Calorimetric studies of CeCu AND CeMgCu alloys

Using different calorimeters, the following measurements have been carried out.

• 1.(i) The integral enthalpies of mixing of CeCu binary and some CeMgCu ternary liquid alloys,
• 2.(ii) The enthalpy of formation and the enthalpy of melting of the intermetallic compound CeCu₂.
• 3.(iii) The heat content of solid and liquid CeCu₂.

The observed concentration and temperature dependence of the measured values of the enthalpies of mixing as well as the glass-forming abilities of these alloys are explained on the basis of an association model.     

Thermodynamic properties of liquid copper–lanthanum alloys

Mixing enthalpies of alloys in the Cu–La system are measured using isoperibolic calorimetry method over the ranges 0 < x _La < 0.185 at 1400–1430 K and 0.659 < x _La < 1 at 1370 K. They have moderate exothermic values over the whole concentration range and agree with literature data. Activities of the components, enthalpies and entropies of formation of intermetallics in this system, and its phase diagram are optimized using an ideal associated solution (IAS) model, and agree with most literature data. The updated thermodynamic properties can be used in further investigation of multicomponent systems based on the binary Cu–La.     

Viscosity of liquid Cu–Sn alloys

We investigated of the kinematic viscosity of liquid Cu–Sn alloys upon heating and subsequent cooling by the method of the oscillating cylinder. For the liquids alloys Cu75Sn25, Cu50Sn50, Cu48Sn52, Cu32Sn68, and Cu17Sn83, the temperature dependencies of the viscosity upon heating deviate from the Arrhenius relation. The temperature dependencies of viscosity show the Arrhenius-like behaviour upon cooling for all investigated alloys. A discrepancy between the temperature dependencies of viscosity obtained upon heating and cooling arised. We built the concentration dependences of the kinematic viscosity of liquid Cu–Sn alloys upon cooling. The increase of the values of viscosity and activation energy of viscous flow in the concentration range corresponding to the existence of intermetallic compounds Cu₃Sn in the solid state was observed. These results were qualitatively interpreted using the concept of microheterogeneities of liquid alloys.     

The excess enthalpies of liquid GaGeTe and GaSnTe alloys

The excess enthalpies of the liquid alloys GaGeTe and GaSnTe were measured in a heat-flow calorimeter at 1203 K. The enthalpy surface in the ternary space in both systems is characterized by a valley stretching from the exothermic minimum in the GaTe system to the minima of the GeTe and SnTe systems. The minima in the ternary systems were found in this valley, i.e. on the sections Ga₂Te₃-GeTe and Ga₂Te₃-SnTe. A comparison of the experimental data with those calculated from the excess enthalpies of the constituent binaries with the aid of the Bonnier model, reveals only small deviations. A preliminary investigation was made into the ternary phase diagram of GaSnTe. This system contains the two quasibinary sections Ga₂Te₃-SnTe, GaTe-SnTe and the ternary compound Ga₆SnTe₁₀. The previously reported compounds Ga₂SnTe₃ and GaSnTe₂ do not exist.     

Modeling of the thermodynamic properties of lead–tellurium liquid alloys

Application of the Redlich–Kister polynomial with varied number of parameters for describing the concentration dependence of thermodynamic systems of liquid metallic systems with a strong interaction between their components is considered for the example of the lead–tellurium system. Particular attention is given to the range of dilute solutions of tellurium in liquid lead.     

Thermodynamic properties of alloys of the binary In–La system

The thermochemical properties of melts of the binary In–La system were studied by the calorimetry method at 1250–1480 K over the whole concentration interval. It was shown that significant negative heat effects of mixing are characteristic features for these melts. Using the ideal associated solution (IAS) model, the activities of components, Gibbs energies and the entropies of mixing in the alloys, and the phase diagram of this system were calculated. They agree with the data from literature.     

Mass spectrometry measurements of activities in liquid Ag-Ge alloys: Critical assessment of the thermodynamics of the AgGe system and short distance order

In the system AgGe, the tendency to cluster formation or the setting up of a local order effect can be explained by the thermodynamics of liquid alloys. For a precise and reliable knowledge of their activities, we measured them by multiple Knudsen cell mass spectrometry. The assumptions used to evaluate this local order from neutron diffraction measurements agree with our calculations from thermodynamics and the mixing volume.     

Electrodeposition of nanocrystalline aluminium, copper, and copper–aluminium alloys from 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate ionic liquid

In this paper, we show that nanocrystalline aluminium, copper, and copper–aluminium alloys can be electrodeposited from the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate, [Py_1,4]TfO. Furthermore, Al deposition was studied in 1-ethyl-3-methylimidazolium trifluoromethylsulfonate, [EMIm]TfO for comparison. The two employed ionic liquids exhibit different concentration-dependent phase behaviour with AlCl₃. This study comprises cyclic voltammetry, potentiostatic electrolysis, scanning electron microscopy, X-ray diffraction, atomic absorption spectroscopy, and inductively coupled plasma optical emission spectroscopy. Thick (in micrometre regime) and uniform layers of aluminium deposits were obtained from 2.75?M AlCl₃ in [Py_1,4]TfO at 100?°C. The average crystallite size of aluminium was found to be around 40 to 50?nm. However, a coarse and cubic-shaped Al deposit with crystal sizes in the micrometre regime was obtained from [EMIm]TfO. Electrodeposition of copper was investigated in [Py_1,4]TfO-containing Cu(TfO)₂ at 100?°C. The average grain size of the copper deposit obtained from the electrolysis is around 20 to 40?nm. Electrodeposition of copper–aluminium alloys was successful in the same ionic liquid at 100?°C. Thick layers of copper–aluminium alloys were obtained from the employed ionic liquid. XRD analysis of the obtained deposits from electrolysis experiments revealed that Cu₃Al alloy was formed. SEM analysis indicated that the nanocrystalline copper–aluminium deposits have an average grain size of 60 to 70?nm.     

Determination of non-steroidal anti-inflammatory drugs in urine by the combination of stir membrane liquid–liquid–liquid microextraction and liquid chromatography

A stir membrane liquid phase microextraction procedure working under the three-phase mode is proposed for the first time for the determination of six anti-inflammatory drugs in human urine. The target compounds are isolated and preconcentrated using a special device that integrates the extractant and the stirring element. An alkaline aqueous solution is used as extractant phase while 1-octanol is selected as supported liquid membrane solvent. After the extraction, all the analytes are determined by liquid chromatography (LC) with ultraviolet detection (UV). The analytical method is optimized considering the main involved variables (e.g., pH of donor and acceptor phases, extraction time, stirring rate) and the results indicate that the determination of anti-inflammatory drugs at therapeutic and toxic levels is completely feasible. The limits of detection are in the range from 12.6 (indomethacin) to 30.7 μg/L (naproxen). The repeatability of the method, expressed as relative standard deviation (RSD, n = 5) varies between 3.4% (flurbiprofen) and 5.7% (ketoprofen), while the enrichment factors are in the range from 35.0 (naproxen) to 72.5 (indomethacin).     

Determination of the secondary well in the 62P12 CsXe potential

Experimental data existing in the literature on broadening and shift at low densities and on position of the red satellite band of the D₁ line of Cs perturbed by Xe are used to obtain information on the range 6Å-∞ of the difference potential. Assuming a Lennard-Jones (n-6) model, best agreement is obtained for n=8 and n=7, in accordance with the low curvature expected for a secondary well. Potential for the first excited state is obtained by addition of the difference potential to the ground state potential, and the parameters of the resulting secondary well are given.     

Determination of the isobaric liquid–liquid ternary system water–sodium hydroxide-1,3-diaminopropane for the demixing of diaminopropane

This study relates to a determination of liquid–liquid ternary system water–sodium hydroxide-1,3-diaminopropane to optimize the conditions of the isolation of hydrazine by liquid–liquid extraction, generated by the addition of solid sodium hydroxide. Three isotherms were established at 293, 313, and 323 K by Isoplethic Thermal Analysis, method developed in our laboratory and consists of the evolution of one or more physical properties of the system when its composition is modifying, and chemical titrations. The coordinates of the critical point were determined using the diameter method.     

High-Tc superconductivity in the ErBaCuO and related systems

ErBa₂Cu₃O₇ and Er_0.5Y_0.5Ba₂Cu₃O₇ are both high-T_c superconductors attaining zero resistance above 80 K. Preliminary studies indicate that Yb_1−xY_xBa₂Cu₃O₇ also exhibits zero resistance above 77 K.     

Hydrogen absorption and phase transitions in rapidly quenched LaNi alloys

Several LaNi binary alloys were rapidly quenched by melt spinning. A metastable phase and an uniform Laves phase were obtained. Differences in behaviour were observed between hydrogenation of quenched materials and of as-cast materials whose compositions were identical. The quenched materials, in contrast to the as-cast phases, had a tendency to form amorphous LaNiH alloys. The amorphous alloy was stable, in particular when the ratio La:Ni was 1:2.     

Comments on the article ‘Thermodynamics of Na-based liquid binary alloys’

The discrepancy between results presented in the article ‘Thermodynamics of Na-based liquid binary alloys’ and the nature of such quantities as the heat of mixing and entropy of mixing as well as the discrepancy between results obtained and their interpretation in this paper are discussed. It is concluded that the model pseudopotential used in the work above is not useful for calculating the thermodynamic properties of liquid metal alloys as it is declared by authors of the aforementioned paper.