The enthalpies of formation of natural and synthetic nanotubular chrysotile

The thermochemical properties of natural chrysotile-asbestos and synthetic nanotubular chrysotile were studied on a high-temperature heat conducting Tian-Calvet microcalorimeter. The enthalpies of their formation from the elements at 298.15 K were determined by mélt solution calorimetry at 973 K. The Δ_f H _el ^° (298.15 K) value obtained for natural chrysotile-asbestos was close to that reported in the literature. The enthalpy of formation of synthetic nanotubular chrysotile was determined for the first time. The relation between the microstructural features of nanotubes and calorimetric data is discussed.     

Specific Features of BiFeO3 Formation in a Mixture of Bismuth(III) and Iron(III) Oxides

Active formation of BiFeO₃ was observed at temperatures exceeding the temperature limit of its stability. The process mechanism was elucidated.     

Kinetics of Ruddlesden-Popper Phase Formation: III. Mechanism of Gd2SrAl2O7 Formation

Studies on phase formation in the system Gd₂O₃-SrO-Al₂O₃ in the range 900-1530°C showed that the synthesis of Gd₂SrAl₂O₇ occur by a mechanism differing from the mechanism of Ln₂SrAl₂O₇ formation (Ln = La, Nd, Sm), and the limiting stage is reaction between Gd₂O₃ and SrAl₂O₄.     

Formation of BiFeO<Subscript>3</Subscript> Nanoparticles Using Impinging Jets Microreactor

The influence of the reactants mixing in an impinging jets microreactor of the formation of singlephase nanocrystals of bismuth orthoferrite has been studied. The 30–100 nm amorphous particles are formed under the impinging jets microreactor conditions, which are converted in bismuth orthoferrite with mean crystallite size 17 nm at 420°С.     

Mass spectroscopic study of 2,5-dimethyl-4-benzoyl- and 2,5-dimethyl-4-benzylpyridine derivatives

The dissociative ionization of sixteen 4-benzoyl- and 4-benzylpyridine derivatives and their deuteroanalogs has been studied. An ortho effect, due to the benzoyl and benzyl radicals in the methyl group in the 5-position of the pyridine ring, has been detected. It has also been established that fragmentation of 4-benzoylpyridines substituted with a nitro group in the benzene ring leads to [M-OH]⁺ ions, due to the ortho effect, whereas fragmentation of 4-benzylpyridines leads to [M-C₆H₅R]⁺ ions. The probability of a given process depends on the position and nature of any substituent in the benzene ring; this makes it possible to identify different isomers in a given series of compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 810–816, June, 1987.     

Effect of surface melting on the formation and growth of nanocrystals in the Bi2O3-Fe2O3 system

Formation of nanocrystals in the Bi₂O₃-Fe₂O₃ system prepared by the co-precipitation of bismuth and iron hydroxides has been studied. The temperature of onset of the BiFeO₃ and Bi₂Fe₄O₉ nanocrystals formation is correlated with the melting point of the non-autonomous phases. The optimal temperature of BiFeO₃ and Bi₂Fe₄O₉ nanoparticles synthesis is 460–520 and 500–550°C, respectively.