X-ray Powder Diffraction Patterns Research Articles

Perchiazziite, Co2(CO3)(OH)2, a New Member of the Rosasite–Malachite Group from the Monte Ramazzo Mine, Italy

ABSTRACT Perchiazziite, ideally Co2(CO3)(OH)2, is a new mineral discovered at the Monte Ramazzo Mine, Genova Province, Liguria, Italy. It occurs as globular aggregates up to 0.1 mm in diameter, composed of very thin fibers. These develop on a matrix composed mostly of goethite and magnetite, in association with calcite and Co-bearing malachite. Aggregates of perchiazziite are pale orange-pink on their outer surfaces but white in thin section. It is translucent with white streak, silky luster, brittle tenacity, and uneven fracture. No cleavage and parting are observed. The Mohs hardness is ∼4. Dcalc. = 3.970 g/cm3. The mean refractive index calculated using the Gladstone-Dale equation is 1.77. The main bands in the Raman spectrum are at 154, 511, 707, 1085, 1526, 3304, aXnd 3479 cm−1. The chemical composition (by electron microprobe; CO2 and H2O by stoichiometry) of perchiazziite is (in wt.%): MgO 1.81, CaO 0.41, MnO 0.32, FeO 0.12, CoO 32.45, NiO 4.02, CuO 5.40, ZnO 25.60, CO2 20.63, H2O 8.42, total 99.18. The empirical formula calculated on the basis of 5 O apfu is: (Co0.93Zn0.67Cu0.15Ni0.12Mg0.10Ca0.02Mn0.01)Σ2.00(CO3)(OH)2. The crystal structure was refined by the Rietveld method. Perchiazziite is monoclinic, space group P21/a, a = 12.1832(16) Å, b = 9.3187(16) Å, c = 3.1570(3) Å, β = 97.165(15)°, V = 355.62(8) Å3, and Z = 4. The strongest lines of the X-ray powder diffraction pattern [d, Å (I, %) (hkl)] are 6.040 (22) (200), 5.073 (38) (210), 3.694 (53) (220), 2.599 (100) (021), 2.535 (26) (420), 2.480 (27) (221̄), 2.140 (26) (231̄), 1.561 (25) (202̄). Perchiazziite is a new member of the rosasite–malachite group.

Ho3+ -doped BaGd2 ZnO5 green-emitting phosphor for solid-state lighting: synthesis, characterization, and photoluminescence properties.

In this work, we present the synthesis of a green-emitting series of BaGd2 ZnO5 :xHo3+ (0.5-3mol%) phosphors using a high-temperature solid-state reaction method. Phase purity and crystal structure information were evaluated through X-ray powder diffraction patterns. Optical properties were examined through diffuse reflectance spectra, revealing that the prepared phosphor exhibited a band gap of 4.65 eV. The effect of Ho3+ doping on the morphology and ion distribution on the surface was assessed using scanning electron microscopy and time-of-flight secondary ion mass spectrometry techniques, respectively. The excitation spectra of the synthesized phosphor exhibited a charge transfer band and strong absorption transitions. The emission spectra displayed typical holmium emission characteristics, featuring a strong green emission band associated with f-f transitions from 5 F4 + 2 S2 → 5 I8 . Decay dynamics of the synthesized phosphor exhibited a single-exponential decay pattern, with lifetimes ranging from 0.103 to 0.053 ms. The intrinsic radiative lifetime, calculated through Auzel's fitting was determined to be 0.14 ms. Using the emission spectra, colorimetric behaviour was analyzed, revealing that the Commission Internationale de l'éclairage (CIE) coordinates exclusively lay within the green region at (0.285, 0.705), with an impressive colour purity of 99.6%. Given these marked properties, the synthesized phosphor exhibits great potential for a wide range of green-emitting applications, including displays, white light-emitting diodes, and security signage.

Determination of two structures of the solvent 3-hydroxypropionitrile crystallized at low temperatures

The title compound, 3-hydroxypropionitrile, was crystallized repeatedly in situ inside a quartz capillary using a liquid nitrogen cryostream. The X-ray powder diffraction patterns obtained indicated the presence of two distinct crystalline phases. The cleanest datasets for each of the phases were used to solve the crystal structures via simulated annealing, followed by refinement and optimization via dispersion-corrected density functional theory (DFT) calculations, with a final Rietveld refinement against the experimental data. The two structures appear to correspond to those proposed in a 1960s literature vibrational spectroscopy paper, one being the more stable with a gauche molecular conformation and the second metastable phase more complex with mixed conformations. Dispersion-corrected DFT computation using lattice parameters for both phases obtained from a single 84 K dataset with co-existing phases shows the stable and metastable phases to differ in energy by less than 0.5 kJ mol−1. A comparison of experimental far infrared spectra published in the 1960s with those calculated from the proposed crystal structures provides some independent supporting evidence for the proposed structures.

Crystal chemistry and molar volume of potassic-chloro-hastingsite

Abstract. Several geological processes such as crustal and mantle metasomatism, high-grade metamorphism, and the formation of ore deposits involve the exchange of halogens, especially chlorine, between silicate minerals and fluids. It is well established that the presence of octahedral iron is vital to the process of Cl incorporation into amphiboles. However, other compositional controls on Cl incorporation, such as the effect of TAl, ANa, AK, and A-site occupancy are not as well constrained. This study reports on the compositional and structural relationships amongst a suite of 25 synthetic calcium amphiboles with a diverse range of Cl contents (0–1.68 atoms per formula unit (apfu)). Most amphiboles were synthesized along the potassic-hastingsite–potassic-chloro-hastingsite join (KCa2(Fe4Fe3+)(Al2Si6)O22(OH,Cl)2). Additional work involved substitution of Na for K, variable Al content, and substitution of Mg for Fe2+ in the bulk composition to explore these compositional effects on Cl incorporation. The relationship between pressure and the Cl content of amphiboles was also explored over the pressure range 0.3–2.0 GPa. Otherwise, synthesis conditions were 700 °C and 0.3 GPa with fO2 near Ni–NiO. Iron (II) chloride was used as the source of Cl. Some experiments used variably concentrated FeCl2 brines (0–100 molal), while others were nominally anhydrous, containing only the water absorbed by the hygroscopic FeCl2. All amphiboles were characterized by Rietveld refinements of powder X-ray diffraction patterns, electron microprobe analysis, and Mössbauer spectroscopy, the latter to determine Fe3+ fraction. This study finds a positive relationship between pressure and the Cl content of the amphibole. Both Fe2+ and Fe3+ are positively correlated with Cl among amphiboles with variable Fe#, but the correlation is poor to nonexistent for Mg-free amphiboles. Results indicate that the substitution of CFe2+,3+ for CMg and CFe2+,3+ for CAl facilitate Cl incorporation, with the former having a larger effect. The A-site occupancy is positively correlated with Cl in all amphiboles except those synthesized in dilute FeCl2 brines (≤ 6 m), which are negatively correlated. No correlation is observed between the Cl content of the amphibole and either the species of A cation (K vs. Na) or TAl. The composition vs. unit cell parameter data were analyzed using multivariate linear regression to better understand the process of Cl incorporation and to predict the molar volume of endmember chloro-amphiboles. The regression indicates an expansion of 0.181 Å (0.99 %) and 0.048 Å (0.90 %) along the b and c edges respectively, a reduction in β by 0.76° (0.72 %), and a contraction of 0.060 Å (0.59 %) along a when fully substituting Cl for OH in potassic-hastingsite. The multivariate linear regression equations allow the prediction of molar volumes for select endmember chloro-amphiboles, such as potassic-chloro-hastingsite = 964.63 ± 1.29 Å3 or 290.5 ± 0.4 cm3 mol−1.

Testibiopalladite, PdSbTe: A Valid Mineral and Sb-Analogue of Michenerite

Abstract Testibiopalladite was reported from two unnamed deposits in China by Anonymous (1974) to be ideally PdSbTe. The description of the mineral included an indexed X-ray powder diffraction pattern, space group determination, electron probe micro-analyses, reflectance, and micro-indentation hardness measurements. This description was published without prior submission to the IMA, which was the norm at the time before China became a member. It is unknown as to why the Commission for New Minerals and Mineral Names (CMNMN) did not examine and vote on the mineral as had been done for all other Chinese mineral descriptions published at the time. It is surprising because the chairman of the CMNMN at the time had reviewed the mineral (Fleischer et al. 1976) and concluded it was a valid species, i.e., the Sb analogue of michenerite (PdBiTe). Further, the same article included a description of “hexastibiopanickelite” which was voted on and rejected by the CMNMN in 1976. From 1981 to 2021 there were many papers published reporting testibiopalladite from several deposits in different countries (e.g., Hudson et al. 1978, Chen et al., 1993, Stepanets et al. 2019, 2020), as well as a single-crystal structure analysis of synthetic PdSbTe which confirmed the assigned space group (Foecker & Jeitschko 2001). The published data (e.g., Barkov et al. 2002, Liang et al. 2019, 2023) suggest that testibiopalladite is a valid mineral species, ideally PdSbTe, and is the Sb analogue of michenerite, PdBiTe, both crystallizing in space group P213. Both the name testibiopalladite and the mineral, ideally PdSbTe, were approved by the Commission of New Minerals, Nomenclature and Classification of the International Mineralogical Association (CNMNC-IMA), Nomenclature Voting Proposal 23-H. Liang et al. (2019, 2023) studied samples from the type locality (Yangliuping deposit, PRC) that are to be considered as a neotype.

Enricofrancoite, KNaCaSi4O10, a new Ca–K–Na silicate from Somma–Vesuvius volcano, southern Italy

Abstract Enricofrancoite (IMA2023–002), ideally KNaCaSi4O10, is a new litidionite-group member found as the product of high-temperature alteration of hosting silicates with the enrichment by Cu-bearing fluids at the rock–fumaroles interface related to the 1872 eruption of Somma–Vesuvius volcano, southern Italy. It occurs as euhedral and platy crystals or crusts together with litidionite, tridymite, wollastonite and Al- and Fe-bearing diopside, kamenevite, perovskite, rutile, Ti-rich magnetite and colourless Si-glass. Single crystals of enricofrancoite are transparent colourless or light blue with a vitreous lustre. Mohs hardness is 5.5. Dmeas is 2.63(3) g/cm3 and Dcalc is 2.63 g/cm3. The mineral is optically biaxial (−), α = 1.542(5), β = 1.567(5),γ = 1.575(5); 2V(meas) = 60(2)° and 2Vcalc = 58°. The mean chemical composition (wt.%, electron-microprobe data) is: SiO2 64.81, Al2O3 0.03, TiO2 0.08, FeO 0.07, MgO 1.71, CaO 10.64, CuO 2.22, Na2O 8.56, K2O 11.41, total 99.94. The empirical formula based on 10 O apfu is: K0.90Na1.03(Ca0.71Mg0.16Cu0.10)Σ0.97Si4.02O10. The Raman spectrum contains bands at 133, 248, 265, 290, 335, 400, 438, 510, 600, 690 and 1120 cm–1 and the wavenumbers of the IR absorption bands are: 424, 470, 492, 530, 600, 630, 690, 750, 788, 970, 1040 and 1160 cm–1. The eight strongest lines of the powder X-ray diffraction pattern are [d, Å (I, %) hkl]: 6.75 (42) 01 $\bar{1}$ , 3.65 (20) 11 $\bar{2}$ , 3.370 (100) 02 $\bar{2}$ , 3.210 (52) 102, 3.051 (18) 111, 3.033 (25) 2 $\bar{1}\bar{2}$ , 2.834 (22) 02 $\bar{3}$ and 2.411 (72) 03 $\bar{2}$ . Enricofrancoite is triclinic, space group P $\bar{1}$ , unit-cell parameters refined from the single-crystal data are a = 7.0155(4) Å, b = 8.0721(4) Å, c = 10.0275(4) Å, α = 104.420(4)°, β = 99.764(4)°, γ = 115.126(5)° and V = 472.74(5) Å3. The crystal structure has been refined from single-crystal X-ray diffraction data to R1 = 0.035 on the basis of 2078 independent reflections with Fo > 4σ(Fo). Enricofrancoite is an H2O-free analogue of calcinaksite with 5-coordinated Ca2+ at the M site.

An effective material for solar steam generation applications: Gradient graphene sponge

The efficient use of solar energy for clean water is a renewable and environmentally-friendly route to solve global water scarcity. For this, we report the preparation of light, mechanically durable, and effective photothermal material. A simple acid impregnation method was applied to graphene sponge material (GSM) possessing hydrophobic character to gain partial hydrophilicity to obtain a gradient structure. The morphological and structural properties of the gradient graphene sponge material (GGSM) were carried out using scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray powder diffraction patterns, Fourier-transformed infrared spectroscopy, and water drop contact angle measurements. GGSM showed fast and effective water vapor conversion performance due to the gradient structure, as well as the high rate of sunlight absorption and photothermal conversion thanks to graphene. With the advantageous feature of gradient structure, GGSM achieved a high water vapor conversion capacity (1.79 kg/m2h) and solar thermal efficiency of 57% compared to GSM (1.58 kg/m2h; 45%). This new material provides a novel approach to solar energy applications.

Mckelveyite group minerals – Part 3: Bainbridgeite-(YCe), Na2Ba2YCe(CO3)6 ⋅ 3H2O, a new species from Mont Saint-Hilaire, Canada

Abstract. The new mckelveyite group mineral bainbridgeite-(YCe), ideally Na2Ba2YCe(CO3)6 ⋅ 3H2O, was found at Mont Saint-Hilaire, Quebec, Canada. Bainbridgeite-(YCe) occurs as pseudotrigonal and pseudohexagonal hemimorphic crystals that show platy, columnar, tabular, cone-shaped, barrel-shaped, saucer-shaped, or spindle-shaped habit. They often form stacked or parallel growth aggregates, rosettes, and groups of radiating crystals. The crystals are usually less than 1 mm in size. Bainbridgeite-(YCe) varies in colour from pale yellow to yellow, grey to almost black, bluish grey, green-grey, or white. The streak is white; the lustre is vitreous. The mineral has no cleavage. The Mohs hardness is 3. Dcalc is 3.49 g cm−3. Bainbridgeite-(YCe) is optically biaxial (+), α= 1.572(2), β= 1.586(2), γ= 1.628(2), 2 V (calc.) = 62∘, 2 V (meas.) = 45(4)∘(589 nm). The IR spectrum is reported. The composition (wt %, average of five analyses) is Na2O 6.86, CaO 0.59, SrO 4.01, BaO 25.71, Y2O3 8.24, La2O3 4.96, Ce2O3 8.38, Pr2O3 0.48, Nd2O3 1.87, Sm2O3 0.23, Gd2O3 0.67, Tb2O3 0.07, Dy2O3 1.38, Ho2O3 0.32, Er2O3 0.94, Tm2O3 0.08, Yb2O3 0.49, CO2 27.03, H2O 5.67, total 97.98. The empirical formula of the holotype calculated on the basis of six cations is as follows: Na2.11Ca0.10Sr0.37Ba1.60Y0.70La0.29Ce0.49Pr0.03Nd0.11Sm0.01Gd0.03Dy0.07Ho0.02Er0.05 Yb0.02(CO3)5.86(H2O)3.00. The mineral is triclinic, P1, a= 9.1079(2) Å, b= 9.1066(3) Å, c= 6.9332(2) Å, α= 102.861(2)∘, β= 116.148(2)∘, γ= 60.181(2)∘, V= 447.85(2) Å3, and Z= 1. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are 6.22(42)(001, 1‾1‾1, 1‾01), 4.430(100)(01‾1, 2‾1‾1, 120), 4.094(37)(1‾2‾1, 1‾11, 210, 111), 3.263(26)(11‾1, 2‾1‾2, 121), 2.888(67)(1‾2‾2, 1‾12, 211), 2.633(38)(3‾01, 030, 3‾3‾1), 2.263(23)(2‾21, 2‾4‾1, 4‾2‾1). 2.010(20)(03‾2, 3‾3‾3, 3‾03, 301, 032, 331). The crystal structure, solved and refined from single-crystal X-ray diffraction data (R1= 0.040), is of the weloganite type.

Dmitryvarlamovite, Ti2(Fe3+Nb)O8, a new columbite-supergroup mineral related to the wolframite group

AbstractThe new columbite-supergroup mineral dmitryvarlamovite, ideally Ti2(Fe3+Nb)O8, was discovered in weathered alkaline metasomatic assemblages formed after late Riphaean sedimentary carbonate rocks of the Verkhne-Shchugorskoe deposit, Middle Timan Mts., Russia. The associated minerals are columbite-(Fe), pyrochlore-group minerals, monazite-(Ce), xenotime-(Y), baryte, pyrite, drugmanite and plumbogummite. Dmitryvarlamovite occurs as isolated anhedral equant grains up to 0.5 mm across. The colour of dmitryvarlamovite is black, the streak is black and the lustre is submetallic. The new mineral is brittle, with the mean VHN hardness of 753 kg mm–2 corresponding to the Mohs’ hardness of 6. No cleavage is observed. The fracture is conchoidal. The calculated density is 4.891 g⋅cm–3. In reflected light, dmitryvarlamovite is light grey; no pleochroism is observed. The reflectance values (Rmin, % / Rmax, % / λ, nm) are: 19.8/20.3/470, 18.3/18.9/546, 17.8/18.5/589 and 17.3/17.8/650. The chemical composition is (electron microprobe data, with iron divided into Fe2O3 and FeO based on the charge balance, wt.%): MnO 0.11, FeO 1.51, V2O3 0.89, Cr2O3 0.28, Fe2O3 19.26, TiO2 37.72, Nb2O5 40.08, total 99.85. The IR and Raman spectra indicate the absence of H-, C- and N-bearing groups. The empirical formula is (Fe2+0.08V3+0.05Cr3+0.01Fe3+0.92Ti1.79Nb1.15)Σ4.00O8. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.048. Dmitryvarlamovite is orthorhombic, space group P21212, a = 4.9825(6), b = 4.6268(4), c = 5.5952(6) Å and V = 5.5952(6) Å3 (Z = 1). The structure is related to those of wolframite-group minerals but differs in the scheme of cation ordering. The crystal-chemical formula derived based on the structural data is (Ti0.57Nb0.21Fe3+0.15Fe2+0.04V0.02Cr0.01)2(Nb0.36Ti0.33Fe3+0.31)2O8. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 3.58 (40) (011), 2.911 (100) (111), 2.809 (40) (002), 2.497 (38) (020), 2.447 (29) (103), 1.7363 (32) (103) and 1.7047 (29) (220). Dmitryvarlamovite is named after Dmitry Anatol'evich Varlamov (b. 1965).

Impact of transparent conducting substrates on structural and optical of Titanium(IV) phthalocyanine dichloride (TiPcCl2) thin films

This study investigates the impact of transparent conducting substrates, specifically indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO), on the structural and optical characteristics of thermally evaporated Titanium phthalocyanine chloride (TiPcCl2) thin films. The crystalline structure of TiPcCl2/quartz thin films was verified by X-ray powder diffraction (XRD) patterns while amorphous phases were detected in TiPcCl2/ITO and TiPcCl2/FTO thin films. Field emission scanning electron microscopy (FESEM) images provided evidence that the morphology of TiPcCl2 thin films may be affected by a lattice mismatch between TiPcCl2 and substrates. Fourier-transform infrared spectroscopy (FT-IR) also showed that the substrates did not change the molecular structure of TiPcCl2. UV–Vis-NIR spectroscopy demonstrated that the substrates had a significant influence on the optical gap, optical constants, dielectric constant dielectric loss functions and optical conductivity of TiPcCl2 thin films. Lastly, the nonlinear susceptibility χ(3), the nonlinear refractive index n2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\varvec{n}}}_{2}$$\\end{document} and the nonlinear absorption coefficient β(c) for TiPcCl2/ITO, TiPcCl2/FTO, and TiPcCl2/quartz were obtained using a semi-empirical approach. The changes seen in optical properties could be due to changes in the crystal structure and morphology, which are closely connected to the properties of the substrate material. Overall, the results for TiPcCl2 thin films are promising, and they are appropriate for novel optoelectronic device applications.

Using synchrotron high-resolution powder X-ray diffraction for the structure determination of a new cocrystal formed by two active principle ingredients.

The crystal structure of a new 1:1 cocrystal of carbamazepine and S-naproxen (C15H12N2O·C14H14O3) was solved from powder X-ray diffraction (PXRD). The PXRD pattern was measured at the high-resolution beamline CRISTAL at synchrotron SOLEIL (France). The structure was solved using Monte Carlo simulated annealing, then refined with Rietveld refinement. The positions of the H atoms were obtained from density functional theory (DFT) ground-state calculations. The symmetry is orthorhombic with the space group P212121 (No. 19) and the following lattice parameters: a = 33.5486 (9), b = 26.4223 (6), c = 5.3651 (10) Å and V = 4755.83 (19) Å3.

Na2[Pd(saccharinate)4]: A new phosphine-free water-soluble catalyst with singular structure for modification of ribose nucleosides at room temperature

The easy synthesis of the anionic palladium catalyst containing saccharinate as only ligand Na2[Pd(saccharinate)4] (I), starting from either Na2[PdCl4] or Pd(AcO)2, is reported here, together with its complete characterization. It includes high resolution powder X-ray diffraction pattern obtained on a synchrotron source, subsequent elucidation of the crystal structure, and structural refinement using the Rietveld method. The structure consists of linear chains that are linked by non-covalent interactions, and results in a porous structure with channels. This air and light water-soluble complex has shown an outstanding performance for room temperature Pd-catalyzed Suzuki functionalization of the purine base in unprotected nucleosides, improving the best results reported to date.

Thermoelectric properties of aliovalent Zn doped Cu1.8S polycrystalline materials

Cu1.8S-based materials are regarded as promising thermoelectric materials due to their super ionic nature. The Cu1.8-xZnxS (x = 0, 0.01, 0.03, and 0.09) samples were synthesized by the hydrothermal method followed by cold pressing and sintering. The powder X-ray diffraction pattern has confirmed the phase purity and rhombohedral crystal structure of Cu1.8S. Additionally, FE-SEM micrographs along with the EDX elemental mapping detected the existence of CuS as the secondary phase in the Cu1.8S matrix and uniform distribution of the constituent elements. Upon doping the Zn atom, the Seebeck coefficient subsequently increases owing to the decrement in the carrier concentration, whereas the electrical conductivity gradually reduces. Essentially, the presence of CuS secondary phase and the defects induced by the Zn atom effectively scattered low-mid wavelength phonons, where a very low thermal conductivity of 3.65 W/mK was achieved for Cu1.71Zn0.09S at room temperature. Ultimately, an overall maximum zT of 0.07 at 573 K was observed for Cu1.77Zn0.03S, which is about 3.5 times greater than that of the pristine sample.

Pressure Dependence of the Structural and Superconducting Properties of the Bi-Based Superconductor Bi2Pd3Se2.

The structural and superconducting properties of the Bi-based compound Bi2Pd3Se2 were investigated over a wide pressure range. The prepared Bi2Pd3Se2 sample was a superconductor with a superconducting transition temperature, Tc, of approximately 3.0 K, which differed from a previous report (Tc of less than 1.0 K). At ambient pressure, the powder X-ray diffraction (XRD) pattern of the Bi2Pd3Se2 sample was consistent with that previously reported for Bi2Pd3Se2. The Rietveld method was used to refine the crystal structure, which had a space group of C2/m (No. 12), as reported previously. This compound showed no clear anomaly due to the charge-density-wave (CDW) transition, as seen from the temperature dependence of magnetic susceptibility. However, the temperature dependence of electrical resistivity indicated a clear anomaly, presumably because of the CDW transition in the low-pressure range; the CDW transition temperature was approximately 230 K. The XRD patterns of the Bi2Pd3Se2 sample were measured at 0.160-22.7 GPa, and the patterns were well analyzed by both the Le Bail and Rietveld refinement methods, showing no structural phase transitions in the above pressure range. The pressure dependence of Tc of Bi2Pd3Se2 was recorded based on the temperature dependence of the electrical resistance, which showed an almost constant Tc at 0-13.7 GPa, and the Tc-pressure (p) behavior was fully discussed.

Thermotropic Structure Phase Transitions and Two Types of Thermochromic Behaviors in a Bromoargentate Cluster [Pr-dabco]2Ag4Br6.

Organic-inorganic silver halide hybrids show abundant phase transitions and thermochromism. However, it is very rare that silver halides exhibit thermochromism related to thermotropic structure phase transition. Herein, a bromoargentate hybrid, [Pr-dabco]2Ag4Br6 (1) (Pr-dabco+ = 1-propyl-1,4-diazabicyclo-[2.2.2]octan-1-ium), with tetranuclear [Ag4Br6]2- clusters was prepared and characterized by microanalysis, ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy, and thermogravimetric (TG) and differential scanning calorimetry (DSC) techniques. Interestingly, 1 undergoes an irreversible structure phase transition at ∼436 K in the first heating process, which is accompanied by an abrupt color change from colorless to yellow; however, a reversible color change between pale yellow and yellow is observed in the next heating-cooling cycles. Notably, DSC measurement revealed that a reversible phase transition is associated with the change in color between pale yellow and yellow, while the powder X-ray diffraction (PXRD) patterns corresponding to pale yellow and yellow phases are quite similar to each other. These observations demonstrate that thermochromism in the next heating-cooling runs is associated with a reversible structure phase transition, which perhaps concerns the disorder-order transformation of alkyl chains in the cationic ligand [Pr-dabco]+, and relevant to the anharmonic fluctuations of the Ag-Br and Ag-N bonds, a strong electron-phonon coupling effect is seen within the bromoargentate cluster.

Preparation of Polyethylene Clay Composites via Melt Intercalation Using Hydrophobic and Superhydrophobic Organoclays and Comparison of Their Textural, Mechanical and Thermal Properties.

Polymer clay nanocomposites, which can exhibit many superior properties compared to virgin polymers, have gained increasing interest and importance in recent years. This study aimed to prepare composites of two organoclays with unusual ratios and different degrees of lyophilicity with low-density polyethylene and compare their textural structures and thermal and mechanical properties with those of virgin polymer. For this purpose, firstly, organoclays, hydrophobic and superhydrophobic organoclays (OC and SOC), were prepared by solution intercalation method using cetyltrimethylammonium bromide with and without addition of a hydrocarbon substance. Then, using both organoclays, polyethylene organoclay composites were prepared and characterized using X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Additionally, tensile and hardness tests were performed to determine the mechanical properties of the composites, and differential scanning calorimetry (DSC) thermograms were taken to examine their thermal behavior. XRD patterns and HRTEM images of hydrophobic and superhydrophobic organoclays and the composites show that the characteristic smectite peak of the clay shifts to the left and expands, that is, the interlayer space widens and, in the composites, it deforms immediately at low clay ratios. HRTEM images of the composites prepared especially with low clay ratios indicate that a heterogeneous dispersion of clay platelets occurs, indicating that nanocomposite formation has been achieved. On the contrary, in the composites prepared with high clay ratios, this dispersion behavior partially turns into aggregation. In the composites prepared using up to 20% by weight of superhydrophobic organoclay, extremely stable and continuous improvements in all mechanical properties were observed compared to those of the composites prepared using hydrophobic organoclay. This indicates that by using superhydrophobic organoclay, a ductile nanocomposite of polyethylene containing inorganic components in much higher than usual proportions can be prepared.

Synthesis, characterization, antimicrobial, molecular docking simulation, and antitumor assays of nanometric complexes based on new thiazole Schiff base derivative

For further pharmaceutical applications, a novel Schiff base derivative of aminothiazole and its Co (II), Cu (II), Zn (II), and Th (IV) chelates were designed and prepared. For this purpose, 2‐aminothiazole and 2,4‐dihydroxybenzaldehyde have been coupled before the complexation reaction with the metal salts. Elemental analysis, FT‐IR, 1HNMR, UV–Vis spectra, transmission electron microscopy (TEM), X‐ray powder diffraction (XRD), molar conductance, and magnetic moment measurements were used to determine the structural formula of the ligand and its produced chelates. The acquired data pointed out that the ligand was chelated with metal through the nitrogen of azo group and deprotonated ortho phenolic oxygen atoms. In Cu (II) complex the copper ion chelated with two ligand molecules, whereas in other complexes the metal binds with one molecule only of ligand. It was shown by XRD patterns and high‐resolution TEM images that the complex particles had a uniform distribution across the chelates' surfaces and were nanometric in size. Extremely, antimicrobial and anticancer activity for the prepared ligand and complexes were investigated, which showed high activity, especially after complex formation. Docking studies have been performed to predict the compounds' efficacy as antitumor agents through their interaction with the co‐crystal structure of proteins for breast cancer cells (PDB ID: 3S7S) and protein of liver cancer 2 (PDB ID: 2JW2). The experimental results of the anticancer activity showed promising results, especially for Cu (II) compound which exhibited the greatest antitumor efficacy (IC50 = 12.81 μg/ml) contra HepG‐2 carcinoma and Mcf‐7 cells (IC50 = 18.92 ± 0.91 μg/ml). Antimicrobial activity against the strains Klebsiella pneumoniae (K. pneumoniae), Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), C. albicans (C. albicans), and Aspergillus niger (A. niger) also gave very promising results when it is compared with the standard drugs.

Pilanesbergite: a new rock-forming mineral occurring in nepheline syenite from the Pilanesberg Alkaline Complex, South Africa

Abstract. The new mineral pilanesbergite, with the ideal formula Na2Ca2Fe2Ti2(Si2O7)2O2F2, was found in a nepheline syenite, locally known as green foyaite, from the Pilanesberg Complex located in the North West Province of South Africa. Pilanesbergite occurs in green foyaite in association, and partly intergrown, with aegirine. The two minerals share an assemblage of inclusions, comprising euhedral nepheline, titanite and minor sodalite. Pilanesbergite belongs to the wöhlerite group and is isomorphic with låvenite, normandite and madeiraite. It is related to these species through the homovalent chemical substitutions Mn2+↔Fe2+ and Zr4+↔Ti4+. The empirical formula calculated on the basis of 18 anions is Na2.00(Ca1.74Na0.26)Σ2.00(Fe1.00Mn0.52Ca0.49Zr0.05)Σ2.06(Ti1.69Zr0.14Mg0.09Nb0.08)Σ2.00(Si2O7)2.00O1.84F2.16 (Z=2). The new mineral is translucent with a brown orange colour and a brownish streak. The Mohs hardness is estimated between 5 and 6 by comparison with låvenite, and no cleavage is observed. Measured and calculated densities are Dmeas=3.47 g cm−3 and Dcalc=3.40 g cm−3. In the thin section the pleochroism is strong, between straw yellow and orange red, while in immersion the strong pleochroism is observed between light yellow (α) and yellowish orange (γ). The crystals are optically biaxial (+) with α=1.743(3), β=1.768(3), γ=1.795(5) and a 2 V angle close to 90∘. The crystal structure is monoclinic (P21/a), with the unit-cell parameters a=10.7811(2), b=9.7836(1), c=7.0348(1) Å, β=108.072(2)∘ and V=705.41(2) Å3, and has been refined to R1=2.06 %. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (h k l)] are 3.219 (60) (310), 2.851 (100) (12-2), 2.802 (51) (320), 2.743 (27) (22-2), 2.423 (19) (40-2) and 1.723 (19) (44-2). Pilanesbergite formed under relatively reducing conditions from an agpaitic nepheline syenite magma that had evolved by fractional crystallization mainly of aegirine. Further crystallization of arfvedsonite caused an increase in oxygen fugacity and a change towards higher Mn/Mn+Fe of the magma, causing a change of mineral composition from pilanesbergite towards normandite.

Natromelansonite, Na3Zr[Si7AlO19]⋅4–5H2O, a new member of the rhodesite mero-plesiotype series from Mont Saint-Hilaire, Quebec, Canada

AbstractNatromelansonite, Na3Zr[Si7AlO19]⋅4–5H2O, was found at the Poudrette (Demix) quarry, Mont Saint-Hilaire, Quebec, Canada in a highly altered pegmatite together with a clay mineral, steacyite, polylithionite and rhodochrosite. It occurs as an outer zone of tabular crystals to 0.1 × 0.3 × 1 mm in size flattened on (001). The inner zone is made of melansonite. The mineral is grey with white powder colour and vitreous lustre. The cleavage is parallel to {010}, perfect. The Mohs hardness is 3.5. The mineral has green fluorescence under short-wave ultraviolet light. The Dcalc is 2.31 g/cm3. The infrared spectrum is reported. The composition (wt.%, average of 8 analyses) is Na2O 10.08, K2O 1.72, CaO 0.24, BaO 0.32, MnO 0.10, Al2O3 6.86, Y2O3 0.35, Yb2O3 0.55, SiO2 56.23, ZrO2 14.78, H2O 9.52, total 100.75. The empirical formula calculated on the basis of O = 23 apfu and H = 8 apfu is Na(□Na0.38Ca0.02Mn0.01)2(Na0.70K0.28Ba0.02)Σ1.00(Zr0.91Y0.02Yb0.02)Σ0.95(Si7.08Al1.02)Σ8.10O19⋅4H2O. The mineral is monoclinic, P21/m, a = 6.5156(3) Å, b = 24.061(1) Å, c = 6.9759(6) Å, β = 90.453(5)° and V = 1093.61(9) Å3 and Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 12.02(100)(020), 6.97(89)(001), 6.51(39)(100), 3.416(37)(160), 3.062(42)($\bar{1}$61, 102, 161 and $\bar{1}$12), 3.018(38)(230 and 042), 2.864(40)(240 and 132). The crystal structure, solved and refined from single-crystal X-ray diffraction data (R1 = 0.042), is based on a double sheet of tetrahedra (T) and a sheet of octahedra (O) that alternate along the [010] direction forming a TOT structure typical for members of the rhodesite mero-plesiotype series.

Arsenoústalečite, Cu12(As2Te2)Se13, a new mineral, and crystal structures of arsenoústalečite and stibioústalečite

AbstractArsenoústalečite is a new mineral discovered in a sample collected from the abandoned Ústaleč deposit near Horažďovice, SW Bohemia, Czech Republic. It occurs as rare anhedral grains, up to 40 μm in size, in a calcite gangue, associated with stibioústalečite, hakite-(Hg), berzelianite and uraninite. Arsenoústalečite is dark grey, with a metallic lustre. Mohs hardness is ca. 3½–4; calculated density is 5.730 g/cm3. In reflected light, arsenoústalečite is pale grey with a yellowish shade; it is isotropic. Internal reflections were not observed. Reflectance values for the four COM wavelengths in air [R (%) λ (nm)] are: 33.3 (470); 33.1 (546); 33.0 (589); and 32.9 (650). The empirical formula of arsenoústalečite is (Cu5.81Ag0.17)Σ5.98(Cu5.95Fe0.02Zn0.02Hg0.01)Σ6.00(As1.40Sb0.87Te1.73)Σ4.00(Se10.30S2.32)Σ12.61. The ideal formula is Cu12(As2Te2)Se13, which requires (in wt.%) Cu 34.76, As 6.83, Te 11.63, Se 46.78, total 100.00. Arsenoústalečite is cubic, I$\bar{4}$3m, with unit-cell parameters a = 10.6580(19) Å, V = 1210.7(6) Å3 and Z = 2. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I, %) hkl] are: 3.077 (100) 222, 2.848 (10) 321, 1.946 (12) 521, 1.884(52) 440 and 1.608(21) 622. According to the single-crystal X-ray diffraction data (R1 = 0.0285 on the basis of 334 unique reflections with Fo > 4σFo and 24 refined parameters), arsenoústalečite is isotypic with other tetrahedrite-group minerals. The crystal structure of co-existing stibioústalečite, with an empirical formula of (Cu5.69Ag0.07)Σ5.76(Cu5.80Zn0.13Fe0.06Hg0.01)Σ6.00(Sb1.82As0.42Te1.76)Σ4.00(Se9.52S3.10)Σ12.62 and unit-cell parameters a = 10.6975(16) Å, V = 1224.2(5) Å3 and Z = 2, was refined to R1 = 0.0191 on the basis of 267 unique reflections with Fo > 4σFo and 24 refined parameters. Structural relationships and crystal-chemistry of both members of the ústalečite series are discussed. Arsenoústalečite is named after its type locality, the Ústaleč deposit and its chemical composition. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2022-116).