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The correlations of values of the crystal structure complexity indices were calculated using the major modern approaches (10 indices in total), in particular, those, proposed by Krivovichev, Oganov, the concept of implicit hierarchical depth, as well as, for the comparison, the measure of regularity of (r, R)-system introduced by Blatov. To find the correlations, a series of 33 mercury-containing mineral structures with a non-repeating system of crystallographic positions occupied by atoms without any partial occupancy was used. It was shown that almost all pairs of complexity indices are statistically significantly (p < 0.05) positively or negatively correlated. The discriminating power of the indices for the set of structures was calculated. It is discussed that all the indices can be used to assess the complexity for any series of the crystal structures, but each of them has its particular advantages and limitations. [ABSTRACT FROM AUTHOR]

Microporous materials containing hydrated silanol groups Si–OH as well as hydrated proton complexes, H2n+1On+, including hydronium (n = 1), Zundel (n = 2), and Eigen (n = 4) cations, are of practical importance as potential ion exchangers and ion conductors. In this paper, we provide data on crystal‐chemical features, hydrogen bonding and Raman spectra of alkaline microporous titano‐, niobo‐, zircono‐, and aluminosilicate minerals belonging to the labuntsovite, lovozerite, eudialyte, and sodalite groups in which a part of sodium was substituted by hydrated proton complexes under low‐temperature hydrothermal or supergene conditions. Most minerals studied in this work do not have synthetic analogues and are considered as possible natural prototypes of microporous materials with technologically important properties. The obtained experimental data and their comparison with the results of ab initio theoretical calculations published elsewhere show that Raman spectroscopy is an effective tool for the precise identification of hydrated proton complexes with extremely strong hydrogen bonds and estimation of corresponding O···O distances in the range of 2.37–2.68 Å. The presence of hydrated proton complexes in microporous silicates is a clear and sensitive geological indicator showing that a rock underwent the low‐temperature alteration. [ABSTRACT FROM AUTHOR]

Purple crystals of ethylenediammonium cobalt bis(hydrogen phosphite) dichloride were produced from an aqueous solution containing ethylenediamine, cobalt chloride, and phosphorous acid. The new compound is monoclinic, P21/c, a = 8.6665(3) Å, b = 7.2866(2) Å, c = 9.7300(3) Å, β = 112.726(3); V = 566.74(3) Å3, Z = 2. The 2D structure comprised ethylenediammonium cations sandwiched between the [Co(HPHO3)2Cl2]2− layers. The latter are built of trans-CoO4Cl2 octahedra linked by hydrogen-bonded dimers of hydrophosphite ions, (HPHO3)22−. The new compound is a complete structural analog of the recently reported (C2N2H10)[Co(HSeO3)2Cl2] and isostructural analogs with other transition metal dications; it is, in fact, the first representative of a new "layered hydrophosphite" family. Its structure provides yet another illustration of essential similarities in the crystal chemistry of selenites and phosphites, including protonated species, wherein the lone pair of SeIV and the nearly nonpolar P–H enhance formation of loose and/or open-framework structural architectures. [ABSTRACT FROM AUTHOR]

Single crystals of two new intermetallic phases Sm2Mn1−xGa6−yGey (x = 0.1–0.3, y = 0.6–1.0) and Sm4MnGa12−yGey (y = 3.0–3.5) were grown using a self-flux technique. According to single crystal X-ray diffraction data, Sm4MnGa12−yGey is characterised by the Y4PdGa12 structure type (a ∼ 8.65 Å; Im3¯m), while Sm2Mn1−xGa6−yGey formally adopts the K2PtCl6 structure type (a ∼ 8.71 Å; Fm3¯m). The general features of both compounds with rather similar crystal structures are represented by the alternation of empty and Mn-filled p-element octahedra, the order of which is determined by the Mn concentration. The diffraction data for Sm2Mn1−xGa6−yGey reveal a large concentration of Mn vacancies (x ∼ 0.3), which affects adjacent Ga/Ge atoms leading to their shift towards the vacancy. Both compounds demonstrate two ferromagnetic-like transitions and the presence of two interacting Mn and Sm magnetic sublattices. The Mn sublattice orders at TC1 of 143 K and 318 K, while the Sm one orders at lower temperatures at TC2 of 50 K and 280 K for Sm4MnGa8.6Ge3.4 and Sm2Mn0.74Ga5.1Ge0.9, respectively. The increase in Mn content not only increases the ordering temperatures, but also dramatically decreases the coercivity μ0HC from 230 mT to just 6.5 mT at 2 K. Despite the presence of two magnetically active sublattices in Sm2Mn0.74Ga5.1Ge0.9, the magnetic entropy change is quite low and only reaches 0.3 J kg−1 K−1 at T = 300 K and μ0H = 5 T, while the estimated relative cooling power (RCP) is about 36 J kg−1 at 5 T. [ABSTRACT FROM AUTHOR]

A new series of Sr-based phosphates, Sr9−xMnxEu(PO4)7, were synthesized using the high-temperature solid-state method in air. It was found that these compounds have the same structure as strontiowhitlockite, which is a β-Ca3(PO4)2 (or β-TCP) structure. The concentration of Mn2+ ions required to form a pure strontiowhitlockite phase was determined. An unusual partial reduction of Eu3+ to Eu2+ in air was observed and confirmed by photoluminescence (PL) and electron spin resonance (ESR) spectra measurements. The PL spectra recorded under 370 nm excitation showed transitions of both 4f5d–4f Eu2+ and 4f–4f Eu3+. The total integral intensity of the PL spectra, monitored at 395 nm, decreased with increasing Mn2+ concentration due to quenching effect of Eu3+ by the Mn2+ levels. The temperature dependence of Eu2+ photoluminescence in a Sr9−xMnxEu(PO4)7 host was investigated. The conditions for the reduction of Eu3+ to Eu2+ in air were discussed. [ABSTRACT FROM AUTHOR]

β-Tricalcium phosphate (β-TCP) is widely used as bone implant material. It has been observed that doping the β-TCP structure with certain cations can help in combating bacteria and pathogenic microorganisms. Previous literature investigations have focused on tricalcium phosphate structures with silver, copper, zinc, and iron cations. However, there are limited studies available on the biological properties of β-TCP containing nickel and cobalt ions. In this work, Ca10.5−xNix(PO4)7 and Ca10.5−xCox(PO4)7 solid solutions with the β-Ca3(PO4)2 structure were synthesized by a high-temperature solid-state reaction. Structural studies revealed the β-TCP structure becomes saturated at 9.5 mol/% for Co2+ or Ni2+ ions. Beyond this saturation point, Ni2+ and Co2+ ions form impurity phases after complete occupying of the octahedral M5 site. The incorporation of these ions into the β-TCP crystal structure delays the phase transition to the α-TCP phase and stabilizes the structure as the temperature increases. Biocompatibility tests conducted on adipose tissue-derived mesenchymal stem cells (aMSC) using the (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay showed that all prepared samples did not exhibit cytotoxic effects. Furthermore, there was no inhibition of cell differentiation into the osteogenic lineage. Antibacterial properties were studied on the C. albicans fungus and on E. coli, E. faecalis, S. aureus, and P. aeruginosa bacteria strains. The Ni- and Co-doped β-TCP series exhibited varying degrees of bacterial growth inhibition depending on the doping ion concentration and the specific bacteria strain or fungus. The combination of antibacterial activity and cell-friendly properties makes these phosphates promising candidates for anti-infection bone substitute materials. [ABSTRACT FROM AUTHOR]

Aminoguanidinium thiosulfate, (CN4H7)2S2O3 (1), was prepared via an exchange route from barium thiosulfate and aminoguanidinium sulfate. The new compound is monoclinic, a=12.8344(6) Å, b=13.9134(6) Å, c=6.8757(3) Å, β=115.529(5)°, and crystallizes in a centrosymmetric C2/m space group. Its crystal structure can be considered either as pseudo‐columnar comprised of stacked [CN4H7]+ cations and isolated [S2O3]2− anions which are actively involved in hydrogen bonding, or as H‐bonded bilayers comprised of both [CN4H7]+ and [S2O3]2− of topologic type 3,6L60. The latter ones are H‐bound into a 4,8‐coordinated bearing framework of the type scu. [ABSTRACT FROM AUTHOR]

VO and VO2 vanadyl groups with short (typically 1.57–1.68 Å), essentially covalent, V—O bonds are common for V4+‐bearing oxysalts with [5]‐ and [6]‐coordinated vanadium. There is a clear negative correlation between vanadyl bond lengths and wavenumbers of the bands of V—O stretching vibrations in infrared spectra (in the range 1000–880 cm−1). Optical, structural and chemical data for vanadyl minerals are used to calculate Gladstone–Dale compatibility coefficients. Gladstone–Dale compatibility indices of minerals containing vanadyl bonds are compared with total electronic polarizabilities of V4+. Unlike compounds of [5]‐coordinated Ti4+, for most minerals with V4+=O (vanadyl) bonds there is good agreement between measured refractive indices and those calculated based on the polarizability concept. [ABSTRACT FROM AUTHOR]

In situ thermo‐Raman spectroscopy is used to study a single crystal of natural orthorhombic cubanite from the Talnakh copper‐nickel sulfide deposit (Norilsk, Russia). The dependence of the wavenumbers and FWHMs of vibrational modes on temperature, including the cubanite → isocubanite phase transition region, is studied in the range of 83–873 K. For the first time, the polarized Raman spectra of cubanite have been interpreted according to ab initio calculations performed using the density functional theory (DFT) implemented in the VASP package. In spite of the tetrahedral environment of Cu and Fe atoms in cubanite, the spectra demonstrate the presence of different types of bending (twisting, wagging, scissoring, etc.) and stretching vibrations in two different triatomic (S2‐Cu‐S2) and (Fe‐S1‐Fe) fragments for Ag and B2g symmetries, and in three‐ and four‐atomic (S1‐Cu‐S1) and FeS(2)3 fragments, respectively, for B1g and B3g symmetries. [ABSTRACT FROM AUTHOR]

Na3R(BO3)2 (R = La–Gd) borates, grown with Na2O–B2O3–NaF flux, crystallize in the space group P21/n. Contrary to previously published data, the peaks in the 980(La)–950(Gd) °C range are attributed to phase transition process, while the melting process occurs at about 100° higher. Another feature of thermal behavior consists of the gradual decomposition of the compound into Na3R2(BO3)3. The end member in the decomposition series is Na2R2O(BO3)2, which originates under oxygen/water atmosphere. In addition, the components of the thermal expansion tensor and the dependings of the unit-cell parameters of Na3Nd(BO3)2 on temperature were defined. A series of Pr3+, Nd3+, and Sm3+-doped Na3Gd(BO3)2 (NGB) borates were prepared from mixtures of grown crystals by solid-state synthesis, and their photoluminescence properties were studied in detail. The excitation and emission spectra of NGB: Pr3+ and NGB: Nd3+ are comparable with similar compounds, and the relative intensity reaches the maximum at 1 mol% of Pr3+, Sm3+, and 10 mol.% for Nd3+ doping. [ABSTRACT FROM AUTHOR]

Based on Krivovichev information measures for crystal structures and the universal partitioning scheme for different sources of information described previously by Hornfeck, a ladder of information for crystal structures with primary motifs of different dimensionalities (0D, 1D, or 2D) is proposed. Ethanol (0D), SnIP (1D), and TlOH (2D) are discussed as examples of the introduced concept. The proposed calculation technique allows to explicitly obtain contributions of substructures of ordered structures into the information content of a structure conforming to the rule of strong additivity, thus giving a simple assessment of complexity at different hierarchical levels of organization, and takes into account partitioning contacts formed by structural units into equivalence classes, which is poorly dependent on that of the structural units themselves. The technique is a complementation to the multilevel topological analysis performed in the ToposPro program package. [ABSTRACT FROM AUTHOR]