Tracer-diffusion of Zn2+ ions in cobalt sulphate

Tracer-diffusion of Zn²⁺ ions in the presence of CoSO₄ is studied at 25°C in 1% agar gel over a concentration range of 10^–5 to 0.25M using a zone-diffusion technique. The deviations observed between experimental and theoretical values of diffusion coefficients are explained by considering different types of interactions occurring in the ion-gel-water system. Further, study of the obstruction, effect in the diffusion of Zn²⁺ ions at different concentrations of CoSO₄ reveals that the -value decreases with increasing concentration of the electrolyte. This observation is accounted on the basis of competitive hydration between ions and agar molecules.     

Influence of preparation route and slip casting conditions on titania and barium titanate ceramics

Titania (TiO₂) and barium titanate (BaTiO₃) were synthesized using three different dicarboxylates, which included oxalate, malate and tartarate. These powders were characterized by X-ray powder diffraction, scanning electron micrographs, BET specific surface area and particle size distribution. Their properties depended to a great extent on the nature of the precursor. The titania and barium titanate powders obtained from the tartarate precursor were found to be good for slip casting. Slips of these oxides with different solids contents were prepared at different pH values using both distilled water and ethanol as the dispersing agent and also with and without deflocculant. The rheological behaviors of the suspensions were then determined, and the slip, green and sedimentation bulk densities were measured. The minimum viscosities were observed at pH 8.2 for the TiO₂–water and pH 10.2 for the BaTiO₃–water system.     

Activation energy of self-diffusion of zinc,chloride and chromate ions

Theoretical activation energy of self-diffusion of zinc, chloride and chromate ions has been computed on the basis of the Onsager and Arrhenius equations. These values are compared with the experimentally determined ones for the self-diffusion of Zn²⁺ ions in the present work as well as previously reported values for self-diffusion of Cl^– and CrO ₄ ^2– ions. A reasonably good agreement is observed between the two values.     

Electrolyte diffusion of ZnCl2 and self-diffusion of Cd2+ ions in agar gel medium at different temperatures

The values of activation energy required for the diffusion of ZnCl₂ and for Cd²⁺ ions in Cd/Ac/₂ are reported in agar gel medium at 5×10^–5 and 0.001M concentration, respectively. These values are compared with the previously reported values in the same systems at different concentrations. The decrease in activation energy with concentration of electrolyte is in agreement with the Wang's model.     

Synthesis and deposition of nanostructured SnS for semiconductor-sensitized solar cell

Journal of Solid State Electrochemistry - Structural, electrical, and optical properties of SnS nanoparticles and films deposited by ultrasound-assisted chemical bath were studied. The SnS was...     

Effect of supporting electrolyte on the activation energy for diffusion of some monovalent ions

The effect of some alkali metal bromides, iodides and sulphates on the diffusion of bromide, iodide and thallium ions, respectively, is studied at various temperatures. The activation energy required for the process of diffusion of these three ions in different supporting electrolytes have been calculated. It is found that activation energy for a given ion decreases in the reverse order of the charge density of alkali metal ions of the supporting electrolyte. This observed trend in activation energy is explained qualitatively by considering the distortion in the water structure caused by these ions and agar molecules.     

Tracer-diffusion of Zn2+ ions in some transition metal sulphates

Tracer-diffusion of Zn²⁺ ions is studied in zinc, manganese and copper sulphates over a concentration range of 10^–4 to 0.25M using 1% agar gel medium at 25 °C. A comparison of the experimental and theoretical values of tracer-diffusion coefficients shows a deviation from the theory. This is explained in the light of different types of interactions occurring in the ion-gel-water system. The effect of supporting electrolytes and its concentration on the obstruction effect in the tracer-diffusion of zinc ions is also examined. The obstruction effect decreases with increasing charge density of the cation of the electrolytes at a given concentration and for a particular elecrolyte it decreases with its concentration. These observations are accounted on the basis of competitive hydration between ions and agar macromolecules.     

Neutron activation analysis of manganese and nickel in commercial steel samples

The non-destructive thermal neutron activation analysis of some commercially available steel samples viz. SS-316, SS-310, SS-304, Tiscral, CA55 and EN 8 is carried out using a²⁵²Cf source. The manganese content of these steel samples is estimated by measuring the -activity of⁵⁶Mn using a single channel analyzer on integration mode and a NaI/Tl/ detector as well as using a high purity germanium detector coupled to a 4K multichannel analyzer. The results obtained by both procedures show reasonable agreement with each other. The nickel content of the various steel samples is also estimated.     

Electrical and humidity characterization of m-NA doped Au/PVA nanocomposites

The Meta-Nitroaniline (m-NA) doped (by varying weight percentage (wt. %)) gold/polyvinyl alcohol (Au/PVA) nanocomposites were synthesized using gold salt and hydrazine hydrate (HH) by in situ process. The composite was coated on ceramic rods having two end electrodes by drop casting method for studying their electrical behavior at different relative humidity (RH) levels, ranging from 4 to 95% RH at room temperature. The optimized wt. % was used to prepare coatings of various thicknesses (20-40 μm) of the films. As the humidity decreases, the resistance increases. The low humidity sensing characteristic can be tailored by varying wt. % of m-NA and thicknesses of the nanocomposite films. The resistive-humidity sensor shows two regions of sensitivity having highest sensitivity for lower RH. The sensor response and recovery time is about 6-10 s and 52 s respectively. The dynamic range of variation of the resistance allows a promising use of the films as a humidity sensor. The material was characterized by X-ray diffraction (XRD) and impedance spectroscopy at 60% RH.     

Preparation, characterization and non-linear optical properties of pristine m-nitroaniline (m-NA) and its recycled polystyrene (Re-PS) coated single crystals

Meta-nitroaniline (m-NA) is one of the organic single crystals extensively studied due to its high non-linear effect. m-NA is also known to exhibit comparable or even better non-linear optical (NLO) properties than known inorganic materials. In this paper, we report development of m-NA single crystals by solution growth technique using different solvent systems. The size of the single crystal varies depending on solvent. The highest average crystal size acquired was 10 mm×5 mm×5 mm using methyl ethyl ketone and acetone as solvent. These single crystals were characterized using various physico-chemical techniques such as XRD and scanning electron microscopy (SEM). The developed crystals were subsequently coated with recycled polystyrene (Re-PS) (1, 2, 5 and 10 wt% concentrations) to study the effect of polymer coating on the second harmonic generation (SHG) properties of the single crystals. The purpose of polymer coating on m-NA single crystal is to improve surface morphology of crystal (i.e. it makes surface smooth) and to enhance power handling capacity for pulse laser of a crystal which, in turn, improves the SHG intensity. The optimum percentage of coating was determined for the m-NA single crystals obtained from different solvent systems. Furthermore, the polymer coating also plays key role in preventing the degradation of the m-NA crystal (well-known as highly sublime material) and ultimately increasing the shelf life of the crystal for its device application.