Reactive Ion Exchange Processes of Nonferrous Metal Leaching and Dispersion Material Synthesis

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала

Reactive Ion Exchange Processes of Nonferrous Metal Leaching and Dispersion Material Synthesis

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала

Synthesis of gelatin-stabilized concentrated hydrosols of copper nanoparticles

В работе изучено влияние реакционных условий (концентраций сульфата меди, гидразина, желатина, твердости желатина по Блуму, рН и температуры синтеза) на процесс формирования наночастиц меди при восстановлении сульфата меди (II) раствором гидразина. Найдены условия формирования устойчивых к окислению и агрегации концентрированных (0,4 М) гидрозолей металлической меди. По данным ПЭМ, полученные гидрозоли содержат сферические наночастицы металлической меди размером 30-60 нм, стабилизированные 2-3 нм слоем желатина

Synthesis of gelatin-stabilized concentrated hydrosols of copper nanoparticles

В работе изучено влияние реакционных условий (концентраций сульфата меди, гидразина, желатина, твердости желатина по Блуму, рН и температуры синтеза) на процесс формирования наночастиц меди при восстановлении сульфата меди (II) раствором гидразина. Найдены условия формирования устойчивых к окислению и агрегации концентрированных (0,4 М) гидрозолей металлической меди. По данным ПЭМ, полученные гидрозоли содержат сферические наночастицы металлической меди размером 30-60 нм, стабилизированные 2-3 нм слоем желатина

Effect of Polysaccharide Additions on the Anion-Exchange Deposition of Cobalt Ferrite Nanoparticles

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.A facile and rapid method easily reproducible in ordinary laboratory settings is proposed for preparing nanosized cobalt ferrite powders, where the precipitate used is a strongly basic anion exchange resin in the OH form. The effects caused by additions of polysaccharides having various chain natures and various molar weights on the composition, yield, and particle size of the deposition product are studied. Suggested mechanisms underlying these effects are studied. This method makes it possible to appreciably reduce the precursor annealing temperature compared to that in the state-of-art methods for preparing similar oxide systems due to the formation of highly reactive precursors. Optimal conditions are found to prepare stoichiometric precursors such that, once annealed at 600°C, would form a CoFe2O4 pure phase with particle sizes of 10–20 nm. The stability of hydrosols of the thus-prepared cobalt ferrite nanoparticles is studied by dynamic and electrophoretic light scattering. The prepared material is found to be useful for the design of magnetic core–shell hybrid nanostructures. © 2020, Pleiades Publishing, Ltd

ANION-EXCHANGE SYNTHESIS OF COPPER FERRITE POWDERS

Amethod is proposed for synthesizing copper ferrite, consisting in anion-exchange precipitation of copper (II) and iron (III) from solutions of their salts in the presence of tartrate ions as complexing agents followed by calcination of the obtained precipitate. The precursors and the products of their heat-treatment or studied by means of chemical, complex thermal and x-ray phase analyses, IR spectroscopy, scanning electron microscopy, and x-ray spectral microanalysis; the magnetic properties of the obtained samples were also studied. It was determined that a ferromagnetically ordered phase is present in the synthesized materials and their magnetic properties are close to those of bulk CuFe2O4

ANION-EXCHANGE SYNTHESIS OF YTTRIUM-ALUMINUM GARNET POWDERS

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On the nature of citrate-derived surface species on Ag nanoparticles: insights from X-ray photoelectron spectroscopy

Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles 3 immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag+ ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered