Materials Literature
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A method of obtaining polymer with markedly decreased entanglements concentration in melt, via high-pressure crystallization of high-density polyethylene (HDPE), is elaborated. It is shown, by calculations and experiments, that melting of chain-extended crystals obtained in this process provides a chain-disentangled m…
Spider dragline silk is Nature's high-performance protein fiber. This biomaterial has attracted much interest from scientists in various disciplines since it has become feasible to produce spider silk proteins by means of biotechnology. This article reports on research directed toward the regeneration of spider silk.…
We present a model calculation for the temperature dependent behaviour of surface states on a ferromagnetic local-moment film. The film is described within the s-f model featuring local magnetic moments being exchange coupled to the itinerant conduction electrons. The surface states are generated by modifying the hopp…
We use Monte-Carlo simulations to study island formation in the growth of thin semiconducting films deposited on lattice-mismatched substrates. It is known that islands nucleate with critical nuclei of about one atom and grow two dimensionally until they reach a critical size s$_c$, when it is favorable for the island…
A comprehensive theoretical and experimental study is presented of the magnetic susceptibility versus temperature χ(T) of spin S = 1/2 two- and three-leg Heisenberg ladders and ladder oxide compounds. Extensive quantum Monte Carlo simulations of χ(T) were carried out for both isolated and coupled two-leg ladders with…
Polyelectrolytes in poor solvents show a necklace structure where collapsed polymer pearls are linked to stretched strings. In the present paper the elasticity of such chains is studied in detail. Different deformation regimes are addressed. The first is the continuous regime, where many pearls are present. A continuo…
The physical and chemical properties of nanophase materials rely on their crystal and surface structures. Transmission electron microscopy (TEM) is a powerful and unique technique for structure characterization. The most important application of TEM is the atomic-resolution real-space imaging of nanoparticles. This ar…
The light deflection phenomenon is studied in ammonium pentafluoro antimonate (APFA) crystals versus the laser beam incidence related to the twinned sample. The variations of the orientation of the deflected beams, as well as of their polarization are measured and theoretically explained. A simplified model allows one…
The mechanical properties of a fiber-reinforced plastic are influenced by the adhesion between a reinforced fiber and a matrix resin. In this work it is shown how to obtain strong adhesion between a carbon yarn and an epoxy resin through the formation of covalent bonds. Acid amide groups reactive with epoxy groups wer…
A new parametrization of the classical shell model for the cubic phase of the perovskite KNbO 3 has been derived and used to calculate the structural, elastic and dielectric properties of this material. Using this parametrization, the defect formation and migration energies, as well as atomic displacements, have been…
Harmonic generation in a three-component Fibonacci optical superlattice (3CFOS) is analysed theoretically. The Fourier spectrum of the structural function of the 3CFOS is numerically calculated. The positions of reciprocal vectors are in good agreement with the theoretical prediction. The intensities of the second har…
The emission properties of the 3 P 0 state of praseodymium ions in lithium niobate crystal have been studied. Blue-green emission at 510 nm corresponding to the 3 P 0 3 H 4 transition in Pr 3+ :LiNbO 3 crystals was generated after direct and up-conversion excitation with orange and infrared radiation around 920 nm. Th…
Superlattices of a-SiO x /nc-CdSe and thin composite films of SiO x doped with CdSe nanocrystals have been investigated. The CdSe nanocrystals size in both kinds of samples was determined by x-ray diffraction and HREM measurements. A significant difference has been found in the size values determined by both methods,…
A systematic investigation of the magnetic and transport properties of perovskites La 0.67 Sr 0.33 (Mn 1- x Ni x )O 3 ( x ⩽ 0.2) is reported. The replacement of the Mn ion by a Ni ion results in a reduction of ferromagnetism and metallic conduction. For the sample with x = 0.1, in addition to a metal-insulator (M-I) t…
The implementation of a new model to simulate the oxidation of Silicon (see Part I) is presented in this paper. The implementation is done within a finite element framework. The work involves representation of the Silicon–Silicon dioxide interface in a mesh-independent manner. The interface description and evolution i…
Interstitial O3 molecules in 7.9 eV photon-irradiated silica are identified. Their optical absorption band at 4.8 eV nearly coincides with the 4.8 eV band of nonbridging oxygen hole centers. The O3-related band is distinguished by a smaller halfwidth (0.84 vs 1. 05 eV), by susceptibility to ultraviolet bleaching, by l…
A functionalized high-density polyethylene (HDPE) with maleic anhydride (MAH) was prepared using a reactive extruding method. This copolymer was used as a compatibilizer of blends of polyamide 6 (PA6) and ultrahigh molecular weight polyethylene (UHMWPE). Morphologies were examined by a scanning electron microscope. It…
A new type of hybrid material of clay with poly (butyl acrylate) (PBA) has been prepared successfully using intercalation-polymerization process. The structure of the composite was investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Transmission electron microscope (TEM), and Thermogravimetric…
This work focuses on a new mathematical framework to model the process of thermal oxidation in silicon. The mathematical model is derived from the fundamental conservation equations of mechanics. The mass balance law provides the description of the oxidant transport and the Si–SiO2 interface motion, and momentum balan…
A detailed study was performed on unirradiated low- and high-density polyethylene (LDPE and HDPE) films as well as irradiated films with different types of radiation such as 60Co γ rays, thermal and fast neutrons, and electron beam irradiation. The structural changes of PE films were characterized by Fourier transform…