Cl–OH ion-exchanging process in chlorapatite (Ca₅(PO₄)₃Cl_x(OH)_1 − x) – a deep insight

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.

Comparative modular analysis of two complex sulfosalt structures: sterryite, Cu(Ag,Cu)₃Pb₁₉(Sb,As)₂₂(As–As)S₅₆, and parasterryite, Ag₄Pb₂₀(Sb,As)₂₄S₅₈

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.

Crystal structures of calcium hemicarboaluminate and carbonated calcium hemicarboaluminate from synchrotron powder diffraction data

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.

Theoretical hardness calculated from crystallo-chemical data for MoS₂ and WS₂ crystals and nanostructures

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

Unique thermodynamic relationships for Δ_fH^o and Δ_fG^o for crystalline inorganic salts. I. Predicting the possible existence and synthesis of Na₂SO₂ and Na₂SeO₂

Unique thermodynamic relationships for Na₂SO_x and Na₂S₂O_x salts, and prediction of the thermodynamic stability of Na₂SO₂ and Na₂SeO₂ and the connection with the oxidation–pressure concept are discussed.

Topological studies of three related metal-organic frameworks of Gd^III and 5-nitroisophthalate

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.

Four polymorphs (polytypes) of 5,6-di­methylbenzofurazan 1-oxide

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.

Structure of twisted BNC nanotubes with polygonal cross-section

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.

Single-crystal investigation of L-tryptophan with Z′ = 16

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.