Ray Diffraction Data Research Articles

Ultraviolet photoconductivity and photoluminescence properties of spray pyrolyzed ZnO nanostructure: Effect of deposition temperature

The current investigation focuses on the influence of substrate temperature on Zinc Oxide (ZnO) thin films synthesized on glass substrates using 0.1 M precursor solution by low-cost spray pyrolysis technique. The x-ray diffraction peaks matched the hexagonal wurtzite structure of ZnO with the highest intensity along the (1 0 1) plane. Estimated the crystallite size, dislocation density, micro-strain, and the number of crystallites in the deposits using X ray diffraction (XRD) data. The crystallinity of the films deposited at 450 °C was maximum. Fibrous surface morphology is altered by varying the deposition temperature. The enhancement of optical transmittance and energy bandgap of the deposits with deposition temperature. The reduction of Urbach energy with an increase in the substrate temperature confirmed the improvement of crystallinity. The photoluminescence study revealed peaks associated with electron-hole pair recombination, zinc, and oxygen-related defects. The samples deposited at 450 °C showed minimum defects. Commission Internationale de l'éclairage (CIE) chromaticity diagram showed white light emission for sample deposited at 450 °C with the color temperature equal to 5378 °C which is agreeing with the temperature of a normal white light source. Improvement of free carrier concentration and n-type conductivity due to the enhancement of crystallinity was observed. ZnO thin films deposited at 450 °C showed maximum photocurrent when illuminated with UV light and faster rise and fall of photo resistance due to the improvement in the crystallinity and carrier concentration. The maximum photosensitivity was observed for the samples synthesized at 450 °C. Hence the ZnO thin films deposited at 450 °C can be used as ultraviolet photodetector material.

Denitrification performance of nitrate–dependent ferrous (Fe2+) oxidizing Aquabacterium sp. XL4: Adsorption mechanisms of bio–precipitation of phenol and estradiol

In this study, a nitrate–dependent ferrous (Fe2+) oxidizing strain under anaerobic conditions was selected and identified as XL4, which belongs to Aquabacterium. The Box–Behnken design (BBD) was used to optimize the growth conditions of strain XL4, and the nitrate removal efficiency of strain XL4 (with 10% inoculation dosage, v/v) could reach 91.41% under the conditions of 30.34 ℃, pH of 6.91, and Fe2+ concentration of 19.69 mg L–1. The results of Fluorescence excitation–emission matrix spectra (EEM) revealed that the intensity of soluble microbial products (SMP), aromatic proteins and the fulvic–like materials were obvious difference under different Fe2+ concentration, pH, and temperature. X–ray diffraction (XRD) data confirmed that the main components of bio–precipitation were Fe3O4 and FeO(OH), which were believed to be responsible for the adsorption of phenol and estradiol. Furthermore, the maximum adsorption capacity of bio–precipitation for phenol and estradiol under the optimal conditions were 192.6 and 65.4 mg g–1, respectively. On the other hand, the adsorption process of phenol and estradiol by bio–precipitation confirmed to the pseudo–second–order and Langmuir model, which shows that the adsorption process is chemical adsorption and occurs on the uniform surface.

Studies on the physical properties of green synthesized cerium oxide nanoparticles using Melia dubia leaf extract

Cerium oxide nanoparticles were prepared by green synthesis method using Melia dubia leaves extract. The synthesized cerium oxide nanoparticles were characterized by powder X ray diffraction, Raman Spectroscopy and UV–visible spectroscopy to investigate the structural and optical properties respectively. The obtained powder X- ray diffraction data and Raman Spectrum confirmed that the prepared samples are nanocrystalline in nature and belong to cubic crystal structure. Optical absorbance was studied from the diffuse reflectance spectra and it showed that the nanoparticles are opaque in the ultraviolet light region. The dielectric characteristics of the nanoparticles were recorded, where the dielectric constant and dielectric loss factor were observed to increase with increase in frequency and temperature. The AC conductivity of the prepared sample was analyzed as a function of frequency at different temperatures and the activation energy for conduction was determined.

Preparation of nanostructured cerium-doped MnS/Si heterojunction photodetector by chemical spray pyrolysis: Influence of doping concentration

We report on the preparation of MnS/Si and cerium-doped MnS /Si heterojunction photodetectors by spray pyrolysis technique. The effect of doping concentration on the structural, optical and electrical properties of the MnS film was investigated. X–ray diffraction (XRD) data show that the pure MnS film was crystalline with mixed α-MnS and γ-MnS phases and the doped films exhibited poor crystallinity. Scanning electron microscope (SEM) results illustrate that the film doped with 1 wt% Ce has nanowires morphology, while the other films have spherical grains morphology. Energy dispersive x-ray (EDX) and elemental mapping showed the presence of cerium, magnesium and sulfur elements. The optical transmittance of the film decreases as doping concentration increase. The optical energy gap of decreased from 2.8 eV to 2.58 eV after cerium doping with 3 wt%. Raman spectra of pure MnS and Ce-doped MnS films revealed the presence of vibration mode at 365 and 635 cm−1. The electrical resistivity and mobility of the film after doping with different contents of Ce were measured. The figures of merit of the MnS:Ce/Si heterojunction photodetector as a function of doping concentration were investigated. The current-voltage characteristics under dark and illuminated conditions were investigated. The maximum responsivity was 0.71 A/W at 350 nm for the Mn:Ce (1 wt%)/Si photodetector.

A-site substituted BiFeO3 ceramics: A study of structural and electrical properties

This work presents the influence of La3+ and Sr2+ substitution at Bi-site of BiFeO3 in the sense of phase, crystal structure and dielectric properties. The Bi1-x (Lax-y Sry)FeO3 (x = 0.1, y = 0, 0.05) ceramics with perovskite structure were synthesized by standard solid state route. Phase analysis exploiting X–ray diffraction (XRD) data disclosed formation of single phased trigonal structure with R3c space group. The calculated lattice parameters for Bi0.9La0.1FeO3 ceramic were a = b = 5.5771 Å and c = 13.8021 Å and Bi0.9La0.05Sr0.05FeO3 ceramic were a = b = 5.5844 Å and c = 13.8215 Å which witness trigonal structure. The calculated average crystallite size for Bi0.9La0.1FeO3 and Bi0.9La0.05Sr0.05FeO3 ceramics were 47.39 nm and 31.20 nm respectively. The dielectric analysis reveals that both the ceramics to exhibit good dielectric behavior with high dielectric constant and lower tangential loss value. In addition, Cole-Cole plot (M′ vs. M′′) and Nyquist plot (Z′ vs Z′′) exposed the non-Debye behavior of the ceramics and distribution of different relaxation phenomena in the ceramics.

Spectroscopy driven DFT computation for a structure of the monomeric Cu2+-Curcumin complex and thermodynamics driven evaluation of its binding to DNA: Pseudo-binding of Curcumin to DNA

In an attempt to overcome limitations of Curcumin from being an important molecule in biology and medicine, a monomeric complex of CuII [Cu(Cur)(OCOCH3)(H2O)] was prepared. Physico-chemical studies in solution using copper acetate and Curcumin indicate formation of a 1:2 CuII:Curcumin species. However, attempts to prepare it always led to the formation of a 1:1 CuII:Curcumin species, if CuII-acetate was used as the starting material. In the absence of a single crystal or an appropriate powder X ray diffraction data that would allow solving of the structure, it was arrived at by spectroscopy guided DFT calculations. Unlike Curcumin, the prepared complex was stable under physiological conditions, an advance achieved through complex formation. Effective binding of the complex to DNA with an ability to enhance cellular uptake owing to the presence of CuII are other benefits of complex formation that might increase its cytotoxic potential. The complex has a reasonably strong affinity for DNA realized from binding constant values obtained with calf thymus DNA at different temperatures in the range 25 °C–35 °C. This enabled an evaluation of thermodynamic parameters (ΔH, ΔS and ΔG), that helped in determining the mode of binding between the complex and DNA as realized from a correlation of thermodynamic signatures to binding types. The study may be considered a case of pseudo-binding of Curcumin to DNA since the complex containing a Curcumin bound the metal ion does not dissociate in solution under physiological conditions, i.e. remains as one unit. Hence binding of the complex to DNA is also the binding of Curcumin to it present as one “single unit”, a major advancement based on a biophysical approach. Besides, aspects like stability of the complex in solution, prevention of degradation of Curcumin in aqueous buffer or biological milieu, binding with mammalian DNA are other aspects that are significant for use of the complex on biological targets.

MINERALOGICAL PROPERTIES OF OAK FOREST SOILS IN IRAQI KURDISTAN REGION

This experiment was conducted from 1/7/2016 to 20/12/2018 to study the mineralogical properties of oak forest at 12 locations (Gara, Matin and Brifca) from Dohuk governorate, (Bilah, Malakan and Awagrd) from Hawler Governorate, (Bardanga, Badawan and Chwarta) from Sulaimani Governorate, and (Bakhakon, Hawar and Sartak) from Halabja governorate in Iraqi Kurdistan region. The samples collected from a depth of (0 – 60) cm for laboratory analysis. The study includes qualitative identification of clay minerals by X- ray diffraction data. Peak height was used as a rough indicator of relative abundance of minerals. In general, the expansion of 14°A to ≈ 17°A in ethylene glycol treatment was not detected because the measuring was started from 5θ (degree 5 theta) so the differentiation between Chlorite and Semectite was not done in this treatment. The main results indicated that the swelling chlorite being the dominant mineral in these soils. While the miner clay mineral in that locations were Kaolinite. Mica was identified in all location except of Bilah site, the dominant type of Mica was Muscovite which was obtained from 6 Locations, while Biotite obtained from 5 sites. It appears that Muscovite was recorded from 50% of Forest sites while Biotite recorded at 41.7% of Forest sites and Both Mica mineral type was not recorded from 8.3% of studied Forest soils.

Structural and thermal investigations of CaU(PO4)2; phase diagram study of MO−UO2–P2O5 systems (M = Ca, Sr, Ba)

Structure of monoclinic CaU(PO4)2, synthesized in argon atmosphere at 1473 K, was derived from powder X−ray diffraction (XRD) data using Rietveld refinement method. Thermogravimetric (TG) Curve recorded up to 1573 K in argon atmosphere showed thermal as well as structural stability of CaU(PO4)2. When heated in air, TG curve of CaU(PO4)2 showed weight gain between 1100–1673 K due to oxidation of U(IV) to U(VI). Molar heat capacity of CaU(PO4)2 as well as some ternary alkaline earth phosphates were calculated using differential scanning calorimeter technique. Phase diagrams of pseudo ternary alkaline earth metal−uranium (IV)−phosphates were derived and phase boundaries were established. All the ternary and quaternary compounds used for deriving the phase diagrams were synthesized in an argon atmosphere at 1473 K. X-ray diffraction (XRD) was used as a prime analytical tool to investigate the phase mixtures and draw phase boundaries. Phase diagram of SrO–UO2–P2O5 and BaO–UO2–P2O5 systems confirm the existence two quaternary compounds, (Sr/Ba)U(PO4)2 and (Sr/Ba)7U(PO4)6 in the systems whereas in CaO–UO2–P2O5 system only one quaternary compound, CaU(PO4)2, was identified.

Control of Pharmaceutical Cocrystal Polymorphism on Various Scales by Mechanochemistry: Transfer from the Laboratory Batch to the Large-Scale Extrusion Processing

We demonstrate a controllable mechanochem. synthesis of cocrystal polymorphs of ascorbic acid (vitamin C) and nicotinamide (vitamin B3) on different scales and without using bulk solvents. Next to the previously described polymorph of the 1:1 cocrystal, which is one of the first cocrystals approved for human consumption, we report here a new, thermodynamically more stable polymorph detected during in situ synchrotron powder X-​ray diffraction monitoring of milling reactions. The new polymorph is currently available exclusively by mechanochem. synthesis, and its crystal structure was detd. from synchrotron powder X-​ray diffraction data. Lab. in situ monitoring by Raman spectroscopy provided direct insight into the cocrystals formation and was further used to optimize the manufg. procedure. Subgram synthesis using a lab. mixer mill was transferred to the 10 g scale on a planetary ball mill and continuous manufg. using a twin-​screw extruder. Both cocrystal polymorphs perform excellently in tableting, thus alleviating the notoriously poor compactible properties of vitamin C, while the mechanochem. cocrystn. does not harm its antioxidant properties.

Structural and magnetic studies on Co-Zn nanoferrite synthesized via sol-gel and combustion methods

Abstract Co–Zn nanocrystalline ferrites with chemical composition Co0:5Zn0:5Fe2O4 were synthesized by sol-gel and combustion methods. The sol-gel method was carried out in two ways, i.e. based on chelating agents PVA and PEG of high and low molecular weights. In auto-combustion method, the ratio of citric acid to metal nitrate was taken as 1:1, while in sol-gel method the chelating agents were taken based on oxygen balance. All the three samples were studied by thermogravimetric and differential thermal analysis for the identification of phase formation and ferritization temperature. The synthesized samples were characterized by powder X-ray diffraction and FT-IR spectroscopy without any thermal treatment. The measured lattice constants and observed characteristic IR absorption bands of the three samples are in good agreement with the reported values showing the formation of a cubic spinel structure. The crystallite sizes of all samples were determined using high intensity peaks and W-H plot. Size-Strain Plot method was also implemented since two of the samples showed low crystallite sizes. The least crystallite size (5.5 nm) was observed for the sample CZVP while the highest (23.8 nm) was observed for the sample CZCA. Cation distribution was proposed based on calculated and observed intensity ratios of selected planes from X ray diffraction data. All structural parameters were presented using experimental lattice constant and oxygen positional parameter, and they correlated with FT-IR results. Magnetic measurements were carried out using vibrating sample magnetometer at room temperature to obtain the characteristic parameters such as saturation magnetization, coercivity, remanence, squareness ratio and Bohr magnetons. Among all, the sample synthesized via citric acid autocombustion method displayed a remarkably higher magnetization of 53 emu/g and the remaining two samples displayed low magnetization values owing to their smaller crystallite sizes.

Investigation of the effect of electron beam irradiation on the structural and transport properties of half doped Nd0.5Sr0.5MnO3 manganites

A systematic investigation on the effect of electron beam irradiation on the structural, electrical properties and thermopower of half doped Nd0.5Sr0.5MnO3 manganites is presented in this report. Elemental analysis of the samples through Energy Dispersive X-ray Spectroscopy (EDS) confirm the desired stoichiometry. Rietveld refinement of the X Ray diffraction data reveals that the samples are single phased. Further, no change in crystal structure or symmetry is observed as an after-effect of electron beam radiation. The samples exhibit insulating behaviour in the entire temperature range 10–300 K. Though the resistivity value changes as a result of electron beam irradiation but the insulating behaviour is unaffected. It is validated from both resistivity as well as thermopower analysis that small polarons are responsible for conduction in the high temperature region. On the contrary, variable range hopping is responsible for the conduction mechanism at low temperatures. The absolute value of thermopower is observed to decrease with increasing dose of electron beam. Moreover, thermopower data indicates n-type conductivity for the samples under investigation.

Composition dependence of giant electrocaloric effect in PbxSr1-xTiO3 ceramics for energy-related applications

PbxSr1-xTiO3 (x = 0.30, 0.35, 0.40, 0.45, 0.50 and 0.55) ceramics were fabricated by a solid-state reaction route. X–ray diffraction data at room temperature show PST samples shift from cubic to tetragonal phase with the increase of Pb2+ content. The microstructures were observed by scanning electron microscopy. Dielectric measurement was employed to investigate the ferroelectric–paraelectric phase transition behavior. Temperature dependent polarization–electric field hysteresis loops were conducted to study the electrocaloric effect (ECE) of the ferroelectric ceramics by indirect methods over a wide temperature range. Direct measurement of temperature change (ΔT) at room temperature for all samples can achieve 0.79–1.86 K. What's more, a giant ECE (ΔT = 2.05 K, EC strength (ΔT/ΔE) = 0.51 × 10−6 K m/V, under 40 kV/cm) was obtained in the sample of x = 0.35 near phase transition temperature. Our results suggest that the ceramics are promising cooling materials with excellent EC properties for energy related applications.

Electron structure and thermodynamics of solid solutions in Ni–H system

The widespread concept of nickel hydride in the Ni–H system is discussed based on the first–principle atomic calculations and experimental X–ray diffraction data. The total cohesion energy in Ni–H solid solution has been determined using the density functional theory and program package Wien2k. Its dependence on hydrogen concentration is shown to be linear, which suggests the absence of any energy barrier for precipitation reaction. Moreover, the second derivative of the calculated solution enthalpy is negative within the hydrogen–to–nickel ratios, H/Ni, of 0.03 to 0.75, which is a sign of spinodal decomposition. These hydrogen concentrations are consistent with the measurements of X–ray diffraction, of which results are traditionally interpreted in terms of Ni hydride. The density of electron states has been calculated, and its non–monotonous concentration dependence correlates with that of solution enthalpy, which is also expected for spinodal decomposition. The obtained results are interpreted as miscibility gap in the Ni–H system with spinodal decomposition having the electron origin. In addition, using mechanical spectroscopy, the strain dependent internal friction has been observed in the hydrogen–charged nickel with H/Ni ratio of about 0.7. This effect is controlled by irreversible plastic deformation, which is typical for solid solutions, not for brittle chemical compounds. Finally, the “hydrides” in a number of metals are discussed in terms of two Gibb’s types of precipitation reactions. Keywords: nickel, hydrogen, ab initio calculations, spinodal decomposition, hydride

Three new 5-fold interpenetrating diamondoid frameworks constructed by rigid diimidazole and dicarboxylate ligands

A series of three-dimensional coordination polymers, namely, [Cd(BIMB)(SCA)]n (1), [M(BIMB)(trans-CHDC)]n (2, M = Cd2+; 3, M = Co2+), where BIMB = 1,4-di(1H-imidazol-1-yl)benzene, SCA2− = succinate dianion, CHDC2− = cyclohexane-1,4-dicarboxylate dianion) are synthesized hydro/solvatothermal methods. The products are characterized by elemental analysis and single–crystal X-ray diffraction data. Both the dianion and BIMB bridge different pairs of the metal ions, the three complexes are polymeric and their three-dimensional topology feature a diamond-like metal–organic framework (MOF). Owing to the length of the two bridging ligands, moderate size voids are formed in the diamondoid networks. However, the voids are filled by mutual interpenetration of four independent equivalent frameworks in a 5-fold interpenetrating architecture, and there is no sufficient void volume available for any guest molecules. The phase purity and thermal stability of the compounds are verified by powder X–ray diffraction (PXRD) and thermogravimetric (TG) data. The solid–state fluorescence spectra for the 3d10 Cd2+ MOF's 1 and 2 reveal significant enhancement in their emission intensities in comparison to the non-metallated BIMB. The enhanced emission is attributed to perturbation of intra-ligand emission states due to Cd2+ coordination.

Electronic structure and excited states of molecular crystals of antimony and tellurium hexahalogenides

The article examines the electronic structure and orbital nature of luminescence excitation in a series of molecular crystals with the general formula E n AX6, where E n are organic and inorganic cations (diphenylguanidinium, guanidinium, and cesium); n is the number of cations; AX6 are Te(IV) and Sb(III) anions; X are the atoms of halogens Cl or Br. The electronic structure of these molecular crystals is determined from the data of X–ray photoelectron spectroscopy of the core and valence levels and еру quantum chemical modeling фе the density functional theory level together with the previously obtained single crystal X–ray diffraction data.

Understanding electronic and magnetic transitions in ball milled diluted magnetic semiconductor Si1-xNix through experimental electron density distribution

The diluted magnetic semiconductor (DMS) Si1-xNix with four different dopant concentrations x = 0, 0.03, 0.06, 0.09 and 0.12 has been processed using ball milling technique. Powder X – ray diffraction data sets were collected for the samples and the structural and charge density analysis were carried out using Rietveld technique and maximum entropy method (MEM) respectively. The local structure was analyzed using pair distribution function (PDF) analysis. Magnetic measurements taken using vibrating sample magnetometer (VSM) reveal the ferromagnetic nature of the prepared DMS samples. Experimental estimation of charge density using maximum entropy method (MEM) complements semiconductor to metal transition and p – n type transition of Si1-xNix system as a function of concentration of Ni impurity in the system. The utility of Si1-xNix as a DMS material is established from these studies.

Structural and thermal studies of SrU(PO4)2 and BaU(PO4)2

Compounds SrU(PO4)2 (SUP) and BaU(PO4)2 (BUP) were synthesized by solid state method in high purity argon atmosphere at 1473 K. Structures of both the compounds were derived using Rietveld method from powder X–ray diffraction (XRD) data. Compound SUP is orthorhombic and has ordered cheralite type structure with alternate layers of SrO10 and UO8 polyhedra. Compound BUP is monoclinic and has a non cheralite structure with Ba and U in 14 and 8 coordinations, respectively. Thermogravimetric (TG) curves obtained by heating both the compounds in air confirm the oxidation of U(IV) to U(VI) between 600 and 1573 K. High temperature XRD data collected in vacuum up to 1473 K indicated positive thermal expansion for both the compounds. Heat capacity (Cp) measurements were also carried out for both the compounds by heat flow Differential Scanning Calorimeter (DSC) in argon atmosphere from 300 to 873 K.

Electrical and structural properties enhancement in plasticized high Tg polymers using metal salts

ABSTRACTPlasticized polymer electrolyte composite has been prepared in the form of a film by solution casting method. Poly (ethyl methacrylate) (PEMA) acts as a host polymer and is doped with Sodium Iodide (NaI). Ethylene carbonate (EC) added as a plasticizer and also enhances amorphicity of the polymer electrolyte. The electrical conductivity of the PEMA+NaI was evaluated using complex impedance spectroscopy. Maximum ionic conductivity obtained at room temperature was 8.75 × 10−6 S/cm with the composition of PEMA: NaI (30%) + 60% EC. The conductivity further increased with increase in temperature and moved up to 5.8 × 10−5 S/cm. Scanning electron microscopy was used to study the surface morphology of the composite film. Fourier transform infrared ray and X-ray diffraction data confirmed the complexation of material.

Crystallization of FcpA from Leptospira, a novel flagellar protein that is essential for pathogenesis.

The protein FcpA is a unique component of the flagellar filament of spirochete bacteria belonging to the genus Leptospira. Although it plays an essential role in translational motility and pathogenicity, no structures of FcpA homologues are currently available in the PDB. Its three-dimensional structure will unveil the novel motility mechanisms that render pathogenic Leptospira particularly efficient at invading and disseminating within their hosts, causing leptospirosis in humans and animals. FcpA from L. interrogans was purified and crystallized, but despite laborious attempts no useful X ray diffraction data could be obtained. This challenge was solved by expressing a close orthologue from the related saprophytic species L. biflexa. Three different crystal forms were obtained: a primitive and a centred monoclinic form, as well as a hexagonal variant. All forms diffracted X-rays to suitable resolutions for crystallographic analyses, with the hexagonal type typically reaching the highest limits of 2.0 Å and better. A variation of the quick-soaking procedure resulted in an iodide derivative that was instrumental for single-wavelength anomalous diffraction methods.

Micro structural and dielectric property analysis on hydrothermally grown gadolinium doped SnO2 crystals

A series of SnO2–Gd2O3 mixed oxides were grown in aqueous medium by varying the thermodynamic parameters by hydrothermal method. X ray diffraction data identified tetragonal phases corresponding to tin oxide. The average crystallite size of the samples were between 21 and 31 nm. The morphological studies were conducted using scanning electron microscopy and compositional purity confirmed using energy dispersive spectroscopy. Detailed dielectric studies on the samples were performed in the frequency range 100 Hz–5 MHz, which showed that dielectric constant decreases with frequency in the low frequency range, whereas remains constant at higher frequencies. Impedance analysis is used to explain the effects of grain and grain boundary on transport mechanism of Gd:SnO2 particles synthesised at various pH.