Synthesis of Mg(Fe<Subscript>0.8</Subscript>Ga<Subscript>0.2</Subscript>)<Subscript>2</Subscript>O<Subscript>4</Subscript> by Gel Combustion Using Glycine and Starch

A powdery material Mg(Fe_0.8Ga_0.2)₂O₄ has been prepared by combusting a gel containing magnesium(II), iron(III), and gallium(III) nitrates and a glycine–starch mixture. The gel produced during the synthesis has been studied by thermal analysis (TGA/DSC) and IR spectroscopy. This mixture has been shown to be efficient to produce a homogeneous nanosized powderlike material Mg(Fe_0.8Ga_0.2)₂O₄. The morphology and properties of ceramic samples are characterized by scanning electron microscopy, X-ray powder diffraction, neutron diffraction, and vibrational magnetometry.     

Crystal structure and magnetic properties of nanosized Mg(Fe0.8Ga0.2)2O4-δ films on Si substrates

Film samples of nominal Mg(Fe_0.8Ga_0.2)₂O_4-δ composition were obtained on Si(100) substrates by oxygen-ion-beam sputtering of a Mg(Fe_0.8Ga_0.2)₂O_4-δ ceramic target. The film thicknesses were ～200 and ～400 nm. Field dependences of the specific magnetization of ～200-nm films annealed at different temperatures (800–1000°C) have been measured. The crystal structure, surface morphology, and magnetic characteristics of films of different thicknesses (～200 and ～400 nm) are investigated. The reasons for the discrepancy between the specific magnetizations of the films obtained and their ceramic analog are discussed.     

Dearomative (3+2) cycloaddition of 2-substituted 3,5-dinitropyridines and N-methyl azomethine ylide

Chemistry of Heterocyclic Compounds - 1,3-Dipolar cycloaddition of various 2-substituted 3,5-dinitropyridines and unstabilized N-methyl azomethine ylide has been studied. It was found that,...     

4,6-Dinitrobenzo[c]isothiazole: synthesis and 1,3-dipolar cycloaddition to azomethine ylide

1,3-Dipolar cycloaddition of 4,6-dinitrobenzo[c]isothiazole to (N-methyl-N-methylideneammonio)methanide (2 equiv.) gives 5,8-dimethyl-3b,6b-dinitrodecahydroisothiazolo[3,4-e]pyrrolo[3,4-g]isoindole, whose structure was confirmed by X-ray diffraction analysis.     

Synthesis of new 5‐acetyl(arylmethyliden)‐4‐thiazolidones

A new approach to the synthesis of new heterocyclic compounds with triazine and 4‐thiazolidone fragments in one molecule is developed. The synthesis methods comprise [2+3]‐cyclocondensation reactions essential in the preparative synthesis of 4‐thiazolidone derivatives. The reactions of S,N‐nucleophiles with C₂‐cyclization agents for the synthesis of a number of biologically active 2‐triazin‐4‐thiazolidones were investigated. The interaction of thiosemicarbazone of sym‐triazine with derivatives of α‐halogencarboxylic acids and maleic anhydride resulted in correspondent (2‐[2‐(4,6‐dichloro‐1,3,5‐triazin‐2‐yl)hydrazino]‐5‐(3,4,5‐ R‐p‐phenyl‐methyliden)‐1,3‐thiazol‐4‐ones obtained in the one‐step synthesis. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:392–396, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20631     

Initial stages of Ge epitaxy on Si(111) under quasi-equilibrium growth conditions

The results of the structural and morphological studies of Ge growth on a Si(111) surface at the initial stages of epitaxy by means of scanning tunneling microscopy and high-resolution transmission electron microscopy are presented. Epitaxy of Ge has been performed in the temperature range of 300 to 550°C under the quasi-equilibrium growth conditions and low deposition rates of 0.001–0.01 bilayers per minute. The stages of the formation and decay of the nanoclusters as a result of the redistribution of the Ge atoms into two-dimensional pseudomorphic Ge islands before the formation of the continuous wetting layer have been experimentally detected. The positions of the preferable nucleation of three-dimensional Ge islands on the wetting layer formed after the coalescence of the two-dimensional islands have been analyzed. The c2 × 8 → 7 × 7 → c2 × 8 phase transitions due to the lateral growth of the islands and the plastic relaxation of the misfit strains occur on the surface of the three-dimensional Ge islands when their strain state changes. The misfit dislocations gather at the interface and two types of steps lower than one bilayer are formed on the surface of the three-dimensional islands during the relaxation process.