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X-ray powder diffraction data, unit-cell parameters, and space group for a new Ru Cl diamide complex, C36H48N2SO3RuCl, are reported [a = 12.487(4) Å, b = 16.624(5) Å, c = 17.230(3) Å, unit-cell volume V = 3576,79 Å3, Z = 4, and space group P212121]. All measured lines were indexed and are consistent with the P212121 space group. No detectable impurity was observed.
A CO2-pulsed laser plasma deposition (CO2-PLD) system is installed and used for the quick synthesis of various hexagonal boron nitride (h-BN) and zinc oxide (ZnO) nanostructures. Each part of the CO2-PLD system, such as focusing of laser beam on the target surface, sample holder, shutter, heater, type of the gas, and gas flow rate, can be easily controlled independently to fit different experimental conditions. After installation of the system, a series of experiments were conducted using hBN and ZnO targets. Scanning electron microscopy images showed that the entire surface (2 × 2 cm2) of the substrate is covered with the conical- and disk-shaped BN nanostructures and web-like highly dense ZnO nanowires, indicating a significantly short-time approach to grow mass product nanostructures. Raman spectroscopy identified the hexagonal structure of the synthesized samples.
A kinetic model of crystallization based on two-dimensional nucleation and growth of plate-like crystals with constant thickness is analyzed. It is shown that plate thickness required for nucleation is limited. The lower limit is determined by zero Gibbs’ free energy of transition, the upper one corresponds to the conditions when the critical cluster volume of nucleation is equal to two elementary kinetic units. Effects of plate thickness on crystallization kinetics are discussed. In the lower temperature range, creation of thicker plates is preferred. For a given plate thickness, frequency of the phase transition decreases with increasing temperature. Numerical calculations for α-polypropylene concern kinetics of primary nucleation and global phase transition in a system of one or several fractions of plate-like kinetic elements.
The apparatus for X-ray diffraction imaging (XRDI) of 450-mm wafers, is now placed at the ANKA synchrotron radiation source in Karlsruhe, is described in the context of the drive to inspect wafers for plastic deformation or mechanical damage. It is shown that full wafer maps at high resolution can be expected to take a few hours to record. However, we show from experiments on 200-, 300-, and 450-mm wafers that a perimeter-scan on a 450-mm wafer, to pick up edge damage and edge-originated slip sources, can be achieved in just over 10 min. Experiments at the Diamond Light Source, on wafers still in their cassettes, suggest that clean-room conditions may not be necessary for such characterization. We conclude that scaling up of the 300-mm format Jordan Valley tools, together with the existing facility at ANKA, provides satisfactory capability for future XRDI analysis of 450-mm wafers.
Grain size influences the mechanical strength of materials. In polycrystalline materials, strength increases with decreasing average grain size (for grains larger than 100 nm). This well-known Hall–Petch relationship typifies a strengthening mechanism, in which dislocation motion is impeded by grain boundaries. As grains become smaller, higher stresses are required to deform them. However, this formalism only considers the role of the “average” size of grains. Heterogeneous materials, however, have a broad “distribution” of grain sizes. Here we show that materials with narrowed grain size distributions have mechanical properties that differ from Hall–Petch predictions. Narrower distributions show increased strength, as their homogeneously sized grains yield at higher loads than the large grains in materials with broader grain size distributions. Plastic deformation depends on the coarsest grains, which yield first. These results suggest new routes for tailoring material properties.
The ternary Cu–Co–Fe alloy was rapidly solidified by using the high pressure gas atomization technique. Powders with a well-dispersed microstructure resulting from the liquid–liquid phase transformation were obtained. A model describing the microstructure evolution in an atomized drop during the liquid–liquid phase transformation was developed. The kinetic details of the liquid–liquid phase transformation were discussed. The numerical results show a favorable agreement with the experimental ones. They demonstrate that under the rapid cooling conditions of gas atomization, the spatial phase separation due to the Marangoni migration of the minority phase droplets is very weak. Also, the effect of Ostwald coarsening of the minority phase droplets on the microstructure is negligible. For Cu-10 wt% Co-10 wt% Fe alloy, the average radius and number density of the Fe–Co-rich particles depend exponentially on the cooling rate of the melt during the nucleation period of the Fe–Co-rich droplets.
Publicly available mass absorption coefficients (MAC) tables do not comprise accuracy data and are typically created from relatively old sources. The idea of comparing tables is not new (De Boer), but current software tools make it possible to quickly develop interactive software to analyze the discrepancies in finer detail and get hints to the reason for the difference. Such a tool has been created and used to compare six public domain databases. Several reasons for sizeable discrepancies have been identified, ranging from probable typos to misplaced or missing absorption edges. In addition to the discrepancies that can reasonably be pigeonholed huge differences exist for all elements below 1000 eV. Since there are many cases where reliable standards are scarce or inexistent the development of a better, consistent MAC table especially in the low energy and low Z regions, and with reliable error bars is a requirement for further development of XRF methods in many advanced fields such as waste management, user safety (RoHS), renewable energy sources, and many more. The international initiative for improved FP which involves several industrial and academic organizations aims to address the issue as a whole, i.e. not only for MAC. Creating such a complete database requires considerable resources; the comparison tool may alleviate the effort in the MAC field by readily showing which energy regions and elements deserve more attention.
The martensitic transformation behavior of the meta-stable austenite phase in low alloyed TRIP steels has been studied in situ using high-energy X-ray diffraction during deformation. The stability of austenite has been studied at different length scales during tensile tests and at variable temperatures down to 153 K. A powder diffraction analysis has been performed to correlate the macroscopic behavior of the material to the observed changes in the volume fraction of the phases. Our results show that at lower temperatures the deformation induced austenite transformation is significantly enhanced and extends over a wider deformation range, resulting in a higher elongation at fracture. To monitor the austenite behavior at the level of an individual grain a high-resolution far-field detector was used. Sub-grains have been observed in austenite prior to transformation.
X-ray reflectometry is a powerful tool for investigating rough surface and interface structures. Presently, X-ray reflectivity is based on Parratt formalism, accounting for the effect of roughness by the theory of Nevot–Croce. However, the calculated results showed a strange phenomenon in that the amplitude of the oscillation because of interference effects increases in the case of a specific roughness of the surface. We propose that the strange results originated from the currently used equation because of a serious error in which the Fresnel transmission coefficient in the reflectivity equation is increased at a rough interface, and the increase in the transmission coefficient completely overpowers any decrease in the value of the reflection coefficient because of lack of consideration in diffuse scattering. In the present study, we present a new improved formalism that corrects this error, and thereby derives an accurate analysis of X-ray reflectivity from a multilayer surface, taking into account the effect of roughness-induced diffuse scattering.
A new Matlab-based software suite called Tilt-A-Whirl has been applied to XRD data from textured gold films electro-deposited onto nickel substrates. The software routines facilitate phase identification, texture analysis via pole figure visualization, and macrostrain determination. The use of principal component analysis with multivariate curve resolution (PCA/MCR) revealed the extraction of texture components. The unusual hardness properties of one Au film (deposited from a 30% gold depleted BDT-200 bath) were found to be dependent on the (210) out-of-plane preferred orientation of the polycrystalline gold film. The progressive nucleation of Au crystallites during electro-plating has been tied to improved hardness properties of this film.
InN films have been grown on sapphire substrates nitrided by N plasma with different durations by radio-frequency plasma assisted molecular beam epitaxy (RF-MBE). In-depth investigation reveals that AlN is generated on a sapphire surface during the nitridation, and 60 min nitridation helps in the formation of an ordered and flat AlN interlayer between the substrate and the InN film, which improves the surface migration of In atoms on the substrate, and consequently helps in obtaining a single-crystalline c-plane InN film of high quality with 1.0 × 1019 cm−3 carrier density and 1350 cm2/(V·s) carrier mobility. Too short nitridation duration will result in a polycrystalline InN film, and too long nitridation duration will damage the surface quality of the newly generated AlN interlayer which consequently deteriorates the InN film quality. Control of the AlN interlayer quality plays a critical role in the growth of a high-quality InN epitaxial film on the sapphire substrate.
We present the study of the synthesis of (001) nickel oxide (NiO) epitaxial nanocrystals grown on (001) strontium titanate (SrTiO3) single crystal substrates. Pulsed laser deposition of the bismuth nickel oxide (BiNiO3, BNO) perovskite precursor followed by post-deposition processing is carried out to form the NiO nanocrystals. A detailed analysis of the dimensions of nanocrystals reveals that the morphology attained differs from the thermodynamically expected equilibrium shape. The deviations from the equilibrium shape are found to follow a systematic trend where the in-plane basal dimensions, that is, the length and width of the nanocrystals grown differ in discretized dimensions. This discretization suggests that for a given interfacial area of nanocrystals there are multiple stable basal rectangular geometries attainable.
Clenbuterol hydrochloride is an active pharmaceutical ingredient usually prescribed for treatment of respiratory diseases due to its activity as a decongestant and bronchodilator. It has also been used as a performance-enhancing drug. In the PDF-4/Organics 2012 database there are six entries related to this compound: three for its hydrochloride phase calculated using single-crystal data, two for a MeOH and a DMSO solvate of two Cu-clenbuterol complexes, and one experimental unindexed pattern. In this contribution the powder diffraction pattern and the crystal structure, determined using single crystal X-ray diffraction techniques of clenbuterol hemihydrate, C12H18Cl2N2O·0.5H2O, an unreported phase, are presented.
A new methodology based on maximum likelihood estimation for structure refinement using powder diffraction data is proposed. The method can not only optimize the parameters adjusted in Rietveld refinement but also parameters to specify errors in a model for statistical properties of the observed intensity. The results of structure refinements with relation to fluorapatite Ca5(PO4)3F, anglesite PbSO4, and barite BaSO4 are demonstrated. The structure parameters of fluorapatite and barite optimized by the new method are closer to single-crystal data than those optimized by the Rietveld method, while the structure parameters of anglesite, whose values optimized by the Rietveld method are already in good agreement with the single-crystal data, are almost unchanged by the application of the new method.
Recently, a new experimental setup for quick X-ray reflectivity (q-XRR) measurements was proposed, which is based on simultaneous recording of an X-ray reflectivity curve over all angles of interest. This new setup for q-XRR allows measurements to be done within seconds, thus permitting studies of the time evolution of chemical, thermal, and mechanical changes at the surfaces and interfaces of different materials. Since the q-XRR measurement setup utilizes an extended X-ray source and detector, it is important to develop models and to account for the following two effects: (i) diffuse scattering associated with different points of the source and (ii) sample curvature. Models accounting for both effects are presented, and their influences on interpretation of the q-XRR measurement results are discussed.
X-ray powder diffraction data, unit-cell parameters, and space group for deoxyschisandrin, C24H32O6, are reported [a = 13.083(3) Å, b = 19.563(9) Å, c = 8.805(6) Å, β = 90.472(0)°, unit-cell volume V = 2253.82 Å3, Z = 4, and space group P21]. All measured lines were indexed and are consistent with the P21 space group. No detectable impurity was observed.
A novel concept of immobilization of light water nuclear reactor fuel reprocessing waste effluent through interaction with sodium zirconium phosphate (NZP) has been established. It was found that a large number of hazardous cations could be loaded in the NZP-based matrix without significant change of three-dimensional framework structure. Starting from the raw powder diffraction data of polycrystalline solid phases, crystal structure of substituted NZP phases has been investigated using the General Structure Analysis System (GSAS) package. Cation(s) substituted NZP phases crystallize in rhombohedral symmetry (space group R-3c and Z = 6). Powder diffraction data have been subjected to Rietveld refinement to reach satisfactory structural convergence of R-factors. Unit cell parameters, inter atomic distances, bond angles, reflecting planes (h, k, l), structure factors, polyhedral (ZrO6 and PO4) distortion, and particle size have been reported. PO4 stretching and bending vibrations in the Infra red (IR) region have been assigned. SEM and EDAX analysis provide analytical evidence of fixation of cations in the matrix.
Optimization of the pore topology in organosilicate glass (OSG) is crucial in the development of dielectrics with an extremely low k-value and a relatively high Young’s modulus. In this paper, a finite-element modeling strategy is applied to develop a general understanding of the relationship between porosity, pore topology, and elastic modulus for the porous OSG thin films. This relationship in combination with the experimental elastic modulus data from nanoindentation (NI) studies is used to predict the pore structure of various OSG films. In addition, positron annihilation spectroscopy measurements are performed to determine the threshold porosity for the transition from nonoverlapping to overlapping porous structure. A similar threshold value is determined based on the finite-element modeling and experimental NI data.
A number of spatially resolved elemental imaging techniques are commonly employed to examine plutonium and other nuclear materials (e.g., scanning electron microscopy). Up until the past 10–15 years, micro-X-ray fluorescence (MXRF) instrumentation had been relatively uncommon, and even currently, it is underutilized for spatially resolved nuclear materials analysis and imaging. In the current study, a number of plutonium materials problem solving applications are presented to demonstrate the power and utility of MXRF for providing unique, spatially resolved elemental composition information. Applications discussed include identification of multiple insoluble fractions in plutonium and neptunium mixed oxide, spatially resolved imaging of plutonium residue and other elements on surface swipes, and spatial mapping of impurities in plutonium metal. The mixed oxide particle analysis demonstrated the ability to non-destructively identify particles of interest for potential extraction and analysis by other methods. The surface swipes study demonstrated the unique ability of MXRF to non-destructively image large multiple cm2 sized, non-conducting, radiologically contaminated samples. The plutonium metal investigation showed the capability of MXRF to non-destructively map elemental heterogeneity directly in an actinide matrix. Such information is extremely valuable prior to using destructive analysis (DA) trace elemental analytical chemistry techniques. If a metal is found to contain significant elemental impurity heterogeneity by MXRF, time consuming destructive sample preparation and analysis do not need to be repeated to confirm that the sample is indeed heterogeneous.
In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.