E. P. Turevskaya

Bio: E. P. Turevskaya is an academic researcher from Moscow State University. The author has contributed to research in topic(s): Alkoxide & Crystal structure. The author has an hindex of 16, co-authored 41 publication(s) receiving 610 citation(s). Previous affiliations of E. P. Turevskaya include Russian Academy of Sciences.

Bimetallic alkoxides of niobium

Abstract: The formation of the I–III group metal alkoxoniobates has been studied using the physicochemical analysis method, namely the investigation of solubility isotherms for the M(OR) n -Nb(OR) 5 -ROH systems (M = Li, Ba, Sc, La; R = 2Et, Pr i ). The crystallization of the following complexes has been observed: LiNb(OEt) 6 ( I ), [LiNbO(OEt) 4 (EtOH)] 2 ( II ), [BaNbO(OEt) 5 (EtOH) 1,5 ] 4 ( III ), BaNb 2 (OPr i ) 12 (Pr i OH) 2 ( IV ) and LaNb 2 (OPr i ) 13 ( V ). It has been found that the bimetallic isopropoxide of Sc and Nb does not exist in the solid state. The oxo complexes II and III are formed on storage (or more rapidly on refluxing) of the solutions of non-oxo compounds in alcohols in the presence of dry air and are, in fact, the products of these compounds oxidation by oxygen. The structure of II is built of dimeric molecules with the metal-oxygen coer analogous to that of Ti 4 (OMe) 16 . The molecule of III is constructed around the [Ba 4 O 4 ] cubane-like unit, whose oxygen vertices are occupied by the oxo atoms of NbO(OEt) 5 octahedra. The structures of the molecules of IV, V and recently studied Nb(OPr i ) 5 are based on the common motif featuring the M 2 O 2 four-membered cycles in edge sharing octahedra. All the observed [NbMNb] units are non-linear, the molecule of V being asymmetric, for the central [LaO 6 ] octahedron is sharing simultaneously an edge with one [NbO 6 ] octahedron and a face with the other. The conditions leading to the formation of oxo groups and the influence of the latter on the complexation process have been discussed. The literature data on the existence of 3 d transition metals alkoxoniobates have not been confirmed. It has been found that interaction of Nb and Co or Ni isopropoxides takes place only due to preliminary microhydrolysis or pyrolysis and leads to formation of oxoalkoxoniobates.

Sol-Gel Derived Ferroelectric Thin Films: Avenues for Control of Microstructural and Electric Properties

Abstract: The paper presents short review of the works performed during the last few years in the field of the alkoxy-derived ferroelectric films. PZT films were prepared using titanium and zirconium alkoxides and Pb(CH3COO)2· 2H2O as precursors. Different way of lead acetate dehydration and the impact of lead excess in the precursor solutions on the properties of the PZT films are discussed. Trimetallic alkoxide systems Bi(OR)3-Ta(OR)5-ROH (R = Me, Et or i Pr) were studied as precursors for preparation of SrBi2Ta2O9 films. Films prepared from these solutions and annealed at the temperature between 700 and 750°C demonstrated the remanent polarization Pr* − P^r = 7–9 μC/cm2. Ba1-xSrxTiO3 films we applied from modified alkoxide solutions. Decomposition of the organic phase in the course of thermal treatment of the films is studied by IR-spectroscopy. The dependence of the dielectric permittivity of the films via the annealing temperature is reported. Preparation of LiNbO3, SrZr0.2Ti0.8O3, Zr0.8Sn0.2TiO4 is briefly discussed.

Synthesis, crystal and molecular structure of calcium oxo ethoxide, [Ca6(µ4-O)2(µ3-OEt)4(OEt)4]·14EtOH

Abstract: The hexanuclear complex of calcium oxo ethoxide ethanol solvate, [Ca6O2(OEt)8]·14EtOH 1 has been isolated after the prolonged refluxing of an ethanol solution of calcium ethoxide in the presence of the oxygen in air and studied by X-ray diffraction; the metal-oxygen framework is built of two [Ca4O4] cubes sharing a common [Ca2O2] face, which involves both oxo groups.

The structure of the crystal solvate of magnesium methoxide with methanol, Mg(OMe)2·3.5MeOH

Abstract: The X-ray diffraction study of the crystals deposited from the solution obtained by the reaction of magnesium with methanol allowed the formulation of the product as Mg(OMe)2·3.5MeOH (I). Its structure is built of the residues of four types, namely cubane [Mg4(μ3-OR)4(OR)4(ROH)8] neutral molecules, [Mg4(μ3-OR)4 (OR)2(ROH)10]2+ cations, [(RO)2H]− anions (R = Me) and eight crystallographically independent non-coordinated solvating methanol molecules. All residues are linked into a three-dimensional framework by means of a complicated hydrogen-bonding system. The crystal structure provides the basis for discussion of the possible mechanism of desolvation of I.

Nanocomposites: synthesis, structure, properties and new application opportunities

Abstract: Nanocomposites, a high performance material exhibit unusual property combinations and unique design possibilities. With an estimated annual growth rate of about 25% and fastest demand to be in engineering plastics and elastomers, their potential is so striking that they are useful in several areas ranging from packaging to biomedical applications. In this unified overview the three types of matrix nanocomposites are presented underlining the need for these materials, their processing methods and some recent results on structure, properties and potential applications, perspectives including need for such materials in future space mission and other interesting applications together with market and safety aspects. Possible uses of natural materials such as clay based minerals, chrysotile and lignocellulosic fibers are highlighted. Being environmentally friendly, applications of nanocomposites offer new technology and business opportunities for several sectors of the aerospace, automotive, electronics and biotechnology industries.

Aliphatic cyclic carbonates and spiroorthocarbonates as monomers

Abstract: In this review the synthesis and polymerization of aliphatic cyclic carbonates of different size and type are presented. The mechanisms of cationic, anionic, coordination and enzymatic polymerization of cyclic carbonates are discussed for obtaining polymers with well-defined structures and oligomers with reactive pendant and end groups. The reactions of cyclic carbonates with different nucleophilic reagents leading to products with CO2 retention or with decarboxylation are reported. Special attention has been paid to the synthesis and polymerization of spiroorthocarbonates, bicyclic acetals, which are the intermediates in the reaction of cyclic carbonates with cyclic ethers. The influence of the presence of neighboring groups such as methylene or epoxy groups on the polymerization mechanism of spiroorthocarbonates, as well as the volume expansion during polymerization is discussed. As a result of the above synthetic findings, a variety of novel materials have been developed with versatile applications in different fields such as biomedicine and electronics.

Magnetic, electronic, and structural characterization of nonstoichiometric iron oxides at the nanoscale.

Abstract: We have investigated the structural, magnetic, and electronic properties of nonstoichiometric iron oxide nanocrystals prepared by decomposition of iron(II) and iron(0) precursors in the presence of organic solvents and capping groups. The highly uniform, crystalline, and monodisperse nanocrystals that were produced enabled a full structural and compositional survey by electron microscopy and X-ray diffraction. The complex and metastable behavior of nonstoichiometric iron oxide (wustite) at the nanoscale was studied by a combination of Mossbauer spectroscopy and magnetic characterization. Deposition from hydrocarbon solvents with subsequent self-assembly of iron oxide nanocrystals into superlattices allowed the preparation of continuous thin films suitable for electronic transport measurements.

Sol−Gel Materials in Electrochemistry

Abstract: The subject of sol−gel electrochemistry is introduced, starting with a brief account of milestones in its evolution. Then, the types of sol−gel materials that are useful for electrochemistry are presented, followed by a description of recent advances in the various fields of sol−gel electrochemistry. Modified electrodes, solid electrolytes, electrochromic devices, and corrosion protection coatings are described. Emerging fields such as RuO2 supercapacitors and electrochemical synthesis of sol−gel precursors are also addressed.