Materials Literature
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The formation of cristobalite and tridymite compounds is described in the system SiO 2 -V 2 O 5 -M 2 CO 3 (M = Na, K). Syntheses were performed with various vanadium concentrations at annealing temperatures between room temperature and 1000°C. Crystallization of cristobalite occurs at much lower temperatures (about 80…
An investigation was made of the potentialities of aperiodic multilayer structures (AMSs) optimised to obtain a preassigned reflection spectrum in the x-ray range (λ < 300 Å) and also starting from other criteria. It was found that among the multitude of realisations of AMSs there exist those which are superior to the…
Magnetostrictive FeCo films (thickness 300 nm) have been produced by RF magnetron sputter deposition. The effects of the substrate, composition and thermal treatment on the structural and magnetic properties of the films have been determined. Structural analysis was performed using transmission electron microscopy and…
The N -alkylation of polyaniline (PANi) was investigated by treating the fully reduced state (leucoemeraldine or LM) and the 50% oxidized state (emeraldine or EM) directly with various alkyl halides. The degree of alkylation of LM is low (<10%), while that of EM base is much higher (can be >30%), suggesting that the i…
The film-forming potential of isolate of sunflower proteins (ISFP) was investigated. Homogeneous films were obtained by dissolution of ISFP in alkaline water (pH 12), addition of a plasticizer, casting, and drying. Maximum protein solubilization and unfolding led to films with the highest elasticity. The effects of fi…
One selected composition within the system Na2O-Al2O3-B2O3-SiO2-H2O (NABSH) was studied with the aim of synthesizing the new tourmaline end member olenite with the theoretical formula NaAl3Al6 [Si6O18] (BO3)O3(OH). The starting material consisted of a gel with the anhydrous composition 0.625Na2O.4.5Al2O3.6SiO2, but wi…
Polypropylene copolymer (PP-cp) has a large number of applications and is preferred over the homopolymer due to its higher impact strength. These impact properties can be further improved by blending with polyolefinic elastomer (POE). Blends were prepared by using commercially available POE (Engage® EG 8150, Dupont–Do…
The reaction mechanism for the selective oxidation of methane with hydrogen peroxide was investigated for a H 4 PV 1 Mo 11 O 40 catalyst precursor, which has been reported to be the most active among various Keggin-type heteropolyacids and vanadium complexes in trifluoroacetic acid anhydride. The conversion vs selecti…
The syntheses and X-ray structures of novel porphyrinoids, “N-fused porphyrins (NFPs)”, and their reactivity were described. NFP was spontaneously produced from the bromo-substituted N-confused tetraarylporphyrin in a pyridine solution at room temperature. X-ray diffraction analyses revealed that the porphyrinoid core…
Alternating thin films of the anionic dye pyrenetetrasulfonic acid (4-PSA) and poly(allylamine hydrochloride) (PAH) were formed by the squential deposition of 4-PSA and PAH from aqueous solution onto solid substrates. Film growth was followed by absorption spectroscopy, and the resulting polyelectrolyte-dye multilayer…
We study the structural and thermodynamic properties of a model of point particles interacting by means of a Gaussian pair potential first introduced by Stillinger [Stillinger F H 1976 J. Chem. Phys. 65, 3968]. By employing integral equation theories for the fluid state and comparing with Monte Carlo simulation result…
An efficient (simplified) method for solving problems of spherically symmetric dynamics of a small gas bubble in a compressible fluid is proposed. The method is based on the joint use of the full problem statement (the gas dynamics equations for the gas and the fluid) and its relevant simplifications. Some approximate…
The gradient flow approach to the Cahn-Hilliard and phase field models is developed, and some basic mathematical properties of the models, especially phase separation phenomena, are reviewed. 1 Introduction Materials exhibiting a fine mixture of phases are a familiar and well studied phenomenon in many settings. Such…
By means of NMR experiment and MD computer simulation we investigate the dynamical properties of a chloroadamantane orientationally disordered crystal. We find a plastic-plastic dynamical transition at T_x ~ 330 K in the pico-nanosecond regime. It is interpreted as the rotational analogue of the Goldstein crossing tem…
Quantum phase interference and spin-parity effects are studied in biaxial molecular magnets in a magnetic field at an arbitrarily directed angle. The calculations of the ground-state tunnel splitting are performed on the basis of the instanton technique in the spin-coherent-state path-integral representation, and comp…
Results of measurements of dynamic tensile strength (“spall strength”) of aluminum single crystals are presented. In the shock-wave experiments the load duration was about 40 ns, the initial temperature was varied from 20 to 648 °C that is only 12 °C less than the melting temperature of aluminum. Under these condition…
Excitation pattern and decay kinetics of ultraviolet photoluminescence of porous silica are investigated between 4.5 and 10 eV by means of synchrotron radiation. Spectra are dominated by a 3.7 eV emission similar to the recently observed ultraviolet emission of oxidized porous Si and Si nanostructures. Emission intens…
The influence of local electronic correlations on the properties of colossal magnetoresistive manganites is investigated. To this end, a ferromagnetic two-band Kondo lattice model is supplemented with the local Coulomb repulsion missing in this model and is analyzed within dynamical mean-field theory. Results for the…
We have fabricated a (La1−xSrx) MnO3/SrTiO3 heterostructure and measured the temperature dependence of magnetization and resistivity under white light irradiation. We found that increased resistivity and a decrease of the metal-to-insulator transition temperature by 10 K occur under illumination of light at a waveleng…
A continuous CO2 laser beam was focused on a surface of hexagonal boron nitride under low nitrogen pressure, inducing a stiff radial temperature gradient, rising locally over the dissociation temperature. Boron nitride nanotubes and faceted boron nitride onions were found on the heated surface, segregated in specific…