Energy Dispersive X-ray Powder Diffraction Research Articles

Deoxygenation of Palmitic Acid to Produce Diesel-like Hydrocarbons over Nickel Incorporated Cellular Foam Catalyst: A Kinetic Study

Nickel incorporated mesostructured cellular foam (NiMCF) was studied as a catalyst for palmitic acid deoxygenation to primarily synthesize n-pentadecane and 1-pentadecene. The kinetic behaviour was tested in a temperature range from 280 to 300°C. The reaction was found to follow a first order kinetic model with respect to the palmitic acid with an activation energy of 111.57 KJ/Mol. In the reusability study, it was found that the average reduction in palmitic acid conversions was about 40.5%, which indicated the occurrence of catalyst deactivation during the deoxygenation. Fresh and spent catalysts were characterized by means of scanning electron microscope. Energy-dispersive X-ray spectroscopy and X-ray powder diffraction correlate their characteristics with catalytic activity and to identify the main catalyst deactivation mechanism. The catalyst deactivation was mainly due to phase transformation of metallic nickel (Ni0) to nickel ion (Ni2+) and the deposition of organic molecules on the catalyst during the deoxygenation. Regeneration of spent catalyst successfully reduced the drops in the palmitic acid conversions between the reaction cycles from 40.5% to 11.3%.

High Response Gas Sensors for Formaldehyde Based on Er-doped In2O3 Nanotubes

Pure and Er-doped In2O3 nanotubes were systematically fabricated by using a single nozzle eletrospinning method followed by calcination. The as-synthesized nanotubes were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectrometry and X-ray powder diffraction (XRD). Compared with pure In2O3 nanotubes, Er-doped In2O3 nanotubes exhibit improved formaldehyde sensing properties at 260 °C. The response of Er-doped In2O3 nanotubes to 20 ppm formaldehyde is about 12, which is 4 times larger than that of pure In2O3 nanotubes. The response and recovery times of Er-doped In2O3 nanotubes to 20 ppm formaldehyde are about 5 and 38 s, respectively. Furthermore, the response of Er-doped In2O3 nanotubes to 100 ppb formaldehyde is 2.19.

Archaeometric Investigation of Medieval Pottery from Excavations at Novo Brdo, Serbia

Medieval pottery from excavations at Novo Brdo, Serbia, an important mining and trading centre during the 14th and 15th centuries, was investigated by a combination of optical microscopy, inductively coupled plasma – optical emission spectrometry, Fourier transform infrared, micro-Raman and energy-dispersive X-ray fluorescence spectroscopy and X-ray powder diffraction methods in order to determine its composition and firing temperature. The samples investigated were made of medium- to coarse-grained, non-calcareous clay, by a relatively well-controlled firing procedure in an oxidizing atmosphere. The firing temperature was estimated to be 850–950°C. The similarity between the chemical composition of the investigated pottery and the local raw clay, combined with the outward appearance and the archaeological findings, indicate domestic production. The pottery is covered with the transparent lead-rich glaze. Iron and copper were used as colourants.

Sunroot mediated synthesis and characterization of silver nanoparticles and evaluation of its antibacterial and rat splenocyte cytotoxic effects.

A rapid, green phytosynthesis of silver nanoparticles (AgNPs) using the aqueous extract of Helianthus tuberosus (sunroot tuber) was reported in this study. The morphology of the AgNPs was determined by transmission electron microscopy (TEM). Scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS) and X-ray powder diffraction (XRD) analysis confirmed the presence of AgNPs. Fourier transform infrared spectroscopy (FTIR) analysis revealed that biomolecules in the tuber extract were involved in the reduction and capping of AgNPs. The energy-dispersive spectroscopy (EDS) analysis of the AgNPs, using an energy range of 2–4 keV, confirmed the presence of elemental silver without any contamination. Further, the synthesized AgNPs were evaluated against phytopathogens such as Ralstonia solanacearum and Xanthomonas axonopodis. The AgNPs (1–4 mM) extensively reduced the growth rate of the phytopathogens. In addition, the cytotoxic effect of the synthesized AgNPs was analyzed using rat splenocytes. The cell viability was decreased according to the increasing concentration of AgNPs and 67% of cell death was observed at 100 μg/mL.

The stability of Pb species during the Pb removal process by growing cells of Phanerochaete chrysosporium

Extensive studies have been operated on the biosorption of heavy metal using white-rot fungi, whereas information on the stability of the sorbed metal species has never been taken into consideration, which is important for the later disposal of the used biomass. In this study, the growing cells of Phanerochaete chrysosporium were used to remove Pb from the fungal living environment. The bioremoval of Pb proceeded continually until 121 h. The bioremoved Pb was found to be stabilized at the first time P. chrysosporium was exposed to Pb ions. The extractable rate of removed Pb decreased constantly and kept at a stable level around 20 % after 121 h. The results indicated that the growing biomass is efficient for the stabilization of Pb, and the used biomass was suitable to be separated for further disposal at 121 h. With environment scanning electron microscopy coupled with energy-dispersive X-ray analysis (ESEM-EDAX) and X-ray powder diffraction (XRD) analysis, the stabilized Pb species were identified to be lead oxalate and lead chloride phosphate. Further, it is found that the stabilization of Pb by growing P. chrysosporium is not strictly limited in the aspect of pH when pH in the environment is in the range of 4-6.

Transport Property Measurements in Doped Bi2Te3 Single Crystals Obtained via Zone Melting Method

Single crystals of Se- and Fe-doped Bi2Te3 have been synthesized via the zone melting method. Energy-dispersive x-ray and x-ray powder diffraction analyses have been carried out to identify the constituent elements and determine the lattice parameters of the grown crystals. Surface topological features of the as-grown single crystals have been studied. The transport properties of doped stoichiometric Bi2Te3 single crystals have been studied by measuring the thermoelectric power and electrical conductivity in the temperature range from 303 K to 473 K. The thermoelectric power, S, effective mass, scattering parameter, and Fermi energy have been calculated from thermoelectric power measurements. The temperature dependence of the electrical conductivity, σ, shows that the dopants in the crystals are thermally activated. All the crystals exhibit semiconducting behavior as confirmed by the temperature dependence of σ and S. The effective mass of electrons and the effective density of states have been determined and are reported for Bi2Te3−x Se x (0 ≤ x ≤ 0.3) and Bi2−y Fe y Te3 (0 ≤ y ≤ 0.3).

Sequestration of phosphorus from wastewater by cement-based or alternative cementitious materials

Cement-based and alternative cementitious materials were tested in the laboratory for their capability of removing phosphate from wastewater. The results demonstrated that both Langmuir and Freundlich adsorption isotherms were suitable for describing the adsorption characteristics of these materials. Among the four types of filter media tested, the cement-based mortar A has the highest value of maximum adsorption (30.96 mg g−1). The P-bonding energy (KL) and adsorption capacity (K) exhibited a positive correlation with the total content of Al2O3 and Fe2O3 in each mortar. The maximum amount of P adsorbed (Qm) and adsorption intensity (1/n) exhibited a positive correlation with the CaO content in each mortar. For three of them, the P-removal rates were in excess of 94 percent for phosphorus concentrations ranging from 20 to 1000 mg L−1. The underlying mechanisms were examined using field emission scanning microscopy (FESEM), coupled with energy-dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD). The results reveal that the removal of phosphate predominantly followed a precipitation mechanism in addition to weak physical interactions between the surface of adsorbent filter media and the metallic salts of phosphate. The use of cement-based or alternative cementitious materials in the form of ground powder shows great promise for developing a cost-effective and environmentally sustainable technology for P-sequestration and for wastewater treatment.

Sonochemical synthesis of HgSe nanoparticles: Effect of metal salt, reaction time and reductant agent

A convenient sonochemical process for the preparation of mercury selenide (HgSe) nanoparticles has been developed based on the reaction of mercury salt and SeCl4 in the presence of triethanolamine (TEA) as complexing agent and N2H4·H2O (hydrazine hydrate) as the reductant agent at room temperature. The effects of preparation parameters such as metal salt, reaction time, reductant agent and its quantity on the morphology, the particle size and the phase of the final products have been investigated. The products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray powder diffraction (XRD).

Analysis of Preferred Orientations in Linear Friction Welded (LFW) Aluminium Alloy Specimens using “One-shot” Multi-element Energy Dispersive Synchrotron X-ray Diffraction

Linear Friction Welding (LFW) has tremendous potential for joining components from similar and dissimilar materials, avoiding material melting and introducing minimal distortion and only moderate levels of residual stress. However, the significant amount of attendant shear introduces preferred crystal orientations that have not yet been well studied. The “one-shot” approach to the interpretation of multi-element energy-dispersive X-ray powder diffraction data allows preferred orientation analysis without any sample preparation (cutting or polishing) or sample rotation. The key step for texture analysis by X-ray powder diffraction is the derivation of the orientation distribution function (ODF) from experimental data. Matlab toolbox “MTEX” provides a powerful function “calcODF” based on the harmonics method for this purpose. In the study reported in this paper, energy dispersive X-ray diffraction patterns were collected using the “horseshoe” multi-element energy-dispersive Ge detector installed on the JEEP beamline at Diamond Light Source. A single exposure was used for each gauge volume of interest, and a line was scanned across an Aluminum 2024 alloy LFW sample. The patterns were converted into raw pole figures through single peak fitting and equal area projection. The ODF calculation was performed based on these pole figures using Matlab toolbox “MTEX”. As a result, full pole figures obtained after ODF calculation were obtained. These are presented and discussed. The results show that the thermal-mechanical processes that occur during the LFW process lead to significant modification of the orientation distribution, but cause only moderate changes in the texture index.

The isothermal section at 800 °C and an AlSb–Zn quasi-binary cut in the Al–Sb–Zn system

The Al–Sb–Zn ternary phase diagram was calculated from thermodynamic Gibbs energies using the CALPHAD method and experimentally investigated using differential thermal analysis (DTA), differential scanning calorimetry (DSC) and a Calvet-type micro-calorimeter. An SSOL4 thermodynamic database was used for the thermodynamic predictions. A scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS) and X-ray powder diffraction (XRD) analyses were used to confirm the predicted phase diagram. Good agreement was found between the experimental results and the predictions.

A time-resolved diffraction study of a window of stability in the synthesis of a copper carboxylate metal–organic framework

An in situ, time-resolved energy dispersive powder X-ray diffraction study of the solvothermal crystallisation of the copper(II) 4,4′,4″-benzene-1,3,5-triyl-tris(benzoate) metal–organic framework MOF-14 shows how reaction conditions must be carefully chosen to allow successful preparation of the material, since on prolonged heating at ≥120 °C the material irreversibly collapses into Cu2O under solvothermal conditions in less than 2 hours. This situation is in contrast to the related Cu(II)-containing metal–organic framework HKUST-1, which shows solvothermal stability over similar temperatures and reaction times. The kinetics of crystallisation of both MOFs are examined using a mathematical model proposed by Gualtieri for zeolite crystallisation: this allows separation of the nucleation and growth regimes to yield two rate constants. Arrhenius analysis gives activation energies that reveal in both cases the crystallisations are nucleation controlled. For MOF-14 we can additionally simulate its decomposition as dissolution of the first-formed interpenetrating structure: this produces a complete picture of the solvothermal stability of MOF-14 as nucleation-growth crystallisation, with some evidence of secondary nucleation, followed by dissolution.

Rapid preparation of flexible porous coordination polymer nanocrystals with accelerated guest adsorption kinetics

Porous coordination polymers, in particular flexible porous coordination polymer networks that change their network structure on guest adsorption, have enormous potential in applications involving selective storage, separation and sensing. Despite the expected significant differences in their adsorption properties, porous coordination polymer nanocrystals remain largely unexplored, and there have been no reports about studies on flexible porous coordination polymer nanocrystals, mainly due to a lack of preparation methods. Here, we present a new technique for the rapid preparation of porous coordination polymer nanocrystals that combines non-aqueous inverse microemulsion with ultrasonication. Uniform nanocrystals of {[Zn(ip)(bpy)]}(n) (ip = isophthalate, bpy = 4,4'-bipyridyl; CID-1), a flexible porous coordination polymer, have been prepared by this method and analysed using field-emission scanning electron microscopy, energy-dispersive X-ray analysis, infrared spectroscopy, Raman spectroscopy and X-ray powder diffraction. A model for particle formation and growth is presented and discussed. Adsorption experiments with methanol show that the overall adsorption capacities of nanoparticles and bulk are almost identical, but the shapes of the sorption isotherms differ significantly and the adsorption kinetics increase dramatically.

Structural evolution of aqueous mercury sulphide precipitates: energy-dispersive X-ray diffraction studies

AbstractIn situ, high-temperature energy-dispersive X-ray powder diffraction (EDXRD) data have been collected on synthetic and a natural sample of mercury sulphide (HgS). These measurements were made between temperatures of 295 and 798 K. Synthetic samples of HgS were prepared by reaction between sulphide and mercury in aqueous solution. In a subsequently dried and aged synthetic HgS sample, heated in vacuo, there is a change from a poorly crystalline pseudocubic material into a well crystalline cubic material in the temperature region 583–623 K. At higher temperature (748 K), there is evidence for a partial phase transition to the high temperature hypercinnabar HgS structure. In a neoformed synthetic sample, heated in a sealed Ti container, the initial ‘pseudocubic’ metacinnabar phase partially transforms to a previously unknown phase (XHgS) in the temperature range 467–522 K. This phase disappears at 527 K, and the metacinnabar phase changes to a well crystalline cubic phase; cinnabar develops at 542 K. The proportion of cinnabar continues to increase up to 647 K. Both metacinnabar and cinnabar phases are retained on cooling. No phase transitions were observed for the natural cinnabar sample.

A thermodynamically stable layered double hydroxide heterostructure

A novel heterostructure was synthesised via the intercalation of 4-nitrophenolate (4-NP) into [LiAl2(OH)6]Cl·xH2O ([Li-Al-Cl]). Its interlayer spaces are alternatively occupied by 4-NP and chloride ions. The intercalate is structurally analogous to staging intermediates reported previously. However, data obtained from time-resolved in situ energy-dispersive X-ray powder diffraction clearly differentiate it from a reaction intermediate. The [Li-Al-Cl–4-NP] heterostructure is formed as a thermodynamically stable product when [Li-Al-Cl] is treated with a small excess of 4-NP over an extended period of time at elevated temperatures (above 70 °C). The heterostructural compound exhibits selective anion exchange when reacted with a range of organic and inorganic anions.

Equation of state of cubic hafnium(IV) nitride having Th 3P 4 -type structure

Pressure dependence of the specific volume, V ( P ) , of the recently discovered high-pressure compound Hf 3N 4 having cubic Th 3P 4-type structure (c- Hf 3N 4) has been measured at room temperature up to 43.9 GPa in a diamond anvil cell using energy-dispersive X-ray powder diffraction combined with synchrotron radiation. A least-square fit of the Birch–Murnaghan equation of state to the experimental V ( P ) -data yielded for c- Hf 3N 4 the bulk modulus of B 0 = 227 ( 7 ) GPa and its first pressure derivative of B 0 ′ = 5.3 ( 6 ) . For B 0 ′ fixed at 4 the bulk modulus of c- Hf 3N 4 was determined to be B 0 = 241 ( 2 ) GPa . The obtained B 0 -value is only insignificantly below that estimated in preliminary measurements. Existing theoretical predictions for B 0 scatter around the present experimental data. The observation of a high bulk modulus of c- Hf 3N 4 supports the suggestion that this compound could have high hardness.

Equation of state and thermal stability of Al 3BC

The lattice parameters of Al 3BC have been measured up to 5 GPa at ambient temperature using energy-dispersive X-ray powder diffraction with synchrotron radiation. A fit to the experimental p– V data using Birch–Murnaghan equation of state gives values of the Al 3BC bulk modulus 116(4) GPa and its first pressure derivative 9(2). In the 1.6–4.8 GPa range at temperatures above 1700 K Al 3BC undergoes incongruent melting that results in the formation of Al 3BC 3, AlB 2 and liquid aluminum.

Isomer selective ion-exchange intercalation of nitrophenolates into the layered double hydroxide [LiAl2(OH)6]Cl·xH2O

The anions 4-nitrophenolate (4-NP) and 2,4-dinitrophenolate (2,4-DNP) undergo anion-exchange intercalation with [LiAl2(OH)6]Cl·xH2O, ([Li-Al-Cl] LDH), to yield the fully exchanged intercalates [LiAl2(OH)6]{4-NP}·2H2O and [LiAl2(OH)6]{2,4-DNP}·H2O respectively. 4-NP can be selectively intercalated in [Li-Al-Cl] LDH from an equimolar mixture of 2-nitrophenolate (2-NP), 3-nitrophenolate (3-NP) and 4-nitrophenolate (4-NP). Intercalation of 2,4-DNP is competitive with intercalation of 4-NP into [Li-Al-Cl] LDH from an equimolar solution of the two NPs. The observed intercalation preferences of these two NPs is found to be dependent on both temperature and solvent. 2,4-DNP is selectively intercalated into [Li-Al-Cl] LDH compared to 4-NP at high temperature and in polar solvents. The kinetics of intercalation of 4-NP and 2,4-DNP into [Li-Al-Cl] LDH has been studied using time-resolved in situ energy dispersive X-ray powder diffraction (EDXRD). The rate of intercalation of 4-NP is faster that of 2,4-DNP, but 2,4-DNP is thermodynamically preferred by [Li-Al-Cl] LDH.

Selective intercalation of chlorophenoxyacetates into the layered double hydroxide [LiAl2(OH)6]Cl·xH2O

Chlorophenoxyacetic acids are a well known family of herbicides. 4-Chlorophenoxyacetate (4-CPA), 2,4-dichlorophenoxyacetic (2,4-D), 2,4,5-trichlorophenoxyacetate, (2,4,5-T) have been intercalated into [LiAl2(OH)6]Cl·xH2O LDH ([Li–Al–Cl] LDH) by ion-exchange. The kinetics and mechanisms involved in the intercalation of each chlorophenoxyacetate have been studied by time-resolved in-situ energy dispersive X-ray powder diffraction (EDXRD). The kinetic preferential order of the intercalation of these herbicides into [Li–Al–Cl] LDH is found to be 4-CPA > 2,4-D > 2,4,5-T. In contrast, thermodynamic guest preference, as determined by performing competitive intercalation reactions is 2,4-D > 4-CPA > 2,4,5-T. The results indicate chlorophenoxyacetate-LDH compounds could have application for the purification, storage and release of chlorophenoxyacetic acid–based agrochemicals.

Archaeometric analyses of game counters from Pompeii

Abstract Among the glass finds of the Pompeii excavations, numerous objects of opaque and transparent glassy material of different colours were recovered and classified as game counters. The main aims of this work were to characterize these samples so as to identify the materials used as colorants and opacifying agents, and subsequently to deduce the technology used for their production. The results of the chemical and mineralogical analyses obtained for game counters were also compared with those obtained for transparent and opaque glass artefacts. The chemical analyses were carried out, using only 300 mg of sample, by both wavelength-dispersive electron microprobe and X-ray fluorescence analysis. The crystalline phases present in the opaque glass were identified using both an automatic X-ray powder diffractometer and a Gandolfi camera. Secondary and backscattered electron images were obtained to study the distribution and morphology of the opacifier particles, and qualitative chemical analyses were obtained with an energy-dispersive system. All the game counters analysed can be classified as silica-soda-lime glass. Two calcium antimonates (CaSb 2 O 6 and Ca 2 Sb 2 O 7 ) were identified in the opaque white, green and blue glass, and Pb 2 Sb 2 O 7 particles were detected in the opaque yellow glass. Particles of metallic copper were detected by both energy-dispersive system and X-ray powder diffraction. These results support the hypothesis that transparent game counters were obtained by remelting of fragments of common transparent artefacts. In contrast, opaque finds were probably produced using the glassy paste employed in the production of mosaic tesserae.

Equation of state of graphite-like BC

The compressibility of turbostratic boron-substituted graphite (t-BC) was measured up to 12 GPa at room temperature using energy-dispersive X-ray powder diffraction with synchrotron radiation. A fit to the experimental p- V data using Birch–Murnaghan equation of state gives values of the t-BC bulk modulus 23(2) GPa and its pressure derivative 8.0(6). These values point to a higher compressibility of t-BC as compared to turbostratic graphite.