Forms of iron occurrence in a series of binary tellurides Fe<Subscript>x</Subscript>Ti<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Te<Subscript>1.45</Subscript>

Nonstoichiometric tellurides Fe_xTi_1–x Te_1.45 synthesized at 850°C were studied by X-ray phase and X-ray fluorescence analysis and by ⁵⁷Fe Mössbauer spectroscopy. The mutual iron-titanium substitution is limited in this series. The system contains four individual phases in which iron is in three different states: Fe²⁺ in an asymmetric environment, Fe²⁺ in a symmetric environment, and Fe⁰. The distribution of various iron states in the system depends not only on the Fe : Ti ratio, but also on the structure of phases.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1761–1764.Original Russian Text Copyright © 2004 by Pankratova, Zabolotnaya, Panchuk, Semenov, Zvinchuk, Suvorov.This revised version was published online in April 2005 with a corrected cover date.     

The use of a diammonium salt in the synthesis of organic carbonates from epoxides and CO2: promoting effect of support

Russian Chemical Bulletin - Onium salt, N1, N1, N1, N5, N5, N5-hexaethylpentane-1,5-diammonium dibromide, was used as a catalyst for the addition of CO2 to epoxides. An influence of insoluble...     

Sodium and potassium halides as catalysts for the addition of carbon dioxide to epoxides: the effect of co-solvents

A complex study of sodium and potassium halides as catalysts of the addition of CO₂ to epoxides to yield organic carbonates was carried out. The activity of these metal iodides was investigated. The conditions allowing achievement of a quantitative conversion of epoxides into carbonates were found by varying the temperature, carbon dioxide pressure, and available co-solvents.

     

Iodine as an efficient and available activator of sodium and potassium halides in carbon dioxide addition to epoxides

Sodium and potassium halides in combination with molecular iodine are efficient catalysts for the solvent-free addition of CO₂ (10–56 atm) to epoxides giving organic carbonates.

     

Cation Distribution and Interatomic Interactions in Oxides with Heterovalent Isomorphism: V. Complex Aluminates LnCaAl3O7

A short-range ordering of lanthanide and calcium atoms was found in isomorphous La^{3 +} and Ca^{2 +} cations in stoichiometric oxides LnCaAl₃O₇ (Ln = La, Nd, Sm, Gd, Ho, Er). It takes place almost exclusively within the first cation coordination sphere. The cations form electrostatically linked mixed cation pairs Ln^{3 +}-Ca^{2 +} in the nearest neighboring points of a common structural site. No spatial ordering of the pairs themselves is observed.     

Amine-Iodine Adducts as Simple but Effective Catalysts for the Synthesis of Organic Carbonates from Epoxides and CO2

Catalysis Surveys from Asia - New catalysts prepared by simple mixing of molecular iodine and inexpensive monodonor amines can efficiently catalyze the coupling of CO2 with different epoxides at...     

Features of phase formation and state of iron in the quasibinary system FeTe1.65-TiTe1.65

A series of tellurides Fe_xTi_1?x Te_1.65 (x = 0, 0.1, 0.2 …, 1.0) synthesized at 850°C were studied by X-ray phase and X-ray fluorescent analysis and Møssbauer spectroscopy on ⁵⁷Fe. In this series two solid solutions are formed: phases I and II with homogeneity regions within the limits of 0 ≤ x ≤ 0.3 and 0.9 ≤ x ≤ 1.0, respectively. Iron in this series exists in two various states: Fe²⁺ _sym and Fe²⁺ _asym as differentiated from the series of tellurides Fe_xTi_1?x Te_1.45 where three states of iron Fe²⁺ _sym, Fe²⁺ _asym, and Fe⁰ were found. On passing from Fe_xTi_1?x Te_1.45 to Fe_xTi_1?x Te_1.65 the number of formed phases decreases, and phase relations become simpler. The absence of Fe⁰ from phase I of tellurides Fe_xTi_1?x Te_1.65 can point to the fact that TiTe_1.45 and TiTe_1.65 belong to different homogeneity regions.     

Mössbauer Studies on the Quasibinary System FeTe1.45–TiTe1.45

Hyperfine Interactions - In this work the synthesis, powder XRD and Mössbauer studies of the quasibinary system FeTe1.45–TiTe1.45 were carried out. A series of nonstoichiometric...     

Thermal Decomposition of Ti<Subscript>5</Subscript>(Se,Te)<Subscript>8</Subscript> in Argon and Nitrogen Atmospheres

Chalcogenides TiSe_1.60−x Te_x (0 ≤ x ≤ 1.60), forming a continuous series of hexagonal solid solutions, were prepared by the direct ampule procedure. The thermal decomposition of TiSe_1.60−x Te_x was studied for the samples with x = 0, 0.16, 0.80, 1.44, and 1.60 in Ar and N₂ atmospheres in the course of heating from 25 to 1000°C. The selenide undergoes no weight loss under Ar, in contrast to the telluride which disproportionates and loses weight owing to the formation of volatile TiTe₂. At high temperatures, tellurides are more sensitive than selenides to the presence of nitrogen: The disproportionation is accompanied by the reaction of TiTe₂ with N₂, yielding low-volatile titanium nitride and free tellurium. Titanium selenide and telluride as components of the solid solutions behave similarly to the corresponding individual chalcogenides.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 7, 2005, pp. 1063–1067.Original Russian Text Copyright © 2005 by Pankratova, Zvinchuk, Suvorov, Hatanpaa, Kozlov, Leskela.