Materials Literature
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A brief introduction is presented on transition metal oxide bronzes and their relationship to the phosphate tungsten bronzes; the latter compounds are the major focus of this review. The phosphate tungsten bronzes (PTB) are a new class of quasi-low-dimensional materials which exhibit charge density wave (CDW) instabil…
The physical properties of the low dimensional molybdenum bronzes showing charge density wave (CDW) instabilities are reviewed. The mechanisms of the Peierls transition, CDW and spin density wave (SDW) instabilities are first introduced. The properties of the quasi-one-dimensional (1D) blue bronze, A 0.30 MoO 3 , incl…
The formation of high-quality thin films of polytetrafluoroethylene (PTFE) is important in many applications ranging from material reinforcement to molecular electronics. Laser ablation, a technique widely used to deposit a variety of inorganic materials, can also be used as a simple and highly versatile method for fo…
The lattice parameters a, b and c of TmCu 2 have been measured in the temperature range from 4.2 K up to 300 K using X-ray powder diffraction. The influence of the crystal field on the thermal expansion in TmCu 2 in the paramagnetic region has been determined by comparing the thermal expansion of the non-magnetic YCu…
It is shown that there exists a numerical relationship between the position of the first sharp diffraction peak, Q 1 , and the first interatomic distance, r 1 , which obeys a simple equation d=ar 1 +b where d=2 pi /Q 1 is the equivalent distance and the coefficients (a, b) specify the group of amorphous substances-gla…
Dielectric and thermodynamic properties have been investigated in isotopically mixed crystals ${\mathrm{K}}_{3}$${\mathrm{D}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{H}}_{\mathit{x}}$(${\mathrm{SO}}_{4}$${)}_{2}$ with isolated hydrogen bonds interconnecting the dimeric ${\mathrm{SO}}_{4}^{2\mathrm{\ensuremath{-…
This paper reports electron paramagnetic resonance (EPR) measurements of Cr 3+ ions in YAlO 3 (YAP) at 1.6 K and room temperature along with their optical absorption and luminescence spectra The polarization of the excitation spectrum of the Cr 3+ luminescence has also been measured. The EPR spectrum is ascribed to su…
The phase diagram of dipolar hard spheres has been determined by Monte Carlo simulation for reduced densities ${\mathrm{\ensuremath{\rho}}}^{\mathrm{*}}$ ranging from 0.02--0.3 and reduced temperatures ${\mathit{T}}^{\mathrm{*}}$ from 0.08--0.25. For ${\mathit{T}}^{\mathrm{*}}$\ensuremath{\lesssim}0.15 the particles a…
The non-equilibrium critical relaxation of systems in which the order parameter couples reversibly to conserved densities is investigated. The initial state which may be macroscopically prepared by a quench from a temperature T >> T c to the critical temperature T c is characterized by short-range correlations. In the…
An immersion grating with a high refractive index, n, increases the spectral resolution by a factor n over that of a reflective surface grating of equal length. A silicon immersion grating has been developed and tested; initial results are reported here.
Abstract Blends of Thermoplastic polyurethane (TPU) and poly(styrene‐co‐acrylonitrile) (SAN) (34% acrylonitrile and 24% acrylonitrile) and polyurethane ionomer (PUI) with SAN (34% acrylonitrile) were prepared in the melt. The structural properties and morphology of the blends were investigated. TPU and SAN blends were…
Abstract This article includes the doping and dedoping behaviors, the electrical conductivity, and the spectral properties of poly(2‐ethynylpyridine) and iodine‐doped poly(2‐ethynylpyri‐dine). The doping ability of poly(2‐ethynylpyridine) having a pyridine substituent was greater than that of polyphenylacetylene havin…
Abstract Cellulose fibers were grafted with compatibilizing agents, such as maleated polypropylenes of different molecular weights. Steric effects and surface free‐energy effects were found to stimulate the stretching of grafted chains away from the cellulose fiber surface, giving rise to a brushlike configuration in…
Abstract Preliminary investigations have been conducted on the graft copolymerization of meth‐ylmethacrylate onto Caesarweed fiber, initiated by potassium permanganate and the toluene redox system. The percentage graft yield increased with permanganate up to 132% in the concentration range, 1.0×10 −2 to 5.0×10 −2 M at…
A particularly popular and powerful use of fluorescent indicators is nondestructive monitoring of the activity or free concentration of important ions or messengers such as Ca 2+, H +, Na +, Mg 2+, Cl -, or cyclic adenosine 3′,5′-monophosphate (cAMP) inside living cells and tissues. Successful indicators and chelators…
Light scattering and absorption by spherical particles is extended to aggregates of spheres with arbitrary shape and size. We applied the theory of G6rardy and Ausloos [Phys. Rev. B 25, 4204-4229 (1082)] to compute the total extinction loss spectra of several aggregates of nanometer-sized silver spheres from the near…
Electric field-induced changes in the extraordinary and ordinary refractive indices of a Pb(Zr0.53Ti0.47)O3 thin film were independently determined using waveguide refractometry. Under an electric field, applied normal to the film plane and corresponding to saturation of the electric polarization, the ratio of the ext…
A novel hard magnetic compound series with composition Sm2Fe14Ga3Cx (x=0, 0.5, 1.0, 1.5, 2.0, and 2.5) was prepared by arc melting. The carbides crystallize in the rhombohedral Th2Zn17-type structure and are single phase except for Sm2Fe14Ga3 and Sm2Fe14Ga3C0.5 which contain some amounts of α-Fe. The substitution of G…
Free-standing chemically vapor deposited (CVD) single-crystalline diamond films have been fabricated by a sequence of processes including high energy ion implantation, microwave plasma enhanced chemical vapor deposition, and the final separation of the diamond epilayer from the substrate by heating in oxygen. The homo…
The dynamics of a very fragile glass-forming polymer is studied by time of flight neutron scattering in a time scale from ${10}^{\mathrm{\ensuremath{-}}13}$ to ${10}^{\mathrm{\ensuremath{-}}11}$ s. We observe a crossover from a Debye-like to a non-Debye behavior at a characteristic time which is effectively independen…