I. E. Obvintseva

Bio: I. E. Obvintseva is an academic researcher from Moscow State University. The author has contributed to research in topics: Tungsten & Molybdenum. The author has an hindex of 2, co-authored 5 publications receiving 72 citations.

Hydrolysis of molybdenum and tungsten alkoxides: sols, powders and films

Abstract: Hydrolysis of molybdenum and tungsten alkoxides of the two series MO(OEt)4 and MO2(OEt)2 (M = Mo, W) has been studied. Hydrolysis products and the partially hydrolyzed solutions have been characterized by means of X-ray diffraction, IR, electron spectroscopy and small-angle X-ray scattering. Preparation of stable sols is reported and their structures are discussed in terms of a fractal model. While ‘tungsten solutions’ may be described as typical polymeric sols, ‘molybdenum solutions’ should be regarded as particulate sols. The reason for this difference has its origin in the structures of alkoxides and mechanisms of their hydrolysis. Sols were used for the preparation of electrochromic and photochromic films by spin-coating techniques. A coloration mechanism is discussed in terms of the percolation model. Some properties of the composite structures WO3TiO2, n-SiWO3 are also reported.

Application of metal alkoxides in the synthesis of oxides

Abstract: Powders and thin films of the following simple and complex oxides have been obtained from metal alkoxides: MIITiO3 (M= Mg, Ca-Ba), MM1/3B2/3O3 (M= Sr, Ba, M' = Mg-Zn; B= Nb, Ta); MNbO3(M= Li, Na); ZrTiO4; PbTiO3; PZT, PLZT-materials; M2BO4 (M= Li, Na; B= Mo, W), Bi2BO6(B= Mo, W); LixWO3, WO3, MoO3, Bi2O3-WO3(solid solutions), YFeO3, Y3Fe5O12; YBa2Cu3O7-; Bi2Sr2CaCu2Ox; Bi2Sr2Ca2Cu3Ox. For synthesis of metal alkoxides and solutions containing two or more elements electrochemical technique (the anodic dissolution of metals in alcohols) has been used. Analysis of different examples emphasises that considerable attention in sol-gel chemistry of oxides should be paid to decomposition of M(OR)n with elimination of ether and formation of oxoalkoxides, containing M-O-M' bonds-the basis of future oxide phases.

Preparation of Powders and thin Films of Complex Oxides From Metal Alkoxides

Abstract: Preparation of complex oxides in the form of powders and thin films from metal alkoxides is discussed. Most attention is paid to ferroelectric and related materials - complex titanates and zirconates. Techniques for preparation of high-purity morphologically homogeneous powders Ti2, ZrO2 barium titanate and BaTiO3-based solid solutions, MgTiO3, Bi2WO6, Bi2MoO6 are proposed and discussed wilh respect to their application in ceramics technology. The solutions prepared electrochemically in methoxyethanol were widely used for formation of thin films, e.g. Y2O3-stabilized ZrO2 and PZT solid solutions on Pt-coated silicon substrates.

Photochromism of molybdenum oxide

Abstract: Molybdenum oxide can exhibit pronounced photochromism and thus might act as an excellent photonic material for a number of technical applications. In the early stage of the research, the attention was focused mainly on the (band) structure, photochromic mechanism and the behavior of the oxide. Later, many investigations were carried out on the factors that might influence the photochromic performance. At the same time, the photochromic response has been extended from UV light to visible light. In this review, the progress in all of these areas will be reviewed thoroughly.

Aerogels in catalysis

Abstract: Introduction Aerogels offer interesting opportunities for catalysis due to their unique morphological and chemical properties. These properties originate from their wet-chemical preparation by the solution-sol-gel (SSG) method and their subsequent liberation from the solvent via critical-point drying or supercritical (or hypercritical) drying (SCD). Due to the “structure-preserving” ability of SCD, the usually oxidic (or metallic) aerogels are solids of high porosity and specific surface area.

Industrial applications

Abstract: This first technical session is further developing the technological dimensions of technology transfer, with three illustrations of successful and representative industrial applications. It covers the cases of embedded autonomy in spacecraft applications, advanced avionics solutions for satellite communication and component hybridization for navigation.