Materials Literature
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Different types of electron (hole) ground energy level renormalization due to confined (L) and interface (I) phonons in a spherical quantum dot embedded in a semiconductor medium are investigated on the example of β-HgS/CdS nanoheterosystem. It is shown that for all QD sizes the shift of the ground energy level (Δ) is…
We have studied the crystallization and melting of poly(n-octadecyl methacrylate) (PNODMA) by performing temperature and pressure jump experiments from the melt to the final semicrystalline state. The evolution of the crystallization process is studied in real time by recording the changes in the dielectric spectrum.…
X-ray scattering experiments have demonstrated that for thin films (100 Å to 500 Å) of La 0.9 Sr 0.1 MnO 3 epitaxially grown on SrTiO 3 (100) substrates, the accommodation of the lattice mismatch between film and substrate gives rise to a modulated structure. The non-bulk-like structural properties of these thin films…
The oxidation behaviour of a three-dimensional woven C/SiC composite protected with an SiC seal coating and with an SiC coating combined with an SiO2–B2O3 glassy coating have been respectively investigated through an experimental approach based on mass and flexural strength changes. Three main temperature domains exis…
Radiation hardness is one of the fundamental parameters characterizing a scintillator. The reason is that ionizing radiation often induces the formation of color centers in the irradiated material. These centers are related to lattice defects and may absorb light in the visible range. Possible overlap of the induced a…
The properties of materials derived from diphenolic acid (4-(bis(hydroxyphenyl))pentanoic acid, DPA), such as polycarbonate homo- and co-polymers (with bisphenol A, BPA), have been determined. The influence of copolymer composition on the thermal properties of these materials has been determined. Blends of polycarbona…
A modeling technique for rate-independent (quasistatic) scalar magnetic hysteresis is presented, using neural networks. Based on the theory of dynamic systems and the wiping-out and congruency properties of the classical scalar Preisach hysteresis model, the choice of a feed-forward neural network model is motivated.…
We have fabricated semiconductor-based magnetic superlattices (SLs) containing GaAs:MnAs granular material in which MnAs nanoclusters are embedded in GaAs, and have characterized their structural, optical, and magneto-optical properties. SLs consisting of GaAs:MnAs and AlAs are shown to have good crystalline quality a…
Monte Carlo simulations of amorphous polyethylene (PE) nanoparticle have been performed on the second nearest neighbor diamond lattice by including short and long-range interactions. A droplet can be either obtained from equilibrated PE bulk or from nanofiber snapshots by modifying periodic boundary conditions. The pr…
Abstract The reaction of Te, TeCl 4 and BiCl 3 in a sealed evacuated glass ampoule in a temperature gradient 160 to 90 °C yields Te 8 [Bi 4 Cl 14 ] as black platelike crystals with a golden lustre which are deposited in the temperature zone 150 to 130 °C. The best yield is obtained with a Te/TeCl 4 /BiCl 3 molar ratio…
Self-assembling systems confined in slit-like pores of a width L are studied. We focus on phase transitions between uniform and ordered periodic phases. As shown by previous experimental and theoretical studies, the periodic phases respond elastically to the applied stress when the size λ of the unit cell is much larg…
Polypyrrole was prepared by chemical methods (in water by mixing a solution of pyrrole with an oxidizing solution of FeCl3) and by electrochemical methods. FTIR spectroscopy was used for determining the structure and reaction mechanisms. The main aims were first to prepare some conductive polymers by applying new, eff…
cis-Cyclotetrasiloxanes of the formula cis-[PhSi(O)(OSiMe2 R)]4 with R = Me, CH2Cl, CH CH2 and cis-[ClC6H4Si(O)(OSiMe3)]4 were synthesized and investigated in terms of their thermotropic phase transitions. Two ordered phases were observed for the cis-cyclotetrasiloxanes, one at lower temperature exhibiting the propert…
Magnetic properties of single crystalline Ga1−xFexSe have been measured. This material is in the new class of diluted magnetic semiconductors based on the III–VI semiconductors. The magnetization versus field for an x=0.05 sample deviates from the linear response seen previously in Ga1−xMnxSe and Ga1−xMnxS and reaches…
Hyperbranched aromatic polyamides and copolymers were prepared by direct polycondensation in the presence of condensation agents. Three strategies were described: (1) self-polycondensation of AB x -type monomers, (2) copolymerization of AB 2 and AB monomers and (3) polymerization of A 2 and B 3 monomers. The self-poly…
The morphology of the diglycidyl ether of bisphenol-A/poly(3-aminopropylmethylsiloxane) (DGEBA/PAMS) reactive blends was studied by fluorescence techniques as a function of the initial composition. Some fluorescence results were compared with those from optical and electron microscopy investigations. Several morpholog…
The growth of (010)-oriented CrO2 thin films on Al2O3(0001) substrates leads to a higher grain boundary density than the growth of (100)-oriented CrO2 thin films on isostructural TiO2(100) substrates. For both types of films an intrinsic linear contribution to the high field magnetoresistance (MR) due to spin disorder…
The need to destabilize foams and control their formation arises in many industrial processes. Mechanical foam breakers, mechanical vibration and ultrasonic vibration are examples of physical destructive techniques which do not suffer from the drawbacks associated with the use of chemical antifoams and defoamers. This…
Frozen-in phason fluctuations in single grains of icosahedral Al-Pd-Mn quasicrystals have been studied by high-resolution coherent X-ray scattering. Bragg peak widths scale as expected for a distribution of uniform phason strains. Strong relaxation of the uniform phason strain is observed after sample annealing. Large…
Low impurity content is the essential requirement to many applications of vitreous arsenic chalcogenides as a material for optoelectronics. Investigations carried out in last ten years in-creased the knowledge volume about the nature and origin of impurities in chalcogenide glasses, their effect on glass properties, e…