Acta Crystallographica Section B
Structural Science
Volume 63, Part 3 (June 2007)
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Cover illustration: The cover illustration represents the high- and incommensurately modulated room-temperature phases of Na2CO3 and its reconstructed reciprocal (h2lm) layer [![[gamma]](/logos/entities/gamma_rmgif.gif) -Na2CO3; Dusek et al. (2003). Acta Cryst. B59, 337-352]. Main reflections (open circles) and satellites aligned along parallel lines are indicated. A comparison of the two structures represented by slices parallel to the vertical axis c illustrates their relationship [Arakcheeva & Chapuis (2005). Acta Cryst. B61, 601-607]. ![[beta]](/logos/entities/beta_rmgif.gif) -Na2CO3 at 746 K (C2/m; pseudohexagonal) is shown on the left. All C and Na atoms closer than 3.12 Å are linked. The corresponding non-periodic slice of -Na2CO3 indicates how the modulation creates additional close contacts (Ivan Orlov's design is kindly acknowledged). |
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Acta Cryst. (2007). B63, 339-345 [ doi:10.1107/S0108768107019167 ]
Pseudoatoms and preferred skeletons in crystals
Synopsis: A generalization of the Zintl-Klemm concept (ZKC) explains the complex structures of alloys as well as the cation arrays of oxides. This generalization helps to establish a univocal link between chemical composition (in terms of Klemm's pseudoatoms) and the structures observed experimentally.
Online 16 May 2007
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Acta Cryst. (2007). B63, 353-362 [ doi:10.1107/S0108768107015583 ]
Crystal chemistry of borates: the classification and algebraic description by topological type of fundamental building blocks
Synopsis: A novel systematic classification and a convenient algebraic description of borates were proposed on the basis of the topological structure and polymerization of FBBs (fundamental building blocks) in the borate crystallographic frame. The current work gives an impetus to elucidate topological features in borate chemistry and provides some useful statistical information to design and search for novel borate structures.
Online 16 May 2007
Acta Cryst. (2007). B63, 363-372 [ doi:10.1107/S0108768107001140 ]
On the polyhedral volume ratios VA/VB in perovskites ABX3
Synopsis: We present the formulae for the calculation of polyhedral volume ratios VA/VB for perovskite-type structures ABX3 in terms of atomic coordinates. The analysis of crystallographic data for approximately 1300 perovskite structures from the Inorganic Crystal Structure Database resulted in the estimated values of ratios at which phase transitions occur.
Online 16 May 2007
Acta Cryst. (2007). B63, 373-383 [ doi:10.1107/S0108768107012220 ]
Superspace crystal symmetry of thermoelectric misfit cobalt oxides and predicted structural models
Synopsis: The superspace crystal symmetry of two new misfit lamellar thermoelectric cobalt oxides is described. Structural models are deduced from generalized metric considerations and from observed crystal symmetries.
Online 16 May 2007
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Acta Cryst. (2007). B63, 384-389 [ doi:10.1107/S0108768107007720 ]
In situ observation of the tetragonal-cubic phase transition in the CeZrO4 solid solution - a high-temperature neutron diffraction study
Synopsis: The crystal structure of the ceria-zirconia solid solution CeZrO4 is refined by Rietveld analysis of neutron diffraction data measured in situ over the temperature range 296-1831 K. The cubic-to-tetragonal phase transition between 1542 and 1831 K is accompanied by the displacement of oxygen atoms and elongation of the c axis.
Online 16 May 2007
Acta Cryst. (2007). B63, 390-395 [ doi:10.1107/S0108768107010154 ]
Electron diffraction and microscopy study of the structure and microstructure of the hexagonal perovskite Ba3Ti2MnO9
Synopsis: The space group of the hexagonal perovskite Ba3Ti2MnO9 has been determined using convergent-beam electron diffraction (CBED) and the microstructure investigated using high-resolution electron microscopy (HREM).
Online 16 May 2007
Acta Cryst. (2007). B63, 396-401 [ doi:10.1107/S0108768107010130 ]
LiNaSiB3O7(OH) - novel structure of the new borosilicate mineral jadarite determined from laboratory powder diffraction data
Synopsis: Owing to the absence of crystals suitable for single-crystal X-ray diffraction, the structure of a new mineral, jadarite, with the composition LiNaSiB3O7(OH), has been determined using laboratory powder diffraction data. Its novel architecture consists of lithium, silicon and two of the B atoms forming unbranched vierer single layers of corner-sharing tetrahedra, themselves decorated by triangular borate groups, and connected by distorted NaO6 octahedra. The structure was validated using ab initio modelling because of the extreme difficulty in obtaining neutron diffraction data from such a boron-rich sample.
Online 16 May 2007
Acta Cryst. (2007). B63, 411-417 [ doi:10.1107/S0108768107010968 ]
Structural similarities in tetraaryltins described by virtual non-crystallographic rotations or translations: Kitaigorodskii's morphotropism is revisited
Synopsis: The reinvestigation of tetraaryltins together with the semantic elucidation of morphotropism revealed that isostructural groups of crystals are occasionally linked by non-crystallographic rotations and/or translations.
Online 16 May 2007
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Acta Cryst. (2007). B63, 418-425 [ doi:10.1107/S0108768107013961 ]
Structures of artificial sweeteners - cyclamic acid and sodium cyclamate with other cyclamates
Synopsis: The crystal structures of cyclamic acid and sodium cyclamate together with other cyclamates have been determined in the course of a study on artificial sweeteners.
Online 16 May 2007
Acta Cryst. (2007). B63, 426-432 [ doi:10.1107/S0108768107014826 ]
Rapid structure determination of the hydrogen-containing compound Cs2C2O4·H2O by joint single-crystal X-ray and powder neutron diffraction
Synopsis: An accurate and precise crystallographic description for all atom types has been obtained rapidly for a hydrogenous material by the combined analysis of single-crystal X-ray diffraction and powder neutron diffraction data.
Online 16 May 2007
Acta Cryst. (2007). B63, 459-468 [ doi:10.1107/S010876810701107X ]
X-ray studies of crystalline complexes involving amino acids and peptides. XLIV. Invariant features of supramolecular association and chiral effects in the complexes of arginine and lysine with tartaric acid
Synopsis: The crystal structures of tartaric acid complexes of arginine and lysine provide insight into the invariant and variable features of supramolecular association involving amino acids. The structures also contribute to information about the effect of chirality on such an association.
Online 16 May 2007
Acta Cryst. (2007). B63, 469-476 [ doi:10.1107/S0108768107006969 ]
The application of cluster analysis to identify conformational preferences in enones and enimines from crystal structural data
Synopsis: Cluster analysis using the program dSNAP has been applied to the conformational analysis of enones and enimines using data from the Cambridge Structural Database.
Online 16 May 2007
Acta Cryst. (2007). B63, 485-496 [ doi:10.1107/S0108768107018034 ]
Isostructuralism among `bridge-flipped' isomeric benzylideneanilines and phenylhydrazones
Synopsis: The crystal structures of three pairs of isomeric benzylideneanilines and one pair of isomeric phenylhydrazones are described. The pairs are `bridge-flipped' isomers, related by the reversal of the bridge of atoms connecting the major parts of the molecules; all pairs but one are isostructural.
Online 16 May 2007
Acta Cryst. (2007). B63, 497-504 [ doi:10.1107/S0108768107016965 ]
Investigation of hydrogen-bond network in bis(glycinium) oxalate using single-crystal neutron diffraction and spectroscopic studies
Synopsis: Single-crystal neutron diffraction studies showed that the short hydrogen bond between the glycinium cation and the oxalate anion in the title compound is asymmetric in nature with no hydrogen disorder.
Online 16 May 2007
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. Refinement was carried out by restrained Rietveld refinement as well as by structure optimization by energy minimization in the solid state at the DFT level of theory.