Центральная Научная Библиотека УрО РАН

Вид документа : Статья из журнала
Шифр издания : 54
Автор(ы) : Mikhalev K. N., Rebrin S. O., Gerashenko A. P., D'yachkova T. V.
Заглавие : 63,65Cu NMR study of low-frequency spin dynamics in the infinite-layer antiferromagnetic compound SrCuO2
Место публикации : JETP Letters (Translation of Pis'ma v Zhurnal Eksperimental'noi i Teoreticheskoi Fiziki). - 2004. - Vol. 80, № 8. - С. 540-543
Примечания : Библиогр. : с. 543 (15 назв.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): антиферромагнетики--ямр--медь
Аннотация: The spin–lattice and spin–spin relaxation times have been measured for 63,65Cu NMR in the infinite-layer antiferromagnet SrCuO2 in the ordered state for temperatures from 4.2 to 361 K. In the region of low temperatures (T£ 250 K), both relaxation processes are of the same nature and the main contribution to the relaxation rate is associated with the diffusion of a small number of holes with an activation energy of ~42 meV. In the hightemperature range (T 250 K), contributions to the transverse relaxation rate exhibit redistribution and this relaxation process is determined predominantly by indirect interactions
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Вид документа : Статья из журнала
Шифр издания : 54/K 93
Автор(ы) : Kurlov A. S., Gusev A. I.
Заглавие : Atomic-vacancy ordering in the lowest tungsten carbide W2C
Место публикации : Journal of Experimental and Theoretical Physics. - 2007. - Vol. 105, № 4. - С. 710-721
Примечания : Библиогр. : с. 721 (22 назв.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): атомно-вакансионное упорядочение--карбид вольфрама
Аннотация: Atomic–vacancy ordering in the lowest tungsten carbide W2C with an L'3-type basic hexagonal structure has been studied by neutron diffraction and X-ray diffraction. In the temperature range 2700–1370 K, the only ordered phase of the lowest tungsten carbide is shown to be the trigonal ε-W2C phase (space group P1m). This trigonal ε-W2 C phase is found to form via a disorder–order phase transition channel, which includes three superstructure vectors (k15(1), k15(2), k17(1) ) of two Lifshitz stars ({k15}, {k17}, and to be described by two long-range order parameters (η15,η17). The distribution function of carbon atoms in the trigonal ε-W2C superstructure is calculated, and the orresponding region of the allowable values of the long-range order parameters η15 and η17 is found. Symmetry analysis of other possible superstructures of the lowest tungsten carbide W2C is performed, and the physically acceptable sequence of phase transformations in W2 C is determined
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Вид документа : Статья из журнала
Шифр издания : 54/P 80
Автор(ы) : Polyakov E. V.
Заглавие : Behavior of Ionic and Colloid Forms of Microelements in Colloidal Chemical Extraction from Humic Acid Solutions
Место публикации : Radiochemistry. - 2007. - Vol. 49, № 4. - С. 432-438: il.
Примечания : Bibliogr. : p. 437-438 (44 ref.)
ISSN: 1066-3622
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): коллоидно-химическая экстракция--гуминовая кислота--растворы--микроэлементы
Аннотация: Speciation and extractability of humic acids (HAs) and humate complexes of microelements are studied using the colloidal chemical extraction method in combination with ICP MS with an example of natural mineral water with high HA concentration (800 -1200 mg l(1) collected from the Salekhard region. Joint extraction behavior of ionic and colloid forms of anionic and cationic species of a large number of microelements, including U(VI) and Th(IV), and HAs is examined at their natural abundance in mineral water, as influenced by pH and HA concentration. Humic acids proved to behave in natural water as a pool of ioncolloidal species, whose protonation results in precipitation at pH 2.0 -3.5. In this case, some chemical elements are sorbed on the resulting solid and may be separated along with HAs by colloidal chemical extraction into isobutanol. In natural humate solutions, a considerable fraction (10 -99 mol %) of chemical elements is associated with HAs in the form of colloid species extractable with isobutanol
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Вид документа :
Шифр издания : 54/C 91
Автор(ы) : Zhuravlev V. D., Zubkov V. G., Tyutyunnik A. P., Velikodnyi Yu. A., Koryakin N. D.
Заглавие : Crystal Structures of La1-xSr2+x(GeO4)(V1-xMoxO4) (x=0-0.4) Solid Solutions
Место публикации : Russian Journal of Inorganic Chemistry. - 2009. - Vol. 54, № 1. - С. 134-136: il.
Примечания : Bibliogr. : p. 136 (11 ref.)
ISSN: 0036-0236
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): ортованадат лантана--твердые растворы
Аннотация: The phase compositions of theLaVO4–SrMoO4(1) and Sr2GeO4–SrMoO4(2) binary systems, which bound the Sr2GeO4–LaVO4–SrMoO4(3) ternary system, and the LaSr2(VO4)(GeO4)– Sr2GeO4+SrMoO4 section (4) of system 3 are studied at subsolidus temperatures. Systems 1 and 2 consist of a mixture of the initial compounds, and the La1 –xSr2 + x(GeO4)(V1 – xMoxO4) (where 0 ≤ x ≤ 0.4) region of substitutional solid solutions with a palmierite structure is formed in system 3. The unit cell parameters of the solid solutions are determined. The distribution of the lanthanum and strontium cations over two positions of the cationic sublattice is described
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Вид документа : Статья из журнала
Шифр издания : 54/L 79
Автор(ы) : Lipatnikov V. N., Gusev A. I.
Заглавие : Dependence of the resistivity of nonstoichiometric titanium carbide TiCy on the density and distribution of carbon vacancies
Место публикации : Journal of Experimental and Theoretical Physics. - 1999. - Vol. 70, № 4. - С. P. 294-300: il.
Примечания : Bibliogr. : p. 300 (17 ref.)
ISSN: 0021-3640
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): нестехиометрия--карбид титана
Аннотация: The influence of temperature and of the density and distribution of structural vacancies in the carbon sublattice on the resistivity of nonstoichiometric titanium carbide TiCy (0.5y0.98) is studied. It is shown that in titanium carbide TiCy with y,0.7 reversible disorder– order structural phase transitions occur at temperatures below 1000 K. The temperatures of order–disorder phase transformations are determined. The dependence of the residual resistivity on the composition of the disordered titanium carbide is explained by the change in the carrier density in the region of homogeneity of the carbide TiCy , on the one hand, and the atom–vacancy interaction, on the other
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Вид документа : Статья из журнала
Шифр издания : 54/S 98
Автор(ы) : Lipatnikov V. N., Zueva L. V., Gusev A. I., Kottar A.
Заглавие : Disorder-order phase transformations and electrical resistivity of nonstoichiometric titanium carbide
Место публикации : Physics of the Solid State. - 1998. - Vol. 40, № 7. - С. 1211-1218
Примечания : Bibliogr. : p. 1218 (30 ref.)
ISSN: 1063-7834
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): карбид титана--нестехиометрия--фазовый переход--электросопротивление
Аннотация: Phase transformations of the disorder-order type in the homogeneity region of nonstoichiometric titanium carbide TiCy (0.5y1.0) have been studied. It has been established that, depending on the actual composition of TiCy , there may form in it for T980– 1000 K a cubic or a trigonal ordered Ti2C phase (space groups Fd3m and R3¯m, respectively) and a rhombic ordered Ti3C2 phase (space group C2221). The effect of ordering on the electrical resistivity of the nonstoichiometric carbide TiCy was studied, and the temperatures of the reversible disorder-order equilibrium transitions determined. The ordering in titanium carbide is shown to be a first-order phase transition
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Вид документа : Статья из журнала
Шифр издания : 54/S 12
Автор(ы) : Sadovnikov S. I., Gusev A. I.
Заглавие : Effect of particle size on the thermal expansion of nanostructured lead sulfide films
Место публикации : Journal of Alloys and Compounds. - 2014. - Vol. 610. - С. 196-202.
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): нестехиометрия--тепловое расширение--размер наночастиц--сульфид свинца
Аннотация: The effect of particle size on the thermal expansion of nanostructured lead sulfide films produced by hydrochemical deposition has been studied. The coherent scattering region size and thermal expansion coefficients of PbS nanofilm have been measured depending on the annealing temperature in the interval 293–473 K and on the duration of annealing at a constant temperature of 423 K. It is found that the thermal expansion coefficient α of nanostructured PbS film is nearly twice as large as that of bulk lead sulfide. It is shown that the observed large difference in the coefficients α is due to the small size of PbS particles in the film that leads to the change of the phonon spectrum boundaries and to the growth of anharmonicity of atomic vibrations. The additional contribution to the thermal expansion coefficient caused by the small particle size in PbS nanofilm is estimated theoretically.
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Вид документа : Статья из журнала
Шифр издания : 54/E 43
Автор(ы) : Zainullina V. M., Zhukov V. P., Zubkov V. G., Tyutyunnik A. P.
Заглавие : Electronic structure and chemical bonding in Sr4Nb17O26
Место публикации : Journal of Structural Chemistry. - 1998. - Vol. 39, № 5. - С. 627-635: il.
Примечания : Bibliogr. : p. 634-635 (15 ref.)
ISSN: 0022-4766
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): оксониобат стронция--метод лмто
Аннотация: The electronic structure of oxoniobate Sr4Nb17026 is studied by the linear muffin-tin orbital (LMTO) method. It is shown that the high-energy conduction band consists of the Nb4d states and the hybridized valence band is formed by the Nb4d and 02p states. The band structure of this compound is characterized by superposition of the bands of the 2p states of perovskite oxygen atoms and the 4d states of monoxide niobium atoms. The degree of oxidation of the perovskite and monoxide niobium atoms is + 5 and + 2.56, respectively. Chemical bonding is analyzed using the electron localization function and model Hiickel calculations. The niobium-oxygen bond is shown to be the strongest. The Fermi level is localized in the vicinity of the bottom of the niobium antibonding state band, which explains the existence of Sr4-xNb17026 in the homogeneity region corresponding to 0 x 0.3
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Вид документа : Статья из журнала
Шифр издания : 54/S 53
Автор(ы) : Shein I. R., Medvedeva N. I., Ivanovskii A. L.
Заглавие : Electronic structure of silver-deficient hexagonal AgB2
Место публикации : arXiv.org, e-Print Archive, Condensed Matter. - 2004. - С. 6 pp.: il.
Примечания : Bibliogr. : p. 3 (26 ref.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): структура электронная--борид серебра--нестехиометрия
Аннотация: Electronic structure and cohesive properties of metastable hexagonal AgB2 and silver-deficient borides Ag0.875B2 and Ag0.750B2 were investigated by means of the projected augmented wave method in the framework of the density functional theory (VASP package). We found that the density of states at the Fermi level for nonstoichiometric diborides is almost constant within a range of vacancy content up to 25%. The formation energy of metal vacancies in silver diboride is the least among all 4d metal diborides, i.e. for AgB2 is possible to expect the wide homogeneity region
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10.

Вид документа : Статья из журнала
Шифр издания : 54/G 51
Автор(ы) : Vyatchina V. G., Perelyaeva L. A., Zuev M. G., Mamoshin V. L., Baklanova I. V.
Заглавие : Glass formation and vibrational spectra of glasses in the RSO4-Na2B4O7-K2SO4 (R = Mg, Ca, Sr, Ba) systems
Место публикации : Glass Physics and Chemistry. - 2006. - Vol. 32, № 6. - С. 634-637
Примечания : Библиогр. : с. 637 (10 назв.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Аннотация: The regions of glass formation in the RSO4-Na2B4O7-K2SO4 (R = Mg, Ca, Sr, Ba) systems are determined. These regions are completely concentrated in the borate-rich region of the concentration triangle and occupy approximately 20% of the triangle area. The IR and Raman spectra of the glasses under investigation are recorded. It is revealed that the vibrational spectra of the glasses depend on the type of alkaline-earth metal cation. It is assumed that the structure of the glasses is determined by the glass-forming borate motifs with embedded sulfate anion tetrahedra.
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11.

Вид документа : Статья из журнала
Шифр издания : 54/G 51
Автор(ы) : Vyatchina V. G., Perelyaeva L. A., Zuev M. G., Mamoshin V. L.
Заглавие : Glass Formation and Vibrational Spectra of Glasses in the SrSO4–KPO3–Na2B4O7 System
Место публикации : Glass Physics and Chemistry. - 2003. - Vol. 29, № 6. - С. 522-525: il.
Примечания : Bibliogr. : p. 524-525 (10 ref.)
ISSN: 1087-6596
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): стекла фосфатные--стеклообразование--системы сульфатоборатные
Аннотация: The glass formation region in the SrSO4–Na2B4O7–KPO3 system is determined for the first time. This region occupies 31.8% of the concentration triangle predominantly in the polyphosphate region. The boundary of the glass formation lies along the binary line connecting the sodium tetraborate and potassium metaphosphate regions and reaches compositions with 40 mol % SrSO4. Along the line connecting the potassium phosphate and sodium tetraborate regions, the glass formation at 10 mol % SrSO4 is bounded by the 0.1SrSO4–xNa2B4O7–(0.9 – x)KPO3 join (the Na2B4O7–KPO3 binary join is vitrified completely). From analyzing the IR and Raman spectra, it is assumed that the structure of the glasses under investigation is formed by lattices of two types, namely, the sulfate phosphate and borate lattices
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12.

Вид документа : Статья из журнала
Шифр издания : 54/L 96
Автор(ы) : Kiiko V. S., Makurin Yu. N., Safronov A. A., Enyashin A. N., Ivanovskii A. L.
Заглавие : Luminescence of a transparent alumina ceramic doped with chromium and titanium
Место публикации : Refractories and Industrial Ceramics. - 2003. - Vol. 44, № 2. - С. 94-98: il.
Примечания : Bibliogr. : p. 98 (12 ref.)
ISSN: 1083-4877
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): люминесценция--хром--титан--керамика
Аннотация: Specimens of transparent alumina ceramic (TAC) are prepared by slip casting. An alumina spinel, formed during sintering under vacuum or under reducing conditions, as well as individual phases, produced by thermochemical doping with chromium and titanium, are identified. The spectra of steady-state x-ray luminescence (SXL) and pulsed cathodoluminescence (PCL) and the PCL decay kinetics are studied. The highest STL and PCL intensity were observed in specimens that were prepared by thermal diffusion using a carbon +TiO2 pack. Ti-doped TAC, characterized by a rapid decay of luminescence in the UV region, can be recommended as a promising material for the detector of a scintillation dosimeter. The luminescent chromium ions (isomorphic substituents of aluminum ions in the crystal lattice) are unsuitable for that purpose because of their long luminescence de-excitation time
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13.

Вид документа : Статья из журнала
Шифр издания : 54/G 96
Автор(ы) : Gusev A. I.
Заглавие : of NonstoichiometricEffect of Carbon Vacancies on the Electric Resistivity of Nonstoichiometric VCy Vanadium Carbide
Место публикации : JETP Letters. - 2009. - Vol. 90, № 3. - С. 191-196: il.
Примечания : Bibliogr. : p. 196 (21 ref.)
ISSN: 0021-3640
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): нестехиометрия--карбид ванадия--электросопротивление
Аннотация: The influence of the temperature, concentration, and distribution of structure vacancies of the carbon sub lattice on the electric resistivity ρ of nonstoichiometric VCy vanadium carbide (0.66 ≤ y ≤ 0.875) has been studied in the temperature range of 300–1200 K. The symmetry and structure characteristics of the ordered V6C5 and V8C7 phases formed owing to low temperature annealing on various sections of the homogeneity region of the VCy carbide. The dependence of the residual electric resistivity on the content of the disordered vanadium carbide is explained by the atom–vacancy interaction and the change in the carrier concentration in the homogeneity region of VCy
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14.

Вид документа : Статья из журнала
Шифр издания : 54/O-69
Автор(ы) : Lipatnikov V. N., Gusev A. I., Ettmeier P., Lengauer W.
Заглавие : Order-disorder phase transformations and specific heat of nonstoichiometric vanadium carbide
Место публикации : Physics of the Solid State. - 1999. - Vol. 41, № 3. - С. 474-480: il.
Примечания : Bibliogr. : p. 480 (25 ref.)
ISSN: 1063-7834
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): фазовые переходы--карбид ванадия
Аннотация: A study has been made of the order-disorder phase transformations in the homogeneity region of the VCy nonstoichiometric cubic vanadium carbide (0.66,y,0.88). It has been established that an ordered V6C5 phase with monoclinic ~space group C2/m) or trigonal (P31) symmetry, and a cubic ~space group P4332) ordered V8C7 phase can form in the VCy carbide below 1450 K, depending on the actual composition. The effect of off-stoichiometry and structural vacancy ordering on the specific heat of the VCy carbide has been investigated. The temperatures and heats of the reversible order-disorder equilibrium transitions have been determined. The ordering in the VCy carbide is shown to be a first-order phase transition. An equilibrium diagram of the V-C system taking into account ordering in the nonstoichiometric vanadium carbide has been constructed
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15.

Вид документа : Статья из журнала
Шифр издания : 54/V 18
Автор(ы) : Valeeva A. A., Rempel A. A., Gusev A. I.
Заглавие : Ordering of Cubic Titanium Monoxide into Monoclinic Ti5O5
Место публикации : Inorganic Materials. - 2001. - Vol. 37, № 6. - С. P. 603-612: il.
Примечания : Bibliogr. : p. 611-612 (30 ref.)
ISSN: 0020-1685
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): монооксид титана--нестехиометрия
Аннотация: The structures of ordered and disordered cubic TixOz= TiOy (y = z/x) phases containing both Ti and O vacancies were studied by x-ray diffraction. The results demonstrate that annealing TiOy with y = 0.9–1.1 below 1300 K leads to the formation of a monoclinic ordered Ti5O5 phase (sp. gr. C2/m (A12m/1)). Symmetry analysis of the monoclinic Ti5O5 superstructure indicates that the TiOy–Ti5O5 ordering transition is defined by the {k10} Lifshits and {k4} and {k1} non-Lifshits wavevector manifolds. The ordering is shown to be a firstorder transition accompanied by a decrease in the unit-cell volume of the parent lattice. The Ti and O distribution functions in titanium monoxide are calculated, and the Ti- and O-site near-neighbor environments in the monoclinic Ti5O5 superstructure are identified. The region of possible long-range-order parameters is outlined
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16.

Вид документа : Статья из журнала
Шифр издания : 54/O-97
Автор(ы) : Suntsov A. Yu., Leonidov I. A., Markov A. A., Patrakeev M. V., Blinovskov Ya. N., Kozhevnikov V. L.
Заглавие : Oxygen Nonstoichiometry and the Thermodynamic and Structural Properties of Double Perovskites PrBaCo2-xCuxO5+δ
Место публикации : Russian Journal of Physical Chemistry A. - 2009. - Vol. 83, № 5. - С. 832-838: il.
Примечания : Bibliogr. : p. 838 (11 ref.)
ISSN: 0036-0244
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): нестехиометрия--двойные перовскиты--рзм--барий
Аннотация: The special features of the structure, electrophysical properties, and oxygen nonstoichiometry of new double perovskites PrBaCo2 –xCuxO5 +δ were studied. Within the homogeneity region with respect to copper 0 x≤1, solid solution samples had an orthorhombic structure (space group Pmmm) with the parameters ap×2ap×2ap, where ap≈3.8Å. The oxygen nonstoichiometry of PrBaCo2 –xCuxO5 +δ changes as the copper content increases approximately as δ ≈0.85 –x/2. The content of oxygen was measured by coulometric titration over wide temperature and oxygen pressure ranges. The partial thermodynamic functions of labile oxygen were calculated and the limits of the thermodynamic stability of the solid solution were established
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17.

Вид документа : Статья из журнала
Шифр издания : 54/P 41
Автор(ы) : Nosov A. P., Rinkevich A. B., Vasil'ev V. G., Vladimirova E. V.
Заглавие : Penetration of High-Frequency Electromagnetic Field through Bulk Samples of La1-xSrxMnO3 (0.33≤x≤0.60) Manganites
Место публикации : The Physics of Metals and Metallography. - 2008. - Vol. 106, № 1. - С. 34-42: il.
Примечания : Bibliogr. : p. 41-42 (26 ref.)
ISSN: 0031-918X
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): манганиты--электромагнитные поля
Аннотация: —Penetration of radio-frequency electromagnetic field through bulk samples of La1 –xSrxMnO3(0.33≤x≤0.60) manganites has been studied in the frequency range from 20 kHz to 30 MHz at temperatures from 300 to 400 K, which includes the temperature of the magnetic phase transition of some investigated compositions. It has been shown that, in spite of the differences in the static properties, the dynamic properties of the investigated compositions of these manganites are similar; the differences are mainly pronounced at frequencies higher than 1 MHz. In the ferromagnetic range, significant changes in the transmission coeffiicient have been observed for all compositions upon magnetization. The magnitudes of the initial dynamic magnetic permeability have been estimated. The changes in the transmission coefficient in the ferromagnetic region are mainly caused by changes in the dynamic magnetic permeability rather than by agnetoresistance. It is shown that in the paramagnetic temperature range the magnitude of the dynamic reversible permeability exceeds unity for all compositions, which supports the assumption on the retention of local magnetic ordering
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18.

Вид документа : Статья из журнала
Шифр издания : 54/L 96
Автор(ы) : Luk'yanov S. A., Rempel S. V., Gusev A. I.
Заглавие : Phase diagram of V-C system in region of ordering of cubic vanadium carbide
Место публикации : Physics and chemistry of novel materials: 4th Bilateral Russian-German Symposium (Febr. 24-March 1, 1999): Progr. and abstr. - Ekaterinburg, 1999. - С. 2.18
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): диаграммы фазовые--фазовые диаграммы--v-c--карбид ванадия--нестехиометрия--металлы переходные--переходные металлы--беспорядок-порядок--v--ванадий
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19.

Вид документа : Статья из журнала
Шифр издания : 54/S 94
Автор(ы) : Surat L. L., Zuev M. G.
Заглавие : Phase Formation in the V2O5-Nb2O5-MoO3 System
Место публикации : Russian Journal of Inorganic Chemistry. - 2007. - Vol. 52, № 10. - С. 1617-1619: il.
Примечания : Bibliogr. : p. 1619 (9 ref.)
ISSN: 0036-0236
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): ниобий--системы оксидные--гидрокарбид ниобия
Аннотация: The solid-phase interaction in the V2O5–Nb2O5–MoO3 system has been investigated, and the formation of a solid solution bounded by the compositions MoNb2V4O18–δ,Mo2NbV5O21–δ, Mo2Nb3V3O21 – δ, and Mo4Nb9V9O57 – δ has been found (δ is nonstoichiometry). In the V2O5–Nb2O5 system, the formation of three compounds is verified, namely, VNbO5 (tetragonal structure), VNb9O25, and V2Nb23O62.5. The first two compounds are isostructural and form a continuous solid solution with tetragonal symmetry. A new compound of the composition Mo3NbVO14 – δ has been synthesized. This compound is isostructural to the Mo3Nb2O14 compound described in the literature and forms a tetragonal solid solution with it. The phase equilibria in the V2O5−Nb2O5–MoO3 system in the subsolidus region have been determined
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20.

Вид документа :
Шифр издания : 54/K 81
Автор(ы) : Krasil'nikov V. N.
Заглавие : Phase Ratios in the K2O-V2O4-SO3 System at High Sulfur Trioxide Concentrations
Место публикации : Russian Journal of Inorganic Chemistry. - 2007. - Vol. 52, № 2. - С. 258-262: il.
Примечания : Bibliogr. : p. 262 (15 ref.)
ISSN: 0036-0236
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): оксидные системы--ванадиевые катализаторы--триоксид серы
Аннотация: Phase ratios in the three-component oxide system K2O–V2O4–SO3 in the region of the sulfur trioxide concentrations corresponding to its concentrations in the active component of vanadium catalysts for SO2 to SO3 conversion have been studied using powder X-ray diffraction, IR spectroscopy, microscopy, and chemical analysis. Four individual compounds (K2VO(SO4)2, K2(VO)2(SO4)3, K2VO(SO4)2S2O7, and K2(VO)2(SO4)2S2O7) and K2(VO)2(SO4)2S2O7 and VOSO4-base solid solutions of composition K2(VO)2 + x(SO4)2 + xS2O7 (0 ≤ x ≤ 1.5) were found in the system. K2VO(SO4)S2O7 and K2(VO)2(SO4)2S2O7 lose their sulfur trioxide when heated above 350°C under an inert atmosphere, and convert to K2VO(SO4)2 and K2(VO)2(SO4)3, respectively. This implies that K2VO(SO4)2S2O7 and K2(VO)2(SO4)2S2O7, as well as K2(VO)2 + x(SO4)2 + xS2O7 solid solution, cannot exist in the active component of real industrial catalysts
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