issue contents

ISSN: 2052-5206

October 2012 issue

Highlighted illustration

Cover illustration: A high-angle annular darkfield scanning transmission electron microscopy image of the decagonal quasicrystal Al72Co8Ni20 overlaid with a structure model. Clusters of type 1 (occupied center) highlight transition metal sites (white spheres) and clusters of type 2 (empty center) possess both transition metal and mixed aluminum/transition metal (red) sites. Decagonal-shaped clusters are outlined and exhibit two types of overlap as a unifying building feature of aperiodic quasicrystals of decagonal Al-Co-Ni, Al-Co-Cu and Al-Fe-Ni [Deloudi et al. (2011). Acta Cryst. B67, 1-17, based on Abe & Tsai (2004) J. Non-Cryst. Solids, 334, 198-201]. The 2011 Nobel prize in chemistry was awarded to D. Shechtman for his discovery of quasicrystals.

research papers

link to html
Chlorapatite (ClAp) single crystals have been synthesized and described as stoichiometric with hexagonal structure. The heat treatment of these crystals at high temperature led to systematic structural modifications due to the Cl by OH anion replacement.

link to html
The crystal structures of two complex minerals of the lead sulfosalt type, sterryite, Cu(Ag,Cu)3Pb19(Sb,As)22(As–As)S56, and parasterryite, Ag4Pb20(Sb,As)24S58, were solved and compared according to modular analysis. These quasi-homeotypic structures are expanded derivatives of owyheeite, Ag3Pb10Sb11S28.

link to html
The solution and refinement of the crystal structures of two cementitious phases formed at the beginning of the carbonation reaction of many building materials are reported.

link to html
A theoretical hardness model based on crystallo-chemical data has permitted the separate calculation of Hmin (derived from weak bonds acting along the c axis), as well as Hmax [derived from strong bonds acting within the (0001) plane] in the space group P63/mmc anisodesmic compounds. Experimental hardness has confirmed the calculated Hmin.

link to html
Unique thermodynamic relationships for Na2SOx and Na2S2Ox salts, and prediction of the thermodynamic stability of Na2SO2 and Na2SeO2 and the connection with the oxidation–pressure concept are discussed.

link to html
Three gadolinium/5-nitroisophthalate metal-organic frameworks (MOFs) have been prepared under controlled but similar conditions. They are found to be related topologically through a simple C—C bond rotation.

link to html

Four types of the title compound are identified, which differ in the stacking of planar layers of the nearly flat molecules. Polytypism is induced by variation of the conditions of crystallization.

link to html
Twisted BNC nanotubes and nanofibers with polygonal cross-section have been synthesized in high isostatic pressure apparatus and analysed using transmission and scanning electron microscopy. Walls of these nanotubes contained fragments of both hexagonal and rhombohedral lattices. We propose mechanisms of nanotube structure formation and reasons for their deformation.

link to html
The crystal structure of the amino acid L-tryptophan has 16 molecules in the asymmetric unit, which are related by intriguing pseudosymmetry that led to exceptional systematic absences in the space group P1.
Follow Acta Cryst. B
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds