Equilibria in a ZnCl2–H2O–NaOH System,According to Data from Potentiometric Titration,and Selecting Conditions for the Hydrochemical Synthesis of ZnS and ZnSe Films

Russian Journal of Physical Chemistry A - Equilibrium processes that occur in the ZnCl2–H2O–NaOH system are studied via the potentiometric titration of zinc chloride in the...     

Chemical sensors based on a hydrochemically deposited lead sulfide film for the determination of lead in aqueous solutions

Chemical sensors for determining lead in aqueous solutions are developed based on hydrochemically deposited lead sulfide (PbS) films; their composition and surface morphology are studied. The sensors are sensitive to lead to 31.5–32.5 mV/pc _Pb with the limit of detection of the metal 1.5 × 10^–8 M. The role of photoactivation and doping of films in increasing the sensitivity of the film sensor to lead is determined. The studied chemical sensors can be relatively easily regenerated by soaking in distilled water for 10–30 min; they have sufficiently high selectivity to lead in the presence of sodium, nickel, zinc, and cadmium salts in solution.     

Peculiarities of the Composition and Morphology of CdxPb1 – xS Films Formed on Various Substrates

Physics of the Solid State - Chemical deposition from aqueous solutions of films of substitutional CdxPb1 – xS solid solutions with a cubic B1 structure on substrates made...     

Deposition conditions,composition, and structure of chemically deposited In<Subscript>2</Subscript>Se<Subscript>3</Subscript> films

In₂Se₃ films up to 300 nm thick have been obtained for the first time by hydrochemical deposition on glass, glass ceramic, and molybdenum substrates in the In(NO₃)₃–C₄O₆H₆–CSeN₂H₄ system with the use of selenourea as a chalcogenizing agent. The phase and element composition and morphological features of layers obtained at 353 and 363 K have been studied by X-ray photoelectron spectroscopy, energy-dispersive electron probe X-ray microanalysis, and scanning electron microscopy. The optical band gap width has been determined.     

Temperature dependence of constants of thiourea hydrolytic decomposition and cyanamide. Stepwise ionization

By a combined calculation-experimental method the temperature dependence of the overall constant of the thiourea hydrolytic decomposition in alkaline medium in the range of 298–353 K was found. Potentiometrically ionization constants of cyanamide in the first and second stages, as well as the overall constant value at 298–343 K were determined.     

An Organomineral Composite Sorbent for Selective Recovery of Cu(II) from Aqueous Solutions

The phase composition, microstructure, and volume distribution of the dispersed lead sulfide phase in the matrix of the synthesized organomineral composite sorbent KU-2×8?PbS were studied. The cation exchanger granules are coated with a virtually continuous layer of lead sulfide up to 1.8–2.5 μm thick. In the volume of cation exchanger granules, the PbS phase forms discrete spherical particles with the mean diameter of 90–100 nm. Experiments on competing sorption of Cu(II) and Zn(II) from nitrate solutions revealed high selectivity of the sorbent to copper. Zinc concentrations of up to 0.004 mM do not noticeably affect the copper sorption, ensuring the possibility of separating the metals in the sorption step.     

Kinetics of precipitation and growth of thin indium(III) sulfide films

Thin films of indium(III) sulfide have been prepared by chemical precipitation from aqueous solutions containing indium(III) nitrate, thioacetamide, tartaric acid, and hydroxylamine hydrochloride at 333–368 K. Kinetics of In₂S₃ precipitation and the films growth under conditions of spontaneous formation of the solid phase in the solution has been studied. Formal rate law of indium(III) sulfide formation accounting for the partial orders of In₂S₃ precipitation with respect to the system components and the process activation energy has been derived. The effects of the reaction mixture composition, temperature, and the synthesis duration of In2S3 films growth have been studied.     

Conditions of hydrochemical synthesis, composition, and structure of tellurium films

Conditions of the hydrochemical synthesis of thin tellurium fi lms by reduction of an aqueous solution of tellurous acid with hydrazine were determined. The redox potentials of tellurous acid and hydrazine and their difference in relation to pH of the medium and concentration of tellurite ions were calculated. The kinetics of tellurium layer growth on glass-ceramic substrates and the structure, composition, and morphology of the layers were studied.     

Structure and composition of chemically deposited In2S3 thin films

Nanostructured thin indium(III) sulfide thin films 285–756 nm thick are obtained via chemical deposition from aqueous solutions containing indium chloride, thioacetamide, tartaric acid, and hydroxylamine hydrochloride at temperatures of 343–368 K. Oxygen- and carbon-containing impurities, which are not observed in the film bulk (at a depth of 12 nm), are detected in the surface layers of the films. When the synthesis temperature increases, the layer morphology changes substantially and the crystallite size increases from 70 to 150 nm. Upon annealing at a temperature of 573 K, crystallite aggregates are fused and In₂S₃ films are enriched with 6 to 10 at % of oxygen.