O-69 Ordering of vacancies in vanadium monoxide of under-stoichiometric composition [Текст] / D. A. Davydov, S. Z. Nazarova, A. A. Valeeva, A. A. Rempel` // Izvestiya Rossiiskoi Akademii Nauk, Seriya Fizicheskaya. - 2007. - Vol. 71, № 5. - С. 701-704 Рубрики: ХИМИЧЕСКИЕ НАУКИ |
I-69 Interaction of copper nanoparticles with liposomes [Текст] / G. Yu. Ostaeva, A. A. Yaroslavov, E. D. Selishcheva, D. A. Davydov, I. M. Papisov // Vysokomolekulyarnye Soedineniya, Seriya A i Seriya B. - 2008. - Vol. 50, № 6. - С. 1098-1101 Рубрики: ХИМИЧЕСКИЕ НАУКИ |
D 26 Davydov, D. A. Some characteristics of fine beryllium particle combustion [Текст] / D. A. Davydov, O. V. Kholopova, B. N. Kolbasov // Journal of Nuclear Materials. - 2007. - № 367-370. - С. 1079-1084 Рубрики: ХИМИЧЕСКИЕ НАУКИ |
C 74 Concentration Phase Transition near the StoichiometricComposition of Vanadium Monoxide VO1.00 / D. A. Davydov, S. Z. Nazarova, A. A. Valeeva, A. A. Rempel // Bulletin of the Russian Academy of Sciences: Physics. - 2008. - Vol. 72, № 8. - P.1090-1093 : il. - Bibliogr. : p. 1093 (16 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): ФАЗОВЫЙ ПЕРЕХОД -- СТЕХИОМЕТРИЯ -- МОНООКСИД ВАНАДИЯ Аннотация: The concentration dependences of the magnetic susceptibility and lattice parameter of cubic vanadium monoxide have been measured in the composition range from VO0.81 to VO1.07. Near the stoichiometric composition VO1.00, the concentration dependences exhibit a stepwise increase in the specific magnetic susceptibility??(by approximately 0.7 X 10(-6) cm(3)/g) and lattice constant (by about 0.002 nm). These effects can be??related to the concentration phase transition, which occurs in vanadium monoxide with a change from a substoichiometric composition to superstoichiometric. At such a transition, along with a decrease in the concentration of oxygen vacancies, tetrahedrally coordinated vanadium interstitials are formed, as a result of which the??B1 structure changes to a more complex cubic phase structure with the same space group??Fm-3m \\\\Expert2\\nbo\\Bulletin of the Russian Academy of Sciences Physics\\2008, V. 72, N 8, P. 1090-1093.pdf |
O-69 Ordering of Structural Vacancies in Vanadium Monoxide of Substoichiometric Composition / D. A. Davydov, S. Z. Nazarova, A. A. Valeeva, A. A. Rempel // Bulletin of the Russian Academy of Sciences: Physics. - 2007. - Vol. 71, № 5. - P. 677-680 : il. - Bibliogr. : p. 680 (10 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): СТРУКТУРНЫЕ ВАКАНСИИ -- МОНООКСИД ВАНАДИЯ -- СТЕХИОМЕТРИЯ Аннотация: The order–disorder phase transition in vanadium monoxide of substoichiometric compositions VO y has been studied for the first time in situ by the Faraday method with a pendulum magnetic balance of the Domenically type. A minimum is found on the temperature dependence of the magnetic susceptibility of vanadium monoxide of different compositions at a temperature of about 700 K. X-ray diffraction analysis performed before and after measuring the magnetic susceptibility confirmed the change in the structure of vanadium monoxide and the possibility of atom–vacancy processes upon cooling and heating of the samples \\\\Expert2\\nbo\\Bulletin of the Russian Academy of Sciences Physics\\2007, V. 71, N 5, P. 677-680.pdf |
D 26 Davydov, D. A. Refinement of the V–O Phase Diagram in the Range 25–50 at % Oxygen / D. A. Davydov, A. A. Rempel // Inorganic Materials. - 2009. - Vol. 45, № 1. - P. 47-54 : il. - Bibliogr. : p. 53-54 (36 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): ОКСИД ВАНАДИЯ -- ФАЗОВЫЕ ДИАГРАММЫ Аннотация: The boundaries of the V14O6+VxOz two-phase region in the V–O system at temperatures from ~1050 to ~1650 K have been determined experimentally. The V–O phase diagram has been refined in the range 25–50 at % oxygen using structural and microstructural data for vanadium oxides containing less than 50 at % oxygen in conjunction with earlier results. The possibility of ordering of cubic vanadium monoxide has been examined Полный текст |
D 26 Davydov, D. A. Lattice Parameter, Density, and Defect System of VOy / D. A. Davydov, A. A. Rempel // Inorganic Materials. - 2009. - Vol. 45, № 6. - P. 666-670 : il. - Bibliogr. : p. 670 (13 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): МОНООКСИД ВАНАДИЯ -- ПЛОТНОСТЬ -- КРИСТАЛЛИЧЕСКАЯ РЕШЕТКА Аннотация: Vanadium monoxide, VOy has been studied within its homogeneity range using X-ray diffraction and pycnometric density measurements. The density and lattice parameter of VOy have been shown to vary in a complex manner with oxygen content near the stoichiometric composition VO 1.0. The experimental data have been used to evaluate the vanadium and oxygen vacancy contents in VOy . We assume that two cubic phases close in lattice parameter coexist near the composition VO1.0 and form a solid solution Полный текст |
M 65 Microstructure and Microhardness of Vanadium Oxides in the Range VO0.57-VO1.29 / A. A. Valeeva, D. A. Davydov, S. V. Rempel, A. A. Rempel // Inorganic Materials. - 2009. - Vol. 45, № 8. - P. 905-909 : il. - Bibliogr. : p. 909 (16 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): МИКРОСТРУКТУРА -- МИКРОТВЕРДОСТЬ -- ОКСИД ВАНАДИЯ Аннотация: X-ray diffraction and optical microscopy data are presented which demonstrate that substoichiometric vanadium oxide (VO0.57–VO0.97) consists of a cubic phase with the B1 structure (sp. gr.Fm m) and an ordered monoclinic phase of composition V14O6(sp. gr.C2/m). The content of the latter phase decreases with increasing oxygen content. The superstoichiometric vanadium oxide VO1.29 is shown to contain trace amounts of V52O64. Vickers microhardness data for nonstoichiometric vanadium oxides in the range VO0.57–VO1.29 show that, with increasing oxygen content, their HV has a tendency to decrease, from 18 to 12 GPa. Their microhardness is shown for the first time to have a maximum near the stoichiometric composition VO1.00 Полный текст |
G 96 Gusev, A. I. Monoclinic Superstructure V14O6 of the Tetragonal Solid Solution of Oxygen in Vanadium / A. I. Gusev, D. A. Davydov // JETP Letters. - 2007. - Vol. 86, № 10. - P657-661 : il. - Bibliogr. : p. 661 (14 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): ТВЕРДЫЕ РАСТВОРЫ -- ОКСИД ВАНАДИЯ -- МОНОКЛИННАЯ СВЕРХСТРУКТУРА Аннотация: The monoclinic (space group C2/m) superstructure of V14O6, which is formed in the atom–vacancy ordering of the tetragonal solid solution of oxygen in vanadium, is studied by the methods of x-ray diffraction and symmetry analysis. It has been found that the channel of the order–disorder phase transition attributed to the formation of the monoclinic suboxide V14O6 includes six superstructure vectors belonging to three non-Lifshitz stars {k1−1}, {k1–2}, and {k1–3} of one type {k1}. The distribution function of the O atoms in the V14O6monoclinic superstructure has been calculated. It has been shown that the displacements of V atoms distort the body-centered tetragonal metal sublattice, thus preparing the formation of the fcc sublattice and the transition from the suboxide V14O6 to the cubic vanadium monoxide with the B1 structure Полный текст |
G 96 Gusev, A. I. V52O64 Tetragonal Superstructure of Cubic Vanadium Monoxide with Vacancies in the Metal Sublattice / A. I. Gusev, D. A. Davydov // JETP Letters. - 2008. - Vol. 88, № 2. - P111-117 : il. - Bibliogr. : p. 117 (21 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): МОНООКСИД ВАНАДИЯ -- ТЕТРАГОНАЛЬНАЯ СВЕРХСТРУКТУРА -- НЕСТЕХИОМЕТРИЯ Аннотация: The atom–vacancy ordering of cubic vanadium monoxide VO1.29, which has basis cubic structure B1 and structural vacancies in the metal sublattice, has been studied using the x-ray diffraction method. It has been shown that the formation of the tetragonal (space group I41/amd) ordered phase V52O64 of cubic vanadium monoxide VOy proceeds as a first-order phase transition through the disorder–order channel including 22 nonequivalent superstructure vectors of four stars {k10}, {k4}, {k3}, and {k2}. The distribution function of the vanadium atoms in the V52O64 tetragonal superstructure has been calculated Полный текст |
D 26 Davydov, D. A. Neutron Diffraction Analysis of a Defect Vanadium Monoxide Close to the Equiatomic Vanadium Monoxide / D. A. Davydov, A. I. Gusev, A. A. Rempel // JETP Letters. - 2009. - Vol. 89, № 4. - P194-199 : il. - Bibliogr. : p. 198-199 (24 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): МОНООКСИД ВАНАДИЯ -- НЕСТЕХИОМЕТРИЯ Аннотация: Neutron and X-ray diffraction analyses are applied to studying the defect structure of synthesis-temperature quenched and low-temperature annealed vanadium monoxides VO (0.90≤y≤0.97) close to the equiatomic monoxide VO1.0. It is found that the monoxides VO0.90 and VO0.97 contain structural vacancies not only in the oxygen sublattice, but also in the metal sublattice. In addition to the cubic disordered phase VOy with the structure B1, the monoclinic superstructure V14O6 with space group C2/m is present in the synthesized VO0.90 sample and in the annealed VO0.90 and VO0.97 samples. The formation of the V14O6 superstructure is attributed to the ordering of oxygen atoms and nonmetal vacancies in the lattice of the tetragonal solid solution of oxygen in vanadium. No simultaneous ordering of metal and oxygen vacancies in two sublattices of the cubic vanadium is observed Полный текст |
D 26 Davydov, D. A. DO3-Type Cubic Structure of Nonstoichiometric Vanadium Monoxide / D. A. Davydov, A. I. Gusev // JETP Letters. - 2010. - Vol. 91, № 6. - P286-291 : il. - Bibliogr. : p. 291 (19 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): МОНООКСИД ВАНАДИЯ -- НЕСТЕХИОМЕТРИЯ Аннотация: An X-ray diffraction study indicates that nonstoichiometric vanadium monoxide VOy ≡ VxOz (y = z/x) has a cubic structure of the DO3 type (space group Fm m), where vanadium atoms are not only at the 4(a) sites of the metal fcc sublattice, but also at the tetrahedral 8(c) sites. This circumstance fundamentally distinguishes monoxide VOy from strongly nonstoichiometric MXy compounds with the B1 structure and the same space group, where atoms M and X and structural vacancies and of the metal and nonmetal sublattices, respectively, are distributed over the 4(a) and 4(b) sites. The dependence of the filling factor q of the tetrahedral interstices by vanadium atoms on the relative content y of oxygen in VOy has been obtained. It has been shown that the composition of cubic vanadium monoxide should be represented as VOy ≡ VxOz ≡ Vx – 2q 1 – x + 2qOz 1 –z, taking into account the structure Полный текст |
D 26 Davydov, D. A. The Disorder–Order Transition in Cubic Vanadium Monoxide with Vacancies in the Metal Sublattice / D. A. Davydov, A. I. Gusev // Journal of Experimental and Theoretical Physics. - 2009. - Vol. 108, № 2. - P267-278 : il. - Bibliogr. : p. 277-278 (22 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): МОНООКСИД ВАНАДИЯ -- ПЕРЕХОД БЕСПОРЯДОК-ПОРЯДОК -- НЕСТЕХИОМЕТРИЯ Аннотация: The disorder–order transition in cubic vanadium monoxide VOy(y= 1.29, 1.30) possessing a B1 type structure and containing vacancies only in the metal sublattice has been studied by X-ray diffraction and symmetry analyses. It is established that the formation of a tetragonal (space group l41/amd) ordered V52O64phase in cubic vanadium monoxide VOyproceeds in the form of the first-order phase transition via a channel involving 22 nonequivalent superstructural vectors of four stars ({k10}, {k4}, {k3}, and {k2}). The distribution function of V atoms in the tetragonal V52 O64 superstructure is calculated, and it is found that the real ordered V51.6O64phase exhibits significant atomic displacements. The boundaries of the domain of existence of the V52O64 phase at 54–60% O are determined in the phase diagram of the V–O system Полный текст |
D 26 Davydov, D. A. Ordered Monoclinic Vanadium Suboxide V14O6 / D. A. Davydov, A. I. Gusev // Physics of the Solid State. - 2009. - Vol. 51, № 1. - P156-164 : il. - Bibliogr. : p. 164 (22 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): ОКСИД ВАНАДИЯ -- МОНОКЛИННАЯ СВЕРХСТРУКТУРА -- ТВЕРДЫЕ РАСТВОРЫ Аннотация: The monoclinic (space group C2/m) superstructure of the suboxide V14O6, which is formed as a result of the atomic and vacancy ordering of the tetragonal solid solution of oxygen in vanadium, is investigated using X-ray diffraction and symmetry analysis. The monoclinic suboxide V14O6 is observed in the vanadium oxide samples VO0.57, VO0.81, and VO0.86 synthesized at 1770 K and the samples VOy(0.87≤y≤0.98) additionally annealed at 1470 K after the synthesis. It is established that the channel of the disorder–order phase transition associated with the formation of the monoclinic suboxide V14O6 includes six superstructure vectors belonging to three non-Lifshitz stars of one type {k1}. The distribution function of the oxygen atoms in the monoclinic superstructure of the suboxide V14O6 is calculated. It is demonstrated that the displacements of vanadium atoms distort the body-centered tetragonal metal sublattice, thus preparing the formation of the facecentered cubic sublattice and the transition from the suboxide V14O6 to the cubic vanadium monoxide with the B1 structure Полный текст |
D 63 Disintegration of a Coarse-Grained Vanadium Monoxide VOy Powder / A. A. Valeeva, D. A. Davydov, H. Schröttner, A. A. Rempel // Technical Physics. - 2009. - Vol. 54, № 11. - P1618-1621 : il. - Bibliogr. : p. 1621 (11 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): МОНООКСИД ВАНАДИЯ -- ПОРОШКИ Аннотация: A coarse grained powder of nonstoichiometric cubic vanadium monoxide VOy is disintegrated in a Retch PM 200 planetary ball mill. Milling of the coarse grained vanadium monoxide powder VOy at a rate of rotation of 500 rpm for 2 h significantly broadens diffraction lines, and the crystal structure of vanadium monoxide VO1.00 after milling remains the same. High resolution scanning electron microscopy and X-ray diffraction studies of the microstructure of vanadium monoxide demonstrate that high energy milling can produce vanadium monoxide powders with an average crystallite size of 23 ± 10 nm. The vanadium monoxide produced by milling has a crystallite size that is half the crystallite size in the titanium monoxide produced by severe plastic deformation Полный текст |