V. V. Kozik

High-yield microwave synthesis of layered Y2(OH)5NO3·xH2O materials

A novel, facile, and versatile microwave-assisted method of high-yield synthesis of layered rare earth hydroxo compounds (LRHs) is proposed. Layered yttrium hydroxonitrates synthesized by the microwave-assisted technique crystallize in the form of thin hexagonal plates aggregated into spheroidal particles. Depending on the conditions of microwave-assisted hydrothermal synthesis, the formation of several phases differing in interplanar spacing along the [00l] direction is possible. The materials obtained are shown to possess good anion-exchange properties. This work provides a route to large-scale synthesis of LRH-based advanced materials.

Gas-sensing properties of antimony-doped SnO2

We report a physicochemical study of the formation of thin-film and particulate SnO2〈Sb〉 materials from film-forming solutions of Sn(II) and Sb(III) complexes during heat treatment and describe the electrical and gas-sensing properties of the films. The particle size and antimony concentration are shown to have a significant effect on carbon monoxide adsorption by the synthesized materials.

Microwave synthesis of a photocatalytically active SnO-based material

Tin(II) oxide nanopowder has been prepared through microwave processing of an ammoniacal Sn6O4(OH)4 suspension, and the effect of synthesis duration on the surface morphology, acid-base properties, and photocatalytic activity of the SnO has been examined. The results demonstrate that the surface morphology plays a key role in determining the photocatalytic activity of powder SnO for methyl orange photo-degradation.

Synthesis and characterization of ZrO 2 thin films

Physicochemical processes involved in the preparation of zirconia thin films by sol-gel technology from film-forming solutions (FFSs) on the basis of zirconium oxochloride and ethanol were studied. The phase composition, structure, and properties of the films were determined.

Nanocrystalline ceria: a novel material for electrorheological fluids

We report on the preparation of novel electrorheological (ER) fluids based on a nanocrystalline ceria suspension in polydimethylsiloxane (PMS-20 silicone oil). Dielectric relaxation spectra of ER fluids were analyzed in the frequency range from 25 Hz to 106 Hz; the values of dielectric permittivity, dielectric loss tangents and tensile strengths of the prepared ER fluids in applied external electric fields up to 5 kV mm−1 were measured. Relaxation characteristics of the dielectric spectra were interpreted in terms of the Cole–Davidson model. The results obtained indicate that the ceria-based materials exhibit excellent ER performance, which depends strongly on the CeO2 concentration in the fluids. High tensile stress values (more than 20 kPa) were registered for ceria-based ER fluids in 5 kV mm−1 static electric fields.

Effect of citric acid and ethylene glycol on the formation of calcium aluminate via the sol-gel method

The processes of formation of calcium aluminate via the sol-gel method has been studied by IR spectroscopy, thermal analysis, X-ray powder diffraction, and scanning electron microscopy. The key stages of synthesis to obtain orthorhombic calcium aluminate (solvent removal, stepwise decomposition of the organic polymeric framework, and formation of crystalline aluminate) have been determined. The effect of the composition of the starting mixture on the formation process and the surface morphology of the final product has been demonstrated.

Thin SiO2–ZrO2Films Prepared from Solutions

Thin SiO2–ZrO2films were prepared from ethanolic solutions of Si(OC2H5)4and ZrOCl2 , and their refractive indices were measured. The storage behavior of the solutions and the reactions underlying the film-formation process were studied.

Film-Forming Capacity of Sn(II), Zr(IV), and Hf(IV) Acetylacetonates

Zr(acac)4, Hf(acac)4, and SnHacacCl2 · 2H2O were prepared in the solid state and in enthanol solutions. The film-forming capacity and thermal stability of these compounds were studied. Films of ZrO2, HfO2, and SnO2 were prepared from film-forming solutions of the corresponding acetylacetonates.

Photocatalytic activity of titania nanopowders prepared by a sol-gel process at various pHs

A strategy has been proposed to prepare photocatalytically active titania nanopowders through a sol-gel route using high-degree molecular separation upon the dilution of reagents, high water/alkoxide ratios, high reagent mixing rates, and pH effects. This strategy has been successfully used to isolate, from sols, anatase powders with high surface areas (100–310 m2/g) dependent on the pH value during the synthesis. The photocatalytic activity of titania nanopowders prepared by the sol-gel process at various pHs has been tested in photodestruction of organic dyes (Rodamine B, Methylene Blue, and Anthraquinone AcidBlue) in acid solutions. UV-radiation-induced dye destruction rates are found to depend on the surface properties (including surface area and ζ potential) and hydration specifics of the titania.

Composition and properties of CeO2-SiO2 composite films prepared from film-forming solution

This study focuses on the preparation and properties of CeO2-SiO2 thin films with thickness ≤60 nm that can be used as protective coatings for solar cell panels and electrochromic counter electrodes. Thin-film CeO2-SiO2 systems on glass and quartz substrates, which are manufactured from film-forming solutions based on cerium(III) nitrate, salicylic acid, and tetraethoxysilane and thermally treated, are mixtures of cerium(IV) (cubic modification) and silicon(IV) (amorphous phase) oxides. The films synthesized are distinguished by a net structure and high visible transmittance (∼90-100%). The morphology, phase composition, and optical properties of films were studied by X-ray diffraction, X-ray spectral microanalysis, scanning electron microscopy, spectrophotometry, and ellipsometry.