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1.
Piotr Tabero 《Journal of Thermal Analysis and Calorimetry》2010,101(2):561-566
A new, previously unknown phase Al8V10W16O85 has been obtained from reaction taking place in the solid state. It forms continuous solid solution with Fe8V10W16O85 of the Fe8−x
Al
x
V10W16O85 general formula. All these phases are isostructural with M–Nb2O5 and (W0.35V0.65)2O5 and belong to a block structure phases with ReO3 type blocks of 4 × 4×∞ dimensions. Al8V10W16O85 is tetragonal and has the lattice constants a = b = 1.9487(1) nm and c = 0.36706(4) nm. It melts incongruently at 1,183 K depositing Al2(WO4)3 and WO3. The increase of the Al3+ ions content in the crystal lattice of Fe8V10W16O85 causes the melting point increasing, and decreasing of a = b unit cell parameters with c being almost constant. IR spectra of Al8V10W16O85 and Fe8−x
Al
x
V10W16O85 phases have been recorded. 相似文献
2.
M. A. Ryazanov B. N. Dudkin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(13):2318-2321
The distribution of the acid-base centers on the surface of α-Al2O3 suspension particles was studied by potentiometric titration, and the corresponding pK spectra were constructed. It was inferred that the double electric layer created by the supporting electrolyte substantially
affected the screening of the acid-base centers on the particle surface of the suspension. 相似文献
3.
Zh. S. Shukurov S. S. Ishankhodzhaev M. K. Askarova S. Tukhtaev 《Russian Journal of Inorganic Chemistry》2011,56(3):463-466
The solubility of components in the NaClO3 · 2CO(NH2)2-NH2C2H4OH · CH3COOH-H2O system was studied by the visual polythermal method over wide temperature and concentration ranges. In the phase diagram,
crystallization fields were determined for ice, urea, diurea sodium chlorate, acetic acid, monoethanolamine acetate, and the
compound CO(NH2)2 · NH2C2H4OH · CH3COOH. The compound was identified by chemical, thermogravimetric, and X-ray powder diffraction analyses. 相似文献
4.
M. M. Godneva V. Ya. Kuznetsov D. L. Motov M. P. Rys’kina O. A. Zalkind 《Russian Journal of Inorganic Chemistry》2009,54(12):2005-2009
We studied phase formation in the ZrO(NO3)2-H3PO4-RbF-H2O system along PO43−/Zr = 0.5 (mol/mol) and RbF/Zr = 1–5 (mol/mol) sections with 2–10 wt % ZrO2 in the starting solution. We recovered amorphous rubidium oxofluorophosphatozirconate Rb2Zr3OF6(PO4)2 · 2H2O and the following fluorophosphatonitratozirconates: Rb2ZrF4(PO4)0.33NO3, which forms large cubic system crystals; weakly crystallized RbZr3OF3(PO4)2(NO3)2 · 5H2O; and amorphous Zr3OF3(PO4)2NO3 · (7–8) H2O. A shown by its IR spectrum, Rb2ZrF4(PO4)0.33NO3 contains NO3- and PO4 groups that are not coordinated to zirconium, meaning that this is a triple salt ZrF4 · Rb(PO4)0.33 · RbNO3. The formula units of the RbZr3OF3(PO4)2(NO3)2 · 5H2O and Zr3OF3(PO4)2NO3 · (7–8)H2O phases are only conventional. All compounds have been recovered for the first time. 相似文献
5.
6.
The structure of the “Type III” δ-Bi2O3-related superstructure phase in the system Bi2O3-Nb2O5 is presented. A starting model was constructed by considering the crystal-chemistry of the system in the context of symmetry constraints determined by electron diffraction. After applying initial distortions, this could be Rietveld-refined against a combination of synchrotron X-ray and time-of-flight neutron powder diffraction data. The undistorted starting model was independently optimized using solid-state ab initio energy calculations, giving a fully optimized structure in excellent agreement with that obtained by Rietveld refinement. This dual approach both validates the structure and demonstrates the value of combining accurate total energy calculations with traditional refinement techniques for the solution of complex structures using powder diffraction data. The structure (Bi94Nb32O221, Z=1, (#119), a=11.52156(18), ) consists of interacting corner-connected strings of NbO6 octahedra along 〈110〉F directions of the FCC subcell, and can be described as a hybrid of fluorite and pyrochlore types. 相似文献
7.
A. V. Sabylinskii S. P. Gabuda S. G. Kozlova D. N. Dybtsev V. P. Fedin 《Journal of Structural Chemistry》2009,50(3):421-428
Localization and molecular mobility of the ligands ([C8H4O4]2+ and [C6H12N2]0) of the host lattice and (CH3)2NCHO dimethyl formamide guest molecules in the inclusion compound [Zn2(C8H4O4)2(C6H12N2)]·n(H3C)2NCHO were studied on the basis of 1H NMR data. At room temperature, the longest axes of the dimethyl formamide guest molecules are ordered in parallel to the
C
4 symmetry axes, and the symmetry planes of these molecules are disordered, while preserving the tetragonal crystal system
of the inclusion compound. At lower temperatures, a phase transition takes place in view of the ordering in the guest sublattice.
Original Russian Text Copyright ? 2009 by A. V. Sabylinskii, S. P. Gabuda, S. G. Kozlova, D. N. Dybtsev, and V. P. Fedin
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 3, pp. 443–450, May–June, 2009. 相似文献
8.
The solubility at invariant points in the Na2CO3-NaHCO3-NaF-H2O system at 25°C and the structure of its solubility diagram at this temperature were examined. 相似文献
9.
A new compound of C17H20FN3O32+ · 2HSO4−·H2O [ciprofloxacindi-um bis(hydrosulfate) monohydrate], C17H18FN3O3 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid (CfH, ciprofloxacin) is obtained and
its crystal structure is determined. The crystal contains CfH32+ and HSO4− ions and crystallization water molecules. Hydrogen (H3), which forms an intramolecular hydrogen bond with oxygen O2 of the
carboxyl group, is attached to the carbonyl O1 atom. Hydrogen H4 of the carboxyl group is hydrogen bonded to the crystallization
water molecule which links CfH32+ with two HSO4− groups by hydrogen bonds. Both H atoms at N3 of the piperazine ring form hydrogen bonds with two oxygen atoms of other HSO4− anions. Intramolecular hydrogen bonds of two types are present in the CfH32+ cation. One of them forms a six-membered ring, bonding O1 and O2 atoms, while the other, also enclosing a six-membered ring,
links fluorine and carbon C14 atoms.
Original Russian Text Copyright ? 2009 by A. D. Vasiliev, N. N. Golovnev, and I. A. Baidina
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 1, pp. 165–168, January–February, 2009. 相似文献
10.
Todora Ojkova Donka Stoilova Dimitar Barkov 《Monatshefte für Chemie / Chemical Monthly》2000,14(1):1019-1023
The solubilities in the systems Rb2SeO4=ZnSeO4=H2O and Cs2SeO4=ZnSeO4=H2O at 25°C were studied by the method of isothermal decrease of supersaturation. Comparatively wide crystallization fields
of the double salts Rb2Zn(SeO4)2ċ6H2O and Cs2Zn(SeO4)2ċ6H2O are observed in the solubility diagrams. The double salts form monoclinic crystals which are isostructural with those of
the corresponding rubidium and cesium zinc sulfate hexahydrates. TG and TDA measurements indicate that the double salts lose
their crystallization water in one step in the temperature intervals of 50–160°C (rubidium salt) and 70–150°C (cesium salt). 相似文献
11.
Chemiluminescence (CL), HLPC, and volumetry were used to demonstrate that fullerene N60 exerts no inhibiting effect on the liquid-phase chain oxidation of hydrocarbons. Peroxide radicals RO2 · do not add to N60 in hydrocarbons with active C—H bond, because the reaction is suppressed by the competing addition of RO2 · to the hydrocarbon. The addition of RO2 · radicals to N60 does occur in benzene (a solvent with strong C—H bonds) in the presence of low concentrations of the hydrocarbon oxidized.
Fullerene N60 is found to exhibit a new type of liquid_phase CL, which is presumably generated upon thermal decomposition of fullerene
peroxides formed by adding peroxy radicals to fullerene in the C60—AIBN—O2—C2H5Ph—PhH system. The CL spectrum exhibits long-wavelength maxima at 645 and 685 nm. The supposed CL emitters are keto derivatives
of fullerene N60. 相似文献
12.
Zh. S. Shukurov S. S. Ishankhodzhaev M. K. Askarova S. Tukhtaev 《Russian Journal of Inorganic Chemistry》2010,55(10):1630-1633
The solubility in the NaClO3 · 2CO(NH2)2-NH2CH2CH2OH-H2O system was studied over the range from the complete solidification temperature (−54.8°C) to 60°C. A polythermal solubility
diagram was constructed where the regions of crystallization of ice, carbamide, sodium dicarbamidochlorate, monoethanolamine
dihydrate, monoethanolamine monohydrate, and anhydrous monoethanolamine were demarcated. The system is a simple eutonic. 相似文献
13.
From a Cs doped Fe2O3-V2O5 (Fe:V=1.4) catalyst exhibiting an inhomogeneous composition after calcination, three different fractions have been separated by visual inspection. One fraction has been found to consist of mainly -Fe2O3, another one of mainly FeVO4. The third fraction (S1 in the text) is the catalytically most active fraction containing besides both of the former components an amorphous phase of FexVyOz and also the dopant. By combining the results from transmission and conversion electron Mössbauer spectra it has been concluded that the amorphous component is enriched in the surface region of the crystallites of the catalyst. In addition, the formation of a thin surface layer of iron sulfide (Fe1–xS) on the third fraction has been identified. This sulfide is assumed to be formed during calcination from Cs2SO4 used for the preparation of the catalyst.Dedicated to Professor Dr. H. Kriegsmann on the occasion of his 70th birthday 相似文献
14.
Oscillations in the concentration of intermediates were obtained when a model without reaction IO
3
–
+I–+2H+HIO+HIO2 was used for the simulation of the Bray-Liebhafsky process. 相似文献
15.
A Raman spectroscopic study of the XeOF4/XeF2 system and the X-ray crystal structure of α-XeOF4·XeF2
Michael J. Hughes 《Journal of fluorine chemistry》2011,132(10):660-668
The mixed oxidation state complexes, α-XeOF4·XeF2 and β-XeOF4·XeF2, result from the interaction of XeF2 with excess XeOF4. The X-ray crystal structure of the more stable α-phase shows that the XeF2 molecules are symmetrically coordinated through their fluorine ligands to the Xe(VI) atoms of the XeOF4 molecules which are, in turn, coordinated to four XeF2 molecules. The high-temperature phase, β-XeOF4·XeF2, was identified by low-temperature Raman spectroscopy in admixture with α-XeOF4·XeF2; however, the instability of the β-phase precluded its isolation and characterization by single-crystal X-ray diffraction. The Raman spectrum of β-XeOF4·XeF2 indicates that the oxygen atom of XeOF4 interacts less strongly with the XeF2 molecules in its crystal lattice than in α-XeOF4·XeF2. The 19F and 129Xe NMR spectra of XeF2 in liquid XeOF4 at −35 °C indicate that any intermolecular interactions that exist between XeF2 and XeOF4 are weak and labile on the NMR time scale. Quantum-chemical calculations at the B3LYP and PBE1PBE levels of theory were used to obtain the gas-phase geometries and vibrational frequencies as well as the NBO bond orders, valencies, and NPA charges for the model compounds, 2XeOF4·XeF2, and XeOF4·4XeF2, which provide approximations of the local XeF2 and XeOF4 environments in the crystal structure of α-XeOF4·XeF2. The assignments of the Raman spectra (−150 °C) of α- and β-XeOF4·XeF2 have been aided by the calculated vibrational frequencies for the model compounds. The fluorine bridge interactions in α- and β-XeOF4·XeF2 are among the weakest for known compounds in which XeF2 functions as a ligand, whereas such fluorine bridge interactions are considerably weaker in β-XeOF4·XeF2. 相似文献
16.
Yu. S. Okhlupin M. V. Ananyev N. F. Uvarov Yu. N. Bespalko S. N. Pavlova V. A. Sadykov 《Russian Journal of Electrochemistry》2011,47(6):663-670
Full conductivity, diffusion and oxygen exchange processes in composites (100 − x)La0.8Sr0.2Fe0.7Ni0.3O3 − δ−xCe0.9Gd0.1O1.95 (x is the volume fraction, 0 ≤ x ≤ 71.1%) at 700°C over the oxygen partial pressure range from 0.2 to 3 × 10−3 atm are studied by the electrical conductivity relaxation method. The composites’ conductivity was shown to decrease monotonically
with the increasing of Ce0.9Gd0.1O1.95 fraction, while the oxygen chemical diffusion coefficient increased. The oxygen exchange constant is higher for the composites
than for the individual phases of La0.8Sr0.2Fe0.7Ni0.3O3 − δ and Ce0.9Gd0.1O1.95. Possible reason of the dependence of the parameters D
chem and k
chem on the temperature, oxygen pressure, and the composite composition is the effect of the interface on the oxygen transfer
processes. Most effective oxygen transfer occurs in the composites whose composition approaches La0.8Sr0.2Fe0.7Ni0.3O3 − δ-Ce0.9Gd0.1O1.95 (x = 71%). 相似文献
17.
I. V. Desyatov E. A. Paukshtis A. V. Mashkina 《Reaction Kinetics and Catalysis Letters》1993,51(1):45-50
Modification of -Al2O3 by sodium hydroxide promotes the increase of surface basicity but does not exert a strong effect on catalytic activity in the reaction of thiolane production from tetrahydrofuran and H2S. Introduction of NaOH to -Al2O3 in small concentration increases the number of Lewis acid centers but decreases their strength. The activity of Na/-Al2O3 referred to one Lewis acid center drops. 相似文献
18.
H. Nguyen Xuan A. Pisch S. Beauquis F. Bourée-Vigneron 《Journal of solid state chemistry》2005,178(11):3207-3217
The crystal structure and stability of Ba4CaCu3O8+δ have been investigated by neutron powder diffraction, differential thermal analysis and thermogravimetry. It is found that the phase is not stable below 1065 K in p(O2)=1 bar and decomposes according to the eutectoid reaction Ba4CaCu3O8+δ+x O2⇒Ba2CuO3.4+CaO+2BaCuO2. However, the equilibrium with the outer gas is not reached for sintered ceramics so that Ba4CaCu3O8+δ can be obtained in a metastable state after normal cooling conditions. In this case, the crystal structure is cubic (Im-3m, , δ=0.68, Z=2, Rwp=2.5%, RBragg=5.4%) as reported in the literature. In reduced oxygen partial pressure (p(O2)<10−6 bar), Ba4CaCu3O8+δ is stable down to room temperature and has a tetragonal structure with a significant lower oxygen content (P4/mmm, , , δ=-0.81, Z=2, Rwp=2.8%, RBragg=5.1%). The difference between the two crystal structures is discussed in terms of oxygen content, copper formal valence and cation coordination. The influence of the oxygen pressure on the stability of Ba4CaCu3O8+δ is also discussed. 相似文献
19.
The two-state reaction mechanism of the Pt4+/− with N2O (CO) on the quartet and doublet potential energy surfaces has been investigated at the B3LYP level. The effect of Pt4
− anion assistance is analyzed using the activation strain model in which the activation energy (ΔΕ
≠) is decomposed into the distortion energies
(\Updelta E 1 \textdist ) (\Updelta E^{ \ne }_{\text{dist}} ) and the stabilizing transition state (TS) interaction energies
(\Updelta E 1 \textint ) (\Updelta E^{ \ne }_{\text{int}} ) , namely
\Updelta E 1 = \Updelta E 1 \textdist + \Updelta E 1 \textint \Updelta E^{ \ne } = \Updelta E^{ \ne }_{\text{dist}} + \Updelta E^{ \ne }_{\text{int}} . The lowering of activation barriers through Pt4
− anion assistance is caused by the TS interaction
\Updelta E 1 \textint \Updelta E^{ \ne }_{\text{int}} (−90.7 to −95.6 kcal/mol) becoming more stabilizing. This is attributed to the N2O π*-LUMO and Pt d HOMO back-donation interactions. However, the strength of the back-donation interactions has significantly
impact on the reaction mechanism. For the Pt4
− anion system, it has very significant back-bonding interaction (N2O negative charge of 0.79e), HOMO has 81.5% π* LUMO(N2O) character, with 3d orbital contributions of 10.7% from Pt(3) and 7.7% from Pt(7) near the 4TS4 transition state. This facilitates the bending of the N2O molecule, the N–O bond weakening, and an O−(2P) dissociation without surface crossing. For the Pt4
+ cation system, the strength of the charge transfer is weaker, which leads to the diabatic (spin conserving) dissociation
of N2O: N2O(1∑+) → N2(1∑g+) + O(1D). The quartet to doublet state transition should occur efficiently near the 4TS1 due to the larger SOC value calculated of 677.9 cm−1. Not only will the reaction overcome spin-change-induced barrier (ca. 7 kcal/mol) but also overcome adiabatic barrier (ca.
40.1 kcal/mol).Therefore, the lack of a thermodynamic driving force is an important factor contributing to the low efficiency
of the reaction system. 相似文献
20.
Daniel Marinha 《Journal of solid state chemistry》2009,182(7):1742-5348
Ceramics can play a remarkable role in the engineering of intermediate temperature solid oxide fuel cells (IT-SOFCs) capable of meeting the ambitious targets of reduced cost and improved lifetime. While mixed ionic-electronic conductors such as LaxSr1−xCoyFe1−yO3−δ are being used as volumic cathodes to increase the catalytic performance of these components, adequate microstructures are also an important requirement for optimal performance, particularly at lower operating temperatures. This work is devoted to the fabrication of La0.6Sr0.4Co0.2Fe0.8O3−δ films on Ce0.9Gd0.1O2−δ substrates by electrostatic spray deposition (ESD) and to the characterization of the microstructural dependence on the deposition conditions. A wide variety of microstructures ranging from dense to porous, with particular features such as reticulation and micro-porosity, were obtained by varying the ESD deposition parameters: nozzle-to-substrate distance (15, 30, 43, 45, and 58 mm), solution flow rate (0.34 and 1.5 mL/h), and substrate temperature (300, 350, 400 and 450 °C). The correlation between deposition parameters and resulting microstructures was systematically studied and put into evidence. 相似文献