Materials Literature
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We present ab initio quantum chemical embedded cluster calculations of Mn core-valence and $d\ensuremath{-}d$ transitions in ${\mathrm{LaMnO}}_{3}.$ The results are also important for the analysis of recent x-ray absorption and x-ray scattering experiments at the Mn K edge in ${\mathrm{LaMnO}}_{3}.$ We find that the f…
A series of poly(styrene- co -vinylphenol) (PSOH) copolymers were prepared and characterized. The miscibility and hydrogen bonding between the partially hydroxylated polystyrene with poly(ε-caprolactone) (PCL) blend were investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy. The…
The effect of pressure on the $B\ensuremath{-}T$ phase diagram of $\ensuremath{\alpha}\ensuremath{-}(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF}{)}_{2}\mathrm{KHg}(\mathrm{SCN}{)}_{4}$ is studied. The measured phase lines can be well described by a recent model of a charge-density wave system with varying nesting conditio…
Optical conductivity spectra $\ensuremath{\sigma}(\ensuremath{\omega})$ of a ${\mathrm{La}}_{3/2}{\mathrm{Sr}}_{1/2}{\mathrm{NiO}}_{4}$ single crystal were investigated over a wide photon energy range with variations of temperature and polarization. Strong anisotropies in phonon modes and electronic structures are obs…
Abstract Polyethylene‐ g ‐polyacrylamide membranes were prepared by graft polymerization of acrylamide into polyethylene films by preirradiation technique. The characterization and thermal behavior of membranes with different degrees of grafting were evaluated by density, X‐ray diffraction, thermogravimetric analysis,…
Systematic dc and ac magnetic susceptibility studies have been performed on single-phase ${\mathrm{LaCoO}}_{3}$ powder samples. Evidence is presented in support of the existence of ferromagnetic (FM1, FM2) and antiferromagnetic (AFM) interactions at low temperatures. FM1 and FM2 are ferromagnetic interactions that occ…
The formation of the sitting-atop (SAT) complexes of 5,10,15,20-tetraphenylporphyrin (H(2)tpp), 5,10,15,20-tetrakis(4-chlorophenyl)porphyrin (H(2)t(4-Clp)p), 5,10,15,20-tetramesitylporphyrin (H(2)tmp), and 2,3,7,8,12,13,17,18-octaethylporphyrin (H(2)oep) with the Cu(II) ion was spectrophotometrically confirmed in aque…
In this paper we present a review of the recent inelastic x-ray scattering (IXS) studies on the high-frequency collective dynamics in topologically disordered systems. At mesoscopic exchanged momenta ( Q ≈1-10 nm -1 ), these IXS studies allowed experimental demonstration of the existence in glasses of propagating acou…
The alternating-current (ac) conductivity σ(ω) and the dielectric permittivity of polyaniline doped with β-naphthalene sulphonic acid (NSA) have been extensively studied in the temperature range of 300 K to 80 K and in the frequency range of 500 Hz to 10 MHz. The ac conductivity follows a power law in frequency, σ(ω)∝…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTSynthesis and Characterization of a 2,1,3-Benzothiadiazole-b-alkyne-b-1,4- bis(2-ethylhexyloxy)benzene Terpolymer, a Stable Low-Band-Gap Poly(heteroaryleneethynylene)Carlito G. Bangcuyo, Una Evans, Michael L. Myrick, and Uwe H. F. B…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTFunctionalization of [MoW5O19]2- with Aromatic Amines: Synthesis of the First Arylimido Derivatives of Mixed-Metal PolyoxometalatesYongge Wei, Meng Lu, Calida Fung-chi Cheung, Charles L. Barnes, and Zhonghua PengView Author Information Departments of Chemistry, Univers…
A mechanism to enhance hardness in multilayer coatings is proposed. Using the technologically important hard transition metal carbides as prototypes, although the principle is transferable also to other systems, we demonstrate, from first-principles calculations, that by suitable alloying the energy difference between…
In this paper the influence of UV irradiation on the luminescence quantum efficiency of nanocrystalline ZnS:Mn 2+ is studied. Samples passivated with poly(vinylbutyral) (PVB), poly(vinyl alcohol) (PVA), methacrylic acid (MA), and sodium polyphosphate (PP) and samples without passivating polymer were UV irradiated in a…
A platinum electrode was coated with polyelectrolyte multilayer (PEM) films to prepare an amperometric hydrogen peroxide sensor which can be used in the presence of possible interferences such as ascorbic acid, uric acid, and acetaminophen. The PEM films were prepared on the surface of a Pt disk electrode by an altern…
Highly concentrated CdS colloids (about 30 wt %) are prepared in acetone through the grafting of 4-fluorophenylthiol at their surface. 19 F NMR measurements show that the controlled oxidation by an aqueous solution of hydrogen peroxide leads to a mixture of dithiol and fluorosulfonate species. Aggregation of particles…
Multiarm star polymers, consisting of a high number of linear homopolymer arms joined covalently to a central core, represent model soft ‘hybrid’ spheres encompassing both polymeric (arm) and colloidal (core) character. Due to this topology, the single star has a nonuniform monomer density distribution. In nondilute s…
High-temperature electrical property measurements (electrical conductivity, thermoelectric coefficient) on polycrystalline ${\mathrm{CuAlO}}_{2}$ exhibited characteristic small polaron features, i.e., low mobilities (0.1--0.4 ${\mathrm{cm}}^{2}$/V s) and an activation energy of \ensuremath{\sim}0.14 eV. The thermopowe…
The luminescence quantum efficiency of nanocrystalline ZnS:Mn 2+ is studied to provide a better understanding on how the quantum efficiency is influenced by the Mn 2+ concentration, the nature of the passivating polymer, and the synthesis conditions. The results show an increase of the luminescence quantum efficiency…
Within the framework of the mode-coupling theory of super-cooled liquids, we investigate new phenomena in colloidal systems on approach to their glass transitions. When the inter-particle potential contains an attractive part, besides the usual repulsive hard core, two intersecting liquid-glass transition lines appear…
In this review we address some of the experimental challenges found in the x-ray diffraction characterization of the low-symmetry phases recently discovered in the PZT, PZN-PT and PMN-PT piezoelectric systems around their morphotropic phase boundaries. In particular, we discuss the need for special care in the prepara…