Investigation on the Phase Diagram of LiCl-KCl-NdCl<Subscript>3</Subscript> Pseudo-Ternary System

The ternary phase diagram of LiCl-KCl-NdCl₃ system has been investigated by differential thermal analysis (DTA), followed by characterization of the coexisting phases in the solid state by x-ray diffraction, in order to understand the interactions in the NdCl₃-LiCl-KCl ternary system. The results of these experiments showed that LiCl and K₂NdCl₅ form a non binary join section. This divides the LiCl-KCl-NdCl₃ system into two quasi-ternary sections, namely (1) LiCl-KCl-K₂NdCl₅ and (2) LiCl-K₂NdCl₅-NdCl₃ systems. Both are simple eutectic ternary phase diagrams. The ternary eutectic temperatures and eutectic compositions are determined to be 316?±?3 °C and 53.9 mol.% LiCl-38.7 mol.% KCl-7.4 mol.% K₂NdCl₅ in the LiCl-KCl-K₂NdCl₅ quasi-ternary section, while the other eutectic temperature and composition are determined to be 376?±?9 °C and 46.2 mol.% LiCl-32.5 mol.% K₂NdCl₅-21.3 mol.% NdCl₃ in the LiCl-K₂NdCl₅-NdCl₃ quasi-ternary section. A quasi-ternary peritectic reaction is observed at 37.7 mol.% LiCl-36.2 mol.% KCl-26.1 mol.% K₂NdCl₅ at 445?±?1°C. The primary and secondary crystallization temperatures for the samples are deduced from the heating runs of DTA traces, and the phases responsible for the various thermal events are ascertained. Isothermal sections at chosen temperatures and polythermal liquidus projection with isothermal contours are drawn over the ternary phase field.     

Development of compositionally modulated multilayer Zn-Ni deposits as replacement for cadmium

Compositionally modulated multilayer (CMM) Zn-Ni deposits were electrodeposited from single acidic bath (pH = 4.7) by using a potentiostatic sequence. The Zn and Ni composition in the alloy was tailored as a function of distance from the steel substrate. X-ray diffraction studies of the deposit showed the presence of γ-phase with a composition of Ni₅Zn₂₁. The corrosion properties of modulated multilayer coatings were studied in 5% NaCl solution using electrochemical corrosion techniques. The polarization resistance of the deposits varied as a function of Ni content between 1700 and 3440 Ω. CMM Zn-Ni with 20 wt% Ni exposed in ASTM B117 salt spray test did not show any red rust formation after 400 h.     

Dielectric properties of DC reactive magnetron sputtered Al2O3 thin films

Alumina (Al₂O₃) thin films were sputter deposited over well-cleaned glass and Si < 100 > substrates by DC reactive magnetron sputtering under various oxygen gas pressures and sputtering powers. The composition of the films was analyzed by X-ray photoelectron spectroscopy and an optimal O/Al atomic ratio of 1.59 was obtained at a reactive gas pressure of 0.03 Pa and sputtering power of 70 W. X-ray diffraction results revealed that the films were amorphous until 550 °C. The surface morphology of the films was studied using scanning electron microscopy and the as-deposited films were found to be smooth. The topography of the as-deposited and annealed films was analyzed by atomic force microscopy and a progressive increase in the rms roughness of the films from 3.2 nm to 4.53 nm was also observed with increase in the annealing temperature. Al-Al₂O₃-Al thin film capacitors were then fabricated on glass substrates to study the effect of temperature and frequency on the dielectric property of the films. Temperature coefficient of capacitance, AC conductivity and activation energy were determined and the results are discussed.     

Influence of 2,6 (N-pyrazolyl)isonicotinic acid on the photovoltaic properties of a dye-sensitized solar cell fabricated using poly(vinylidene fluoride) blended with poly(ethylene oxide) polymer electrolyte

A novel method of introducing a synthesized organic nitrogenous compound 2,6 (N-pyrazolyl)isonicotinic acid (BNIN) and its effect on the conduction behavior of poly(vinylidene fluoride) (PVdF)–poly(ethylene oxide) (PEO) polymer-blend electrolyte with potassium iodide (KI) and iodine (I₂) and the corresponding performance of the dye-sensitized solar cells (DSSCs) were studied. A systematic investigation of the blends using FTIR provides evidence of interaction of BNIN with the polymer. Differential scanning calorimetry (DSC) study proves the miscibility of these polymers. Due to the coordinating and plasticizing effects of BNIN, the ionic conductivity of polymer blend electrolytes is enhanced. The efficiency of DSSC using BNIN doped polymer blend electrolyte was 7.3% under an illumination of 60 mW cm⁻² were observed for the best performance of a solar cell in this work.     

Viscosities of aluminum-rich Al−Cu liquid alloys

Viscosity data for Al−Cu liquid alloys in the ranges of 0≤C _L≤33.1 wt pct Cu and 1173≤T ≤973 K are reviewed. It was found that Andrade's equation can be used to represent the variation of viscosity with temperature for a given composition, but that each of the two parameters in Andrade's equation shows no systematic variation with composition of the liquid-alloys. Consequently, arithmetic averages of the parameters were used and assumed to apply to all compositions in the range 0≤C _L ≤33.1 wt pct Cu. Such a procedure implies that the viscosity happens to vary with composition solely because the specific volume varies with composition. In order to establish the predictability of extrapolating such simple behavior, a more complex model was considered. The latter model was recently presented by Kucharski and relates viscosity to the structure and thermodynamics of liquid alloys. Viscosities obtained by interpolating Andrade's equation and Kucharski's model compare closely; furthermore, values obtained by extrapolations to lower temperatures also compare favorably. Finally the simpler model was used to calculate the viscosity of the interdendritic liquid during solidification.     

Synthesis and characterisation of organosoluble polyimides containing the anisyl moiety

A new type of diamine monomer containing the anisyl moiety was synthesized via a straight‐forward one‐step procedure. Anisaldehyde was reacted with 2,6‐dimethylaniline in the presence of dry HCl to attain bis(4‐amino‐3,5‐dimethylphenyl)anisylmethane. A series of organo‐soluble polyimides were prepared using the anisyl diamine and various aromatic dianhydrides via a two step method involving thermal imidization. All polyimides are soluble in strong polar solvents such as N‐methyl‐2‐pyrollidone, N,N‐Dimethylformamide, and N,N‐DimethylAcetamide. The polyimides show excellent thermal stability and good mechanical properties. The glass transition temperatures of the polyimides are in the range 265–294 °C. The tensile strengths are in the range 79–99 MPa and the temperatures at which 10 % weight loss occurs are in the range 460–496 °C. Copyright © 2004 Society of Chemical Industry