Effect of shock-wave treatment of zinc sulfide on properties of ZnS:Cu,Mn phosphor

Method was developed for raising the brightness of photo- and electroluminescence from ZnS:Cu,Mn phosphor in dc and ac fields by preliminary shock-wave treatment of a starting zinc sulfide placed in a closed copper ampoule.     

Generalised Maxwell-Garnett equation: application to electrical and chemical transport

In this paper we discuss the implementation of different equilibrium concentrations in each of the phases into the Maxwell-Garnett effective medium formula for diffusion in heterogeneous media. We put the derivation given by Kalnin et al., J. Phys. Chem. Solids, 2002, 63, 449, on safer grounds and extend it to non-dilute carrier concentrations. The relation to Maxwell's mixing rule is also elaborated. It is shown that the formula can not only successfully be applied to conductivity problems but also to describe steady state chemical diffusion in heterogeneous media such as polycrystalline samples. The comparison with the brick layer model corroborates these points but also shows that-in the case of heterogeneous media-one has to be cautious in applying steady state results to transient kinetics.     

Cleaning action and surfactant properties of alkyl glucosides

Cleaning action and surfactant properties of a series of alkyl glucosides, having high detergent power, emulsifying capacity, and biodegradability and low foaming capacity, were studied. The effects of various factors on the cleaning action of the surfactants and compositions on them were investigated, allowing prediction of the cleaning effect on the basis of data on physicochemical characteristics of the solutions and process parameters.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 12, 2004, pp. 2025–2030.Original Russian Text Copyright © 2004 by Yakimchuk, Kotomin, Petelskii, Naumov.     

The non-equilibrium charge screening effects in diffusion-driven systems with pattern formation

The effects of non-equilibrium charge screening in mixtures of oppositely charged interacting molecules on surfaces are analyzed in a closed system. The dynamics of charge screening and the strong deviation from the standard Debye-Hückel theory are demonstrated via a new formalism based on computing radial distribution functions suited for analyzing both short-range and long-range spacial ordering effects. At long distances the inhomogeneous molecular distribution is limited by diffusion, whereas at short distances (of the order of several coordination spheres) by a balance of short-range (Lennard-Jones) and long-range (Coulomb) interactions. The non-equilibrium charge screening effects in transient pattern formation are further quantified. It is demonstrated that the use of screened potentials, in the spirit of the Debye-Hückel theory, leads to qualitatively incorrect results.     

Calculation of energies of radiative tunneling transitions between defects in alkali halides

The procedure for calculating the energies of radiative tunneling transition between spatially separated electron and hole centres in ionic crystals based on semiempirical INDO calculation of a pair of close defects and on a further account of electronic polarization of a crystal due to defects has been presented. Pairs of an electron, F, and hole (H, V_k, V₂) centres in KCl and LiF crystals are studied. The influence of close defect interaction and of polarization upon emitted photon energy has also been considered. It is shown that due to polarization this energy varies with a distance between defects in a more complicated way than $\text{e}{}^2\text{?R}$ shown in semiconductors.     

Rheology of the Melt of Acrylonitrile–Styrene Copolymer Modified with Montmorillonite

The rheological properties of the acrylonitrile–styrene copolymer modified with hydrophobized montmorillonite Cloisite 30B and composites are studied in a wide range of shear rates and shear frequencies at a temperature of 230°C. It is shown that the filler insignificantly affects the viscoelastic properties of the compositions, but the viscosity of composite melts considerably increases at low shear rates and monotonically grows with increasing concentration, whereas at high shear rates the effective viscosity declines appreciably in the concentration range of about 0.3 vol %.