrally with about the same bond distances as in ordinary cubic diamond Si, but f…