Diagrams of the formation of In2S3 and In2Se3 films on vitroceramic upon precipitation, according to potentiometric titration

Boundary conditions and ranges of the formation of indium(III) sulfide and selenide upon precipitation by thiocarbamide and selenocarbamide are determined. Potentiometric titration of indium chloride (InCl₃) in the concentration range of 0.0001 to 0.100 mol/L by a solution of sodium hydroxide is performed. It is found that the following pH ranges are optimal for In₂S₃ and In₂Se₃ film precipitation: from 3.0 to 4.5 and from 9.0 to 14.0. Indium selenide layers 100 to 300 nm thick are prepared on vitroceramic by hydrochemcial precipitation.     

Chemical bath deposition of thin nanocrystalline tin(II) sulfide films with thioacetamide

Nanocrystalline tin(II) sulfide layers 100–650 nm thick were prepared by hydrochemical deposition on glass–ceramic supports from a citrate system at 323?343 K using thioacetamide as chalcogenizing agent. These films are of interest for the development of thin-film solar radiation converters based on the multicomponent compound Cu₂ZnSnS₄ of kesterite structure, prepared using a cost-saving process. Examination by scanning electron microscopy shows that tin(II) sulfide layers are formed from spherical nanocrystallites of 20–40 nm size. X-ray diffraction analysis shows that they crystallize in the orthorhombic system with the unit cell parameters a = 4.276, b = 11.243, and c = 3.986 Å. Analysis by X-ray photoelectron spectroscopy revealed the presence of up to 44.86 at. % oxygen in the surface layer of the film. This oxygen is mainly present in surface contaminants and is also incorporated in SnO present on the surface.     

Catalytic Properties and Structure of Palladium Surface Layer Formed in the Course of a Self-Oscillatory Reaction of Methane Oxidation

Kinetics and Catalysis - The self-oscillatory mode of methane oxidation over Pd foil at temperature of 400°C for 1 h caused the formation of a surface layer containing bulky porous...     

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.     

Comparison of Rate Oscillations in Reactions of CO and Methane Oxidation on a Nickel Catalyst

Self-oscillations of the rate of oxidation reactions of CO and CH₄ on nickel foil are compared. It has been shown that, despite significant differences in the stepwise mechanism of the two reactions, the properties of oscillation regimes are very close. In both reactions, oscillation regimes result from oxidation and reduction of nickel and are accompanied by wave processes on the catalyst surface. The similarity in the properties of rate oscillations in the reactions of CO and CH₄ oxidation shows that a change in the selectivity and the formation of carbon on the nickel surface are not key factors in the mechanism of the rate oscillations in CH₄ oxidation. An observed periodic change in the concentrations of reactants and reaction products when the reaction mixture is supplied in a pulse mode proves that, in both cases, the self-oscillations of the reaction rate are due only to the reaction mechanism and are not caused by a change in the catalyst temperature.     

Investigation of Nickel Surface Layers Formed in the Course of Self-Oscillatory Methane Oxidation

Kinetics and Catalysis - Self-oscillatory methane oxidation over Ni foil at 750°C for 1 h resulted in the formation of a porous layer with a depth of 10–12 μm. The layer depth did...     

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.     

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.     

Nanostructured copper(I) sulfide films: Synthesis,composition, morphology,and structure

Possibility of forming the solid phase of copper(I) and (II) sulfides in ammonia and acetate solutions at pH values exceeding 10 was demonstrated by calculation with the use of thiocarbamide. Mirror-like nanocrystalline layers of exclusively monovalent copper sulfide Cu₂S of stoichiometric composition with thicknesses of up to 110 ± 10 nm were formed on glass-ceramic substrates at 298–343 K via chemical deposition from solutions of both kinds due to the reducing properties of thiocarbamide. The films produced from the acetate system are more uniform and are constituted by globules (~10 nm) forming agglomerates up to 80–150 nm in diameter. According to X-ray diffraction data, they are crystallized in the chalcocite structure (space group P21/c) with crystal lattice constants a = 1.5307(5) Å, b = 1.1908(5) Å, c = 1.3485(6) Å, and β = 116.60(1)°.