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I. V. Arkhangelsky

Bio: I. V. Arkhangelsky is an academic researcher from Moscow State University. The author has contributed to research in topics: Thermal decomposition & Nitric acid. The author has an hindex of 5, co-authored 9 publications receiving 133 citations.

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TL;DR: The nonahydrate of iron(III) nitrate shows no phase transitions in the range of −40 to 0 ǫC as discussed by the authors, which is a different mechanism than those described for other trivalent elements.
Abstract: The nonahydrate of iron(III) nitrate shows no phase transitions in the range of −40 to 0 °C. Both hexahydrate Fe(NO3)3·6H2O and nonahydrate Fe(NO3)3·9H2O have practically the same thermal behavior. Thermal decomposition of iron nitrate is a complex process which has a different mechanism than those described for other trivalent elements. Thermolysis begins with the successive condensation of 4 mol of the initial monomer accompanied by the loss of 4 mol of nitric acid. At higher temperature, hydrolytic processes continue with the gradual elimination of nitric acid from resulting tetramer and dimeric iron oxyhydroxide Fe4O4(OH)4 is formed. After complete dehydration, oxyhydroxide is destroyed leaving behind 2 mol of Fe2O3. The molecular mechanics method provides a helpful insight into the structural arrangement of intermediate compounds.

72 citations

Journal ArticleDOI
TL;DR: In this article, a probable mechanism for the overall decomposition of Al(NO3)3·8H2O has been proposed based on the molecular mechanics method used for comparison of the potential energies of consecutive products of consecutive decomposition permits an evaluation of their structural arrangement.
Abstract: Thermal decomposition of aluminum nitrate hydrate was studied by thermogravimetry, differential scanning calorimetry, and infrared spectroscopy, so that all mass losses were related to the exactly coincident endothermic effects and vibrational energy levels of the evolved gases. The process starts with the simultaneous condensation of two moles of the initial monomer Al(NO3)3·8H2O. Soon after that, the resulting product Al2(NO3)6·13H2O gradually loses azeotrope HNO3 + H2O, then N2O3 and O2 and, through the formation of Al2O2(NO3)2, is transformed into aluminum oxide. The molecular mechanics method used for comparison of the potential energies of consecutive products of thermal decomposition permits an evaluation of their structural arrangement. On the basis of the results obtained, a probable mechanism for the overall decomposition of Al(NO3)3·8H2O has been proposed.

35 citations

Journal ArticleDOI
TL;DR: In this paper, it is assumed that the existence of intermediate structures with six atoms of samarium best fits the experimental results. But no traces of SmONO3 were detected.
Abstract: Thermal decomposition of samarium nitrate hexahydrate Sm(NO3)3·6H2O has been investigated by thermogravimetry, differential scanning calorimetry, infrared spectroscopy, and X-ray diffractometry. This is a complex process that involves slow dehydration and fast concomitant internal hydrolysis. It is markedly different from the processes described for other members of the lanthanide series. At the first stage, pyrolysis is accompanied by removal of water and nitric acid to form samarium pentahydrate Sm(NO3)3·5H2O and intermediate oxonitrates containing O–Sm–OH groups. No traces of SmONO3 were detected. It is assumed that the existence of intermediate structures with six atoms of samarium best fits the experimental results. At higher temperatures, these products undergo further degradation, lose nitrogen dioxide, water, and oxygen, and finally, after having lost lattice water, are transformed into a cubic form of samarium oxide.

19 citations

Journal ArticleDOI
TL;DR: The thermal decomposition of chromium nitrate nonahydrate was studied by thermal analysis, differential scanning calorimetry, infrared spectroscopy, and high temperature X-ray diffraction, so that mass losses were related to coincident endothermic effects and vibrational energy levels of the evolved gases as mentioned in this paper.
Abstract: Thermal decomposition of chromium nitrate nonahydrate was studied by thermal analysis, differential scanning calorimetry, infrared spectroscopy, and high temperature X-ray diffraction, so that mass losses were related to the exactly coincident endothermic effects and vibrational energy levels of the evolved gases. The thermal decomposition of chromium nitrate is a complex process, which begins with the simultaneous dehydration and concurrent condensation of 4 mol of the initial monomer Cr(NO3)3·9H2O. Soon after that, the resulting product Cr4N12O36·31H2O gradually loses water and azeotrope HNO3 + H2O, and is transformed into tetrameric oxynitrate Cr4N4O16. At higher temperatures, the tetramer loses N2O3 and O2 and a simultaneous oxidation of Cr(III) to Cr(IV) occurs. The resulting composition at this stage is chromium dioxide dimer Cr4O8. Finally, at 447 °C the unstable dimer loses oxygen and is transformed into 2Cr2O3. The models of intermediate amorphous compounds represent a reasonably good approximation to the real structures and a proper interpretation of experimental data.

17 citations

Journal ArticleDOI
TL;DR: In this article, the potential energies of consecutive products of thermal decomposition of scandium nitrate were compared for comparison of their stability and a proper interpretation of experimental data, and the structural modeling was aimed to provide detailed information about the bond lengths and bond angles.
Abstract: The thermal decomposition of scandium nitrate is a complex process, which begins with the simultaneous condensation of 4 mol of the initial monomer Sc(NO3)3·6H2O. The resulting cyclic tetramer Sc4O4(NO3)4·2H2O gradually loses azeotrope H2O–HNO3, and an intermediate oxynitrate Sc4O5(NO3)2 is formed. At higher temperature, this oxynitrate is destroyed leaving behind unstable dimer Sc4O6 which is transformed into scandium oxide. The molecular mechanics method used for comparison of the potential energies of consecutive products of thermal decomposition permits an evaluation of their stability and a proper interpretation of experimental data. The structural modeling was aimed to provide detailed information about the bond lengths and bond angles, filling the gap in what we know about amorphous oxynitrates. The models represent a reasonably good approximation to the real structures.

10 citations


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TL;DR: In this paper, the basics of crystallography and diffraction are described using instruction manuals, which are a good way to achieve details about operating certain products and can be found online.
Abstract: the basics of crystallography and diffraction are a good way to achieve details about operating certainproducts. Many products that you buy can be obtained using instruction manuals. These user guides are clearlybuilt to give step-by-step information about how you ought to go ahead in operating certain equipments. Ahandbook is really a user's guide to operating the equipments. Should you loose your best guide or even the productwould not provide an instructions, you can easily obtain one on the net. You can search for the manual of yourchoice online. Here, it is possible to work with google to browse through the available user guide and find the mainone you'll need. On the net, you'll be able to discover the manual that you might want with great ease andsimplicity

232 citations

Journal ArticleDOI
TL;DR: The nonahydrate of iron(III) nitrate shows no phase transitions in the range of −40 to 0 ǫC as discussed by the authors, which is a different mechanism than those described for other trivalent elements.
Abstract: The nonahydrate of iron(III) nitrate shows no phase transitions in the range of −40 to 0 °C. Both hexahydrate Fe(NO3)3·6H2O and nonahydrate Fe(NO3)3·9H2O have practically the same thermal behavior. Thermal decomposition of iron nitrate is a complex process which has a different mechanism than those described for other trivalent elements. Thermolysis begins with the successive condensation of 4 mol of the initial monomer accompanied by the loss of 4 mol of nitric acid. At higher temperature, hydrolytic processes continue with the gradual elimination of nitric acid from resulting tetramer and dimeric iron oxyhydroxide Fe4O4(OH)4 is formed. After complete dehydration, oxyhydroxide is destroyed leaving behind 2 mol of Fe2O3. The molecular mechanics method provides a helpful insight into the structural arrangement of intermediate compounds.

72 citations

Journal ArticleDOI
TL;DR: In this paper, the catalytic graphitization of kraft lignin to nano-materials was investigated over four transitional metal catalysts (Ni, Cu, Fe, and Mo) through a thermal treatment process under an argon flow at 1000°C.
Abstract: Catalytic graphitization of kraft lignin to nano-materials was investigated over four transitional metal catalysts (Ni, Cu, Fe, and Mo) through a thermal treatment process under an argon flow at 1000 °C. The catalytic thermal process was examined using thermal gravimetric analysis (TGA) and temperature-programmed decomposition (TPD) experiments. The crystal structure and morphology of the thermal-treated metal-lignin samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. Catalytic graphitization of kraft lignin to nano-materials was investigated over four transitional metal catalysts (Ni, Cu, Fe, and Mo) through a catalytic thermal treatment process. It was observed that multi-layer graphene-encapsulated metal nanoparticles were the main products, beside along with some graphene sheets/flakes. The particle sizes and graphene shell layers were significantly affected by the promoted metals. BET surface areas of samples obtained from different metal precursors were in the range of 88–115 m2/g within the order of Ni- > Fe- > Mo- > Cu-. Thermal gravimetric analysis (TGA) and temperature-programmed decomposition (TPD) experimental results showed that adding transitional metals could promote the decomposition and carbonization of kraft lignin. The catalytic activity increased with an order of Mo≅Cu < Ni≅Fe. XRD results show that face-centered cubic (fcc) Cu crystals is formed in the thermal-treated Cu-lignin sample, fcc nickel phase for the Ni-lignin sample, β-Mo2C hexagonal phase for the Mo-lignin sample and α-Fe, γ-iron, and cementite(Fe3C) for the Fe-lignin sample. Average particle sizes of these crystal phases calculated using the Scherrer formula are 52.4 nm, 56.2 nm, 21.0 nm, 23.3 nm, 11.3 nm, and 32.8 nm for Ni, Cu, β-Mo2C, α-Fe, γ-iron, and Fe3C, respectively. Raman results prove that the graphitization activity of these four metals is in the order of Cu < Mo < Ni < Fe. Metal properties such as catalytic activity, carbon solubility, and tendency of metal carbide formation were related to the graphene-based structure formation during catalytic graphitization of kraft lignin process.

63 citations