Comparison of the crystal structures of the low- and high-temperature forms of bis[4-(dimethylamino)pyridine]dithiocyanatocobalt(II)

Single crystals of the high-temperature form I of [Co(NCS)2(DMAP)2] (DMAP = 4-dimethylaminopyridine, C7H10N2) were obtained accidentally by the reaction of Co(NCS)2 with DMAP at slightly elevated temperatures under kinetic control. This modification crystallizes in the monoclinic space group P21/m and is isotypic with the corresponding Zn compound. The asymmetric unit consists of one crystallographically independent Co cation and two crystallographically independent thiocyanate anions that are located on a crystallographic mirror plane and one DMAP ligand (general position). In its crystal structure the discrete complexes are linked by C—H...S hydrogen bonds into a three-dimensional network. For comparison, the crystal structure of the known low-temperature form II, which is already thermodynamically stable at room temperature, was redetermined at the same temperature. In this polymorph the complexes are connected by C—H...S and C—H...N hydrogen bonds into a three-dimensional network. At 100 K the density of the high-temperature form I (ρ = 1.457 g cm−3) is lower than that of the low-temperature form II (ρ = 1.462 g cm−3), which is in contrast to the values determined by XRPD at room temperature. Therefore, these two forms represent an exception to the Kitaigorodskii density rule, for which extensive intermolecular hydrogen bonding in form II might be responsible.

Characterization of δ-KZnPO4 by X-ray powder diffraction

The structural parameters of a second low-temperature form of KZnPO4 have been refined using Rietveld analysis of X-ray powder diffraction (XRPD) data. This form of KZnPO4 is isostructural with NH4ZnPO4I and has previously been denoted as KZnPO4II. This article uses the notation δ-KZnPO4, to be consistent with the α, β, and γ notation commonly used for other KZnPO4 phases.

Synthesis and structural characterization of orthorhombic Cu3–δ Sb (δ ≈ 0.1) and hexagonal Cu3Sb1–xInx (x ≈ 0.2) phases

Cu3Sb is a known copper-rich phase in the Cu–Sb binary phase diagram. It is reported to be dimorphic, with a low-temperature form adopting the orthorhombic Cu3Ti structure type (space group Pmmn, No. 59). The high-temperature form crystallizes in the cubic space group F m 3 ‾ m $Fm‾{3}m$ (No. 225), and is isostructural with BiF3. Neither polymorph has been carefully characterized to date, with both structures being assigned to the respective structure type, but never refined. With this study, we provide structural evidence, based on single-crystal and powder X-ray diffraction data that the low-temperature orthorhombic phase exists with a significant amount of defects on one of the Cu-sites. As a result, its composition is not Cu3Sb, but rather Cu3–δ Sb (δ = 0.13(1)). The cubic form could not be accessed as a part of this study, but another Cu-rich phase, Cu3Sb≈0.8In≈0.2, was also identified. It adopts the hexagonal Ni3Sn structure type (space group P63/mmc, No. 194) and represents an In-substituted variant of a hitherto unknown structural modification of Cu3Sb. Whether the latter can exist as a binary phase, or what is the minimum amount of In inclusions needed to stabilize it remains to be determined. Measurements of the thermopower of Cu3–δ Sb (δ = 0.13(1)) were conducted in the range of 300–600 K and demonstrated a maximum value of ca. 50 μV/K at 600 K, indicative of a p-type transport mechanism. Electrical resistivity measurements for the same sample confirmed that it exhibits metallic-like behavior, with a room temperature value of 0.43 mΩ cm. Electronic structure calculations show the absence of a band gap. Thermal analysis was utilized to ascertain the congruent melting of both phases.

REPRESENTATION OF PAIN IN UKRAINIAN LANGUAGE

The article presents the analysis of the metaphorical conceptualization of pain in Ukrainian language on the basis of the noun біль ‘pain’. The noun is widely used in Ukrainian to denote this unpleasant physical and emotional sensation. With the help of cognitive approach, the main aim of which is to analyze the consciousness through the language, the pain sensation and its verbalization in the language were analyzed and the following metaphors were established: PAIN – LIVING BEING, PAIN – OBJECT, PAIN – LIQUID IN A CONTAINER, PAIN – STRUGGLE, PAIN – LIGHT and PAIN – FIRE. The metaphor PAIN – LIVING BEING represents the personification of pain. Metaphorically pain gets the characteristics of the human being, for example, the ability to walk and to talk, as well as the ability to perform some actions either with the help of ‘hands’ or some instruments. As OBJECT pain possesses some characteristics like temperature, form and color. Metaphorically pain is the LIQUID IN A CONTAINER, where container is a human body.

A structural exploration of anisole accessed through extreme crystallisation conditions

A novel high pressure polymorph of anisole has been discovered and investigated with respect to the known low temperature form.

Chemical potential, Gibbs–Duhem equation and quantum gases

Thermodynamic relations like the Gibbs–Duhem are valid from the lowest to the highest temperatures. But they cannot by themselves provide any specific temperature behavior of thermodynamic functions like the chemical potential. In this work, we show that if some general conditions are attached to the Gibbs–Duhem equation, it is possible to obtain the low temperature form of the chemical potential for the ideal Fermi and Bose gases very directly.