X-ray Diffaction Research Articles

Study of the Structural and Switching Properties of Ga2Te5 Crystals

The structural parameters of Ga2Te5 crystals grown using the Bridgman method have been studied. X-ray diffaction analysis revealed the crystal structure of Ga2Te5 in the tetragonal phase. In addition, crystalline size, strain, and dislocation density were calculated with the Sherrer model and the Williamson-Hall (W-H) model. The switching effect was achieved for Ga2Te5 crystals. Furthermore, the effect of temperature and light intensity was studied for Ga2Te5 crystals. The results show that temperature and light intensity affect switching characteristics such as threshold current (ith), threshold voltage (Vth), threshold power (Pth), and resistance ratios from a high-resistance OFF state to a low-resistance ON state (ROFF/RON).

Structural and optical properties of smooth radio frequency sputtered XTe (X=Cd, Zn) thin films

Zinc telluride (ZnTe) and cadmium telluride (CdTe) thin films, with smooth surfaces, were prepared by the radio frequency sputtering method. X-ray diffaction patterns revealed the formation of pure cubic phases and allowed the access of the structural properties. The lattice mismash between the two compounds is found to be around 6%.UV–visible spectroscopy showed a significant absorption coefficient within the visible spectrum, accompanied by an energy band gap measuring 1.9 eVfor the ZnTe film and 1.42 eV for the CdTe film. This study may be benificial for using these materials together of separately in photovoltaic and photocatalytic devices.

Experimental Investigation of Mafic Rocks for Carbon Mineralization Prospect

Carbon capture and storage by mineralization (CCSM) in mafic rock is a viable technology to store captured gaseous carbon dioxide (CO2) into carbonate minerals by chemical reaction with rocks. Here, we investigate the interaction of CO2 with four outcrop mafic rock samples of the Saudi Arabian region for their CCSM potential. Samples interacted with CO2 at 8.27 MPa and 343 K in a batch reactor system for 2 months, and petrophysical and geomechanical properties were analyzed before and after CO2 treatment. The results indicate that the initial state of samples is compromised after exposure to CO2. X-ray diffaction and scanning electron microscopy analyses confirm the reactivity of CO2 with samples. Petrophysical and mechanical parameters also changed after interaction with CO2; i.e., porosity decreased, while Young’s modulus and hardness increased. The results of this study thus shed light on rapid carbon mineralization in the mafic rocks of Saudi Arabia, which can have direct implications for CO2 geo-sequestration in the region.

A relation between the structural diversity and photoluminescent properties in three new classes of Eu3+ hydrocinnamate complexes containing N,N-bidentate and N,N,N-tridentate ancillary ligands

In this work, we present the synthesis, solid state characterization and complete photoluminescence study of three new photoluminescent Eu3+ hydrocinnamate complexes containing the N,N- bidentate and N,N,N-tridentate ancillary ligands 2, 2’: 6′,2″-terpyridine (terpy), 4,4′-dimethyl-2,2′- bipyridine (4,4′-dmbpy) and bathophenanthroline (bath). The spectroscopic and analytical techniques indicate the formation of compounds with the formulas [Eu (cin)3(H2O) (terpy)]. H2O (1), [Eu2 (cin)6 (4,4′-dmbpy)2] (2) and [Eu2 (cin)6 (bath)2] (3), with the monometallic and homobimetallic nature related to the type of ancillary ligand, as evidenced by powder X-ray diffaction data. Through the RM1 model, the optimized ground state geometries of the complexes were obtained, and posteriorly used in the energy transfer elucidation process. The photoluminescent properties show an intimate relationship with the molecular structures, where the 5D0 → 7F0 transition energy and Ω2 Judd-Ofelt parameter value are reflected in the coordination numbers and modes of the carboxylate groups. The intense red emission and structure/photoluminescence interrelationship can opens the possibility to development of new spectroscopic probes based on the Eu3+ coordination compounds.

Karakterisasi Sistem Dispersi Padat Meloksikam Dengan Matriks PEG 6000 Dan Poloxamer 188 Dibuat Dengan Menggunakan Metode Peleburan

Meloxicam is included in the class II Biopharmaceutical Classification System (BCS). This drug has low solubility and high permeability. The solubility is one of the factors that affect in the dissolution rate of drug. One of the effort to increase dissolution of meloxicam is by forming a solid dispersion system made using melting method. The addition of PEG 6000 and poloxamer 188 carriers determine in the solid dispersion system aims to increase the dissolution rate of meloxicam. The purpose of this study is to characterize the meloxicam solid dispersion system with PEG 6000 and poloxamer 188 matrices at a ratio of 99:1 and 98:2 made by the melting method when compared with the physical mixture and its pure compound using Powder X-Ray Diffaction, DSC and FTIR. The results of meloxicam solid dispersion with a ratio 99:1 and 98:2 showed the disappearance of the typical peak of meloxicam at an angel of 2θ 6.5° and 11.2°. The thermogram data using DSC shows a decrease in melting point of solid dispersion system with a ratio of 99:1 and 98:2 namely 64.33°C and 64.21°C. The result of the characterization of meloxicam solid dispersion with FTIR showed that the identified spectrum were in the spectrum range of meloxicam, PEG 6000, poloxamer 188 indicating there was no incteraction in the meloxicam solid dispersion system. Keywords: Meloxicam, PEG 6000, Poloxamer 188, Solid Dispersion, Melting Method, Characterization

Simultaneously deposited Pt-alloy nanoparticles over graphene nanoplatelets via supercritical carbon dioxide deposition for PEM fuel cells

One of the main barriers to the commercialization of polymer electrolyte membrane fuel cell (PEMFC) systems is the cost, which is largely due to the need of platinum (Pt)-containing catalysts. In order to overcome this issue, several methods have been developed. One of them is the supported electrocatalysts prepared by combining a low cost second metal with Pt. Motivated by this idea, in this study, nano-sized Pt-M (M = Ni, Fe, Cu) binary electrocatalysts were synthesized on the graphene nanoplatelets (GNPs) via supercritical fluid deposition (SFD) technique in order to decrease the cost and increase the activity of the catalysts. Because, the unusual properties of supercritical fluids (SFs), including tunable solvent strength, high diffusivity, low viscosity, and low surface tension, offer significant advantages over conventional techniques for materials processing. In this regard, compared to the other SFs, carbon dioxide (CO2) has received much more attention due to its easy accessibility to the supercritical state, relative benignity to the environment, chemical inertness, low toxicity, low cost. The supercritical carbon dioxide (scCO2) deposition technique involves firstly the dissolution of the metal precursor onto the support material, and then conversion of the metal precursor to its metallic form by means of thermal or chemical conversion. Synthesis of supported bimetallic nanoparticles (NPs) via scCO2 can be sequentially or simultaneously. Herein, we investigated the development of Pt-M (PtCu, PtNi, PtFe) alloy NPs on GNPs by scCO2 deposition via simultaneous addition of metal precursors. Subsequently, these catalysts were characterized by employing various characterization techniques and systems such as X-Ray Diffaction (XRD), Thermogravimetric Analysis (TGA), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Transmission Electron Microscopy (TEM), Raman Spectroscopy, Cyclic Voltammetry (CV), Rotating Disk Electrode (RDE) and PEM Fuel Cell performance tests. The obtained results revealed the formation of bimetallic catalysts within the size ranges from 1.6 to 2.1 nm. Furthermore, CV results demonstrate that PtNi/GNPs catalyst exhibit significantly high catalytic activity toward the PEM fuel cell reaction in comparison with the PtFe/GNPs and PtCu/GNPs. Also, PtNi/GNPs catalyst show about 2–4 times higher durability than the PtFe/GNPs and PtCu/GNPs catalysts in the accelerated degradation tests (ADTs). All results suggested that the PtNi/GNPs catalyst has great potential for PEM fuel cell applications.

Evolution of synthesis of FCC nanocrystalline solid solution and amorphous phase in the Ti-Ta based alloy by high milling energy

Pure Ti and Ti-based alloys exhibit two equilibrium phases: at lower temperatures they have a hexagonal close packed (α-Ti) crystalline structure while at higher temperatures they possess a body-centered cubic (β-Ti) structure. However, in special conditions, they could exhibit a metastable face-centered cubic (γ-Ti) crystalline structure. This paper aims to investigate the influence of Sn amount and milling time on the formation of γ-Ti phase on the Ti-Ta based alloy. Four alloys with compositions Ti-13Ta-xSn (x: 3, 6, 9 and 12 at. %) were obtained by high energy milling. The alloys were analyzed by X-ray diffaction patterns, transmission and scanning electron microscopy. For the Ti-13Ta-3Sn alloy, the β-Ti phase is formed in greater quantity, ∼70% at 100 h. For the Ti-13Ta-6Sn and Ti-13Ta-9Sn alloys, the phase that is in greater quantity is γ-Ti, around 100% at 100h. The Ti-13Ta-6Sn alloy shows a greater tendency to form the γ-Ti phase, since the quantity is close to 100% at 50 h milling time. Thermodynamic calculations are comparable with experimental data. The calculations were made using the MAAT software based on Miedema’s model. The MAAT is a free software that can be download from www.rpm.usm.cl.

Surface photochemical studies of nano-hybrids of A3B porphyrins and Fe3O4 silica-coated nanoparticles

This study reports a surface photochemistry behaviour of two tetrapyrrolic structures: 5,10,15,20-tetra-(4-carboxymethylphenyl) porphyrin (P1.1) and 5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (P1.2), covalently bound to silica-coated magnetite nanoparticles (Fe3O4@SiO2) imbibed into a polyethylene glycol (PEG) matrix and in the form of a fine powder. The initial compounds and the nano-hybrids imbibed in the PEG matrix were characterized using Fourier transformed infrared spectroscopy (FT-IR), diffuse reflectance absorption spectroscopy for ground state molecules (GSDR), X-ray diffaction (XRD), transmission electron electron microscopy (TEM) as well as several luminescence emission spectroscopies. The combined use of these methodologies enabled us to obtain a surface photochemistry characterization of these new nano-hybrid materials.For the powdered samples of P1.1 or P1.2 and Fe3O4@SiO2 imbibed into the powdered PEG a detailed absorption study and a correlation of fluorescence emission intensity with the magnetite concentration were performed. New covalent bonds porphyrin-Fe3O4@SiO2 were detected using FT-IR transmission spectra. A donor-acceptor interaction with change of the oxidation level of the porphyrins was also observed. Fluorescence emission quantum yields and lifetimes of the two porphyrins were determined for all samples and two populations of the porphyrin molecules exist, free porphyrin (unquenched) and porphyrin with Fe3O4@SiO2 NPs attached, the quenched porphyrin. In this way, the amount of the available excited porphyrin for singlet oxygen formation is reduced, therefore the presence of the Fe3O4@SiO2 NPs may not favor this specific PDT action by the Type II mechanism, but it prevents aggregation of the porphyrins, even when a PEG matrix is used, and Type I mechanisms remain active.

Oxidation Behavior of Zr-based Amorphous Alloys at 400˚- 450˚C in Air

<em><span lang="EN-US">The study of oxidation behavior of amorphous alloys based on Zirconium with 2 variations in composition was carried out: Zr<sub>64.5</sub>Cu<sub>17</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>and Zr<sub>69.5</sub>Cu<sub>12</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>at temperatures of 400 - 450˚C in air. Amorphous Zr-based alloys were thermally characterized using Differential Scanning Calorimeter (DSC) to determine the crystallization temperature and glass transition temperature. The oxidation characterization was carried out using a Thermo gravimetric Analyzer (TGA) at temperatures of 400, 425, and 450˚C for 4 hours in air. The phase analysis of the oxidation product was identified using X-Ra</span><span>y Diffaction</span><span lang="EN-US"> (XRD). Based on DSC data the crystallization temperature for Zr<sub>64.5</sub>Cu<sub>17</sub>Ni<sub>11</sub>Al<sub>7.5</sub> and Zr<sub>69.5</sub>Cu<sub>12</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>is 426 and 442˚C respectively. The oxidation kinetics of the two alloys follow parabolic law and the oxidation rate increases with the addition of temperature. Oxides formed during isothermal oxidation in the Zr<sub>64.5</sub>Cu<sub>17</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>and Zr<sub>69.5</sub>Cu<sub>12</sub>Ni<sub>11</sub>Al<sub>7.5</sub> alloys are t-ZrO<sub>2</sub> (tetragonal) as the dominant phase and ZrO<sub>2</sub> (monoclinic) and CuO as the minor phase. The intermetallic phase is also formed in both samples, t-Zr<sub>2</sub>Ni and Zr<sub>2</sub>Cu.</span></em>

Authigenic Mg-Clay Minerals Formation in Lake Margin Deposits (the Cerro de los Batallones, Madrid Basin, Spain)

The Madrid Basin contains large and well developed deposits of Mg-clays of Miocene age. These were developed in an environment controlled by a lacustrine saline-alkaline environment with an arid or semi-arid climate, leading to large deposits of Mg-clays. This paper summarizes the study about the formation of Mg-clay minerals in the transition from mudflat lithofacies made-up of Mg-smectite to palustrine lithofacies where sepiolite is predominant. The samples collected in the field were characterized by XRD (X-Ray Diffaction) (bulk sample and clay fraction), examined using SEM (Scanning Electron Microscopy) and analyzed by XRF (X-Ray Fluorescence) and FTIR (Fourier Transform Infrared Spectroscopy). The results suggest that during the formation of these materials dissolution-precipitation, direct precipitation and recrystallization mechanisms intervened. The type of water present (runoff, lake and/or groundwater) is a key factor for the development of the different mineral phases. In the case of the study, the analyzed series goes from mudflat conditions with influence of runoff water to a palustrine environment. During this evolution, the influence of groundwater increases with time. This is reflected in the affinity between the samples analyzed and the presence of certain elements that could serve as indicators of changes between different media.

Synthesis, crystal structure and aggregation-induced emission of a new pyrene-based compound, 3,3-diphenyl-2-[4-(pyren-1-yl)phen-yl]acrylo-nitrile.

The title organic compound, C37H23N, crystallizing in the triclinic space group P [Formula: see text], has been designed, synthesized and characterized by single-crystal X-ray diffaction, MS, NMR and elemental analysis. There are alternating relatively strong and weak intermolecular π-π interactions between adjacent pyrene ring systems, forming a one-dimensional supramolecular structure. The compound is weakly fluorescent in THF solution, but it is highly emissive in the condensed phase, revealing distinct aggregation-induced emission (AIE) characteristics.

Gold Nanoparticles As A Modifying Agent of Ceramic-Polymer Composites

Abstract Much effort has been invested in the development of biomaterials for the repair or replacement of hard tissue. The synthesis of composites based on mineral and organic constituents is nowadays extremely important for the development of materials for biomedical applications. In this paper we report the preparation and characterization of ceramic-polymer composites doped with gold nanoparticles. Properties and applications in medicine and dentistry of colloidal gold nanoparticles depends upon their size and shape. The influence of the presence of the metallic nanoparticles on the degradation process was investigated by pH and conductivity analyses of water filtrates. The nanocomposites were characterized with the use of X-ray Diffaction (XRD) and Fourier Transformed Infrared Spectroscopy (FT-IR) methods.The results of in vitro tests confirmed that it is possible to produce hydroxyapatite/polymer (HA/polymer) composites doped with gold nanoparticles (AuNPs) for medical applications. Tests proved that content of gold nanoparticles in composites had influence on degradation behaviour of HA/Polymer/AuNPs in water environment.

Synthesis and Luminescence Properties of LaVO<SUB>4</SUB>:RE<SUP>3+</SUP> (RE = Sm, Eu, Tb, Tm) Phosphors

Rare earth (RE)-doped lanthanide vanadate phosphors for multicolor display applications were synthesized with different activator ions by using a solid-state reaction method. The effects of activator ions on the structural, morphological, and optical properties of lanthanide vanadate phosphors were investigated. X-ray diffaction data exhibited that the main peak of the phosphors occurs at a (120) plane. Maximum grain size and hexagonal morphology are observed by incorporating Eu3+ activator ions into a host lattice. The emission spectra of RE ions-doped LaVO4 phosphors under excitation at 324 nm consist of multicolor emissions: the main red emission for Eu3+, Orange for Tm3+, green for Tb3+, and blue for Tm3+ activator ions. These results suggest that the multicolor emissions can be realized by controlling activator ions incorporated into host crystals.

NMR Crystallography Comparative Studies of Chiral (1R,2S,3R,5R)-3-Amino-6,6-dimethylbicyclo[3.1.1]heptan-2-ol and Its p-Toluenesulfonamide Derivative

The crystal structure of (1R,2S,3R,5R)-3-amino-6,6-dimethyl-2-hydroxybicyclo[3.1.1]heptane 1 was determined and it is presented in reference to the structure of (1R,2S,3R,5R)-3-(p-tosylamino)-6,6-dimethyl-2-hydroxybicyclo[3.1.1]heptane 2. 1H and 13C chemical shifts parameters for both structures and for whole unit cells were calculated by using the GIPAW (gauge including projector augmented waves) method. Theoretically calculated chemical shift tensor parameters were verified by 13C CP MAS, 2D PASS, and 13C–1H FSLG HETCOR results to obtain a full structural assignment for 13C and 1H resonances in the solid-state. PISEMA MAS experiment was performed to determine the molecular dynamics of aminoalcohol 1. The comparison of two structures, obtained after all-atom positions optimization after the GIPAW calculations, revealed small conformational differences consistent with the single-crystal X-ray diffaction results.

KARAKTERISTIK FILM TIPIS TiO2 DOPING NIOBIUM

Niobium (Nb) doped Titanium dioxide (TiO2) thin films have been successfully grown using spin coating method. Characterizations of thin films was carried out using EDAX (Energy Dispersion Analysis for X-Ray), XRD (X-Ray Diffaction) and SEM (Scanning Electron Microscope) to determine the microstructure of thin films. Determination microstructure, particularly of crystal structure was examined using ICDD data, whereas porosity calculation was done using the toolbox application on Matlab 6.1 software. EDAX, XRD and SEM characterization show that the thin films grown well at the Si substrates with the (002) field orientation is dominant and the thin film has the rutile structure. The TiO2 : Nb thin films product have granules round, uniform grain size and porosity value of about 41%.

Preparation of strontium hexaferrite magnets from celestite and blue dust by mechanochemical route

In the present investigation celestite (natural ore of strontium) and blue dust (iron ore fines) have been used for the preparation of strontium hexaferrite powder. The mechanical alloying process has been adopted to prepare strontium hexaferrite powder. The celestite after chemical upradation and physically upgraded blue dust alongwith sodium carbonate was taken for the preparation of strontium hexaferrite in this experiment. The high-energy planetary ball mill with tungsten carbide jar and ball was used to prepare strontium hexaferrite powder. A long time of ball milling for different duration has led to displacement solid-state reaction. At the end of each experiment the product was washed thoroughly and dried. The X-ray diffaction study after annealing shows the development of single-phase strontium hexaferrite after 40 hrs. of milling. The resultant powder was compacted under magnetic field and sintered to prepare the magnet after annealing the ferrite powder. The magnetic properties were measured by Pulse magneto meter. The moderate value of coercivity, remanence and energy product were observed in this sintered magnet. The work illustrates the feasibility to prepare strontium hexaferrite magnetic powders directly from natural ores which can reduce the total cost of production as compared to conventional method.

Phase transition in Pd40Ni10Cu30P20 bulk metallic glass under HP & HT

The phase transitions in Pd40Ni10Cu30P20 bulk metallic glass (BMG) have been studied under high pressure and high temperature (HP & HT) by X-ray diffaction measurements with synchrotron radiation source. We found that the BMG underwent a phase transitions of amorphous-crystalline-amorphous at 10 GPa upon heating. The parallel experiments were carried out at 7 GPa, while we did not observe the amorphous-crystalline-amorphous transitions by increasing temperature. Quenching the melted BMG at 7 GPa, it was found that the phase crystallized from the melt differed from the primary phase crystallized from the starting amorphous solid upon heating suggesting there existed a distinct mechanism in two cases.

Preparation of a new hybrid organic/inorganic material by cholina intercalation into molybdenum bronzes

Intercalation of a organic compound, 2-hydroxyl etil trimetil ammonium, in the layered host molybdenum bronzes was achieved. Full characterization of solids was performed using chemical analysis, X-ray diffaction, thermal analysis and IR spectroscopy. Using fresh sodium hydrated layered molybdenum bronce yields a monofasic layered solid. The hybrid organic-inorganic compound exhibs a high lamellar order, which is stable at temperatura below 550 K, then collapsing by combustion of organic component. All features show that blue molybdenum bronzes will be a good host for intercalation.

MOCVD growth and properties of Zn3P2 and Cd3P2 films for thermal photovoltaic applications

We report the growth and characterization (structural and electronic) of thin films of Zn3P2 and Cd3P2 grown by MOCVD. Heterojunctions of this pair of dopable semiconductors are being studied for applications as thermophotovoltaic devices. We have grown films of these materials on glass substrates, and X-ray diffaction studies confirm the phase formation and polycrystalline nature of the films. Optical absorption studies revealed three distinct transitions in the Zn3P2 films, at 1.3, 1.55, and 1.85 eV (in agreement with literature values found in single crystals). Analysis of optical spectra of the films showed direct transitions at 0.62, 0.65, and 0.71 eV. We also report measurements of photoconductivity and photoluminescence in these films. Hall effect measurements show the Cd3P2 films to be n-type with mobilities as high as 429 cm2/V s. Carrier lifetimes were also measured directly by a photoconductive decay technique. The films show promise for TPV devices, although fabrication of such multilayer devices is in only a preliminary stage.

Magnetic and structural behaviours of nanocrystalline Fe 70.8 Nb 3.7 Cu 1 Al 2.7 Mn 0.7 Si 13.5 B 7.6 alloy

The crystallization behaviour of Fe 70.8 Nb 3.7 Cu 1 Al 2.7 Mn 0.7 Si 13.5 B 7.6 alloy prepared in the form of amorphous ribbons by melt-spinning technique was studied using differential scanning calorimetry and the temperature variation in resistivity. An X-ray diffaction and transmission electron microscopy study showed the formation of f-Fe(Si, Al) and/or Fe 3 (Si, Al) nanoparticles after the first stage of crystallization. The activation energy for this nanophase formation was 68 kcal mol m1 . The brittleness of the alloy increased with the formation of nanoparticles after heat treatment. Superior soft magnetic properties were achieved when the material was heat treated at 790 K for 15 min. The particle size at the optimum heat treatment condition for superior soft magnetic properties was found to be 6.0 -0.5 nm which was less compared than for the Fe-Nb-Cu-Si-B system. The observed coercivity value at the optimum heat treatment condition was found to be 0.32 A m m1 (approximately 4 mOe). The presence of Al in the alloy reduced the particle size and the magnetic anisotropy energy of the system, which resulted in superior soft magnetic properties of the heat-treated materials.