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1.
Anna Blonska-Tabero 《Journal of Thermal Analysis and Calorimetry》2007,88(1):201-205
Thermal properties of Co2FeV3O11
have been reinvestigated. It has been proved that this compound does not exhibit
polymorphism. It melts incongruently at the temperature of 770±5°C
and the phase with lyonsite type structure is the solid product of this melting.
Phase relations in the whole subsolidus area of the CoO–V2O5–Fe2O3 system have been determined. The solidus area projection onto
the component concentration triangle plane of this system has been constructed
using the DTA and XRD methods. 15 subsidiary subsystems can be distinguished
in this system. 相似文献
2.
Yu. F. Kargin S. N. Ivicheva L. I. Shvorneva M. G. Komova V. A. Krut’ko 《Russian Journal of Inorganic Chemistry》2008,53(9):1512-1516
Phase relations in the CaO-Bi2O3-B2O3 system have been investigated by X-ray powder diffraction and differential thermal analyses, and the isothermal section at 600°C has been constructed. The formation of ternary compounds at the component ratios 1CaO: 1Bi2O3: 1B2O3 (CaBi2B2O7) and 1CaO: 1Bi2O3: 2B2O3 (CaBi2B4O10) has been established X-ray diffraction characteristics of these phases are presented. 相似文献
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G. A. Bandurkin V. A. Krut’ko G. V. Lysanova M. G. Komova 《Russian Journal of Inorganic Chemistry》2011,56(1):82-92
The cationic networks in the structures of the initial oxides and all binary and ternary compounds forming in the Ln2O3-GeO2-P2O5 systems have been studied. In the phase diagrams of the Nd2O3-GeO2-P2O5 and Er2O3-GeO2-P2O5 systems, the regions of the structural influence of individual compounds with topologically identical cationic networks—anisotropic
(A), combined (C), and isotropic (I)—are united into common areas. The A: C: I area ratio is 1: 1: 1 in the neodymium system
and 1.7: 1: 3.4 in the erbium system. 相似文献
5.
Edward E. vila Asilo J. Mora Gerzon E. Delgado Belkis M. Ramírez Alí Bahsas Sonia Koteich 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(10):o759-o761
In the title compound, C7H13NO2·0.5H2O, cis‐4‐aminocyclohexanecarboxylic acid exists as a zwitterion and co‐crystallizes with water molecules in a 2:1 amino acid–water ratio. The cyclohexane ring adopts a chair conformation, with the carboxylate and ammonium groups in axial and equatorial positions, respectively. The basic motif in the crystal structure is a sandwich structure, formed by two amino acid units linked by head‐to‐tail hydrogen bonds. Hydrogen bonds of the type N+—H⋯O—C—O− link these motifs, forming helicoidally extended chains running along the c axis. The water molecule lies on a twofold axis and interacts with the chains by means of O—H⋯O hydrogen bonds. 相似文献
6.
Christopher Glidewell Debbie Cannon Antonio Quesada John N. Low Susan A. McWilliam Janet M. S. Skakle James L. Wardell 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):455-458
Molecules of 1,3‐diamino‐4‐nitrobenzene, C6H7N3O2, are linked by N—H?O hydrogen bonds [N?O 2.964 (2) and 3.021 (2) Å; N—H?O 155 and 149°] into (4,4) nets. In 3,5‐dinitroaniline, C6H5N3O4, where Z′ = 2, the molecules are linked by three N—H?O hydrogen bonds [N?O 3.344 (2)–3.433 (2) Å and N—H?O 150–167°] into deeply puckered nets, each of which is interwoven with its two immediate neighbours. 相似文献
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The reactivity of SbVO5, a compound known since a short time, with T-Nb2O5 in solid state in air has been investigated over the whole component concentration range of a system built by these two reacting
substances. The investigation results have shown that an equimolar mixture of SbVO5 and T-Nb2O5 reacts with a subsequent formation of a hitherto unknown compound of the formula Nb2VSbO10. This compound has been characterized by the methods XRD, DTA/TG, and SEM. Its orthorhombic unit cell parameters have been
calculated, and its stability in air up to 880 ± 10 °C has been proved. At this temperature, the compound melts incongruently
with an accompanying deposition of solid Nb9VO25, i.e., of a compound that crystallizes in the binary oxide system V2O5–Nb2O5. 相似文献
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J. E. Scott 《Structural chemistry》2007,18(3):257-265
Our shape is defined and maintained by the connective tissues (skin, tendons, cartilages, blood vessels, etc.) or more precisely
by their extracellular matrices. These highly ordered supramolecular organisations are modules of protein fibrils held together
by elastic carbohydrate strings. I called these the ‘shape modules.’ The ‘laws.’ which underpin this tissue jigsaw, the changes
which come with age and the insight that the concepts give in economically important disorders such as osteoarthrosis begin
to provide a new and coherent picture stretching across the animal world and its evolution. This structure/function picture
is built on biochemical analyses, which developed into histochemical microscopy and thence into electron histochemistry, and
from nuclear magnetic resonance (NMR), molecular modelling and computer simulations on the physicochemical and biomechanical
side. As usual, originality bred dissent. 相似文献
14.
Boris Shivachev Rosica Petrova Emilia Naydenova 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(8):o524-o526
The title compound [systematic name: 1′‐aminocyclohexanespiro‐4′‐imidazole‐2′,5′(3′H,4′H)‐dione], C8H13N3O2, has been synthesized and was found to crystallize in two different structures, both monoclinic and both with the same P21/c space group. In the first structure, there are two molecules in the asymmetric unit, one of which uses all of its hydrogen‐bond donors and acceptors and forms undulating layers, while the other forms chains propagating perpendicular to the layers. In the second structure, there is only one independent molecule and the packing is based on a chain structure mediated by hydrogen bonding between the hydantoin moieties and further grouped into hydrophilic layers separated by layers of the hydrophobic cyclohexyl groups. 相似文献
15.
A. V. Kulebyakin E. E. Lomonova N. I. Medvedovskaya A. V. Shcherbakov 《Russian Journal of Electrochemistry》2009,45(4):444-449
This work represents the results of oxygen redistribution studies at quantitative and isotopic levels in synthesis and thermal treatment of ZrO - (0 to 35 mol %) Y2O3 solid solution crystals. The crystals were grown by directed melt crystallization method in a cold container using direct high-frequency heating. The crystal oxygen content and isotopic composition data was collected with respect to stabilizer concentration and technological conditions of synthesis. The temperature and frequency relationships of crystal electroconductivity were also studied. Some strength and tribological characteristics of the given materials were represented. The solid state formation by directional melt crystallization was shown to involve oxygen isotopic exchange interaction between the melt, growing crystal, and gas phase. 相似文献
16.
Stuart R. Batten Alexander R. Harris Keith S. Murray 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1394-1395
The title compound, C24H20P+·ClO4?, undergoes a sudden reversible phase change in the region of 173–180 K which involves ordering of three quarters of the perchlorate anions. 相似文献
17.
I. Khidirov N. N. Mukhtarova L. N. Padurets A. L. Shilov S. Yu. Zaginaichenko D. V. Shchur V. K. Pishchuk 《Russian Journal of Inorganic Chemistry》2008,53(4):509-514
The structure of a solid solution with a combined isotope composition based on TiN0.40H0.19D0.19 (space group \(P\overline 3 m1\)) has been studied by neutron diffraction. The isotope effect in the distribution of H and D isotopes has been found: the isotopes are located in tetrahedral interstices of the same type but with different z coordinates; there is splitting of 2d tetrahedral interstices into two groups, the protium (H) and deuterium (D). Therefore, in the ordered “layered” structure of the TiN0.40H0.19D0.19 solid solution, two different isotopes of the same element cannot be located at the same plane perpendicular to the threefold axis. The crystal-chemical analysis of the surroundings of H and D has been performed, and considerable differences have been revealed between the coordination polyhedra surrounding different hydrogen isotopes. It has been found that, in some metal-hydrogen systems, protium and deuterium should be treated as independent chemical components. 相似文献
18.
V. H. Rodrigues J. A. Paixo M. M. R. R. Costa A. Matos Beja 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):417-420
In the title compound, C4H10NO2+·C2F3O2?, the main N—C—COOH skeleton of the protonated amino acid is nearly planar. The C=O/C—N and C=O/O—H bonds are syn and the two methyl groups are gauche to the methylene H atoms. The conformation of the cation in the crystal is compared to that given by ab initio calculations (Hartree–Fock, self‐consistent field molecular‐orbital theory). The trifluoroacetate anion has the typical staggered conformation with usual bond distances and angles. The cation and anion form dimers through a strong O—H?O hydrogen bond which are further interconnected in infinite zigzag chains running parallel to the a axis by N—H?O bonds. Weaker C—H?O interactions involving the methyl groups and the carboxy O atoms of the cation occur between the chains. 相似文献
19.
David J. Brauer Konstantin W. Kottsieper 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(5):o244-o246
The title compound, C2H7N4O+·CH4O3P−·H2O, crystallized with one carbamoylguanidinium cation, one methylphosphonate anion and one water molecule in the asymmetric unit. All H atoms of the carbamoylguanidinium ion are involved in a hydrogen‐bonded network. The CH3PO2(OH) anions, together with the water molecules, build O—H⋯O hydrogen‐bonded ribbons around a 21 screw axis parallel to the b axis. Neighbouring ribbons are not directly connected via hydrogen bonding. The carbamoylguanidinium cations are linked to these ribbons by N—H⋯O bridges and build a slightly buckled layer structure, the interlayer distance being b/2. 相似文献