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Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials

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https://www.readbyqxmd.com/read/30141425/compositionally-induced-phase-transitions-and-symmetry-relations-between-space-groups-in-the-layered-system-fein-1-x-y-x-ge-2-o-7
#1
Rosario Moreno-Tovar, Lauro Bucio, Ivonne Rosales, Eligio Orozco
Symmetry reduction in the basic structure of thortveitite-type compound FeInGe2 O7 -mC22 (C12/m1, No. 12) promoted by the incorporation of yttrium in the formula FeIn1-x Yx Ge2 O7 gives rise to a derivative structure called thortveitite-like AA'Ge2 O7 -mP44, with symmetry described by the space group P121 /m1 (No. 11) for x = 0.50, 0.75 and 0.90. The structure remains unchanged within the structural type of thortveitite when x = 0.25. In order to establish structural models for performing a Rietveld refinement to the derivative structure, symmetry relations between space groups connecting the basic and derivative structures were used...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141424/high-density-hniw-tnt-cocrystal-synthesized-using-a-green-chemical-method
#2
Yan Liu, Chongwei An, Jin Luo, Jingyu Wang
The main challenge for achieving better energetic materials is to increase their density. In this paper, cocrystals of HNIW (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, often referred to as CL-20) with TNT (2,4,6-trinitrotoluene) were synthesized using ethanol in a green chemical method. The cocrystal was formulated as C13 H11 N15 O18 and possesses a higher density (1.934 g cm-3 ) than published previously (1.846 g cm-3 ). This high-density cocrystal possesses a new structure, which can be substantiated by the different types of hydrogen bonds...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141423/similarities-and-differences-in-the-crystal-packing-of-halogen-substituted-indole-derivatives
#3
Rahul Shukla, Paramveer Singh, Piyush Panini, Deepak Chopra
The role of different intermolecular interactions in the crystal structures of halogen-substituted indoles which are fused with six-membered or seven-membered cyclic rings is investigated here. Several crystal structures show isostructural characteristics due to the presence of similar supramolecular motifs. In the absence of any strong hydrogen bonds, the molecular packing of reported structures is primarily stabilized by the presence of non-classical N-H...π and C-H...π interactions in addition to C-H....
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141422/-al-mg-3-la-a-new-phase-in-the-mg-al-la-system
#4
Charlotte Wong, Mark J Styles, Suming Zhu, Dong Qiu, Stuart D McDonald, Yuman Zhu, Mark A Gibson, Trevor B Abbott, Mark A Easton
During an investigation of the Mg-rich end of the Mg-Al-La system, a new ternary phase with the composition of (Al,Mg)3 La was identified. The crystal structure of this phase was determined by conventional X-ray powder diffraction and transmission electron microscopy analysis and refined using high-resolution X-ray powder diffraction. The (Al,Mg)3 La phase is found to have an orthorhombic structure with a space group of C2221 and lattice parameters of a = 4.3365 (1) Å, b = 18.8674 (4) Å and c = 4...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141421/nollmotzite-mg-u-v-u-vi-o-2-2-o-4-f-3-%C3%A2-4h-2-o-the-first-natural-uranium-oxide-containing-fluorine
#5
Jakub Plášil, Anthony R Kampf, Radek Škoda, Jiří Čejka
Nollmotzite (IMA2017-100), Mg[UV (UVI O2 )2 F3 O4 ](H2 O)4 , is a new uranium oxide fluoride mineral found in the Clara mine, Black Forest Mountains, Germany. Electron microprobe analysis provided the empirical formula (Mg1.06 Cu0.02 )Σ1.08 [UV (UVI O2 )2 O3.85 F3.15 ][(H2 O)3.69 (OH)0.31 ]Σ4.00 based on three U and 15 O + F atoms per formula unit. Nollmotzite is monoclinic, space group Cm, with a = 7.1015 (12) Å, b = 11.7489 (17) Å, c = 8.1954 (14) Å, β = 98.087 (14)°, V = 676.98 (19) Å3 and Z = 2...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141420/control-of-crystal-structure-using-temperature-and-time
#6
Savannah C Zacharias, Gaëlle Ramon, Susan A Bourne
Three novel crystal structures were obtained from iron(III) acetylacetonate and 2,6-pyridinedicarboxylic acid. The structures elucidated were found to be dependent on the temperature and length of time allowed for the reaction. The product of the reaction between iron(III) acetylacetonate and 2,6-pyridinedicarboxylic acid in acetonitrile at room temperature is [FeC12 H12 NO7 ]·CH3 CN, (I). When the reaction temperature was increased to 60°C, FeC12 H10 NO6 , (II), was isolated after 2 h and [FeC12 H10 NO6 ]4 , (III), was isolated after 24 h...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141419/vanadium-clusters-formation-in-geometrically-frustrated-spinel-oxide-alv-2-o-4
#7
Mikhail V Talanov, Vladimir B Shirokov, Leon A Avakyan, Valeriy M Talanov, Khisa Sh Borlakov
The spinel oxide AlV2 O4 is a unique material, in which the formation of clusters is accompanied by atomic, charge and orbital ordering and a rhombohedral lattice distortion. In this work a theory of the structural phase transition in AlV2 O4 is proposed. This theory is based on the study of the order-parameter symmetry, thermodynamics, electron density distribution, crystal chemistry and mechanisms of formation of the atomic and orbital structures of the rhombohedral phase. It is established that the critical order parameter is transformed according to irreducible representation k9 (τ4 ) (in Kovalev notation) of the Fd \bar{3}m space group...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141418/jinshajiangite-structure-twinning-and-pseudosymmetry
#8
Shiyun Jin, Huifang Xu, Seungyeol Lee, Pingqiu Fu
The crystal structure of jinshajiangite based on a sample from its original discovery location is studied using single-crystal X-ray diffraction and transmission electron microscopy methods. Jinshajiangite is a titanium silicate mineral with an ideal chemical formula of BaNaFe4 Ti2 (Si2 O7 )2 O2 (OH)2 F. The structure of jinshajiangite is of P\bar 1 symmetry (triclinic system), with a = 8.7331 (2) Å, b = 8.7366 (2) Å, c = 11.0404 (3) Å, α = 81.477 (1)°, β = 110.184 (1)°, γ = 104.384 (1)° and V = 764...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141417/crystallographic-searches-for-weak-interactions-the-limitations-of-data-mining
#9
Hans Jörg Schneider
No abstract text is available yet for this article.
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927394/hydrophobic-dipeptides-the-final-piece-in-the-puzzle
#10
Carl Henrik Görbitz
The crystal structure of L-valyl-L-leucine acetonitrile solvate presented here adds to 24 previously reported structures of dipeptides constructed from the five nonpolar amino acids L-alanine, L-valine, L-isoleucine, L-leucine and L-phenylalanine. It thus constitutes the final piece in the 5 × 5 puzzle of hydrophobic dipeptide structures. This opportunity is taken to review the crystal packing arrangements and hydrogen-bonding preferences of a rather unique group of substances, with updated information on the various hydrogen-bonding patterns and the associated peptide conformations...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927393/a-crystallographic-and-thermal-study-of-pridinol-mesylate-and-its-monohydrated-solvate
#11
Pablo Gaztañaga, Ricardo Baggio, Daniel Roberto Vega
Herein are reported the crystal and molecular structures of the pridinol mesylate salt (C20 H25 NO+ ·CH3 O3 S- ) (I) and its monohydrated solvate form (C20 H25 NO+ ·CH3 O3 S- ·H2 O) (II). A comparison of both with the already reported structure of pure pridinol [1,1-diphenyl-3-piperidino-1-propanol, C20 H25 NO; Tacke et al. (1980). Chem. Ber. 113, 1962-1980] is made. Molecular structures (I) and (II) are alike in bond distances and bond angles, but differ in their spatial conformation, and, more relevant still, in their hydrogen-bonding motifs...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927392/structure-of-russellite-bi-2-wo-6-origin-of-ferroelectricity-and-the-effect-of-the-stereoactive-lone-electron-pair-on-the-structure
#12
Hiroki Okudera, Yuka Sakai, Kentaro Yamagata, Hiroaki Takeda
The structure of the low-temperature polar (orthorhombic) phase of russellite (Bi2 WO6 ) was examined on artificial specimens with precise single-crystal X-ray diffraction experiments. The final atomic arrangement thus obtained was identical to that reported by Knight [Miner. Mag. (1992), 56, 399-409] with powder neutron diffraction. The residual density attributable to a stereochemically-active lone pair of electrons of bismuth was prominent at approximately the centre of a larger cap of BiO8 square antiprisms, that is on the line from the Bi sites to an adjacent WO4 2- slab along the b-axis direction...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927391/crystal-structure-analysis-of-a-star-shaped-triazine-compound-a-combination-of-single-crystal-three-dimensional-electron-diffraction-and-powder-x-ray-diffraction
#13
Tatiana E Gorelik, Jacco van de Streek, Herbert Meier, Lars Andernach, Till Opatz
The solid-state structure of star-shaped 2,4,6-tris{(E)-2-[4-(dimethylamino)-phenyl]ethenyl}-1,3,5-triazine is determined from a powder sample by exploiting the respective strengths of single-crystal three-dimensional electron diffraction and powder X-ray diffraction data. The unit-cell parameters were determined from single crystal electron diffraction data. Using this information, the powder X-ray diffraction data were indexed, and the crystal structure was determined from the powder diffraction profile. The compound crystallizes in a noncentrosymmetric space group, P21 21 21 ...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927390/crystal-structures-of-k-2-xsi-5-o-12-x-fe-2-co-zn-and-rb-2-xsi-5-o-12-x-mn-leucites-comparison-of-monoclinic-p2-1-c-and-ia-overline-3-d-polymorph-structures-and-inverse-relationship-between-tetrahedral-cation-t-si-and-x-o-bond-distances-and-intertetrahedral
#14
COMPARATIVE STUDY
Anthony M T Bell, C Michael B Henderson
The leucite tectosilicate mineral analogues K2 X2+ Si5 O12 (X = Fe2+ , Co, Zn) and Rb2 X2+ Si5 O12 (X = Mn) have been synthesized at elevated temperatures both dry at atmospheric pressure and at controlled water vapour pressure; for X = Co and Zn both dry and hydrothermally synthesized samples are available. Rietveld refinement of X-ray data for hydrothermal K2 X2+ Si5 O12 (X = Fe2+ , Co, Zn) samples shows that they crystallize in the monoclinic space group P21 /c and have tetrahedral cations (Si and X) ordered onto distinct framework sites [cf...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927389/theory-of-order-disorder-phase-transitions-of-b-cations-in-ab-1-2-b-1-2-o-3-perovskites
#15
V P Sakhnenko, N V Ter-Oganessian
Perovskite-like oxides AB'1/2 B''1/2 O3 with two different cations in the B-sublattice may experience cation order-disorder phase transitions. In many cases the degree of cation ordering can be varied by suitable synthesis conditions or subsequent sample treatment, which has a fundamental impact on the physical properties of such compounds. Therefore, understanding the mechanism of cation order-disorder phase transition and estimation of the phase transition temperature is of paramount importance for tuning of properties of such double perovskites...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927388/investigation-of-interactions-in-lewis-pairs-between-phosphines-and-boranes-by-analyzing-crystal-structures-from-the-cambridge-structural-database
#16
Milan R Milovanović, Jelena M Andrić, Vesna B Medaković, Jean Pierre Djukic, Sneǽana D Zarić
The interactions between phosphines and boranes in crystal structures have been investigated by analyzing data from the Cambridge Structural Database (CSD). The interactions between phosphines and boranes were classified into three types; two types depend on groups on the boron atom, whereas the third one involves frustrated Lewis pairs (FLPs). The data enabled geometric parameters in structures to be compared with phosphine-borane FLPs with classical Lewis pairs. Most of the crystal structures (78.1%) contain BH3 as the borane group...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616997/crystal-structures-of-alkali-metal-group-1-citrate-salts
#17
Alagappa Rammohan, James A Kaduk
The crystal structures of 16 new alkali metal citrates were determined using powder and/or single crystal techniques. These structures and 12 previously determined citrate structures were optimized using density functional techniques. The central portion of a citrate ion is fairly rigid, while the conformations of the terminal carboxylate groups exhibit no preferences. The citrate-metal bonding is ionic. Trends in metal-citrate coordination are noted. The energy of an O-H...O hydrogen bond is proportional to the square root of the H...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616996/crystal-structure-phase-transition-and-structural-deformations-in-iron-borate-y-0-95-bi-0-05-fe-3-bo-3-4-in-the-temperature-range-90-500-k
#18
Ekaterina S Smirnova, Olga A Alekseeva, Alexander P Dudka, Vladimir V Artemov, Yan V Zubavichus, Irina A Gudim, Leonard N Bezmaterhykh, Kirill V Frolov, Igor S Lyubutin
An accurate X-ray diffraction study of (Y0.95 Bi0.05 )Fe3 (BO3 )4 single crystals in the temperature range 90-500 K was performed on a laboratory diffractometer and used synchrotron radiation. It was established that the crystal undergoes a diffuse structural phase transition in the temperature range 350-380 K. The complexity of localization of such a transition over temperature was overcome by means of special analysis of systematic extinction reflections by symmetry. The transition temperature can be considered to be Tstr ≃ 370 K...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616995/phase-transitions-in-ferroelectric-4-aminopyridinium-tetrachloroantimonate-iii-revisited
#19
Anna Gągor
New X-ray diffraction studies on the crystal structure of ferroelectric [4-NH2 C5 H4 NH][SbCl4 ] indicate that in the broad temperature range from 240 to 304 K covering the three intermediate phases, the crystal structure is modulated. Phase II is incommensurately modulated with modulation vector q = βb*, β varying from 0.60 to 0.66 and monoclinic C2/c(0β0)s0 superspace group. Ferroelectric phase III is commensurate with q = 2\over 3b* and Cc(0β0)0 symmetry. Polar phase IV is incommensurately modulated with β varying from 0...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616994/accurate-and-precise-lattice-parameters-of-h-2-o-and-d-2-o-ice-ih-between-1-6-and-270-k-from-high-resolution-time-of-flight-neutron-powder-diffraction-data
#20
A Dominic Fortes
Accurate and precise lattice parameters for D2 O and H2 O varieties of hexagonal ice (ice Ih, space group P63 /mmc) have been obtained in the range 1.6 to 270 K. Precision of the lattice parameters (∼0.0002% in a and 0.0004% in c for D2 O, 0.0008% in a and 0.0015% in c for H2 O) is ensured by use of the time-of-flight method on one of the longest primary neutron flight-path instruments in the world, the High-Resolution Powder Diffractometer at the ISIS neutron source. These data provide a more precise description of the negative thermal expansion of the material at low temperatures than the previous synchrotron `gold standard' [Röttger et al...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
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