Single Diffraction Peak Research Articles

Effect of different metallic doping elements on the physical properties of iron oxide thin films

This study investigates the physical properties of pure and Co, Cr, Mn, and Ni-doped Fe2O3 thin films fabricated using spray pyrolysis techniques on glass substrates. The primary aim is to understand how doping influences the structural, optical, and dielectric properties of Fe2O3 thin films. The deposition parameters were kept constant for all samples, with a fixed dopant concentration of 3 weight percent (wt%). X-ray diffraction (XRD) analysis revealed a single diffraction peak indexed as (104), decreasing in crystallite size from 17.27 nm for the pure film to approximately 11.5 nm for all doped films. Field emission scanning electron microscopy (FE-SEM) images displayed non-homogeneous grain formation, characterized by an average grain size larger than the crystallite size, indicating agglomeration. The optical band gap value shifted from 2.54 eV for the pure film to higher values upon doping with various elements, signifying direct allowed transitions. Changes in refractive index dispersion with wavelength were observed based on the dopant type. The application of the Spitzer-Fan model revealed an increase in high-frequency dielectric constant upon doping compared to the pure film, varying across different dopants. Photoluminescence (PL) spectra recorded under excitation at 340 nm exhibited multiple emission peaks within the spectral range of 399 to 600 nm.

The fabrication, microstructure, rheological properties and interactions of soft solid oleogels of hazelnut oil body

Trans and saturated fatty acids in dietary solid fats have negative effects on human health, such as chronic diseases, making the development of a fat substitute an urgent matter. The plant derived oil body-hazelnut oil body (HOB) as the oil droplets, and the hydrogel formed by xanthan gum (XG) and type B gelatin (GEL) as the outer layer were used to encapsulate HOB and construct the oleogel. The OBC, microstructure, and rheological results indicated that the XG-GEL formed a sponge-like, tightly packed three-dimensional network structure on the surface of HOB, effectively preventing oil leakage. The hazelnut oil body oleogel exhibited 100% OBC, excellent deformation resistance, and thixotropic recovery ability. FTIR spectroscopy results revealed that changes in the amide I, II, III, and A bands indicated the formation of hydrogen bonds, with pronounced hydrogen bonding occurring between the amino/hydroxyl groups of HOB and the hydroxyl/carboxyl groups of XG-GEL. Raman spectroscopy results suggested that HOB-XG-GEL likely exhibited stronger hydrophobic interactions, while XG-GEL had no significant impact on the unsaturation level, membrane composition, or lipid acyl chain disorder of HOB. XRD results showed a single broad diffraction peak at 2θ = 19.6°, corresponding to π-π stacking interactions between HOB and XG-GEL. Interfacial characterization and zeta potential results demonstrated that HOB-XG-GEL had stronger surface activity and electrostatic repulsion. XRD and DSC results confirmed that the hazelnut oil body oleogel displayed an amorphous structure and good thermal stability. This study provides a new strategy for fabricating oil bodies to produce edible oleogels instead of solid fats.

Role of cholesterol in pulmonary surfactant at ambient and physiological temperatures.

Pulmonary surfactant is the mixture of lipids and proteins that lowers surface tension in the lungs. The material forms a thin film on the aqueous layer that lines the alveolar air-sacks. When compressed by the shrinking alveolar surface area during exhalation, the surfactant film achieves very low surface tensions. Our studies used monolayers of DPPC with variable amounts of cholesterol as a simple model of the alveolar film. A widely held supposition contends that, relative to the multilamellar vesicles secreted by the type II pneumocytes, the alveolar film is greatly enriched in DPPC. We have recently published that structural changes by which cholesterol causes faster collapse of DPPC monolayers and determined the structure of calf lung surfactant extract (CLSE) and DPPC/cholesterol mixed films with Xchol = 0.0-0.4. This work is an extension of this effort, but at physiological temperature of 37⁰C. Here, we compare the structure of CLSE and DPPC/cholesterol mixtures with varying Xchol at ambient and physiological temperatures. We have used grazing incidence X-ray off-specular scattering (GIXOS) and grazing incidence X-ray diffraction (GIXD) to obtain the detailed structural data of the interfacial films. GIXOS measurements showed that CLSE remains a single monolayer at surface pressures from 15mN/m to 45 mN/m, contrary to popular predictions that pulmonary surfactant must form a multilayer at low surface pressures. Both CLSE and DPPC/cholesterol films at 37C produced a single diffraction peak, indicating little change in the lattice-parameters of the ordered film. Predictably, with heating both CLSE and DPPC/cholesterol films showed the significant broadening of the GIXD peak and the dramatic decrease in its maximum scattered intensity, indicating a radical loss of the long range order among the hydrocarbon chains and the extensive conversion of ordered to disordered structures.

Growth mechanism, phase transition and optical properties of large-size and high-quality perovskite CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub> single crystal

According to the phenomenon that the solubility of CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub> decreases with the increase of temperature in different solvents, CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub> perovskite single crystal with a maximum dimension of 11 mm × 11 mm × 2 mm is grown by introducing a high-quality seed crystal via the seed-induced inverse temperature crystallization method in this work. X-ray diffraction and Rietveld refinements show that the full widths at half maximum (FWHM) of CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub> single crystal diffraction peaks are 0.1527°, 0.1353°, 0.2295° and 0.3452°, corresponding to the crystal plane indices of (100), (200), (300) and (400), respectively. And there are no miscellaneous peaks, indicating a good crystal quality. As a result, CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub> single crystal is of cubic phase at room temperature, its space group belongs to <i>Pm</i><inline-formula><tex-math id="M3">\begin{document}$ \bar{3} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20230097_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20230097_M3.png"/></alternatives></inline-formula><i>m</i>, and the lattice constant is <i>a</i> = 0.56877 nm. The surface morphology and growth mechanism of CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub> crystal are investigated by using a polarizing microscope. It is found that its growth mechanism follows the step horizontal growing mechanism of smooth interface, and its growth direction (that is, step movement direction) is along the outward normal direction of the step. The structural symmetry of CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub> crystal is studied by variable temperature Raman spectroscopy, which reveals an orthogonal-tetragonal phase transition at 160 K. But the tetragonal phase structure is not stable, and its temperature range is very narrow. As temperature rises gradually, the tetragonal phase again transforms into a cubic phase (<i>Pm</i><inline-formula><tex-math id="M4">\begin{document}$\bar{3}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20230097_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20230097_M4.png"/></alternatives></inline-formula><i>m</i>). Results of UV-Vis-NIR absorption and photoluminescence spectra show that the absorption cutoff of CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub> crystal is about 442 nm, and the photoluminescence peak is 450 nm. Thereupon, its band gap is obtained to be about 2.93 eV by a linear fit of Tauc formula, which is slightly higher than the theoretical value of 2.55 eV calculated by first principles simulation. We believe that it is related to the seed crystal, which is introduced into the crystal growth process as the core of heterogeneous nucleation and thus making the lattice more distorted. The lower the lattice symmetry of CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub>, the larger the band gap is, that is, the lattice symmetry determines the degree of distortion for inorganic PbCl<sub>6</sub> octahedral frameworks, resulting in an increase of band gap for CH<sub>3</sub>NH<sub>3</sub>PbCl<sub>3</sub>.

Effects of Thermal Treatment on Microstructure and Wear Properties of Ni60/CeO2 Composite Coating 35CrMoV Steel by Laser Cladding

Laser cladding Ni60/2.0 wt.%CeO2 self-lubricating anti-wear composite coatings on 35CrMoV steel were thermally treated at 25 °C, 500 °C, 600 °C and 700 °C for 1 h, respectively. The macroscopic morphology of composite coatings was characterized by optical microscopy. The evolution of microstructure was studied by scanning electron microscopy. The precipitated phase of the coating was analyzed by X-ray diffractometer. The microhardness and wear properties of the composite coatings were measured by microhardness tester and friction and wear test. The effects of thermal treatment and no thermal treatment on the mechanical properties of the composite coatings were systematically studied by the above experiments. The experimental analysis shows that the main phase composition of Ni60/2.0 wt.%CeO2 composite coating is γ-(Ni, Fe), Cr7C3, Cr23C6, CrB, CrFeB and Cr2Ni3. Meanwhile, in XRD, it can be seen that the diffraction peak has shifted to the left and the single diffraction peak is decomposed into double diffraction peaks with the thermal treatment at 700 °C, which indicates that the lattice in the coating phase has a certain distortion. Compared with the coatings without thermal treatment, Ni60 cladding layer has more uniform solute distribution and a denser and more uniform structure after thermal treatment at 700 °C. The laser cladding anti-wear composite coating demonstrates that the wear resistance performance shows the greatest improvement after thermal treatment at 700 °C.

Defect structure of near-stoichiometric Mg-doped LiNbO3 crystals prepared by different method

Mg-doped (0.5 mol% and 1 mol%) near-stoichiometric lithium niobate (nSLN) crystals were prepared by Li-rich growth method and VTE technique, respectively. Their defect structures were characterized by high resolution X-ray diffraction (HRXRD), OH– vibrational spectra, Raman spectra and ultraviolet-absorption spectra. The crystalline perfection analysis by HRXRD measurements reveals that diffraction curves of all Mg-doped nSLN crystals contain a single diffraction peak, signifying the absence of internal sub-grain boundary. In comparison to SLN-R crystals (grew by Li-rich growth method), the crystalline quality of SLN-V crystals (prepared by VTE technique) is better. The results indicate that MgNb3+ defect complexes exist in SLN-R crystals, even if Mg content is under the threshold, and that most of Mg2+ occupy Li site, extra low Mg2+ and the unavoidable trivalence impurities occupy Nb site in SLN-V crystals. The cation sublattice disorder of SLN-R crystals increases relative to SLN-V crystals. A remarkably weak OH– absorption band indicates that H+ content is extremely low in SLN-V crystals.

Structure, Morphology, Thermal Stability and Oxidation Resistance of Multilayered TiSiN/VN Films: Influence of TiSiN-Layer Thickness

In this paper, the influence of TiSiN layer thickness of TiSiN/VN multilayered films, deposited by DC reactive magnetron sputtering, on the structure, mechanical properties, thermal stability and, essentially, oxidation resistance is investigated. The films adhere well to the substrates and show a columnar structure growth, being the one with the highest TiSiN layer thickness the more compact. The as-deposited films exhibit fcc structure with broad diffraction peaks positioned between the TiN and VN standard peaks. Annealing at 800 °C for 2 h promotes structural changes in the films, i.e., single fcc diffraction peaks are subdivided into two diffraction contributions. The onset point of oxidation of the films is ~ 550 °C, independently of the thickness of the TiSiN layer. A strong diffusion of V to the top surface occurs for the film with the lowest TiSiN layer thickness. Thicker TiSiN layers offer a better barrier layer to the V diffusion due to the formation of a higher amount of protective oxides. The strong diffusion of V produces a plate-like V2O5 discontinuous layer on the top and a porous Ti-Si-V-O rich thick layer underneath.

Study on crystalline phases and degree of crystallinity of the melt compounded PVA/MMT and PVA/PVP/MMT nanocomposites

Polymer nanocomposite (PNC) films comprised poly(vinyl alcohol) (PVA) and also its blend with poly(vinylpyrrolidone) (PVP) (i.e., PVA/PVP = 75/25 wt/wt%) as host matrices loaded with different amounts of montmorillonite (MMT) nanoclay up to 10 wt% were prepared by melt compounded method. X-ray diffraction (XRD) patterns of these PNC films were recorded in the appropriate angular range of 2θ values 3.8°–26° for their crystalline phase structural characterization. In comparison to the broader-type single diffraction peak for the aqueous solution cast prepared pure PVA film and that of the PVA/PVP blend film which is attributed to the hydrogen bonded isotactic and syndiotactic PVA crystals, five sharp diffraction peaks of different intensities corresponding to the evolution of various crystallites in the melt compounded PVA and PVA/PVP blend films were observed. Further, these peaks intensities were found significantly affected by the amounts of loaded MMT in these polymer matrices-based nanocomposites. It was observed that the prominent crystalline phase of the pure PVA converted into alternative tactic phases in the PVA/MMT films with the variation of MMT concentration. The prime crystalline phase of the PVA/PVP/MMT nanocomposites underwent alternative crystal structures formation abruptly on the initial loading of the 1 wt% amount of MMT in the PVA/PVP blend matrix reflecting a substantial alteration in the direction and nature of hydrogen bonding within the PVA crystal structures, and less changes were found with the further increase of MMT concentration up to 10 wt%. The effect of MMT loading on the crystallite sizes, degree of crystallinity, and the exfoliated and intercalated MMT structures in these PNC materials were analyzed in detail.

Enhanced Oxygen Reduction Performance on PtNiN/C Catalysts

The high cost of Pt-based catalysts and their sluggish kinetics for the oxygen reduction (ORR) are still problems hindering the wide application of proton exchange membrane fuel cells (PEMFC).1,2 Lots of efforts in developing low-PGM catalysts with high oxygen reduction activity and durability have been made in recent decades. Ni is one of the mostly studied and best alloying elements with Pt for promoting ORR performances in acidic media,3,4 which can induce favorable compressive strains from its slightly smaller atomic size and significantly enhance the activity of Pt and PGMs due to its similar electronic configurations.5-7 Nitriding PtNi through post-treatment with ammonia was found effective in improving the durability of the PtNi/C catalysts, for a Ni4N core encapsulated by a 2-4 monolayer-thick Pt shell was characterized in X-ray diffraction patterns (XRD) and electron energy loss spectroscopy (EELS) mapping.6 In this work, we reported a facile method for synthesis of PtNiN/C catalyst through annealing the mixture of Vulcan XC72R Carbon, Pt(acac)2 and Ni(acac)2 in ammonia gas flow at 500 °C for 2 h and then 300 °C for 1 h. For comparison, PtNi/C catalyst without nitriding was synthesized under pure hydrogen gas flow with the same condition. As is shown in Figure 1, the single diffraction peak locating between the Pt (111) and Ni4N (111) in the PtNiN/C catalyst indicates a uniform structure of Pt-monolayer-skin covering the PtNiN-core rather than separated Pt- and Ni-rich phases in the PtNi/C catalyst. This may result from the difference of the lattice parameters between Pt (3.924 Å) and Ni4N (3.745 Å) compared with Ni (3.524 Å), indicating the usefulness of introducing N atoms into the PtNi crystalline structures to significantly alleviate the lattice mismatch of the two metal atoms and the feasibility of utilizing Ni4N instead of Ni as a lattice contraction promoter.Figure 2 shows the ORR polarization curves of the PtNi/C and PtNiN/C electrocatalysts measured at 10 mV s-1 in O2-saturated 0.1 M HClO4 solution with a rotation speed of 1600 rpm before and after 5,000 accelerated durability test (ADT) cycles. It can be noticed that the PtNiN/C showed much higher Pt mass activity than the PtNi/C electrocatalyst, which may result from the downshifted d-band center induced by the compressive strains from Ni4N on the Pt-skins leading to easier desorption of the -OH intermediates. Meanwhile, DFT calculations suggested that the presence of N atoms in the core facilitated the diffusion of Pt atoms to the defect sites at surface, which subsequently resulted in the enhancement of durability of the PtNiN/C demonstrating the effectiveness of introducing N atoms into PtNi lattices to form a stable crystalline structure.6 More detailed discussion on the structure and ORR performance of these catalysts will be presented at the meeting. Acknowledgements This research was supported by the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy (EERE) and used instruments of the Center for Functional Nanomaterials at Brookhaven National Laboratory, both under contract DE-SC0012704. References G. Wu, K. L. More, C. M. Johnston, P. Zelenay. Science, 2011, 332, 443–447.K. Sasaki, H. Naohara, Y. Choi, Y. Cai, W. Chen, P. Liu, R. R. Adzic, Nat. Commun., 2012, 3(1115), 1–7.S. Mukerjee, S. Srinivasan, M. P. Soriaga. J. Electrochem. Soc., 1995, 142, 1409–1422.R. Stamenkovic, B. Fowler, B. S. Mun, G. Wang, P. N. Ross, C. A. Lucas and N. M. Marković. Science, 2007, 315, 493–497.L. Song, Z. Liang, M. B. Vukmirovic and R. R. Adzic. J. Electrochem. Soc., 2018, 165, J3288–J3294.K. A. Kuttiyiel, K. Sasaki, Y. Choi, D. Su, P. Liu and R. R. Adzic. Nano Lett., 2012, 12, 6266–6271.L. Song, Z. Liang, K. Nagomori, H. Igarashi, M. B. Vukmirovic, R. R. Adzic, K. Sasaki. ACS Catal., 2020, 10, 4290-4298. Figure 1

Low power consumption UV sensor based on n-ZnO/p-Si junctions

We report on the manufacture of low power consumption UV sensor based on n-ZnO/p-Si Junction. The ZnO thin film was prepared through RF sputtering process. The X-ray diffraction analysis and scanning electron microscopy reveal that the prepared ZnO films exhibit single diffraction peak at a Bragg angle of approximately 34.28° with a homogeneous distribution of nanosized structures. The pn junction exhibit good rectifying behaviour with rectifying ratio of approximately 800 at ± 2 V. At zero bias voltage, the prepared UV photodiode shows the highest photo-to-dark current ratio with a stable dynamic behaviour under the illumination of 360 nm UV light. The prepared UV photodiode show dual polarity behaviour with different proposed sensing mechanisms.

Upconversion luminescence, and temperature sensing properties of 12CaO·7Al2O3 single crystal sensitized with lanthanide ions Er(III) and Yb(III)

12CaO·7Al2O3 (C12A7) single crystal had extraordinary application in optical field, owing to its special structure. Here, Yb3+ and Er3+ co-doped C12A7 single crystal (Er3+/Yb3+/C12A7) were prepared by Czochralski method. XRD patterns of C12A7 single crystal performed a single diffraction peak, indicating that pure single structure was achieved. With over-stoichiometric ratio, infrared absorption spectrum had two peaks between 600 cm−1 and 850 cm−1, which belonged to the frame structure of C12A7 single crystal. The band gap of Er3+/Yb3+/C12A7 single crystal was 4.25 eV, which reduced the temperature quenching of Ln3+ ions. Raman scattering spectra showed that the highest phonon energy of C12A7 single crystal was about 880 cm−1, which was beneficial for upconversion emission. The temperature sensitivity coefficient of Er3+/Yb3+/C12A7 polycrystal and single-crystal were 1124.81 and 1122.69 range from 373 K to 573 K, respectively. Compared with polycrystal, sensitivity coefficient of Er3+/Yb3+/C12A7 single crystal increased. Moreover, absolute sensitivity (SA) of single crystal of Er3+/Yb3+/C12A7 increased with the increasing of temperature, suggesting single crystal was suitable for detecting high temperature.

Characterization of nano-crystalline Co-La mixed oxide thin films prepared by the spray pyrolysis technique

Abstract Nano-crystalline thin films of pure and La-Co mixed oxides were deposited using the spray pyrolysis technique. All deposition parameters were kept constant and the deposition took place at a substrate temperature of 723 K. The structures of all films were evaluated by X-ray diffraction. Films were found to be phase pure Co3O4 with a single diffraction peak for the (3 1 1) plane. By increasing the La/Co ratio the structure was significantly affected and a new phase of cobalt mono-oxide, CoO, was found at La/Co = 0.4. The grain size of all films was found to range from 6.63 to 11.68 nm. Energy dispersive X-ray spectroscopy (EDAX) was used to measure the composition of all films. A perfect ratio transfer from the solution to the solid film was found. The optical transmission and reflection was recorded in the optical spectral range 200–2500 nm. Also the extinction coefficient and absorption coefficients were estimated to determine the transition type. The band gap was found to be constant belonging to the recorded values of Co3O4. Finally the conductivity of the films was recorded using a direct measure of the electrical resistivity with temperature. The activation energy was found to be approximately constant with significant drop at La/Co ratio 0.4.

Characterization of Short-Range Ordered Domains Using Quantitative X-ray Diffraction

Short-range ordered domains, such as nano-scale clusters and intermetallic precipitates are important structural constituents in high-performance materials. A challenge exists in the characterization of these domains although several complementary analytical tools have been applied. This paper present recent development of a quantitative X-ray diffraction method, in which a Gaussian approach is employed to fit every single diffraction peak of a diffraction curve acquired from a material containing nano-scale ordered domains. Consequently, the domains can be quantitatively characterised for their chemical compound identification, coherent lattice mismatch to the parent phase, and grain size. Two sample alloys have been employed to demonstrate the quantitative analysis. In a nickel based alloy, Nimonic 263, the intermetallic Gamma Prime-Ni3(Al,Ti) is an ordered solid solution precipitate coherently precipitating from the Gamma-Ni parent phase. The coherent lattice mismatch between the Gamma Prime and Gamma has been determined through the quantitative analysis. In the second example, the metastable expanded austenite (Gamma-N) phase generated on the surface of an austenitic stainless steel has been characterised to reveal the formation of nano-scale quisi-crystalline clusters of CrN, Cr2N and Fe4N compounds.

Analysis of the shape of x-ray diffraction peaks originating from the hexatic phase of liquid crystal films

ABSTRACTX-ray diffraction studies of the bond-orientational order in the hexatic-B phase of 75OBC and 3(10)OBC compounds are presented. The temperature evolution of an angular profile of a single diffraction peak is analyzed. Close to the hexatic-B–smectic-A transition these profiles can be approximated by the Gaussian function. At lower temperatures in the hexatic-B phase the profiles are better fitted by the Voigt function. Theoretical analysis of the width of diffraction peaks in three-dimentional (3D) hexatics is performed on the basis of the effective Hamiltonian introduced by Aharony and Kardar [1]. Theoretical estimations are in good agreement with the results of x-ray experiments.

Role of oxygen pressure on the structural, morphological and optical properties of c-Al2O3 films deposited by thermal evaporator

Aluminum oxide (c-Al2O3) films are deposited for various (0.5, 1, 1.5 and 2 mbar) oxygen pressures on glass substrates by thermal evaporator. The x-ray diffraction patterns exhibit the development of single diffraction peak related to c-Al2O3 phase which grows along (2 2 0) orientation up to 1.5 mbar pressure. For 2 mbar pressure, the deposited film becomes amorphous because no diffraction peak is observed. A minimum FWHM and maximum crystallite size of c-Al2O3 (2 2 0) plane is observed for 1 mbar pressure. The enhanced crystallite size of c-Al2O3 (2 2 0) plane is responsible to decrease the dislocation density and residual stresses developed during the deposition process. The field emission scanning electron microscopic analysis reveals the formation of smooth, uniform and compact films showing uniform distribution of nano-particles of different shapes and sizes. The energy dispersive x-ray spectroscopic analysis confirms the presence of Al whose content is decreased with the increase of oxygen pressures. The ellipsometric analysis confirms that the refractive index and the thickness of c-Al2O3 film deposited for 0.5 mbar pressure are found to 1.685 and 124.43 nm respectively. In short, the crystal structure, surface morphology, film thickness and refractive index of c-Al2O3 films are associated with the increase of oxygen pressures.

Effect of Precursor Concentration on Structural Optical and Electrical Properties of NiO Thin Films Prepared by Spray Pyrolysis

Undoped nickel oxide (NiO) thin films were deposited on 500°C heated glass substrates using spray pyrolysis method at (0.015–0.1 M) range of precursor. The latter was obtained by decomposition of nickel nitrate hexahydrate in double distilled water. Effect of precursor concentration on structural, optical, and electrical properties of NiO thin films was investigated. X-ray diffraction (XRD) shows the formation of NiO under cubic structure with single diffraction peak along(111)plane at2θ=37.24°. When precursor concentration reaches 0.1 M, an increment in NiO crystallite size over 37.04 nm was obtained indicating the product nano structure. SEM images reveal that beyond 0.04 M as precursor concentration the substrate becomes completely covered with NiO and thin films exhibit formation of nano agglomerations at the top of the sample surface. Ni-O bonds vibrations modes in the product of films were confirmed by FT-IR analysis. Transparency of the films ranged from 57 to 88% and band gap energy of the films decreases from 3.68 to 3.60 eV with increasing precursor concentration. Electrical properties of the elaborated NiO thin films were correlated to the precursor concentration.

A 3D profile function suitable for integration of neutron time-of-flight single crystal diffraction peaks

A 3D profile function is presented suitable to integrate reflections arising in time-of-flight (TOF) single crystal neutron diffraction experiments. In order to account for the large asymmetry of the peak shape in the TOF direction, a 3D Gaussian ellipsoid in the pixel (x, z) and time-of-flight coordinates is convoluted with a rising and falling exponential along the time-of-flight direction. An analytic expression is derived, making it suitable for least-squares fitting. The application of this function in detector space or reciprocal space is straightforward.

Efficient P3HT:PCBM bulk heterojunction organic solar cells; effect of post deposition thermal treatment

Organic solar cells based on P3HT:PCBM bulk heterojunction were prepared and subjected to post annealing at different temperatures (100, 120, 140, 160 and 180 °C). SEM, AFM as well as optical images have revealed that post deposition heat treatment has induced significant phase segregation between P3HT and PCBM which were found to result in growth of PCBM clusters on the films surface. The P3HT:PCBM absorption spectra were found to be blue shifted by 7 nm in films subjected to heat treatment at 160 °C and 180 °C. XRD data show a single diffraction peak at 2θ = 5.33 ± 0.23o for P3HT:PCBM films and was attributed to the edge-on arrangement of the (100) plane. Space charge limited conduction theory was employed to determine the charge carrier mobility; the highest obtained mobility was obtained for devices with active layers heat-treated at 140 °C. The change in the barrier height was derived from dark I–V. The variation in the metal–semiconductor contact between the Al electrode and P3HT:PCBM active layer were addressed and the barrier height has increased to form hole blocking contact and the ideality factor has decreased implying a decrease in the recombination rate. A direct relation between Fermi level, Vbi, and Voc was studied. Efficient device performance was ascribed to P3HT:PCBM layers which were subjected to post deposition heat treatment at 140 °C with PCE = 5.5 %, FF = 65.6 %, Jsc = 12.9 mA cm−2 and Voc = 0.65 V.

Determination of microstructural characteristics of tungsten nanopowders from the profile of a single diffraction peak using WinFit software

WinFit software is used to determine using the profile of a single diffraction peak the sizes of coherent scattering domains and microstrains for tungsten powders obtained through plasma chemical synthesis and hydrogen reduction from tungstic acid. It is shown that the use of the (110), (200) or (211) diffraction peaks is the most expedient for the calculations. At the same time, it should be noted that, in the case of significant microstrains, the sizes of coherent scattering domains calculated using the second and the third peaks are underestimated.

ZnO single crystal microtubes: Synthesis, growth mechanism, and geometric structure using direct microwave irradiation

ZnO single crystal microtubes have been successfully synthesized using direct microwave irradiation via the catalyst-free vapor–solid (V–S) process. Field emission scanning electron microscopy (FE-SEM) showed that ZnO single crystal microtubes exhibit a symmetrical 6-facet structure with an exact hexagonal hollow. ZnO single crystal microtubes have an average outer diameter of 100µm and a length of over 300µm, and the wall thickness ranges from 1 to 2µm. X-ray diffraction (XRD) reveals a single high-intensity diffraction peak along the (101) direction, suggesting good crystallization of the synthesized ZnO single crystal microtubes. Single crystal diffraction (SCD) reveals the obvious polar nature of the ZnO single crystal microtube structure. The room-temperature photoluminescence (PL) spectrum shows an intense ultraviolet (UV) emission at 375.68nm, with weak and broad visible light emissions in the range between 435nm and 700nm at a maximum peak of 588.66nm.