Polarization in RMnO₃ multiferroics

Some comments on the review by Sim et al. [(2016). Acta Cryst. B72, 3–19] are given. The review is devoted to hexagonal multiferroics RMnO₃, in which there are ferroelectric and magnetic orders. Strong interaction between these orders causes a series of interesting properties of multiferroics.

Hexagonal RMnO₃: a model system for two-dimensional triangular lattice antiferromagnets

Here we present a review of the crystal and magnetic structure as well as the spin dynamics of two-dimensional triangular lattice multiferroic hexagonal manganite RMnO₃.

Salt screening and characterization of ciprofloxacin

This paper presents a study of the structures and physicochemical properties of ciprofloxacin's novel salts.

Determining europium compositional fluctuations in partially stabilized zirconia nanopowders: a non-line-broadening-based method

This article discusses a new method to determine the compositional fluctuations in partially stabilized zirconia based on the comparison of the X-ray diffraction patterns of partially transformed samples.

Electron density, disorder and polymorphism: high-resolution diffraction studies of the highly polymorphic neuralgic drug carbamazepine

An experimental charge density study on polymorph (III) of carbamazepine is in excellent agreement with theory and a Hirshfeld atom refinement based on the X-ray data provides positional and anisotropic displacement parameters for the H atoms closely similar to those obtained from the neutron diffraction data. X-ray and neutron diffraction data on the dihydrate of carbamazepine strongly indicate a disordered orthorhombic crystal structure in Cmca, rather than a monoclinic crystal structure in P2₁/c.

Charge distribution as a tool to investigate structural details. IV. A new route to heteroligand polyhedra

A new, more general approach to treat heteroligand polyhedra in the charge distribution algorithm is presented.

Identifying the multiplicity of crystallographically equivalent variants generated by iterative phase transformations in Ti

Utilizing the Burgers Orientation Relationship and the four-dimensional Frank space, we were able to identify the multiplicity of crystallographically equivalent variants generated by iterative phase transformations (h.c.p. to b.c.c. and vice versa) in pure titanium.

Experimental and theoretical charge-density analysis of 1,4-bis­(5-hexyl-2-thienyl)butane-1,4-dione: applications of a virtual-atom model

The electron density of a thiophene compound was determined experimentally and theoretically, using a multipolar model and a virtual spherical atoms model.

Crystal engineering: co-crystals of cinnamic acid derivatives with a pyridyl derivative co-crystallizer

The preparation and structural characterization of co-crystals of cinnamic acid derivatives with pyridyl co-crystallizers are reported through recrystallization and solvent drop grinding.

Crystal structure of monoclinic calcium pyro­phosphate dihydrate (m-CPPD) involved in inflammatory reactions and osteoarthritis

Rietveld refinement of complementary synchrotron powder X-ray diffraction and neutron diffraction data leads to the resolution of the structure of the monoclinic phase of calcium pyrophosphate dihydrate (m-CPPD) including the determination of the precise position of the hydrogen atoms. These new structural data are of particular importance to further understand in vivo phenomena related to osteoarthritis: m-CPPD phase formation and evolution, and structure–inflammatory response relationships.

A double stranded metal–organic assembly accommodating a pair of water trimers in the host cavity and catalysing Glaser coupling

Single strands of copper terephthalate units are connected by a tripodal ligand that bridges two copper(II) nodal points to form a double-stranded one-dimensional chain. The isolated cavities in the assembly stabilize a pair of water trimers by hydrogen bonding. The coordination polymer also catalyses the Glaser–Hay coupling reaction.

(3+1)-Incommensurately modulated crystal structure of Cs₃ScSi₆O₁₅

The structure of Cs₃ScSi₆O₁₅ has been solved and refined as an incommensurately modulated crystal structure in (3+1)-dimensional superspace. Large positional modulations of the constituting atoms give rise to satellite reflections up to the fourth order.

Reversible chair ↔ skew conformational inter­conversion of 1,3,2-dioxa­phosphorinane ring in the solid state

Reversible chair ↔ skew flipping of the 1,3,2-dioxaphosphorinane ring has been shown to take place during three reversible single-crystal-to-single-crystal phase transitions in the β-NH₄[(MeO)₂cDHAP] crystal, revealing the conformational flexibility of the O/P/O/C/C/C ring in the solid state.

The low-temperature crystal structure of the multiferroic melilite Ca₂CoSi₂O₇

The crystal structure of the multiferroic melilite Ca₂CoSi₂O₇ is determined by means of single-crystal neutron diffraction at 10 K.

M_mH_n(XO₄)_{(m + n)/2} crystals: structure, phase transitions, hydrogen bonds, conductivity. II. Structure and properties of Cs₃(HSO₄)₂(H₂PO₄) and Cs₄(HSO₄)₃(H₂PO₄) single crystals

Cs₃(HSO₄)₂(H₂PO₄) and Cs₄(HSO₄)₃(H₂PO₄) single crystals were obtained for the first time based on a systematic study of the phase diagram of the CsHSO₄–CsH₂PO₄–H₂O ternary system and studied by X-ray diffraction. Dielectric and optical properties of these crystals were determined to establish structural conditionality for anomalies in their physical properties.

Charge density of the biologically active molecule (2-oxo-1,3-benzoxazol-3(2H)-yl)acetic acid

The electron density of a bioactive benzoxazolone was determined experimentally by high-resolution X-ray diffraction. Comparison with the results from theoretical calculations reveals the effects of intermolecular interactions and polarization in the crystalline solid.

Variable-temperature single-crystal X-ray diffraction study of tetragonal and cubic perovskite-type barium titanate phases

A variable-temperature single-crystal X-ray diffraction study of a synthetic BaTiO₃ perovskite has been performed over the temperature range 298–778 K.

Structure-forming units of amino acid maleates. Case study of L-valinium hydrogen maleate

A new salt of L-valinium hydrogen maleate was used as an example to study structure-forming units in amino acid maleates. Model calculations have shown the C²₂(12) motif (common for most maleates) to be crucial for the thermodynamic stability of the structure.

Crystallography and Mineralogy