Formation of nanocrystalline BiFeO<Subscript>3</Subscript> under hydrothermal conditions

The formation of bismuth orthoferrite under hydrothermal conditions at temperature 160, 180, or 200°С and pressure 100 MPa in aqueous solution of potassium hydroxide has been studied. The determined composition and structure of polycrystalline phase with sillenite structure have evidenced its formation at the interface of the crystallites of amorphous iron oxide. It has been shown that the formation of polycrystalline round-shaped BiFeO₃ particles with size about 20 μm occurs via aggregation of perovskite-type phase crystallites (38–70 nm). Pycnometric density of BiFeO₃ and the amorphous phase has been determined, and Mossbauer spectra reflecting the state of iron in the phases coexisting during the formation of BiFeO₃ have been analyzed.     

Synthesis of solid solutions of double-layered Ruddlesden-Popper phases in the Gd2O3-SrO-Fe2O3-Al2O3 system

The continuous Gd₂Sr(Al_{1 ? x} Fe _x )₂O₇ solid solution series was synthesized by a solid-state route over the entire concentration range (0 < x < 1). The processing stages of Gd₂Sr(Al_{1 ? x} Fe _x )₂O₇ series were investigated, and phase interaction schemes reflecting the multistaged formation of double-layered Ruddlesden-Popper solid solution are constructed. The closeness of the reactive mixture composition to the composition of individual compounds Gd₂SrAl₂O₇ or Gd₂SrFe₂O₇ is of importance for the realization of a particular way of Gd₂Sr(Al_{1 ? x} Fe _x )₂O₇ solid solutions formation.     

Modeling of Molten Corium Oxidation in the Presence of an Oxide Crust on the Melt Surface

Technical Physics - In the case of a severe accident at a nuclear power plant with light-water reactors, the most effective method for localization of the formed melt (corium) is its retention in...     

Phase states in the Bi4Ti3O12-BiFeO3 section in the Bi2O3-TiO2-Fe2O3 system

Specific features of the thermal behavior of Bi _{m + 1}Fe _m−3Ti₃O_{3m + 3} layered perovskite-like compounds (where m takes integer and some fractional values between 3 and 9) were considered, and the temperature limits of stability of these compounds were determined. The phase diagram of the Bi₄Ti₃O₁₂-BiFeO₃ section through the Bi₂O₃-TiO₂-Fe₂O₃ system was constructed.     

Effect of laser processing on catalytic properties of shungite

A technique of improvement of catalytic activity of a shungite ultrafine powder by its processing by CO₂-laser radiation.     

Uniqueness of the solution of the inverse problem of magnetotelluric sounding for two-dimensional media

Uniqueness of the solution of the inverse problem of magnetotelluric sounding in two-dimensional media is proved under certain assumptions on conductivity.Translated from Metody Matematicheskogo Modelirovaniya, Avtomatizatsiya Obrabotki Nablyudenii i Ikh Primeneniya, pp. 231–242, 1986.     

Noncatalytic Regio- and Stereoselective Addition of Secondary Phosphines to Cyanoacetylenic Alcohols

Secondary phosphines regio- and stereoselectively add to 4-hydroxy-4-methyl-2-pentynenitrile, a typical and available representative of cyanoacetylenic alcohols, without catalyst at room temperature (THF, 3 h) to form (Z)-3-[dialkyl(aryl) phosphino]-4-hydroxy-4-methyl-2-pentenenitriles in 80–85% yields. These compounds relate to a new class of functionalyzed phosphines, promising ligands for the design of metal-complex catalysts.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 552–555.Original Russian Text Copyright © 2005 by Arbuzova, Shaikhutdinova, Gusarov, Nikitin, Mal’kina, Sukhov, Bogdanova, Trofimov.