X-ray Powder Diffraction Methods Research Articles

Effect of divalent transition metal ions on physical, morphological, electrical and electrochemical properties of alluaudite phases Na2M2+2Fe3+(PO4)3 (M = Mn, Co and Ni): Cathode materials for sodium-ions batteries

The limited resources of lithium stimulated the research work to develop new polyanionic cathode materials for sodium-ion batteries. The Na2M2+2Fe3+(PO4)3 (M = Mn, Ni and Co) phases were prepared by autocombustion method assisted by glycine. Structural, morphology, thermal, electrical and electrochemical properties have been investigated. Its structures were determined using Xray powder diffraction and Rietveld method refinements. The two compounds Na2M2+2Fe3+(PO4)3 (M = Mn and Co) are alluaudite-type. Both compounds crystallize in monoclinic system with the space group C2/c and similar parameters: a = 12.0337(3) Å, b = 12.6268(3) Å, c = 6.5070(1) Å, β = 114.563(2)° for Na2M2+2Fe3+(PO4)3 (NMFP) and a = 11.7597(3) Å, b = 12.4579(3) Å, c = 6.4607(1) Å, β = 113.968(1)° for Na2Co2Fe(PO4)3 (NCFP). The NaNiFe2(PO4)3 (NNFP) compounds crystallize in orthorhombic system with the space group Imma and unit cell parameters: a = 10.3993(1) Å, b= 13.1966(1) Å, c = 6.4955(1) Å. The composition and morphology of the compounds were checked by energy dispersive spectroscopy coupled with scanning electron microscope. The thermal analysis confirmed the allotropic transition of the three materials from monoclinic to orthorhombic symmetry with the changing of divalent transitions metal ion. The electrical conductivity results of indicated that NNFP has the lowest value of activation energy of value= 0.63 eV owing to the large size of open channels existed in the orthorhombic symmetry. The electrochemical cycling results showed that NMFP cathode delivered the maximum storage capacity of about 94.2 mAh/g which correspond to coloumbic efficiency of about 75.5% after the initial cycling.

EFFECT OF PREPARATION METHOD OF IRON-, COPPER- CONTAINING OXIDE CATALYSTS ON THEIR ACTIVITY IN THE REACTION OF OXIDATION OF CARBON MONOXIDE TO CARBON DIOXIDE

Iron- and copper-containing oxide catalysts have been synthesized by sol-gel technology with autocombustion using organic reagents - citric acid, glycine, urea as a complexing agent and "fuel"; studied their activity in the oxidation of carbon monoxide to dioxide. The obtained samples were characterized by the methods of X-ray powder diffraction, infrared spectroscopy and electronic paramagnetic resonance, the texture characteristics of these samples was determined by measuring the specific surface area. It is shown that, regardless of the preparation method, all synthesized samples are mixtures of iron oxides Fe 2O3, copper CuO, and copper ferrite CuFe2O4. It was found that the nature of the organic reagent affects the catalytic activity of the synthesized catalysts. On a catalyst with a Cu:Fe=1:1 ratio, prepared by the sol-gel method with autocombustion using urea, the complete conversion of CO is achieved at 130°C. The same catalyst, synthesized with citric acid, is active at 250°C and on a catalyst prepared using glycine, complete conversion of CO occurs at a higher temperature of 350°C. It is assumed that the different nature of combustion leads to the formation of different surface morphology and texture, which ultimately determines the catalytic activity. Thus, the most catalytically active sample was obtained using urea as a "fuel" has a higher specific surface area (25 m2 / g) than the other two samples (for the samples obtained with citric acid and glycine, the specific surface area is 9 m2 / g and 5.8 m2 / g, respectively).

Crystal structure of Li2CuGa and LiCu2Ga compounds

Lithium alloys continue to be promising materials for anodes of chemical current sources, so the search for new lithium-containing intermetallic phases and the study of their crystal structure were the task of our study. In continuation of the study of the Li–Cu–Ga system, two alloys of Li 2 CuGa and LiCu 2 Ga were synthesized. The alloys were synthesized in an electric arc furnace in an atmosphere of purified argon from portions of pure components (content of the main component: Lithium ≥ 99.8 wt. %, copper and gallium ≥ 99.99 wt. %). The alloys were homogenized at 200 °C for two months in tantalum containers sealed in evacuated quartz ampoules. After annealing, the alloys were stored under a layer of purified and dehydrated paraffin oil. X-ray powder diffraction patterns from the synthesized alloys were obtained on a powder diffractometer DRON-2.0 M (Fe Kα -radiation). By comparing the obtained diffractograms with previously studied alloys, it was assumed that the compounds Li 2 CuGa and LiCu 2 Ga will be isostructural with the phases Li 2 AgIn and LiAg 2 In. Based on these models, the crystal structure was refined by the Rietveld method: Li 2 CuGa, (Li2AgSb, F –43 m , a = 6.0942 (7) Å; R Br = 0.0789, R F = 0.0482); LiСu 2 Ga (Cu 2 MnAl, Fm –3 m , a = 5.8964 (8) Å; R Br = 0.0711, R F = 0.0311). In the Li–Cu–Ga system, two ternary compounds are formed with the ratio of components 2:1:1 and 1:2:1, which is quite interesting because Li, Cu and Ga atoms differ greatly by nature ( s -metal, d -metal and p -metal) and size (metal radii: Li – 1.52 Å; Cu – 1.28 Å; Ga – 1.35 Å). Nevertheless, in the structures of both compounds all atoms have a similar coordination of atoms - rhombododecahedron and identical values of interatomic distances: in the structure of the compound Li 2 CuGa eight distances with a length 2.6389 Å and six distances – 3.0471 Å; in the structure of the LiCu 2 Ga compound there are eight distances with a length of 2.5532 Å and six distances with a length of 2.9482 Å. Keywords: lithium, copper, gallium, X-ray powder diffraction method, crystal structure.

The system Ho–Ni–In at 870 K

The components interaction in the Ho–Ni–In system was investigated by X-ray powder diffraction and, partially, scanning electron microscopy with energy-dispersive X-ray spectroscopy. Isothermal section of the phase diagram was constructed in full concentration range at 870 K. The samples were synthesized in an arc-furnace on a water-cooled Cu-plate under an argon atmosphere and annealed in silica tubes at 870 K for 720 h. The phase analysis was performed by X-ray powder diffraction method. Twelve ternary compounds, namely HoNi 9 In 2 (YNi 9 In 2 -type structure), Ho 4 Ni 11 In 2 0 (U 4 Ni 11 Ga 2 0 -type structure), HoNi 4 In (MgCu 4 Sn-type structure), Ho 10 Ni 9 In 20 (Ho 10 Ni 9 In 20 -type structure), HoNi 1.0-0.5 In 1.0-1.5 (ZrNiAl-type structure), Ho 2 Ni 2 In (Mn 2 AlB 2 -type structure), Ho 2 Ni 1.8 In (Mo 2 FeB 2 -type structure), Ho 5 Ni 2 In 4 (Lu 5 Ni 2 In 4 -type structure), Ho 11 Ni 4 In 9 (Nd 11 Pd 4 In 9 -type structure), Ho 6 Ni 2 In (Ho 6 Co 2 Ga-type structure), ~ Ho 6 NiIn 2 (unknown structure) і Ho 13.35 Ni 3.17 In 3.48 (Lu 14 Co 3 In 3 -type structure) exist in the Ho–Ni–In system at the temperature of annealing. The substitution of Ni for In was observed for HoNi 1.00-0.50 In 1.00-1.50 compound. Besides, Ho can enter the structure of NiIn (CoSn-type structure) compound leading to formation of including subtraction type solid solution, which is stable up to 8 at. % Ho. The composition of this solid solution can be described by the formula Ho 0-0 . 08 NiIn 1-0 . 94 . The inclusion of holmium and indium atoms in position (2 e ) with the simultaneous exclusion of a small amount of indium atoms from position (1 a ) takes place in the homogeneity range of this solid solution. The character of interaction between the components in the ternary Ho–Ni–In system is similar to other related system R – T –In ( R – rare earth of the yttrium subgroup). The common feature of all these systems is the existence of large number isotypical ternary compounds, the formation of homogeneity range for compounds with ZrNiAl-type structure and including-subtraction type solid solutions based on the binary compound NiIn. Ke y words: holmium, indium, ternary compound, ternary system, isothermal section.

“Influence of co-doping on structural, morphological, and electrical properties of Ruddlesden-Popper-type [formula omitted] as a cathode material for IT-SOFC”

For electric power generation Solid Oxide Fuel Cells (SOFCs) is the promising technology. Ruddlesden Popper type rare earth Nickelates have shown better performance as cathode with various electrolytes such as SDC and YSZ and possess high catalytic activity for ORR at intermediate temperature range of SOFCs. In the present work, samarium strontium nickelate SmSrNiO4-δ and co-doped (Sm0.95La0.05Sr0.95Ca0.05NiO4-δ) were synthesized by solid state route reaction method. The phase purity of samples is determined by X-ray Powder diffraction method and further confirmed by Rietveld refinement which was performed by using FULLPROF suite with I4/mmm symmetry and space group (139) and χ2 lies appreciably within the experimental errors. Further XRD confirms the single tetragonal phase which does not change with the co-substitution. The porous microstructure has been observed for all the studied samples. The micrograph shows that the average grain size increases with the co-substitution. The conductivity is observed to increase nearly-two folds with the co-substitution as compared to the parent sample. However, the oxygen reduction reaction is nearly same for both the samples.

Nanoarmored Multi-Enzyme Cascade Catalysis.

This chapter reports a single-step preparation of nanoarmored bi-enzyme systems assembled on 1-D and 2-D nanomaterials, with glucose oxidase and peroxidase enzymes as model systems for cascade bio-catalysis. This is a simple and facile method to both exfoliate the bulk 1D (carbon nanotubes, CNT) and 2D nanomaterials (α-Zirconium phosphate, α-ZrP) and bind the enzymes in a single step. Exfoliation of the bulk material enhances the accessible surface area of the materials for the enzyme binding, and it also boosts the diffusion of reagents from the bulk phase to the active sites of the bio-catalysts. For example, a mixture of horseradish peroxidase, glucose oxidase, and bovine serum albumin (BSA) were adsorbed on the surfaces of the α-ZrP nanoplates or carbon nanotubes (CNT) as the bulk materials are exfoliated simultaneously, in a one-step process. The resultingbio-catalysts were thoroughly characterized by powder X-ray diffraction, electron microscopy, biochemicaland biophysical methods, while enzyme activity studies proved successful binding of enzymes with retention of activities or even enhancements in their specific activities. For example, GOx/HRP/BSA/CNT displayed 6 times the activity of a mixture of GOx/HRP/BSA, under otherwise identical conditions. Similarly, GOx/HRP/BSA/ZrP had 3.5 times the activity of the corresponding mixture of GOx/HRP/BSA, in the absence of the nanoplates. These robust nano-dispersions worked extraordinarily well as active bio-catalysts. These two kinds of fabricated biocatalyst dispersions are also highly stable.

Microwave-Assisted Synthesis, Spectral and Biopotential Characterization of Cr(III), Cu(II) and Zn(II) Complexes with 4-Aminothiophenol and Benzoate Ion

Bioactive metal complexes of Cr(III), Cu(II), and Zn(II) were synthesized with 4-aminothiophenol and benzoate ion under microwave irradiation. The synthesized metal chelates were characterized by physical, spectral, biological studies. The geometry and magnetism of all the complexes were monitored by electronic spectra and magnetic studies. The metal complexes possess the metal-ligand ratios is in the order of 1:3:3 metal:ligand1:ligand2 for Cr(III), 1:2:2 metal: ligand1:ligand2 for Cu(II) and Zn(II) complexes were predicted based on the elemental analysis and metal estimation. The synthesized metal chelates are monomeric and neutral in nature and they show well redox properties based on the results of conductivity and electrochemical studies. Octahedral geometry of Cr(III), tetragonal geometry of Cu(II) and square planar geometry of Zn(II) complexes confirmed by IR, far-IR, NMR and EPR spectral studies. The crystalline nature and lattice parameters of Zn(II) complex were predicted by using the X-ray diffraction powder method. Biopotential activities of 4-aminothiophenol compared with metal chelates and standard drug namely chloramphenicol for bacterial and fluconazole for fungal strain by Agar disc diffusion method using Streptococci, Shigella and C. albicans. The results of DNA cleavage of pBR322 DNA and binding nature of ct-DNA to Cr(III) complex possess the binding and cleavage nature of them by predicting the binding constant of the metal complex.

Synthesis and characterization of 5% Ni-ZnO as robust nanocatalyst for Eco-Friendly synthesis of pyrimidines

The present disclosure includes synthesis of high 5 % Ni-ZnO nanomaterial and its application as yielding protocol for the synthesis of wide range of pyrimidines using 5 % Ni-ZnO as robust nanocatalyst. The 5 % Ni-ZnO nanomaterial was synthesized by co-precipitation method and it was characterized by powder X-ray Powder Diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray (EDS) and High Resolution Transmission Electron Microscopy (HR-TEM) methods. XRD method revealed hexagonal wurtzite crystal lattice with crystallite size of 23.45 nm. SEM indicated high porosity of the synthesized nanomaterial while EDS confirmed the element composition. HR-TEM revealed hexagonal crystals. The synthesized 5 % Ni-ZnO nanomaterial was efficiently utilized for one pot multicomponent synthesis of pyrimidine analogues. The synthesized pyrimidines were structurally confirmed on the basis of NMR analysis. Catalyst dose was optimized and the efficacy of catalyst was tested for various aldehydes, 1,3-carbonyl compounds, urea and thiourea which highlights the generality of the green protocol with ample substrate scope. High yield, short reaction time, simple isolation, and purity of the product with column chromatography are key benefits of the synthetic strategy.

Nitriding and Denitriding of Nanocrystalline Iron System with Bimodal Crystallite Size Distribution.

An artificially prepared nanocrystalline iron sample with bimodal crystallite size distribution was nitrided and denitrided in the NH3/H2 atmosphere at 350 °C and 400 °C. The sample was a 1:1 mass ratio mixture of two iron samples with mean crystallite sizes of 48 nm and 21 nm. Phase transformations between α-Fe, γ’-Fe4N and ε-Fe3-2N were observed by the in situ X-ray powder diffraction method. At selected steps of nitriding or denitriding, phase transformations paused at 50% of mass conversion and resumed after prominent variation of the nitriding atmosphere. This effect was attributed to the separation of phase transformations occurring between sets of iron crystallites of 48 nm and 21 nm, respectively. This was due to the Gibbs–Thomson effect, which establishes the dependence of phase transformation conditions on crystallite sizes.

SOLUBILITY OF GERMANIUM DISELENIDE IN THE Cu3AsSe4

Differential thermal analysis and powder X-ray diffraction methods were used for phase equilibria studying in the Cu3AsSe4-GeSe2 system. It was established that wide (up to 30 mol.%) solid solutions based on Cu3AsSe4 are formed. GeSe2-rich alloys consist of various heterogeneous mixtures, including phases outside the T–x plane of this section

Interfacial self-assembly of porphyrin-based SURMOF/graphene oxide hybrids with tunable pore size: An approach toward size-selective ambivalent heterogeneous photocatalysts

New photocatalysts were synthesized from graphene oxide (GO) and zinc porphyrins via non-covalent self-assembly in Pickering emulsions. The formation of surface-attached metal organic frameworks (SURMOFs) with different size of mesopores (1.1. and 1.6 nm) was confirmed by X-ray powder diffraction and BET nitrogen absorption methods. The activity of the SURMOF/GO materials in photodegradation of rhodamine 6G (Rh6G) and 1,5-dihydroxynaphtalene (DHN) were studied spectroscopically. The photocatalysts initiate aerobic oxidative photodestruction with k up to 2.3 × 10−1 min−1 through generation of singlet oxygen on porphyrin centers. Under anaerobic conditions, these materials assist photoreduction of the same dyes in the SURMOF micropores. The mechanisms of photodegradation assisted by SURMOF/GO hybrids were confirmed by a combination of MALDI-TOF spectroscopy, Sensor Green and terephthalic acid probing. The size of the SURMOF pores controls the reduction, which occur due to the effective charge separation between porphyrin SURMOFs and GO. The photocatalyst with larger pores can transform both Rh6G and DHN, whereas that one with smaller pores is active only with respect to small DHN molecules. The ability of as-formed SURMOF/GOs to exploit two mechanisms yielding different products of photodestruction provides a basis for creating novel ambivalent photocatalysts for selective transformations of targeted compounds in molecular mixtures.

Growth and Optical Properties of the Whole System of Li(Mn1-x,Nix)PO4 (0 ≤ x ≤ 0.5) Single Crystals.

A series of single crystals of Li(Mn1-x,Nix)PO4 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.10, 0.15, 0.20, and 0.50) have been grown to large sizes up to 5 mm in diameter and 120 mm in length using the floating zone method for the first time. The comprehensive characterizations of the as-grown crystals were performed before further physical property measurements. The composition of the grown crystals was determined by energy-dispersive X-ray spectroscopy. The crystal structures were characterized by the X-ray powder diffraction method with a GSAS fitting for structural refinement, which reveals a high phase purity of the as-obtained crystals. The polarized microscopic images and Laue patterns prove the excellent quality of the single crystals. Oriented cuboids with sizes of 2.7 × 3.8 × 2.1 mm3 along the a, b, and c crystalline directions were cut and polished for further anisotropic magnetic and transparent measurements. We also first proposed a new potential application in the non-linear optical (NLO) and laser generation application for LiMPO4 (M = transition metal) materials. The optical and laser properties, such as the absorption spectra and the second harmonic generation (SHG), have been investigated and have furthermore confirmed the good quality of the as-grown single crystals.

Desolvation–Solvation-Induced Reversible On–Off Switching of Two Memory Channels in a Cobalt(II) Coordination Polymer: Overlay of Spin Crossover and Structural Phase Transition

Desolvation–Solvation-Induced Reversible On–Off Switching of Two Memory Channels in a Cobalt(II) Coordination Polymer: Overlay of Spin Crossover and Structural Phase Transition

Combined Approach of Mechanochemistry and Electron Crystallography for the Discovery of 1D and 2D Coordination Polymers

Mechanochemical synthesis is an attractive preparative method that combines a green approach with versatility, efficiency, and rapidity of reaction. However, it often yields microcrystalline materials, and their small crystal size is a major hindrance to structure elucidation with conventional single-crystal or powder X-ray diffraction methods. This work presents the novel approach of combining mechanochemistry with electron diffraction techniques to elucidate the crystal structure of metal–organic compounds of zinc(II) and copper(II) with 2,6-pyridinedicarboxylic acid and 4,4′-bipyridine.

Endless extension of life cycle of construction and demolition wastes as the most efficient environmental technology

The main purposes of this study were to confirm the life cycle assessment of traditional construction materials (construction and demolition debris, plaster waste lime production waste) as endless due to the possibility of reusing them multiple times without reducing their mechanical properties and sustainability; to determine the physical–chemical processes of recycled composites structure formation. The research was performed by the methods of X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and laser micro mass analyses. The sample’s axial resistance reached 3.2 MPa on the 3rd day, 8.8 MPa on the 14th day, and up to 16.7 MPa on the 180th day with expansion coefficient values up to 1.81%, water absorption - 14.9%, and apparent density up to 1.95 g/cm 3 . The processes of structure formation showed the hardening of the material due to alkaline corrosion of the solid particles’ surfaces with chemical interaction of these alkaline solutions and synthesis of new predominantly amorphous formations of sol–gel CSH-group and carbonates; over time, these new gel formations were converted into a stony state. The obtained results show that developed composites can be returned unlimited times to construction life cycle as valuable components to produce building materials without the use of traditional natural raw materials like sand, rock, stones, clay, and to avoid irreparable destruction of landscapes by quarries for their extraction. • New composites from plasters wastes, demolition wastes and lime production waste. • New composites have high mechanical and physical properties’ values. • Structure formation processes were established by XRD, SEM and EDS methods. • Utilization of industrial wastes have high economical and environment efficiency.

Aerosol Analysis Using Handheld Raman Spectrometer: On-site Quantification of Trace Crystalline Silica in Workplace Atmospheres.

A method for aerosol chemical analysis using handheld Raman spectrometer has been developed and its application to measurement of crystalline silica concentration in workplace atmosphere is described. The approach involves collecting aerosol as a spot sample using a wearable optical aerosol monitor, followed by direct-on-filter quantitative analysis of the spot sample for crystalline silica using handheld Raman spectrometer. The filter cassette of a commercially available optical aerosol monitor (designed to collect aerosol for post-shift analysis) was modified to collect 1.5-mm-diameter spot sample, which provided adequate detection limits for short-term measurements over a few tens of minutes or hours. The method was calibrated using aerosolized α-quartz standard reference material in the laboratory. Two Raman spectrometers were evaluated, one a handheld unit (weighing less than 410 g) and the other a larger probe-based field-portable unit (weighing about 5 kg). The lowest limit of quantification for α-quartz of 16.6 μg m-3 was obtained using the handheld Raman unit at a sample collection time of 1 h at 0.4 l min-1. Short-term measurement capability and sensitivity of the Raman method were demonstrated using a transient simulated workplace aerosol. Workplace air and personal breathing zone concentrations of crystalline silica of workers at a hydraulic fracturing worksite were measured using the Raman method. The measurements showed good agreement with the co-located samples analyzed using the standard X-ray powder diffraction (XRD) method, agreeing within 0.15-23.2% of each other. This magnitude of difference was comparable to the inter- and intra-laboratory analytical precision of established XRD and infrared methods. The pilot study shows that for silica-containing materials studied in this work it is possible to obtain quantitative measurements with good analytical figures of merit using handheld or portable Raman spectrometers. Further studies will be needed to assess matrix interferences and measurement uncertainty for several other types of particle matrices to assess the broader applicability of the method.

Three Rh-rich ternary germanides in the Ce–Rh−Ge system

The germanides Ce3Rh11Ge5, Ce6Rh30Ge19.5, and CeRh3Ge2, which are new ternary Rh-rich phases in the Ce–Rh−Ge system, were prepared by reactions of the elements. Their crystal structures were determined by single-crystal and powder X-ray diffraction methods. Ce3Rh11Ge5 adopts the Gd3Ru4Al12-type structure, which represents the fully stoichiometric version of the defect Sc3Ni11Ge4-type structure, in hexagonal space group P63/mmc with Z ​= ​2 and cell parameters a ​= ​8.6964 (12) Å and c ​= ​9.2209 (12) Å. Ce6Rh30Ge19.5 is a filled derivative of the U6Co30Si19-type structure in hexagonal space group P63/m with Z ​= ​2 and cell parameters a ​= ​22.8480 (11) Å and c ​= ​3.9208 (2) Å. CeRh3Ge2 is derived from a symmetry-lowered distortion of the hexagonal CeCo3B2-type (or substitutionally ordered CaCu5-type) structure, and crystallizes in orthorhombic space group Fmmm with Z ​= ​16 and cell parameters a ​= ​7.392 (6) Å, b ​= ​11.341 (9) Å, and c ​= ​19.66 (2) Å. As expected by their Rh-rich compositions, the three compounds exhibit extensive Rh–Rh bonding, but surprisingly, they also show some short Ge–Ge contacts. Analysis of the electron localization functions and Bader charges reveals that charge transfer takes place from Ce to Rh atoms, indicative of a polar character in the bonding in these intermetallic compounds.

Thermostructural and Elastic Properties of PbTe and Pb0.884Cd0.116Te: A Combined Low-Temperature and High-Pressure X-ray Diffraction Study of Cd-Substitution Effects

Rocksalt-type (Pb,Cd)Te belongs to IV–VI semiconductors exhibiting thermoelectric properties. With the aim of understanding of the influence of Cd substitution in PbTe on thermostructural and elastic properties, we studied PbTe and Pb0.884Cd0.116Te (i) at low temperatures (15 to 300 K) and (ii) at high pressures within the stability range of NaCl-type PbTe (up to 4.5 GPa). For crystal structure studies, powder and single crystal X-ray diffraction methods were used. Modeling of the data included the second-order Grüneisen approximation of the unit-cell-volume variation, V(T), the Debye expression describing the mean square atomic displacements (MSDs), <u2>(T), and Birch–Murnaghan equation of state (BMEOS). The fitting of the temperature-dependent diffraction data provided model variations of lattice parameter, the thermal expansion coefficient, and MSDs with temperature. A comparison of the MSD runs simulated for the PbTe and mixed (Pb,Cd)Te crystal leads to the confirmation of recent findings that the cation displacements are little affected by Cd substitution at the Pb site; whereas the Te displacements are markedly higher for the mixed crystal. Moreover, information about static disorder caused by Cd substitution is obtained. The calculations provided two independent ways to determine the values of the overall Debye temperature, θD. The resulting values differ only marginally, by no more than 1 K for PbTe and 7 K for Pb0.884Cd0.116Te crystals. The θD values for the cationic and anionic sublattices were determined. The Grüneisen parameter is found to be nearly independent of temperature. The variations of unit-cell size with rising pressure (the NaCl structure of Pb0.884Cd0.116Te sample was conserved), modeled with the BMEOS, provided the dependencies of the bulk modulus, K, on pressure for both crystals. The K0 value is 45.6(2.5) GPa for PbTe, whereas that for Pb0.884Cd0.116Te is significantly reduced, 33.5(2.8) GPa, showing that the lattice with fractional Cd substitution is less stiff than that of pure PbTe. The obtained experimental values of θD and K0 for Pb0.884Cd0.116Te are in line with the trends described in recently reported theoretical study for (Pb,Cd)Te mixed crystals.

New Coordination Polymers of Selected Lanthanides with 1,2-Phenylenediacetate Linker: Structures, Thermal and Luminescence Properties

Solvothermal reactions of lanthanide (III) salts with 1,2-phenylenediacetic acid in N,N′-dimethylformamide (DMF) solvent lead to the formation of the metal complexes of the general formula Ln2(1,2-pda)3(DMF)2, where Ln(III) = Pr(1), Sm(2), Eu(3), Tb(4), Dy(5), and Er(6), 1,2-pda = [C6H4(CH2COO)2]2−. The compounds were characterized by elemental analysis, powder and single-crystal X-ray diffraction methods, thermal analysis methods (TG-DSC and TG-FTIR), infrared and luminescence spectroscopy. They exhibit structural similarity in the two groups (Pr, Sm, and Eu; Tb, Dy, and Er), which was reflected in their thermal behaviours and spectroscopic properties. Single-crystal X-ray diffraction studies reveal that Sm(2) and Eu(3) complexes form 2D coordination polymers with four crystallographically independent metal centers. Every second lanthanide ion is additionally coordinated by two DMF molecules. The 1,2-phenylenediacetate linker shows different denticity being: penta- and hexadentate while carboxylate groups exhibit bidentate-bridging, bidentate-chelating, and three-dentate bridging-chelating modes. The infrared spectra reflect divergence between these two groups of complexes. The complexes of lighter lanthanides contain in the structure coordinated DMF molecules, while in the structures of heavier complexes, DMF molecules appear in the inner and outer coordination sphere. Both carboxylate groups are deprotonated and engaged in the coordination of metal centers but in different ways in such groups of complexes. In the groups, the thermal decomposition of the isostructural complexes occurs similarly. Pyrolysis of complexes takes place with the formation of such gaseous products as DMF, carbon oxides, ortho-xylene, ethers, water, carboxylic acids, and esters. The complexes of Eu and Tb exhibit characteristic luminescence in the VIS region, while the erbium complex emits NIR wavelength.

Ardennite-bearing mineral association related to sulfide-free ores with chalcophile metals at Nežilovo, Pelagonian Massif, North Macedonia

Abstract. Among numerous minerals determined at Nežilovo, Pelagonian Massif, North Macedonia, ardennite-(As) has been discovered in two different associations and studied by means of optical microscopy, electron microprobe analysis (EMPA), and single-crystal and powder X-ray diffraction methods. The refractive indices of ardennite-(As) from Nežilovo are α=1.537(2), β=1.579(1) and γ=1.741(1), where γ corresponds to the c direction. The optical axial angle is 2Vx=49(1)∘. EMPA of the investigated samples yields the following empirical formulae: [Mn3.272+Ca0.73]Σ4.00[Al4.18Mg1.24Fe0.29Mn0.193+Zn0.10]Σ6.00(Si4.73Al0.27)Σ5.00(As0.96Si0.03V0.01)Σ1.00O22 [OH5.36(H2O)0.64]Σ6.00 for ardennite-(As) and (K0.95Na0.04Ba0.02)Σ1.01(Al1.44Fe0.303+Mg0.20Mn0.03Ti0.02 Zn0.01)Σ2.00(Si3.21Al0.79O10) (OH1.97O0.03)Σ2.00 for the associated red mica. The unit cell parameters of ardennite-(As) determined by X-ray powder diffraction are a=8.757(2) Å, b=5.836(2) Å, c=18.578(2) Å and V=941.97 Å3. The unit cell parameters of ardennite-(As) were also determined by single-crystal X-ray diffraction and are a=8.760(1) Å, b=5.838(1) Å, c=18.582(2) Å and V=950.30 Å3. Regularities of isomorphism in ardennite-related minerals are discussed. The presence of ardennite-(As) in association with 2M1 and 3T phengite polytypes provides evidence for three separate stages of formation. Conditions at which ardennite-(As) crystallized have been estimated based on compositional features of associated micas.