Low-temperature Region of the In–Se System

A study of the low-temperature region of the In–Se system has been performed by means of isothermal annealing of diffusion couples as well as by X-ray, microscopic and microprobe analyses. Four binary compounds have been observed – In₄Se₃, InSe, In₆Se₇ and In₂Se₃. Original experimental results about the crystal structure and electrical conductivities of the binary compounds have been compared with available literature data or calculated values. A DSC study of the compound InSe has revealed that it melts peritecticly at about 618 °C. The diffusion controlled transition from one In-Se compound to another can be achieved without kinetic difficulties, following the phase arrangement from the equilibrium phase diagram. There are indications that small deviations from the exact stoichiometric ratios are possible.     

Thermoanalytical and X-ray Studies of Rapidly Solidified K2CO3

Molten K₂CO₃ was rapidly solidified, and investigatcd using DSC, X-ray analysis and infrared spectra. All thermoanalytical investigations have been carried out in the temperature interval from 20 to 450 °C. The sorption of water by the anhydrous potassium carbonate is the reason for appearance of K₂CO₃ · 1.5 H₂O in the specimens. The desorption processes occur in two stages usually. The enthalpics of desorption were estimated to be about 23000 J/mol. The polymorphic phase transitions of K₂CO₃ were studied and compared with literature data.     

Wet‐chemical synthesis and characterization of NiBi nano‐ and micro‐particles

Preparation and characterization of NiBi nano‐ and micro‐particles are presented. Firstly, predetermined compositions were obtained by simultaneous precipitation from solutions of Bi(NO₃)₃ and Ni(NO₃)₂. The precipitates were heated under oxygen flow and in air, and thereafter reduced to metals under hydrogen flow at 673 K. Correlation between the predetermined and the actual compositions of the products was found. Characterization of the precipitates was carried out employing X‐ray diffraction, scanning and transmission electron microscopy. Nickel‐bismuth intermetallic phase (NiBi) particles with nano‐ and micro‐dimensions were observed in the samples after reduction. The other possible Ni–Bi intermediate phase (NiBi₃) did not form at these conditions although its presence was expected according to the phase diagram. This finding might be useful for the implementation of Bi‐based solders where the growth of the compound NiBi₃ in the solder joints must be prevented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Calorimetric and phase equilibria studies of the Ni–Sn–Bi system

The phase equilibria at 1273 K were investigated and an isothermal section of the Ni‐Sn‐Bi phase diagram was constructed. The phase boundaries are inclined to the Bi‐rich region that is agreement with phase equilibria at lower temperatures. The molar enthalpies of formation of liquid ternary Ni–Sn–Bi alloys have been determined at 833, 873 and 933 K by direct reaction calorimetry using pellets of 325 mesh powders of pure Ni, Sn and Bi. Measurements were performed with alloys containing from 0.05 to 0.10 mole fractions of nickel, and at ratios of tin and bismuth mole fractions X_Sn/X_Bi = 2.8, 1.2 and 0.43. The experimental calorimetric data were used to calculate a regular solutions parameter of the ternary liquid phase by means of two different thermodynamic data files. It was found that the Ni–Sn–Bi ternary liquid phase could be described as temperature independent ternary regular solution. The assessed values of the ternary interaction parameter are ‐280 J·mol^–1 and 56 000 J·mol^–1, depending on the binary parameters used. Enthalpies of formation of solid binary phases were measured, too. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Equilibrium Configurations of Lipid Bilayer Membranes and Carbon Nanostructures

The present article concerns the continuum modelling of the mechanical behaviour and equilibrium shapes of two types of nano-scale objects: fluid lipid bilayer membranes and carbon nanostructures. A unified continuum model is used to handle four different case studies. Two of them consist in representing in analytic form cylindrical and axisymmetric equilibrium configurations of single-wall carbon nanotubes and fluid lipid bilayer membranes subjected to uniform hydrostatic pressure. The third one is concerned with determination of possible shapes of junctions between a single-wall carbon nanotube and a flat graphene sheet or another single-wall carbon nanotube. The last one deals with the mechanical behaviour of closed fluid lipid bilayer membranes (vesicles) adhering onto a flat homogeneous rigid substrate subjected to micro-injection and uniform hydrostatic pressure.     

SUPERCONDUCTING MICROSTRIP LINE MODEL STUDIES AT MILLIMETRE AND SUB-MILLIMETRE WAVES

This paper presents results of superconducting microstrip transmission line simulation for the frequency range 100–1100 GHz. The simulation is used to calculate the characteristic impedance and the wave propagation constant in a superconducting microstrip line having different geometry. Indeed, modelling provides the only tool for designing superconducting microstrip-based circuits at millimetre and sub-millimetre wavelengths because no direct measurements of such a line can be made at this wavelengths and at cryogenic temperature of 4 K with ultimate accuracy. Niobium, as the most commonly exploited superconducting material, was used for the modelling, though the same approach would work for any different BCS superconductor. In order to evaluate the model accuracy, we have made an extensive comparison study of the superconducting microstrip models known from earlier publications, performed numerical simulations using 3D EM — solver, HFSS, and used a new model introduced in this paper with all simulation result plotted in the paper.     

X-ray topographic study of GaSb substrates for epitaxial layer growth

The depth of the layer damaged by silicing of GaSb ingots has been determined by X-ray topography. The changes in the defect structure of substrates after successive etching to different depths by Br₂/CH₃OH and 1 HF:3 NNO₃:1 CH₃COOH have been studied. The effect of heat treatment carried out under conditions similar to the epitaxial process of substrates with completely removed damaged layer has been investigated.     

Poly(propylene imine) dendrimer complexes of Cu(II), Zn(II), and Co(III) as catalysts of hydrolysis of p-nitrophenyl diphenyl phosphate

Poly(propylene imine) dendrimers having 8, 32, and 64 primary amine end groups form diamino Cu(II), diamino Zn(II), and tetramino Co(III) complexes that are identified spectrophotometrically and titrimetrically. The dendrimer–metal ion complexes catalyze the hydrolysis of p-nitrophenyl diphenyl phosphate in zwitterionic buffer solutions at pH ≤ 8.1 with relative activities Cu(II) > Zn(II) > Co(III). The rates of hydrolysis are faster with sodium perchlorate than with sodium chloride to control ionic strength. In sodium perchlorate solutions with Cu(II) the rates increase with increasing size of the dendrimer. In sodium chloride solutions with Cu(II) the rates decrease with increasing size of the dendrimer. Rate constants in buffered sodium chloride solutions of dendrimers and 1.0mM Cu(II) are 1.3–6.3 times faster than in the absence of Cu(II). The fastest hydrolyses occurred at a dendrimer primary amine to Cu(II) ratio NH₂/Cu ≤ 2. At NH₂/Cu = 4 and with the 1,4,7,10-tetraazacyclodecane complex of Cu(II) hydrolysis rates were much slower. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2727–2736, 1999