Polycrystalline X-ray Diffraction Research Articles

Magnetically nanorized seaweed residue for the adsorption of methylene blue in aqueous solutions.

The cost-effective and green separation of dye pollutants from wastewater is of great importance in environmental remediation. Industrial seaweed residue (SR), as a low-cost cellulose source, was used to produce carboxylated nanorized-SR (NSR) via oxalic acid (OA)-water pretreatments followed by ultrasonic disintegration. Fourier transform infrared spectroscopy, X-ray polycrystalline diffraction, nitrogen isotherms, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray photoelectron spectrometry, particle charge detection, zeta potential and retro titration experiments were utilized to explore the physiochemical properties of samples. The NSRs with carboxyl content of 4.58-6.73 mmol g-1 were prepared using 10-60% OA-water pretreatment. In the case of 20% OA-water pretreatment, the highest NSR yield (73.9%) and nanocellulose content (80.2%) were obtained. Through self-assembly induced by the electrostatic interaction, magnetic NSR composite adsorbents (MNSRs) were prepared with the combination of NSR and Fe3O4 nanoparticles (NPs). The carboxylated NSR with negative charge demonstrated good affinity for Fe3O4 NPs. The Fe3O4 NPs were perfectly microencapsulated with the NSR when the NSR/Fe3O4 mass ratio was higher than 1/1. The adsorption properties of the MNSR for methylene blue (MB) removal from aqueous solution were investigated. The adsorbent with NSR/Fe3O4 mass ratio of 1/1 (MNSR1/1) exhibited optimum performance in terms of the magnetic properties and adsorption capacity. The MNSR1/1 showed high adsorption ability in a pH ≥7 environment. According to the Langmuir fitting, the maximum adsorption capacity of MNSR1/1 for MB reached 184.25 mg g-1. The adsorption of MB complies with the pseudo-second-order kinetic model. MNSR1/1 still maintained good adsorption properties after the fifth cycle of adsorption-desorption. MNSR1/1 could selectively adsorb cationic dye (i.e., MB and methyl violet) from wastewater, with hydrogen bonding and electrostatic interaction as the main force.

The roles of heteromorphic crystals and organic compounds in the formation of the submandibular stones

ObjectiveThe study aimed to analyze the formation process of submandibular stones based on the theory of biological mineralization and inorganic crystal structure variation. Study designFrom January 2021 to December 2021, patients with submandibular stones treated in the Affiliated Hospital of Stomatology, Sun Yat-sen University (Guangzhou, China) were selected. According to the criterion of maximum transverse diameter ≥3 mm, a total of five submandibular stones meeting the requirement were included. After the surface of sample stones were washed, they were cut along the maximum transverse diameter. Next, the study employed Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and polycrystalline X-ray Diffraction (XRD) to analyze the composition and structure of submandibular stones. ResultsFive submandibular stones were included. The organic and inorganic compounds showed a rhythmic or irregular distribution. Submandibular stones were highly occupied with carbon (C), oxygen (O), calcium (Ca), and phosphorus (P). Hydroxyapatite (HAP) was the primary inorganic component. In addition, the precursor of HAP, namely Amorphous Calcium Phosphate (ACP), was also found. Tetrahedral Substitution Index (TSI) and Ca/P ratio reflected the degree of structural variation in HAP crystal, which fluctuated from 5.62-90.71 and 1.10–1.35, respectively. ConclusionsThe development of submandibular stones was influenced by inorganic crystals’ chemical and structural variation as well as the organics’ regulation towards the inorganic. The isomorphic substitution was accompanied by the occurrence of inorganic crystals, resulting in the crystal structure change. Organics might influence the appearance, aggregation, and mineralization of HAP during its formation.

Preparation, characterization and releasing property of antibacterial nano-capsules composed of ε-PL-EGCG and sodium alginate-chitosan

Aquatic products with high moisture and protein content are susceptible to bacterial growth and spoilage. Searching for efficient and safe natural antibacterial agents to preserve aquatic products has been concerned widely. In this study, ε-poly-lysine-epigallocatechin gallate/sodium alginate-chitosan nanoparticles (ε-PL-EGCG/SA-CS NPs) were prepared using sodium alginate and chitosan as wall materials and ε-PL-EGCG as core material. The size of nanoparticles was about 200 nm and the encapsulation efficiency was 78.2%. Transmission electron microscopy (TEM) images confirmed the prepared spherical nanoparticles. Fourier transform infrared spectroscopy (FTIR) and multifunctional polycrystalline X-ray diffraction (XRD) spectra indicated that ε-PL-EGCG was encapsulated in the nanoparticles. Thermo-gravimetric analysis (TGA) illustrated that the thermal stability of encapsulated ε-PL-EGCG was improved more than that of bare ε-PL-EGCG. In addition, in vitro release assays showed that the ε-PL-EGCG was released continuously over 36 h. Bacteria inhibition results showed that the ε-PL-EGCG/SA-CS NPs significantly inhibited specific spoilage bacteria E3 that screened out of aquatic products, Escherichia coli and Staphylococcus aureus. In conclusion, ε-PL-EGCG/SA-CS NPs are an effective antibacterial means with wide application prospects in the field of aquatic products preservation.

Mineralogical and petrographic study of building materials from the Argentario coastal towers (Tuscan, Italy): anthropic evidence of the ancient landscape

The coastal sight towers and the defensive fortresses were in the past distinctive elements of the coastal landscape. They were distributed in particular along the northern coast of the Mediterranean and were built for sighting purposes from the XVIth century against the raids of barbarian pirates who had their bases in the Maghreb coast.A mineralogical and petrographic characterization of the stone materials and mortars of two coastal towers (i.e. Capodomo and Calamoresca) in ruins of Monte Argentario is shown in the present paper. It was found that local lithotypes (e.g. Calcare Cavernoso, calcitic grey marble, dark grey dolostones) were used as building stones and for production of mortars. A detailed study on mortars was conducted by means of high quality polycrystalline X-ray diffraction, optical and electron microscopy. The analysis reveals the presence of Ca and Mg lime-based mortars in the ruins of Capodomo tower, whereas only Ca lime-based mortars were identified in Calamoresca tower.Reaching the towers walking along the paths allows us to know a good part of the lithologies present in the promontory due to the emerging sites in the local morphology; emersion was produced, both because particular lithologies are resistant to the erosion and also because of particular structural or tectonic elements.

Phosphate substances transformation and vivianite formation in P-Fe containing sludge during the transition process of aerobic and anaerobic conditions

Excess sludge was considered as a promising raw material for phosphorus recovery. In this study, the P-Fe containing sludge came from the aerobic membrane bioreactor with electrocoagulation (EC), which was refluxed to the anaerobic unit for iron reduction. Under anaerobic condition, the ORP and pH maintained at −350 mV and 7.5, which exactly met the conditions for vivianite formation. According to the analysis of X-ray polycrystalline diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), the final product of the sludge after anaerobic condition was mainly vivianite. Microbial analysis showed that there were iron reducing bacteria (IRB) in sludge before and after anaerobic process, including Dechloromonas, Desulfovibrio. Aeromonas and Methanobacterium. During the transition process of aerobic and anaerobic conditions, amorphous phosphate substances in P-Fe containing sludge could be transformed vivianite just with long term standing, which could promote the recovery of phosphate resource from wastewater.

Experimental measurement and analysis methods of polycrystalline X-ray diffraction for lithium batteries

Experimental measurement and analysis methods of polycrystalline X-ray diffraction for lithium batteries

Green synthesis, characterization and in vitro release of cinnamaldehyde/sodium alginate/chitosan nanoparticles

As a natural preservative, cinnamaldehyde (CA) has a bright application prospect. However, CA is sensitive to light and can be easily oxidized. What's more, its water solubility is poor. These properties greatly limit its application. In this study, CA/sodium alginate (SA)/chitosan (CS) nanoparticles (CA/SA/CS NPs) were prepared by using SA and CS as wall materials, and CA as core material. The single factor experiment showed that the optimal CA/SA/CS NPs can be obtained when the mass ratio of SA to CS was 5.5/1, SA to CaCl2 was 5/1, SA to CA was 1/2, and the pH of CS solution was 5.0. Under this condition, the average size of the prepared nanoparticles was 455.2 nm, polymer dispersity index (PDI) value was 0.189, zeta potential was −40.8 mV, and the encapsulation efficiency was 72.92%. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) images confirmed the formation of nanoparticles, which were spherical or ellipsoidal in shape. The fourier transform infrared spectroscopy (FTIR) and multifunctional polycrystalline X-ray diffraction (XRD) spectra indicated that CA was encapsulated in the nanoparticles. Furthermore, in vitro release experiments showed that CA/SA/CS NPs had the function of sustained release. In summary, SA/CS NPs can be used as a promising carrier for CA.

Alteration behavior of mineral structure and hazardous elements during combustion of coal from a power plant at Huainan, Anhui, China

The alteration behavior of minerals and hazardous elements during simulated combustion (100–1200 °C) of a raw coal collected from a power plant were studied. Thermogravimetric analysis indicated that there were mainly four alteration stages during coal combustion. The transformation behavior of mineral phases of raw coal, which were detected by X-ray polycrystalline diffraction (XRD) technique, mainly relied on the combustion temperature. A series of changes were derived from the intensities of mineral (e.g. clays) diffraction peaks when temperature surpassed 600 °C. Mineral phases tended to be simple and collapsed to amorphous glass when temperature reached up to 1200 °C. The characteristics of functional groups for raw coal and high-temperature (1200 °C) ash studied by Fourier transform infrared spectroscopy (FTIR) were in accordance with the result obtained from XRD analysis. The volatilization ratios of Co, Cr, Ni and V increased consistently with the increase of combustion temperature, suggesting these elements were gradually released from the organic matter and inorganic minerals of coal.

Preparation and optical properties of hexa-tungsten bronze-type CsNbW2O9 semiconductor

CsNbW2O9 semiconductor nanoparticles were synthesized by the facile sol-gel method. The morphological characteristics were tested by SEM, TEM, and EDS measurements. The samples crystalized in the uniform nanoparticle with a diameter of about 50 nm. The X-ray polycrystalline diffraction (XRD) measurements and the Rietveld refinements were completed to confirm the successful synthesis of CsNbW2O9 nanoparticles. CsNbW2O9 belongs to an interesting compound of AxWO3-type (A = Cs) hexagonal tungsten bronzes with the partial substitution of W6+ by Nb5+ ions. In contrast to AxWO3 (A = Cs) tungsten bronzes, which are nonstoichiometric compounds with metallic-type conductivity, CsNbW2O9 belongs to a typical semiconductor. The optical absorption, band gap energy and electronic structures were discussed. CsNbW2O9 semiconductor shows an indirect allowed transition with an energy gap of 2.38 eV. Meanwhile, CsNbW2O9 shows a self-activated emission due to d0 transitions in (Nb/W)O6. The luminescence properties of CsNbW2O9 semiconductor with a low quenching temperature were discussed based on the distorted structure.

Neutron and X-ray investigations of the Jahn–Teller switch in partially deuterated ammonium copper Tutton salt, (NH4)2[Cu(H2O)6](SO4)2

The structural phase transition accompanied by a Jahn–Teller switch has been studied over a range of H/D ratios in (NH4)2[Cu(H2O)6](SO4)2 (ACTS). In particular, single-crystal neutron diffraction investigations of crystals with deuteration in the range 50 to 82% are shown to be consistent with previous electron paramagnetic resonance (EPR) experiments exhibiting a phase boundary at 50% deuteration under ambient pressure. Polycrystalline samples show that the two phases can co-exist. In addition, single-crystal neutron and polycrystalline X-ray diffraction pressure experiments show a shift to lower pressure at 60% deuteration versus previous measurements at 100% deuteration.

Fabrication and testing of a newly designed slitsystem for depth-resolved X-ray diffraction measurements.

A new system of slits called `spiderweb slits' have been developed for depth-resolved powder or polycrystalline X-ray diffraction measurements. The slits act on diffracted X-rays to select a particular gauge volume of sample, while absorbing diffracted X-rays from outside of this volume. Although the slit geometry is to some extent similar to that of previously developed conical slits or spiral slits, this new design has advantages over the previous ones in use for complex heterogeneous materials and in situ and operando diffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, over a continuous range of diffraction angles, and work for X-ray energies of tens to hundreds of kiloelectronvolts. The design is generated and optimized using ray-tracing simulations, and fabricated through laser micromachining. The first prototype was successfully tested at the X17A beamline at the National Synchrotron Light Source, and shows similar performance to simulations, demonstrating gauge volume selection for standard powders, for all diffraction peaks over angles of 2-10°. A similar, but improved, design will be implemented at the X-ray Powder Diffraction beamline at the National Synchrotron Light Source II.

Synthesis, surface structure and optical properties of double perovskite Sr2NiMoO6 nanoparticles

Double perovskite Sr2NiMoO6 nanoparticles were synthesized via the chemical sol-gel route. The phase formation was investigated through X-ray polycrystalline diffraction (XRD) and Rietveld refinements. The perovskite crystallized in worm-like nano-grains with the diameter of 20–50nm. The optical properties were measured by the optical absorption spectra. The nanoparticles present an indirect allowed transition with a narrow band gap of 2.1eV. Sr2NiMoO6 nanoparticles have obvious photocatalytic ability on the degradation of Rhodamine B (RhB) solutions under the irradiation of visible light. The transport behaviors of the excitons were investigated from the photoluminescence spectra and the corresponding decay lifetimes. Sr2NiMoO6 nanoparticles present several advantages for photocatalysis such as the appropriate band energy positions, the quenched luminescence, and the coexistence of multivalent ions in the lattices.

Layered oxide semiconductor In2Fe2CuO7: Optical properties and visible-light responsive photocatalytic abilities

Transition metal oxide In2Fe2CuO7 nanoparticles were prepared by the sol-gel film coating and subsequent sintering method. The phase formation was investigated by X-ray polycrystalline diffraction (XRD) measurement. The structure refinement confirmed that the sample has a pure hexagonal phase with the space group of P63/mmc. The detailed surface properties were characterized. In2Fe2CuO7 shows an efficient optical absorption in the region of visible wavelength and has a narrow band-gap of 1.91eV. Particularly, In2Fe2CuO7 presents the efficient photodegradation for methylene blue (MB) solutions under visible-light irradiation. The nanoparticles could be a potential photocatalyst for the photodegradation for organic pollution solutions.

Synthesis, surface properties and optical characteristics of CuV2O6 nanofibers

In3+-doped CuV2O6 nanofibers were prepared via the hydrothermal synthesis method, which produced fibers with a typical diameter of 100 nm, and a length of 1–5 μm. The nanofibers grew in a preferred [020] direction. The crystal phase together with the structure was studied via X-ray polycrystalline diffraction (XRD) and the Rietveld refinement. The surface characteristics of this nanostructure were measured with a scanning electron microscope (SEM), energy dispersive spectra (EDS), transmission electron microscopy (TEM), and N2–adsorption–desorption isotherms. Photo-activities were evaluated by optical absorption, luminescence, and decay behaviors. The band-gap structures and positions were investigated. The vanadate has an efficient optical absorption from the UV to the visible wavelength region with an indirect allowed transition characterized by the narrow gap energy of 1.96 eV. The photocatalysis was investigated by the photo-degradation of RhB solutions irradiated by visible light. Correspondingly, CuV2O6:In3+ nanofibers possess quenched luminescence and have a more efficient photocatalytic activity on the RhB degradation. Photocatalytic mechanisms were proposed based on the experimental results, the band-energy positions, and the trapping experiments. The coexistence of V4+/V5+ ions and induced-color centers was discussed on the proposed photocatalytic mechanism. The results demonstrated the promising potency of such In3+-doped CuV2O6 nanofibers for technological applications due to their high photo-activity and good cycling performance with the fiber morphology.

Surface properties, simultaneous photocatalytic and magnetic activities of Ni2FeVO6 nanoparticles

Nickel-ferro-vanadium oxide Ni2FeVO6 nanoparticles were prepared by the sol–gel film coating and subsequent sintering method. The phase formation was investigated X-ray polycrystalline diffraction (XRD) measurement. The surface characteristics were measured by scanning electron microscope (SEM), transmission electron microscopy (TEM), specific surface area, energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). This vanadate has a narrow band-gap energy of 1.784eV. The investigations concluded that Ni2FeVO6 nanoparticles have photocatalytic ability under visible-light irradiation. The ferromagnetic behavior of the nanoparticles was confirmed by the magnetic hysteresis loops. The nanoparticles can be magnetically recoverable after photocatalytic reactions. The photocatalytic activities were discussed on the base of the multivalent cations in crystal lattices.

Determination of stoichiometry from polycrystalline powders of transition metals lamellar dichalcogenides: MoSe<sub>2</sub>, WSe<sub>2</sub>, obtained by synthesis in laboratory

Polycrystalline molybdenum and tungsten (MoSe 2 , WSe 2 ) diselenides were synthesized at 1323 K for 168 hours in silica tubes sealed secondary vacuum. They were haracterized by diffraction with X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM) and gravimetric analysis show that they are homogeneous and well crystallized. Electrochemical and chemical dosages were used to determine their stoichiometry. The results have shown that stoichiometry is reached only when using B type powders and a difference in layer piling according to the mode of synthesis; this explains why A type powders differ from B type powders due to the piling of 2H: 3R layers. Keywords : Polycrystalline powders, MoSe 2 , WSe 2 , SEM, X-Ray diffraction, gravimetry and electrochemical.

Electrodeposition of Pt–Ru and Pt–Ru–Ni nanoclusters on multi-walled carbon nanotubes for direct methanol fuel cell

A full-electrochemical method is developed to deposit three dimension structure (3D) flowerlike platinum-ruthenium (PtRu) and platinum-ruthenium-nickel (PtRuNi) alloy nanoparticle clusters on multi-walled carbon nanotubes (MWCNTs) through a three-step process. The structure and elemental composition of the PtRu/MWCNTs and PtRuNi/MWCNTs catalysts are characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray polycrystalline diffraction (XRD), IRIS advantage inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS). The presence of Pt(0), Ru(0), Ni(0), Ni(OH)2, NiOOH, RuO2 and NiO is deduced from XPS data. Electrocatalytic properties of the resulting PtRu/MWCNTs and PtRuNi/MWCNTs nanocomposites for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) are investigated. Compared with the Pt/MWCNTs, PtNi/MWCNTs and PtRu/MWCNTs electrodes, an enhanced electrocatalytic activity and an appreciably improved resistance to CO poisoning are observed for the PtRuNi/MWCNTs electrode, which are attributed to the synergetic effect of bifunctional catalysis, three dimension structure, and oxygen functional groups which generated after electrochemical activation treatment on MWCNTs surface. The effect of electrodeposition conditions for the metal complexes on the composition and performance of the alloy nanoparticle clusters is also investigated. The optimized ratios for PtRu and PtRuNi alloy nanoparticle clusters are 8:2 and 8:1:1, respectively, in this experiment condition. The PtRuNi catalyst thus prepared exhibits excellent performance in the direct methanol fuel cells (DMFCs). The enhanced activity of the catalyst is surely throwing some light on the research and development of effective DMFCs catalysts.

ELECTRODEPOSITION OF PtRu/MWCNTs AND PtRuNi/MWCNTs AND THEIR PERFORMANCE IN DIRECT METHANOL FUEL CELLS

PtRu catalyst has long application history in electrochemical field due to the wide prospect in direct methanol fuel cells(DMFCs),but its performance remains to be improved further. There are usually two ways to enhance the catalytic activity of PtRu bimetallic catalyst.One is to add the third metal into alloy;the other is to improve the properties of carbon support.In this work,PtRu and PtRuNi nanoparticle clusters were electrochemically deposited on multi-walled carbon nanotubes(MWCNTs) through a three-step process,including an electrochemical treatment of MWCNTs, electro-oxidation of metal chloride to high valence of metal complex and an electro-conversion of PtRu and PtRuNi nanoparticle clusters on MWCNTs.The structure and elemental composition of the PtRu/MWCNTs and PtRuNi/MWCNTs electrodes were characterized by transmission electron microscopy (TEM),energy dispersive X-ray spectroscopy(EDX),X-ray polycrystalline diffraction(XRD) and X-ray photoelectron spectroscopy(XPS).The electrocatalytic properties of the PtRu/MWCNTs and PtRuNi/MWCNTs electrodes for oxygen reduction reaction(ORR) and methanol oxidation were investigated by cycle voltammetry(CV) method and current-time(CT) method.The results showed that PtRuNi/MWCNTs electrode exhibited a high I_f/I_b(the forward anodic peak/the reverse anodic peak current) value and an appreciably improved resistance to carbon monoxide(CO) poisoning in methanol solution,so a beneficial effect on the oxygen adsorption in dilute sulphuric acid solution was observed.The high electrocatalytic activity and good stability of PtRuNi/MWCNTs was attributed to the synergetic effect of bifunctional catalysis,three dimension structure and oxygen functional groups which generated after electrochemical activation treatment on MWCNTs surface.The successful preparation of PtRu/MWCNTs and PtRuNi/MWCNTs nanocomposites opens a new path for efficient dispersion of promising electrocatalvsts in DMFCs.

Crystal Structures of New Compounds Na<sub>0.5</sub>Sm<sub>4.5</sub>Ti<sub>4</sub>O<sub>15</sub> and Na<sub>0.5</sub>Eu<sub>4.5</sub>Ti<sub>4</sub>O<sub>15</sub>

New compounds of sodium samarium titanate Na0.5Sm4.5Ti4O15and sodium europium titanate Na0.5Eu4.5Ti4O15were synthesized successfully by solid state reaction at 1300 oC and 1200 oC, respectively. The lattice parameters of Na0.5Sm4.5Ti4O15and Na0.5Eu4.5Ti4O15were determined at ordinary temperature by using X-ray powder diffraction method. Their Lattice types were determined, and their patterns were indexed. Polycrystalline X-ray diffraction data of sodium samarium titanate were listed. Differences of their crystal structures were analyzed and discussed.

Structure and electrical properties of Sb2Te3 and Bi0.4Sb1.6Te3 metastable phases obtained by HPHT treatment

We have obtained the metastable phase of the thermoelectric alloy Bi0.4Sb1.6Te3 with electron type conductivity for the first time using the method of quenching under pressure after treatment at P=4.0 GPa and T=400–850 °C. We have consequently performed comparative studies with the similar phase of Sb2Te3. The polycrystalline X-ray diffraction patterns of these phases are similar to the known monoclinic structure α-As2Te3 (C2/m) with less monoclinic distortion, β ≈ 92°. We have measured the electrical resistivity and the Hall coefficient in the temperature range of T=77−450 K and we have evaluated the Hall mobility and density of charge carriers. The negative Hall coefficient indicates the dominant electron type of carriers at temperatures up to 380 K in the metastable phase of Sb2Te3 and up to 440 K in the metastable state of Bi0.4Sb1.6Te3. Above these temperatures, the p-type conductivity proper to the initial phases dominates.