Diffraction based method to reconstruct the spectrum of the Thomson scattering x-ray source

NASA Astrophysics Data System (ADS)

Chi, Zhijun; Yan, Lixin; Zhang, Zhen; Zhou, Zheng; Zheng, Lianmin; Wang, Dong; Tian, Qili; Wang, Wei; Nie, Zan; Zhang, Jie; Du, Yingchao; Hua, Jianfei; Shi, Jiaru; Pai, Chihao; Lu, Wei; Huang, Wenhui; Chen, Huaibi; Tang, Chuanxiang

2017-04-01

As Thomson scattering x-ray sources based on the collision of intense laser and relativistic electrons have drawn much attention in various scientific fields, there is an increasing demand for the effective methods to reconstruct the spectrum information of the ultra-short and high-intensity x-ray pulses. In this paper, a precise spectrum measurement method for the Thomson scattering x-ray sources was proposed with the diffraction of a Highly Oriented Pyrolytic Graphite (HOPG) crystal and was demonstrated at the Tsinghua Thomson scattering X-ray source. The x-ray pulse is diffracted by a 15 mm (L) ×15 mm (H)× 1 mm (D) HOPG crystal with 1° mosaic spread. By analyzing the diffraction pattern, both x-ray peak energies and energy spectral bandwidths at different polar angles can be reconstructed, which agree well with the theoretical value and simulation. The higher integral reflectivity of the HOPG crystal makes this method possible for single-shot measurement.

Diffraction based method to reconstruct the spectrum of the Thomson scattering x-ray source.

PubMed

Chi, Zhijun; Yan, Lixin; Zhang, Zhen; Zhou, Zheng; Zheng, Lianmin; Wang, Dong; Tian, Qili; Wang, Wei; Nie, Zan; Zhang, Jie; Du, Yingchao; Hua, Jianfei; Shi, Jiaru; Pai, Chihao; Lu, Wei; Huang, Wenhui; Chen, Huaibi; Tang, Chuanxiang

2017-04-01

As Thomson scattering x-ray sources based on the collision of intense laser and relativistic electrons have drawn much attention in various scientific fields, there is an increasing demand for the effective methods to reconstruct the spectrum information of the ultra-short and high-intensity x-ray pulses. In this paper, a precise spectrum measurement method for the Thomson scattering x-ray sources was proposed with the diffraction of a Highly Oriented Pyrolytic Graphite (HOPG) crystal and was demonstrated at the Tsinghua Thomson scattering X-ray source. The x-ray pulse is diffracted by a 15 mm (L) ×15 mm (H)× 1 mm (D) HOPG crystal with 1° mosaic spread. By analyzing the diffraction pattern, both x-ray peak energies and energy spectral bandwidths at different polar angles can be reconstructed, which agree well with the theoretical value and simulation. The higher integral reflectivity of the HOPG crystal makes this method possible for single-shot measurement.

Fabrication and testing of a newly designed slit system for depth-resolved X-ray diffraction measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinsheimer, John; Bouet, Nathalie; Ghose, Sanjit

2016-10-06

A new system of slits called `spiderweb slits' have been developed for depth-resolved powder or polycrystalline X-ray diffraction measurements. The slits act on diffracted X-rays to select a particular gauge volume of sample, while absorbing diffracted X-rays from outside of this volume. Although the slit geometry is to some extent similar to that of previously developed conical slits or spiral slits, this new design has advantages over the previous ones in use for complex heterogeneous materials andin situandoperandodiffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, over a continuous range ofmore » diffraction angles, and work for X-ray energies of tens to hundreds of kiloelectronvolts. The design is generated and optimized using ray-tracing simulations, and fabricated through laser micromachining. The first prototype was successfully tested at the X17A beamline at the National Synchrotron Light Source, and shows similar performance to simulations, demonstrating gauge volume selection for standard powders, for all diffraction peaks over angles of 2–10°. A similar, but improved, design will be implemented at the X-ray Powder Diffraction beamline at the National Synchrotron Light Source II.« less

The structural properties of flower-like ZnO nanostructures on porous silicon

NASA Astrophysics Data System (ADS)

Eswar, Kevin Alvin; Suhaimi, Mohd Husairi Fadzillah; Guliling, Muliyadi; Mohamad, Maryam; Khusaimi, Zuraida; Rusop, M.; Abdullah, Saifollah

2018-05-01

The flower-like zinc oxide (ZnO) were successfully synthesized on porous silicon (PSi) via hydrothermal method. The characteristic of ZnO nanostructures was investigated using field emission scanning microscopy (FESEM) and X-ray diffraction (X-Ray). The FESEM images show the flower-like ZnO nanostructures composed ZnO nanoparticles. The X-ray diffraction shows that strong intensity of (100), (002) and (101) peaks. The structural analysis revealed that the peaks angles were shifted due to the stress or imperfection of the crystalline of ZnO nanostructures. The crystalline sizes in range of 42.60 to 54.09 nm were produced.

Synchrotron X-ray reciprocal-space mapping, topography and diffraction resolution studies of macromolecular crystal quality.

PubMed

Boggon, T J; Helliwell, J R; Judge, R A; Olczak, A; Siddons, D P; Snell, E H; Stojanoff, V

2000-07-01

A comprehensive study of microgravity and ground-grown chicken egg-white lysozyme crystals is presented using synchrotron X-ray reciprocal-space mapping, topography techniques and diffraction resolution. Microgravity crystals displayed reduced intrinsic mosaicities on average, but no differences in terms of strain over their ground-grown counterparts. Topographic analysis revealed that in the microgravity case the majority of the crystal was contributing to the peak of the reflection at the appropriate Bragg angle. In the ground-control case only a small volume of the crystal contributed to the intensity at the diffraction peak. The techniques prove to be highly complementary, with the reciprocal-space mapping providing a quantitative measure of the crystal mosaicity and strain (or variation in lattice spacing) and the topography providing a qualitative overall assessment of the crystal in terms of its X-ray diffraction properties. Structural data collection was also carried out at the synchrotron.

Synchrotron X-Ray Reciprocal Space Mapping, Topography and Diffraction Resolution Studies of Macromolecular Crystal Quality

NASA Technical Reports Server (NTRS)

Boggon, T. J.; Helliwell, J. R.; Judge, Russell A.; Siddons, D. P.; Snell, Edward H.; Stojanoff, V.

2000-01-01

A comprehensive study of microgravity and ground grown chicken egg white lysozyme crystals is presented using synchrotron X-ray reciprocal space mapping, topography techniques and diffraction resolution. Microgravity crystals displayed, on average, reduced intrinsic mosaicities but no differences in terms of stress over their earth grown counterparts. Topographic analysis revealed that in the microgravity case the majority of the crystal was contributing to the peak of the reflection at the appropriate Bragg angle. In the earth case at the diffraction peak only a small volume of the crystal contributed to the intensity. The techniques prove to be highly complementary with the reciprocal space mapping providing a quantitative measure of the crystal mosaicity and stress (or variation in lattice spacing) and topography providing a qualitative overall assessment of the crystal in terms of its X-ray diffraction properties. Structural data collection was also carried out both at the synchrotron and in the laboratory.

Comparison of dissimilarity measures for cluster analysis of X-ray diffraction data from combinatorial libraries

NASA Astrophysics Data System (ADS)

Iwasaki, Yuma; Kusne, A. Gilad; Takeuchi, Ichiro

2017-12-01

Machine learning techniques have proven invaluable to manage the ever growing volume of materials research data produced as developments continue in high-throughput materials simulation, fabrication, and characterization. In particular, machine learning techniques have been demonstrated for their utility in rapidly and automatically identifying potential composition-phase maps from structural data characterization of composition spread libraries, enabling rapid materials fabrication-structure-property analysis and functional materials discovery. A key issue in development of an automated phase-diagram determination method is the choice of dissimilarity measure, or kernel function. The desired measure reduces the impact of confounding structural data issues on analysis performance. The issues include peak height changes and peak shifting due to lattice constant change as a function of composition. In this work, we investigate the choice of dissimilarity measure in X-ray diffraction-based structure analysis and the choice of measure's performance impact on automatic composition-phase map determination. Nine dissimilarity measures are investigated for their impact in analyzing X-ray diffraction patterns for a Fe-Co-Ni ternary alloy composition spread. The cosine, Pearson correlation coefficient, and Jensen-Shannon divergence measures are shown to provide the best performance in the presence of peak height change and peak shifting (due to lattice constant change) when the magnitude of peak shifting is unknown. With prior knowledge of the maximum peak shifting, dynamic time warping in a normalized constrained mode provides the best performance. This work also serves to demonstrate a strategy for rapid analysis of a large number of X-ray diffraction patterns in general beyond data from combinatorial libraries.

The Scherrer equation and the dynamical theory of X-ray diffraction.

PubMed

Muniz, Francisco Tiago Leitão; Miranda, Marcus Aurélio Ribeiro; Morilla Dos Santos, Cássio; Sasaki, José Marcos

2016-05-01

The Scherrer equation is a widely used tool to determine the crystallite size of polycrystalline samples. However, it is not clear if one can apply it to large crystallite sizes because its derivation is based on the kinematical theory of X-ray diffraction. For large and perfect crystals, it is more appropriate to use the dynamical theory of X-ray diffraction. Because of the appearance of polycrystalline materials with a high degree of crystalline perfection and large sizes, it is the authors' belief that it is important to establish the crystallite size limit for which the Scherrer equation can be applied. In this work, the diffraction peak profiles are calculated using the dynamical theory of X-ray diffraction for several Bragg reflections and crystallite sizes for Si, LaB6 and CeO2. The full width at half-maximum is then extracted and the crystallite size is computed using the Scherrer equation. It is shown that for crystals with linear absorption coefficients below 2117.3 cm(-1) the Scherrer equation is valid for crystallites with sizes up to 600 nm. It is also shown that as the size increases only the peaks at higher 2θ angles give good results, and if one uses peaks with 2θ > 60° the limit for use of the Scherrer equation would go up to 1 µm.

Nonlinear dependence of X-ray diffraction peak broadening in In x Ga1‑ x Sb epitaxial layers on GaAs substrates

NASA Astrophysics Data System (ADS)

Hoang Huynh, Sa; Ha, Minh Thien Huu; Binh Do, Huy; Nguyen, Tuan Anh; Luc, Quang Ho; Chang, Edward Yi

2018-04-01

The configuration of the interfacial misfit array at In x Ga1‑ x Sb/GaAs interfaces with different indium compositions and thicknesses grown by metalorganic chemical vapor deposition was systematically analyzed using X-ray diffraction (XRD) reciprocal space maps (RSMs). These analyses confirmed that the epilayer relaxation was mainly contributed to by the high degree of spatial correlation of the 90° misfit array (correlation factors <0.01). The anisotropic peak-broadening aspect ratio was found to have a non-linear composition dependence as well as be thickness-dependent, related to the strain relaxation of the epilayer. However, the peak-broadening behavior in each RSM scan direction had different composition and thickness dependences.

A study of mercuric iodide near melting using differential scanning calorimetry, Raman spectroscopy and X-ray diffraction

NASA Astrophysics Data System (ADS)

Burger, A.; Morgan, S.; Jiang, H.; Silberman, E.; Schieber, M.; Van Den Berg, L.; Keller, L.; Wagner, C. N. J.

1989-11-01

High-temperature studies of mercuric iodide (HgI2) involving differential scanning calorimetry (DSC), Raman spectroscopy and X-ray powder diffraction have failed to confirm the existence of a red-colored tetragonal high-temperature phase called α'-HgI2 reported by S.N. Toubektsis et al. [J. Appl. Phys. 58 (1988) 2070] using DSC measurements. The multiple DSC peaks near melting reported by Toubektsis are found by the present authors only if the sample is heated in a stainless-steel container. Using a Pyrex container or inserting a platinum foil between the HgI2 and the stainless-steel container yields only one sharp, single DSC peak at the melting point. The nonexistence of the α' phase is confirmed by high-temperature X-ray diffraction and Raman spectroscopy performed in the vicinity of the melting point. These methods clearly, indicate the existence of only the yellow orthorhombic β-HgI2 phase. The experimental high-temperature DSC, Raman and X-ray diffraction data are presented and discussed.

{ital In-situ} x-ray investigation of hydrogen charging in thin film bimetallic electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jisrawi, N.M.; Wiesmann, H.; Ruckman, M.W.

Hydrogen uptake and discharge by thin metallic films under potentiostatic control was studied using x-ray diffraction at the National Synchrotron Light Source (NSLS). The formation of metal-hydrogen phases in Pd, Pd-capped Nb and Pd/Nb multilayer electrode structures was deduced from x-ray diffraction data and correlated with the cyclic voltammetry (CV) peaks. The x-ray data was also used to construct a plot of the hydrogen concentration as a function of cell potential for a multilayered thin film. {copyright} {ital 1997 Materials Research Society.}

A wavelet transform algorithm for peak detection and application to powder x-ray diffraction data.

PubMed

Gregoire, John M; Dale, Darren; van Dover, R Bruce

2011-01-01

Peak detection is ubiquitous in the analysis of spectral data. While many noise-filtering algorithms and peak identification algorithms have been developed, recent work [P. Du, W. Kibbe, and S. Lin, Bioinformatics 22, 2059 (2006); A. Wee, D. Grayden, Y. Zhu, K. Petkovic-Duran, and D. Smith, Electrophoresis 29, 4215 (2008)] has demonstrated that both of these tasks are efficiently performed through analysis of the wavelet transform of the data. In this paper, we present a wavelet-based peak detection algorithm with user-defined parameters that can be readily applied to the application of any spectral data. Particular attention is given to the algorithm's resolution of overlapping peaks. The algorithm is implemented for the analysis of powder diffraction data, and successful detection of Bragg peaks is demonstrated for both low signal-to-noise data from theta-theta diffraction of nanoparticles and combinatorial x-ray diffraction data from a composition spread thin film. These datasets have different types of background signals which are effectively removed in the wavelet-based method, and the results demonstrate that the algorithm provides a robust method for automated peak detection.

Symmetry and light stuffing of H o 2 T i 2 O 7 ,   E r 2 T i 2 O 7 , and Y b 2 T i 2 O 7 characterized by synchrotron x-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baroudi, Kristen; Gaulin, Bruce D.; Lapidus, Saul H.

2015-07-01

The Ho2Ti2O7, Er2Ti2O7 and Yb2Ti2O7 pyrochlores were studied by synchrotron X-ray diffraction to determine whether the (002) peak, forbidden in the pyrochlore space group Fd-3m but observed in single crystal neutron scattering measurements, is present due to a deviation of their pyrochlore structure from Fd-3m symmetry. Synchrotron diffraction measurements on precisely synthesized stoichiometric and non-stoichiometric powders and a crushed floating zone crystal of Ho2Ti2O7 revealed that the (002) reflection is absent in all cases to a sensitivity of approximately one part in 30,000 of the strongest X-ray diffraction peak. This indicates to high sensitivity that the structural space group ofmore » these rare earth titanate pyrochlores is Fd-3m, and that thus the (002) peak observed in the neutron scattering experiments has a non-structural origin. The cell parameters and internal strain for lightly stuffed Ho2+xTi2-xO7 are also presented.« less

HiSPoD: a program for high-speed polychromatic X-ray diffraction experiments and data analysis on polycrystalline samples

DOE PAGES

Sun, Tao; Fezzaa, Kamel

2016-06-17

Here, a high-speed X-ray diffraction technique was recently developed at the 32-ID-B beamline of the Advanced Photon Source for studying highly dynamic, yet non-repeatable and irreversible, materials processes. In experiments, the microstructure evolution in a single material event is probed by recording a series of diffraction patterns with extremely short exposure time and high frame rate. Owing to the limited flux in a short pulse and the polychromatic nature of the incident X-rays, analysis of the diffraction data is challenging. Here, HiSPoD, a stand-alone Matlab-based software for analyzing the polychromatic X-ray diffraction data from polycrystalline samples, is described. With HiSPoD,more » researchers are able to perform diffraction peak indexing, extraction of one-dimensional intensity profiles by integrating a two-dimensional diffraction pattern, and, more importantly, quantitative numerical simulations to obtain precise sample structure information.« less

Étude de la structure des alliages vitreux Ag-As2S3 par diffraction de rayons X

NASA Astrophysics Data System (ADS)

Popescu, M.; Sava, F.; Cornet, A.; Broll, N.

2002-07-01

The structure of several silver alloyed arsenic chalocgenide has been determined by X-ray diffraction. For low silver doping the disordered layer structure, characteristic to the glassy AS2S3 is retained as demonstrated by the well developed first sharp diffraction peak in the X-ray diffraction pattern. For high amount of silver introduced in the As2S3 matrix, the disoredered layer configurations disappear, as shown by the diminishing and even disappearance of the first sharp diffraction peak in the X-ray patterns. A three-dimensional structure based on Ag2S -type configuration is formed. La structure de quelques alliages sulfure d'arsenic - argent a été determinée par diffraction de rayons X. Pour de faibles dopages à l'argent on conserve la structure desordonnées caractéristique des couches atomique d'As2S3 vitreux ; ceci est prouvé par la forte intensité du premier pic étroit de diffraction. Pour des plus grandes proportions d'argent la structure de l'alliage vitreux fait apparaître des unités structurales caractéristiques du cristal d'Ag2S et la configuration atomique avec des couches desordonnées disparaît (le premier pic étroit de diffraction s'évanouit) en faisant place à une structure tridimensionelle.

Amorphous boron gasket in diamond anvil cell research

NASA Astrophysics Data System (ADS)

Lin, Jung-Fu; Shu, Jinfu; Mao, Ho-kwang; Hemley, Russell J.; Shen, Guoyin

2003-11-01

Recent advances in high-pressure diamond anvil cell experiments include high-energy synchrotron x-ray techniques as well as new cell designs and gasketing procedures. The success of high-pressure experiments usually depends on a well-prepared sample, in which the gasket plays an important role. Various gasket materials such as diamond, beryllium, rhenium, and stainless steel have been used. Here we introduce amorphous boron as another gasket material in high-pressure diamond anvil cell experiments. We have applied the boron gasket for laser-heating x-ray diffraction, radial x-ray diffraction, nuclear resonant inelastic x-ray scattering, and inelastic x-ray scattering. The high shear strength of the amorphous boron maximizes the thickness of the sample chamber and increases the pressure homogeneity, improving the quality of high-pressure data. Use of amorphous boron avoids unwanted x-ray diffraction peaks and reduces the absorption of incident and x rays exiting the gasket material. The high quality of the diffraction patterns makes it possible to refine the cell parameters with powder x-ray diffraction data under high pressure and high temperature. The reactivity of boron prevents its use at high temperatures, however. When heated, boron may also react with the specimen to produce unwanted phases. The relatively porous boron starting material at ambient conditions also poses some challenges for sample preparation.

Effects of Peripheral Architecture on the Properties of Aryl Polyhedral Oligomeric Silsesquioxanes

DTIC Science & Technology

2012-07-26

POSS) molecules are described. These POSS materials were synthesized in our laboratory and characterized by single-crystal and powder X - ray diffraction ...powder X - ray diffraction (XRD), where applicable. 1H, 13C, and 29Si NMR spectra were obtained on Bruker 300 and 400 MHz spectrometers using 5 mm o.d...degree of cage ordering during precipitation. Referring back to Figure 14, strong X - ray scattering peaks in the spectra for 1 in the d- spacing range

Utilizing broadband X-rays in a Bragg coherent X-ray diffraction imaging experiment

DOE PAGES

Cha, Wonsuk; Liu, Wenjun; Harder, Ross; ...

2016-07-26

A method is presented to simplify Bragg coherent X-ray diffraction imaging studies of complex heterogeneous crystalline materials with a two-stage screening/imaging process that utilizes polychromatic and monochromatic coherent X-rays and is compatible with in situ sample environments. Coherent white-beam diffraction is used to identify an individual crystal particle or grain that displays desired properties within a larger population. A three-dimensional reciprocal-space map suitable for diffraction imaging is then measured for the Bragg peak of interest using a monochromatic beam energy scan that requires no sample motion, thus simplifyingin situchamber design. This approach was demonstrated with Au nanoparticles and will enable,more » for example, individual grains in a polycrystalline material of specific orientation to be selected, then imaged in three dimensions while under load.« less

Utilizing broadband X-rays in a Bragg coherent X-ray diffraction imaging experiment.

PubMed

Cha, Wonsuk; Liu, Wenjun; Harder, Ross; Xu, Ruqing; Fuoss, Paul H; Hruszkewycz, Stephan O

2016-09-01

A method is presented to simplify Bragg coherent X-ray diffraction imaging studies of complex heterogeneous crystalline materials with a two-stage screening/imaging process that utilizes polychromatic and monochromatic coherent X-rays and is compatible with in situ sample environments. Coherent white-beam diffraction is used to identify an individual crystal particle or grain that displays desired properties within a larger population. A three-dimensional reciprocal-space map suitable for diffraction imaging is then measured for the Bragg peak of interest using a monochromatic beam energy scan that requires no sample motion, thus simplifying in situ chamber design. This approach was demonstrated with Au nanoparticles and will enable, for example, individual grains in a polycrystalline material of specific orientation to be selected, then imaged in three dimensions while under load.

Time-spliced X-ray diffraction imaging of magnetism dynamics in a NdNiO3 thin film

NASA Astrophysics Data System (ADS)

Beyerlein, Kenneth R.

2018-03-01

Diffraction imaging of nonequilibrium dynamics at atomic resolution is becoming possible with X-ray free-electron lasers. However, there are unresolved problems with applying this method to objects that are confined in only one dimension. Here I show that reliable one-dimensional coherent diffraction imaging is possible by splicing together images recovered from different time delays in an optical pump X-ray probe experiment. The time and space evolution of antiferromagnetic order in a vibrationally excited complex oxide heterostructure is recovered from time-resolved measurements of a resonant soft X-ray diffraction peak. Midinfrared excitation of the substrate is shown to lead to a demagnetization front that propagates at a velocity exceeding the speed of sound, a critical observation for the understanding of driven phase transitions in complex condensed matter.

Time-spliced X-ray diffraction imaging of magnetism dynamics in a NdNiO3 thin film.

PubMed

Beyerlein, Kenneth R

2018-02-27

Diffraction imaging of nonequilibrium dynamics at atomic resolution is becoming possible with X-ray free-electron lasers. However, there are unresolved problems with applying this method to objects that are confined in only one dimension. Here I show that reliable one-dimensional coherent diffraction imaging is possible by splicing together images recovered from different time delays in an optical pump X-ray probe experiment. The time and space evolution of antiferromagnetic order in a vibrationally excited complex oxide heterostructure is recovered from time-resolved measurements of a resonant soft X-ray diffraction peak. Midinfrared excitation of the substrate is shown to lead to a demagnetization front that propagates at a velocity exceeding the speed of sound, a critical observation for the understanding of driven phase transitions in complex condensed matter.

7 Å Resolution in Protein 2-Dimentional-Crystal X-Ray Diffraction at Linac Coherent Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pedrini, Bill; Tsai, Ching-Ju; Capitani, Guido

2014-06-09

Membrane proteins arranged as two-dimensional (2D) crystals in the lipid en- vironment provide close-to-physiological structural information, which is essential for understanding the molecular mechanisms of protein function. X-ray diffraction from individual 2D crystals did not represent a suitable investigation tool because of radiation damage. The recent availability of ultrashort pulses from X-ray Free Electron Lasers (X-FELs) has now provided a mean to outrun the damage. Here we report on measurements performed at the LCLS X-FEL on bacteriorhodopsin 2D crystals mounted on a solid support and kept at room temperature. By merg- ing data from about a dozen of single crystalmore » diffraction images, we unambiguously identified the diffraction peaks to a resolution of 7 °A, thus improving the observable resolution with respect to that achievable from a single pattern alone. This indicates that a larger dataset will allow for reliable quantification of peak intensities, and in turn a corresponding increase of resolution. The presented results pave the way to further X-FEL studies on 2D crystals, which may include pump-probe experiments at subpicosecond time resolution.« less

X-ray diffraction-based electronic structure calculations and experimental x-ray analysis for medical and materials applications

NASA Astrophysics Data System (ADS)

Mahato, Dip Narayan

This thesis includes x-ray experiments for medical and materials applications and the use of x-ray diffraction data in a first-principles study of electronic structures and hyperfine properties of chemical and biological systems. Polycapillary focusing lenses were used to collect divergent x rays emitted from conventional x-ray tubes and redirect them to form an intense focused beam. These lenses are routinely used in microbeam x-ray fluorescence analysis. In this thesis, their potential application to powder diffraction and focused beam orthovoltage cancer therapy has been investigated. In conventional x-ray therapy, very high energy (˜ MeV) beams are used, partly to reduce the skin dose. For any divergent beam, the dose is necessarily highest at the entry point, and decays exponentially into the tissue. To reduce the skin dose, high energy beams, which have long absorption lengths, are employed, and rotated about the patient to enter from different angles. This necessitates large expensive specialized equipment. A focused beam could concentrate the dose within the patient. Since this is inherently skin dose sparing, lower energy photons could be employed. A primary concern in applying focused beams to therapy is whether the focus would be maintained despite Compton scattering within the tissue. To investigate this, transmission and focal spot sizes as a function of photon energy of two polycapillary focusing lenses were measured. The effects of tissue-equivalent phantoms of different thicknesses on the focal spot size were studied. Scatter fraction and depth dose were calculated. For powder diffraction, the polycapillary optics provide clean Gaussian peaks, which result in angular resolution that is much smaller than the peak width due to the beam convergence. Powder diffraction (also called coherent scatter) without optics can also be used to distinguish between tissue types that, because they have different nanoscale structures, scatter at different angles. Measurements were performed on the development of coherent scatter imaging to provide tissue type information in mammography. Atomic coordinates from x-ray diffraction data were used to study the nuclear quadrupole interactions and nature of molecular binding in DNA/RNA nucleobases and molecular solid BF3 systems.

Emerging opportunities in structural biology with X-ray free-electron lasers

PubMed Central

Schlichting, Ilme; Miao, Jianwei

2012-01-01

X-ray free-electron lasers (X-FELs) produce X-ray pulses with extremely brilliant peak intensity and ultrashort pulse duration. It has been proposed that radiation damage can be “outrun” by using an ultra intense and short X-FEL pulse that passes a biological sample before the onset of significant radiation damage. The concept of “diffraction-before-destruction” has been demonstrated recently at the Linac Coherent Light Source, the first operational hard X-ray FEL, for protein nanocrystals and giant virus particles. The continuous diffraction patterns from single particles allow solving the classical “phase problem” by the oversampling method with iterative algorithms. If enough data are collected from many identical copies of a (biological) particle, its three-dimensional structure can be reconstructed. We review the current status and future prospects of serial femtosecond crystallography (SFX) and single-particle coherent diffraction imaging (CDI) with X-FELs. PMID:22922042

International Journal of Quantum Chemistry. Quantum Chemistry Symposium Number 27: Proceedings of the International Symposium on Atomic, Molecular, and Condensed Matter Theory and Computational Methods Held in St. Augustine, Florida on 13-20 March 1993

DTIC Science & Technology

1993-03-20

photochromic glasses, x - ray absorbing television glasses, extrudablc oriented ceramics, and the ultra-pure materials for optical fibers. While...quartz through the analysis of x - ray diffraction experiments. The repeating nature of the quartz crystal give, many diffraction peaks which allow the...fused silica, which serves as a backbone for most of the silicate glasses. Doris Evans, an x - ray crystallographer at Corning, built a model of fused

Diffraction effects on angular response of X-ray collimators

NASA Technical Reports Server (NTRS)

Blake, R. L.; Barrus, D. M.; Fenimore, E.

1976-01-01

Angular responses have been measured for X-ray collimators with half-widths ranging from minutes of arc down to 10 arcsec. In the seconds-of-arc range, diffraction peaks at off-axis angles can masquerade as side lobes of the collimator angular response. Measurements and qualitative physical arguments lead to a rule of thumb for collimator design; namely, the angle of first minimum in the Fraunhofer single-slit diffraction pattern should be less than one-fourth of the collimator geometrical full-width at half-maximum intensity.

Toward in situ x-ray diffraction imaging at the nanometer scale

NASA Astrophysics Data System (ADS)

Zatsepin, Nadia A.; Dilanian, Ruben A.; Nikulin, Andrei Y.; Gable, Brian M.; Muddle, Barry C.; Sakata, Osami

2008-08-01

We present the results of preliminary investigations determining the sensitivity and applicability of a novel x-ray diffraction based nanoscale imaging technique, including simulations and experiments. The ultimate aim of this nascent technique is non-destructive, bulk-material characterization on the nanometer scale, involving three dimensional image reconstructions of embedded nanoparticles and in situ sample characterization. The approach is insensitive to x-ray coherence, making it applicable to synchrotron and laboratory hard x-ray sources, opening the possibility of unprecedented nanometer resolution with the latter. The technique is being developed with a focus on analyzing a technologically important light metal alloy, Al-xCu (where x is 2.0-5.0 %wt). The mono- and polycrystalline samples contain crystallographically oriented, weakly diffracting Al2Cu nanoprecipitates in a sparse, spatially random dispersion within the Al matrix. By employing a triple-axis diffractometer in the non-dispersive setup we collected two-dimensional reciprocal space maps of synchrotron x-rays diffracted from the Al2Cu nanoparticles. The intensity profiles of the diffraction peaks confirmed the sensitivity of the technique to the presence and orientation of the nanoparticles. This is a fundamental step towards in situ observation of such extremely sparse, weakly diffracting nanoprecipitates embedded in light metal alloys at early stages of their growth.

Mapping the continuous reciprocal space intensity distribution of X-ray serial crystallography.

PubMed

Yefanov, Oleksandr; Gati, Cornelius; Bourenkov, Gleb; Kirian, Richard A; White, Thomas A; Spence, John C H; Chapman, Henry N; Barty, Anton

2014-07-17

Serial crystallography using X-ray free-electron lasers enables the collection of tens of thousands of measurements from an equal number of individual crystals, each of which can be smaller than 1 µm in size. This manuscript describes an alternative way of handling diffraction data recorded by serial femtosecond crystallography, by mapping the diffracted intensities into three-dimensional reciprocal space rather than integrating each image in two dimensions as in the classical approach. We call this procedure 'three-dimensional merging'. This procedure retains information about asymmetry in Bragg peaks and diffracted intensities between Bragg spots. This intensity distribution can be used to extract reflection intensities for structure determination and opens up novel avenues for post-refinement, while observed intensity between Bragg peaks and peak asymmetry are of potential use in novel direct phasing strategies.

Applications of a pnCCD detector coupled to columnar structure CsI(Tl) scintillator system in ultra high energy X-ray Laue diffraction

NASA Astrophysics Data System (ADS)

Shokr, M.; Schlosser, D.; Abboud, A.; Algashi, A.; Tosson, A.; Conka, T.; Hartmann, R.; Klaus, M.; Genzel, C.; Strüder, L.; Pietsch, U.

2017-12-01

Most charge coupled devices (CCDs) are made of silicon (Si) with typical active layer thicknesses of several microns. In case of a pnCCD detector the sensitive Si thickness is 450 μm. However, for silicon based detectors the quantum efficiency for hard X-rays drops significantly for photon energies above 10 keV . This drawback can be overcome by combining a pixelated silicon-based detector system with a columnar scintillator. Here we report on the characterization of a low noise, fully depleted 128×128 pixels pnCCD detector with 75×75 μm2 pixel size coupled to a 700 μm thick columnar CsI(Tl) scintillator in the photon range between 1 keV to 130 keV . The excellent performance of the detection system in the hard X-ray range is demonstrated in a Laue type X-ray diffraction experiment performed at EDDI beamline of the BESSY II synchrotron taken at a set of several GaAs single crystals irradiated by white synchrotron radiation. With the columnar structure of the scintillator, the position resolution of the whole system reaches a value of less than one pixel. Using the presented detector system and considering the functional relation between indirect and direct photon events Laue diffraction peaks with X-ray energies up to 120 keV were efficiently detected. As one of possible applications of the combined CsI-pnCCD system we demonstrate that the accuracy of X-ray structure factors extracted from Laue diffraction peaks can be significantly improved in hard X-ray range using the combined CsI(Tl)-pnCCD system compared to a bare pnCCD.

Synchrotron X-ray diffraction investigations on strains in the oxide layer of an irradiated Zircaloy fuel cladding

NASA Astrophysics Data System (ADS)

Chollet, Mélanie; Valance, Stéphane; Abolhassani, Sousan; Stein, Gene; Grolimund, Daniel; Martin, Matthias; Bertsch, Johannes

2017-05-01

For the first time the microstructure of the oxide layer of a Zircaloy-2 cladding after 9 cycles of irradiation in a boiling water reactor has been analyzed with synchrotron micro-X-ray diffraction. Crystallographic strains of the monoclinic and to some extent of the tetragonal ZrO2 are depicted through the thick oxide layer. Thin layers of sub-oxide at the oxide-metal interface as found for autoclave-tested samples and described in the literature, have not been observed in this material maybe resulting from irradiation damage. Shifts of selected diffraction peaks of the monoclinic oxide show that the uniform strain produced during oxidation is orientated in the lattice and displays variations along the oxide layer. Diffraction peaks and their shifts from families of diffracting planes could be translated into a virtual tensor. This virtual tensor exhibits changes through the oxide layer passing by tensile or compressive components.

An X-ray diffraction method for semiquantitative mineralogical analysis of Chilean nitrate ore

USGS Publications Warehouse

Jackson, J.C.; Ericksent, G.E.

1997-01-01

Computer analysis of X-ray diffraction (XRD) data provides a simple method for determining the semiquantitative mineralogical composition of naturally occurring mixtures of saline minerals. The method herein described was adapted from a computer program for the study of mixtures of naturally occurring clay minerals. The program evaluates the relative intensities of selected diagnostic peaks for the minerals in a given mixture, and then calculates the relative concentrations of these minerals. The method requires precise calibration of XRD data for the minerals to be studied and selection of diffraction peaks that minimize inter-compound interferences. The calculated relative abundances are sufficiently accurate for direct comparison with bulk chemical analyses of naturally occurring saline mineral assemblages.

An x-ray diffraction method for semiquantitative mineralogical analysis of chilean nitrate ore

USGS Publications Warehouse

John, C.; George, J.; Ericksen, E.

1997-01-01

Computer analysis of X-ray diffraction (XRD) data provides a simple method for determining the semiquantitative mineralogical composition of naturally occurring mixtures of saline minerals. The method herein described was adapted from a computer program for the study of mixtures of naturally occurring clay minerals. The program evaluates the relative intensities of selected diagnostic peaks for the minerals in a given mixture, and then calculates the relative concentrations of these minerals. The method requires precise calibration of XRD data for the minerals to be studied and selection of diffraction peaks that minimize inter-compound interferences. The calculated relative abundances are sufficiently accurate for direct comparison with bulk chemical analyses of naturally occurring saline mineral assemblages.

Characterization of monoclinic crystals in tablets by pattern-fitting procedure using X-ray powder diffraction data.

PubMed

Yamamura, Shigeo; Momose, Yasunori

2003-06-18

The purpose of this study is to characterize the monoclinic crystals in tablets by using X-ray powder diffraction data and to evaluate the deformation feature of crystals during compression. The monoclinic crystals of acetaminophen and benzoic acid were used as the samples. The observed X-ray diffraction intensities were fitted to the analytic expression, and the fitting parameters, such as the lattice parameters, the peak-width parameters, the preferred orientation parameter and peak asymmetric parameter were optimized by a non-linear least-squares procedure. The Gauss and March distribution functions were used to correct the preferred orientation of crystallites in the tablet. The March function performed better in correcting the modification of diffraction intensity by preferred orientation of crystallites, suggesting that the crystallites in the tablets had fiber texture with axial orientation. Although a broadening of diffraction peaks was observed in acetaminophen tablets with an increase of compression pressure, little broadening was observed in the benzoic tablets. These results suggest that "acetaminophen is a material consolidating by fragmentation of crystalline particles and benzoic acid is a material consolidating by plastic deformation then occurred rearrangement of molecules during compression". A pattern-fitting procedure is the superior method for characterizing the crystalline drugs of monoclinic crystals in the tablets, as well as orthorhombic isoniazid and mannitol crystals reported in the previous paper.

Amorphous Phase Characterization Through X-Ray Diffraction Profile Modeling: Implications for Amorphous Phases in Gale Crater Rocks and Soils

NASA Technical Reports Server (NTRS)

Achilles, C. N.; Downs, G. W.; Downs, R. T.; Morris, R. V.; Rampe, E. B.; Ming, D. W.; Chipera, S. J.; Blake, D. F.; Vaniman, D. T.; Bristow, T. F.;

Hard X-ray irradiation of cosmic silicate analogs: structural evolution and astrophysical implications

NASA Astrophysics Data System (ADS)

Gavilan, L.; Jäger, C.; Simionovici, A.; Lemaire, J. L.; Sabri, T.; Foy, E.; Yagoubi, S.; Henning, T.; Salomon, D.; Martinez-Criado, G.

2016-03-01

Context. Protoplanetary disks, interstellar clouds, and active galactic nuclei contain X-ray-dominated regions. X-rays interact with the dust and gas present in such environments. While a few laboratory X-ray irradiation experiments have been performed on ices, X-ray irradiation experiments on bare cosmic dust analogs have been scarce up to now. Aims: Our goal is to study the effects of hard X-rays on cosmic dust analogs via in situ X-ray diffraction. By using a hard X-ray synchrotron nanobeam, we seek to simulate cumulative X-ray exposure on dust grains during their lifetime in these astrophysical environments and provide an upper limit on the effect of hard X-rays on dust grain structure. Methods: We prepared enstatite (MgSiO3) nanograins, which are analogs to cosmic silicates, via the melting-quenching technique. These amorphous grains were then annealed to obtain polycrystalline grains. These were characterized via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) before irradiation. Powder samples were prepared in X-ray transparent substrates and were irradiated with hard X-rays nanobeams (29.4 keV) provided by beamline ID16B of the European Synchrotron Radiation Facility (Grenoble). X-ray diffraction images were recorded in transmission mode, and the ensuing diffractograms were analyzed as a function of the total X-ray exposure time. Results: We detected the amorphization of polycrystalline silicates embedded in an organic matrix after an accumulated X-ray exposure of 6.4 × 1027 eV cm-2. Pure crystalline silicate grains (without resin) do not exhibit amorphization. None of the amorphous silicate samples (pure and embedded in resin) underwent crystallization. We analyze the evolution of the polycrystalline sample embedded in an organic matrix as a function of X-ray exposure. Conclusions: Loss of diffraction peak intensity, peak broadening, and the disappearance of discrete spots and arcs reveal the amorphization of the resin embedded (originally polycrystalline) silicate sample. We explore the astrophysical implications of this laboratory result as an upper limit to the effect of X-rays on the structure of cosmic silicates.

Structure, Elastic Constants and XRD Spectra of Extended Solids under High Pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batyrev, I. G.; Coleman, S. P.; Ciezak-Jenkins, J. A.

We present results of evolutionary simulations based on density functional calculations of a potentially new type of energetic materials called extended solids: P-N and N-H. High-density structures with covalent bonds generated using variable and fixed concentration methods were analysed in terms of thermo-dynamical stability and agreement with experimental X-ray diffraction (XRD) spectra. X-ray diffraction spectra were calculated using a virtual diffraction algorithm that computes kinematic diffraction intensity in three-dimensional reciprocal space before being reduced to a two-theta line profile. Calculated XRD patterns were used to search for the structure of extended solids present at experimental pressures by optimizing data accordingmore » to experimental XRD peak position, peak intensity and theoretically calculated enthalpy. Elastic constants has been calculated for thermodynamically stable structures of P-N system.« less

Synthesis and characterization of Mn-Bi alloy

NASA Astrophysics Data System (ADS)

Mishra, Ashutosh; Patil, Harsha; Jain, G.; Mishra, N.

2012-06-01

High purity MnBi low temperature phase has been prepared and analyzed using X-ray diffraction, Lorentz-Polarization Factor and Fourier transforms infrared measurement. After synthesis of samples structural characterization has done on samples by X-ray diffraction, which shows that after making the bulk sample is in no single phase MnBi has been prepared by sintering Mn and Bi powders. By Lorentz-Polarization Factor is affecting the relative intensity of diffraction lines on a powder form. And by FTIR which shows absorption peaks of MnBi alloys.

Non-conventional applications of a noninvasive portable X-ray diffraction/fluorescence instrument

NASA Astrophysics Data System (ADS)

Chiari, Giacomo; Sarrazin, Philippe; Heginbotham, Arlen

2016-11-01

Noninvasive techniques have become widespread in the cultural heritage analytical domain. The popular handheld X-ray fluorescence (XRF) devices give the elemental composition of all the layers that X-rays can penetrate, but no information on how atoms are bound together or at which depth they are located. A noninvasive portable X-ray powder diffraction/X-ray fluorescence (XRD/XRF) device may offer a solution to these limitations, since it can provide information on the composition of crystalline materials. This paper introduces applications of XRD beyond simple phase recognition. The two fundamental principles for XRD are: (1) the crystallites should be randomly oriented, to ensure proper intensity to all the diffraction peaks, and (2) the material should be positioned exactly in the focal plane of the instrument, respecting its geometry, as any displacement of the sample would results in 2 θ shifts of the diffraction peaks. In conventional XRD, the sample is ground and set on the properly positioned sample holder. Using a noninvasive portable instrument, these two requirements are seldom fulfilled. The position, size and orientation of a given crystallite within a layered structure depend on the object itself. Equation correlating the displacement (distance from the focal plane) versus peak shift (angular difference in 2 θ from the standard value) is derived and used to determine the depth at which a given substance is located. The quantitative composition of two binary Cu/Zn alloys, simultaneously present, was determined measuring the cell volume and using Vegard's law. The analysis of the whole object gives information on the texture and possible preferred orientations of the crystallites, which influences the peak intensity. This allows for the distinction between clad and electroplated daguerreotypes in the case of silver and between ancient and modern gilding for gold. Analyses of cross sections can be carried out successfully. Finally, beeswax, used in Roman-Egyptian paintings as "encaustic" and in form of emulsion (modified wax), can be detected and, based on the shape of the peaks, these two ways of applying the wax can be distinguished from one another.

Simultaneous, single-pulse, synchrotron x-ray imaging and diffraction under gas gun loading

DOE PAGES

Fan, D.; Huang, J. W.; Zeng, X. L.; ...

2016-05-23

We develop a mini gas gun system for simultaneous, single-pulse, x-ray diffraction and imaging under high strain-rate loading at the beamline 32-ID of the Advanced Photon Source. In order to increase the reciprocal space covered by a small-area detector, a conventional target chamber is split into two chambers: a narrowed measurement chamber and a relief chamber. The gas gun impact is synchronized with synchrotron x-ray pulses and high-speed cameras. Depending on a camera’s capability, multiframe imaging and diffraction can be achieved. The proof-of-principle experiments are performed on single-crystal sapphire. The diffraction spots and images during impact are analyzed to quantifymore » lattice deformation and fracture; diffraction peak broadening is largely caused by fracture-induced strain inhomogeneity. Finally, our results demonstrate the potential of such multiscale measurements for revealing and understanding high strain-rate phenomena at dynamic extremes.« less

Simultaneous, single-pulse, synchrotron x-ray imaging and diffraction under gas gun loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, D.; Huang, J. W.; Zeng, X. L.

We develop a mini gas gun system for simultaneous, single-pulse, x-ray diffraction and imaging under high strain-rate loading at the beamline 32-ID of the Advanced Photon Source. In order to increase the reciprocal space covered by a small-area detector, a conventional target chamber is split into two chambers: a narrowed measurement chamber and a relief chamber. The gas gun impact is synchronized with synchrotron x-ray pulses and high-speed cameras. Depending on a camera’s capability, multiframe imaging and diffraction can be achieved. The proof-of-principle experiments are performed on single-crystal sapphire. The diffraction spots and images during impact are analyzed to quantifymore » lattice deformation and fracture; diffraction peak broadening is largely caused by fracture-induced strain inhomogeneity. Finally, our results demonstrate the potential of such multiscale measurements for revealing and understanding high strain-rate phenomena at dynamic extremes.« less

Low-Q peak in X-ray patterns of choline-phenylalanine and -homophenylalanine: A combined effect of chain and stacking

NASA Astrophysics Data System (ADS)

Campetella, Marco; Martino, Delia Chillura; Scarpellini, Eleonora; Gontrani, Lorenzo

2016-09-01

In this contribution we report for the first time the X-ray patterns of choline-phenylalanine and choline-homophenylalanine ionic liquids. The presence of a low Q peak in both systems is another evidence that a long alkyl chain is not always needed to establish a nanodomain segregation in the liquid sufficient to be revealed by the diffraction experiment. These new data are compared with the diffraction patterns and the theoretical calculations of other choline-aminoacid ionic liquids recently reported. A significant role might be played by the stacking interactions between aromatic rings.

Dynamic X-ray diffraction sampling for protein crystal positioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scarborough, Nicole M.; Godaliyadda, G. M. Dilshan P.; Ye, Dong Hye

A sparse supervised learning approach for dynamic sampling (SLADS) is described for dose reduction in diffraction-based protein crystal positioning. Crystal centering is typically a prerequisite for macromolecular diffraction at synchrotron facilities, with X-ray diffraction mapping growing in popularity as a mechanism for localization. In X-ray raster scanning, diffraction is used to identify the crystal positions based on the detection of Bragg-like peaks in the scattering patterns; however, this additional X-ray exposure may result in detectable damage to the crystal prior to data collection. Dynamic sampling, in which preceding measurements inform the next most information-rich location to probe for image reconstruction,more » significantly reduced the X-ray dose experienced by protein crystals during positioning by diffraction raster scanning. The SLADS algorithm implemented herein is designed for single-pixel measurements and can select a new location to measure. In each step of SLADS, the algorithm selects the pixel, which, when measured, maximizes the expected reduction in distortion given previous measurements. Ground-truth diffraction data were obtained for a 5 µm-diameter beam and SLADS reconstructed the image sampling 31% of the total volume and only 9% of the interior of the crystal greatly reducing the X-ray dosage on the crystal. Furthermore, by usingin situtwo-photon-excited fluorescence microscopy measurements as a surrogate for diffraction imaging with a 1 µm-diameter beam, the SLADS algorithm enabled image reconstruction from a 7% sampling of the total volume and 12% sampling of the interior of the crystal. When implemented into the beamline at Argonne National Laboratory, without ground-truth images, an acceptable reconstruction was obtained with 3% of the image sampled and approximately 5% of the crystal. The incorporation of SLADS into X-ray diffraction acquisitions has the potential to significantly minimize the impact of X-ray exposure on the crystal by limiting the dose and area exposed for image reconstruction and crystal positioning using data collection hardware present in most macromolecular crystallography end-stations.« less

Dynamic X-ray diffraction sampling for protein crystal positioning

DOE PAGES

Scarborough, Nicole M.; Godaliyadda, G. M. Dilshan P.; Ye, Dong Hye; ...

2017-01-01

A sparse supervised learning approach for dynamic sampling (SLADS) is described for dose reduction in diffraction-based protein crystal positioning. Crystal centering is typically a prerequisite for macromolecular diffraction at synchrotron facilities, with X-ray diffraction mapping growing in popularity as a mechanism for localization. In X-ray raster scanning, diffraction is used to identify the crystal positions based on the detection of Bragg-like peaks in the scattering patterns; however, this additional X-ray exposure may result in detectable damage to the crystal prior to data collection. Dynamic sampling, in which preceding measurements inform the next most information-rich location to probe for image reconstruction,more » significantly reduced the X-ray dose experienced by protein crystals during positioning by diffraction raster scanning. The SLADS algorithm implemented herein is designed for single-pixel measurements and can select a new location to measure. In each step of SLADS, the algorithm selects the pixel, which, when measured, maximizes the expected reduction in distortion given previous measurements. Ground-truth diffraction data were obtained for a 5 µm-diameter beam and SLADS reconstructed the image sampling 31% of the total volume and only 9% of the interior of the crystal greatly reducing the X-ray dosage on the crystal. Furthermore, by usingin situtwo-photon-excited fluorescence microscopy measurements as a surrogate for diffraction imaging with a 1 µm-diameter beam, the SLADS algorithm enabled image reconstruction from a 7% sampling of the total volume and 12% sampling of the interior of the crystal. When implemented into the beamline at Argonne National Laboratory, without ground-truth images, an acceptable reconstruction was obtained with 3% of the image sampled and approximately 5% of the crystal. The incorporation of SLADS into X-ray diffraction acquisitions has the potential to significantly minimize the impact of X-ray exposure on the crystal by limiting the dose and area exposed for image reconstruction and crystal positioning using data collection hardware present in most macromolecular crystallography end-stations.« less

Dynamic X-ray diffraction sampling for protein crystal positioning

PubMed Central

Scarborough, Nicole M.; Godaliyadda, G. M. Dilshan P.; Ye, Dong Hye; Kissick, David J.; Zhang, Shijie; Newman, Justin A.; Sheedlo, Michael J.; Chowdhury, Azhad U.; Fischetti, Robert F.; Das, Chittaranjan; Buzzard, Gregery T.; Bouman, Charles A.; Simpson, Garth J.

2017-01-01

A sparse supervised learning approach for dynamic sampling (SLADS) is described for dose reduction in diffraction-based protein crystal positioning. Crystal centering is typically a prerequisite for macromolecular diffraction at synchrotron facilities, with X-ray diffraction mapping growing in popularity as a mechanism for localization. In X-ray raster scanning, diffraction is used to identify the crystal positions based on the detection of Bragg-like peaks in the scattering patterns; however, this additional X-ray exposure may result in detectable damage to the crystal prior to data collection. Dynamic sampling, in which preceding measurements inform the next most information-rich location to probe for image reconstruction, significantly reduced the X-ray dose experienced by protein crystals during positioning by diffraction raster scanning. The SLADS algorithm implemented herein is designed for single-pixel measurements and can select a new location to measure. In each step of SLADS, the algorithm selects the pixel, which, when measured, maximizes the expected reduction in distortion given previous measurements. Ground-truth diffraction data were obtained for a 5 µm-diameter beam and SLADS reconstructed the image sampling 31% of the total volume and only 9% of the interior of the crystal greatly reducing the X-ray dosage on the crystal. Using in situ two-photon-excited fluorescence microscopy measurements as a surrogate for diffraction imaging with a 1 µm-diameter beam, the SLADS algorithm enabled image reconstruction from a 7% sampling of the total volume and 12% sampling of the interior of the crystal. When implemented into the beamline at Argonne National Laboratory, without ground-truth images, an acceptable reconstruction was obtained with 3% of the image sampled and approximately 5% of the crystal. The incorporation of SLADS into X-ray diffraction acquisitions has the potential to significantly minimize the impact of X-ray exposure on the crystal by limiting the dose and area exposed for image reconstruction and crystal positioning using data collection hardware present in most macromolecular crystallography end-stations. PMID:28009558

Dynamic X-ray diffraction sampling for protein crystal positioning.

PubMed

Scarborough, Nicole M; Godaliyadda, G M Dilshan P; Ye, Dong Hye; Kissick, David J; Zhang, Shijie; Newman, Justin A; Sheedlo, Michael J; Chowdhury, Azhad U; Fischetti, Robert F; Das, Chittaranjan; Buzzard, Gregery T; Bouman, Charles A; Simpson, Garth J

2017-01-01

A sparse supervised learning approach for dynamic sampling (SLADS) is described for dose reduction in diffraction-based protein crystal positioning. Crystal centering is typically a prerequisite for macromolecular diffraction at synchrotron facilities, with X-ray diffraction mapping growing in popularity as a mechanism for localization. In X-ray raster scanning, diffraction is used to identify the crystal positions based on the detection of Bragg-like peaks in the scattering patterns; however, this additional X-ray exposure may result in detectable damage to the crystal prior to data collection. Dynamic sampling, in which preceding measurements inform the next most information-rich location to probe for image reconstruction, significantly reduced the X-ray dose experienced by protein crystals during positioning by diffraction raster scanning. The SLADS algorithm implemented herein is designed for single-pixel measurements and can select a new location to measure. In each step of SLADS, the algorithm selects the pixel, which, when measured, maximizes the expected reduction in distortion given previous measurements. Ground-truth diffraction data were obtained for a 5 µm-diameter beam and SLADS reconstructed the image sampling 31% of the total volume and only 9% of the interior of the crystal greatly reducing the X-ray dosage on the crystal. Using in situ two-photon-excited fluorescence microscopy measurements as a surrogate for diffraction imaging with a 1 µm-diameter beam, the SLADS algorithm enabled image reconstruction from a 7% sampling of the total volume and 12% sampling of the interior of the crystal. When implemented into the beamline at Argonne National Laboratory, without ground-truth images, an acceptable reconstruction was obtained with 3% of the image sampled and approximately 5% of the crystal. The incorporation of SLADS into X-ray diffraction acquisitions has the potential to significantly minimize the impact of X-ray exposure on the crystal by limiting the dose and area exposed for image reconstruction and crystal positioning using data collection hardware present in most macromolecular crystallography end-stations.

Properties of micro-arc oxidation coatings on aluminum alloy at different negative peak current densities

NASA Astrophysics Data System (ADS)

Gu, Xin; Jiang, Bailing; Li, Hongtao; Liu, Cancan; Shao, Lianlian

2018-05-01

Micro-arc oxidation coatings were fabricated on 6061 aluminum alloy using whereby bipolar pulse mode in the case of different negative peak current densities. The phase composition, microstructures and wear properties were studied using x-ray diffraction, scanning electron microscopy and ball-on-disk wear tester, respectively. As results indicate, by virtue of negative peak current density, the oxygen can be expelled by produced hydrogen on anode in the case of negative pulse width and via the opened discharge channel. The results of x-ray diffraction, surface and cross-sectional morphology indicated that the coating was structured compactly taking on less small-diameter micro-pores and defects with negative peak current density of 75 A dm‑2. Additionally, as the results of wear tracks and weight loss bespeak, by virtue of appropriate negative peak current density, coatings resisted the abrasive wear and showed excellent wear resistance.

Neutron and X-ray Microbeam Diffraction Studies around a Fatigue-Crack Tip after Overload

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sooyeol; Barabash, Rozaliya; Chung, Jin-Seok

2008-01-01

An in-situ neutron diffraction technique was used to investigate the lattice-strain distributions and plastic deformation around a crack tip after overload. The lattice-strain profiles around a crack tip were measured as a function of the applied load during the tensile loading cycles after overload. Dislocation densities calculated from the diffraction peak broadening were presented as a function of the distance from the crack tip. Furthermore, the crystallographic orientation variations were examined near a crack tip using polychromatic X-ray microdiffraction combined with differential aperture microscopy. Crystallographic tilts are considerably observed beneath the surface around a crack tip, and these are consistentmore » with the high dislocation densities near the crack tip measured by neutron peak broadening.« less

Risk and benefit of diffraction in Energy Dispersive X-ray fluorescence mapping

NASA Astrophysics Data System (ADS)

Nikonow, Wilhelm; Rammlmair, Dieter

2016-11-01

Energy dispersive X-ray fluorescence mapping (μ-EDXRF) is a fast and non-destructive method for chemical quantification and therefore used in many scientific fields. The combination of spatial and chemical information is highly valuable for understanding geological processes. Problems occur with crystalline samples due to diffraction, which appears according to Bragg's law, depending on the energy of the X-ray beam, the incident angle and the crystal parameters. In the spectra these peaks can overlap with element peaks suggesting higher element concentrations. The aim of this study is to investigate the effect of diffraction, the possibility of diffraction removal and potential geoscientific applications for X-ray mapping. In this work the μ-EDXRF M4 Tornado from Bruker was operated with a Rh-tube and polychromatic beam with two SDD detectors mounted each at ± 90° to the tube. Due to the polychromatic beam the Bragg condition fits for several mineral lattice planes. Since diffraction depends on the angle, it is shown that a novel correction approach can be applied by measuring from two different angles and calculating the minimum spectrum of both detectors gaining a better limit of quantification for this method. Furthermore, it is possible to use the diffraction information for separation of differently oriented crystallites within a monomineralic aggregate and obtain parameters like particle size distribution for the sample, as it is done by thin section image analysis in cross-polarized light. Only with μ-EDXRF this can be made on larger samples without preparation of thin sections.

Additional evidence from x-ray powder diffraction patterns that icosahedral quasi-crystals of intermetallic compounds are twinned cubic crystals

PubMed Central

Pauling, Linus

1988-01-01

Analysis of the measured values of Q for the weak peaks (small maxima, usually considered to be background fluctuations, “noise”) on the x-ray powder diffraction curves for 17 rapidly quenched alloys leads directly to the conclusion that they are formed by an 820-atom or 1012-atom primitive cubic structure that by icosahedral twinning produces the so-called icosahedral quasi-crystals. PMID:16593948

Thermoluminescence and X-ray diffraction studies on sliced ancient porcelain samples

NASA Astrophysics Data System (ADS)

Leung, P. L.; Yang, B.

1999-09-01

The thermal activation characteristics (TACs) of the sensitivity of the '110°C' peak in 14 sliced ancient Chinese porcelain samples are studied. Comparing with the TACs of natural quartz and synthetic mullite, the relation between the TACs and the composition of the sample is discussed with reference to the X-ray diffraction (XRD) spectra. It is suggested that in some cases, contribution of the porcelain components other than quartz to the TACs is not negligible.

X-Ray Diffraction Study of the Internal Structure of Supercooled Water

NASA Technical Reports Server (NTRS)

Dorsch, Robert G.; Boyd, Bemrose

1951-01-01

A Bragg X-ray spectrometer equipped with a volume-sensitive Geiger counter and Soller slits and employing filtered molybdenum Ka radiation was used to obtain a set of diffracted intensity curves as a Punction of angle for supercooled water. Diffracted intensity curves in the temperature region of 21 to -16 C were obtained. The minimum between the two main diffraction peaks deepened continuously with lowering temperature, indicating a gradual change in the internal structure of the water. No discontinuity in this trend was noted at the melting point. The internal structure of supercooled water was concluded to become progressively more ice-like as the temperature is lowered.

7 Å resolution in protein two-dimensional-crystal X-ray diffraction at Linac Coherent Light Source

PubMed Central

Pedrini, Bill; Tsai, Ching-Ju; Capitani, Guido; Padeste, Celestino; Hunter, Mark S.; Zatsepin, Nadia A.; Barty, Anton; Benner, W. Henry; Boutet, Sébastien; Feld, Geoffrey K.; Hau-Riege, Stefan P.; Kirian, Richard A.; Kupitz, Christopher; Messerschmitt, Marc; Ogren, John I.; Pardini, Tommaso; Segelke, Brent; Williams, Garth J.; Spence, John C. H.; Abela, Rafael; Coleman, Matthew; Evans, James E.; Schertler, Gebhard F. X.; Frank, Matthias; Li, Xiao-Dan

2014-01-01

Membrane proteins arranged as two-dimensional crystals in the lipid environment provide close-to-physiological structural information, which is essential for understanding the molecular mechanisms of protein function. Previously, X-ray diffraction from individual two-dimensional crystals did not represent a suitable investigational tool because of radiation damage. The recent availability of ultrashort pulses from X-ray free-electron lasers (XFELs) has now provided a means to outrun the damage. Here, we report on measurements performed at the Linac Coherent Light Source XFEL on bacteriorhodopsin two-dimensional crystals mounted on a solid support and kept at room temperature. By merging data from about a dozen single crystal diffraction images, we unambiguously identified the diffraction peaks to a resolution of 7 Å, thus improving the observable resolution with respect to that achievable from a single pattern alone. This indicates that a larger dataset will allow for reliable quantification of peak intensities, and in turn a corresponding increase in the resolution. The presented results pave the way for further XFEL studies on two-dimensional crystals, which may include pump–probe experiments at subpicosecond time resolution. PMID:24914166

Serial femtosecond X-ray diffraction of enveloped virus microcrystals

DOE PAGES

Lawrence, Robert M.; Conrad, Chelsie E.; Zatsepin, Nadia A.; ...

2015-08-20

Serial femtosecond crystallography (SFX) using X-ray free-electron lasers has produced high-resolution, room temperature, time-resolved protein structures. We report preliminary SFX of Sindbis virus, an enveloped icosahedral RNA virus with ~700 Å diameter. Microcrystals delivered in viscous agarose medium diffracted to ~40 Å resolution. Small-angle diffuse X-ray scattering overlaid Bragg peaks and analysis suggests this results from molecular transforms of individual particles. Viral proteins undergo structural changes during entry and infection, which could, in principle, be studied with SFX. This is a pertinent step toward determining room temperature structures from virus microcrystals that may enable time-resolved studies of enveloped viruses.

X-ray diffraction study of the caged magnetic compound DyFe 2 Zn 20 at low temperatures

NASA Astrophysics Data System (ADS)

Ohashi, M.; Ohashi, K.; Sawabu, M.; Miyagawa, M.; Maeta, K.; Isikawa, Y.

2018-05-01

We have carried out high-angle X-ray powder diffraction measurements of the caged magnetic compound DyFe2Zn20 at low temperature between 14 and 300 K. Even though a strong magnetic anisotropy exists in the magnetization and magnetic susceptibility due to strong exchange interaction between Fe and Dy, almost all X-ray powder diffraction peaks correspond to Bragg reflections of the cubic structural models not only at room temperature paramagnetic state but also at low temperature magnetic ordering state. The Debye temperature is obtained to be 227 K from the results of the volumetric thermal expansion coefficient, which is approximately coincident with that of CeRu2Zn20 (245 K) and that of pure Zn metal (235 K).

The classification of secondary colorectal liver cancer in human biopsy samples using angular dispersive x-ray diffraction and multivariate analysis

NASA Astrophysics Data System (ADS)

Theodorakou, Chrysoula; Farquharson, Michael J.

2009-08-01

The motivation behind this study is to assess whether angular dispersive x-ray diffraction (ADXRD) data, processed using multivariate analysis techniques, can be used for classifying secondary colorectal liver cancer tissue and normal surrounding liver tissue in human liver biopsy samples. The ADXRD profiles from a total of 60 samples of normal liver tissue and colorectal liver metastases were measured using a synchrotron radiation source. The data were analysed for 56 samples using nonlinear peak-fitting software. Four peaks were fitted to all of the ADXRD profiles, and the amplitude, area, amplitude and area ratios for three of the four peaks were calculated and used for the statistical and multivariate analysis. The statistical analysis showed that there are significant differences between all the peak-fitting parameters and ratios between the normal and the diseased tissue groups. The technique of soft independent modelling of class analogy (SIMCA) was used to classify normal liver tissue and colorectal liver metastases resulting in 67% of the normal tissue samples and 60% of the secondary colorectal liver tissue samples being classified correctly. This study has shown that the ADXRD data of normal and secondary colorectal liver cancer are statistically different and x-ray diffraction data analysed using multivariate analysis have the potential to be used as a method of tissue classification.

High pressure single-crystal micro X-ray diffraction analysis with GSE_ADA/RSV software

NASA Astrophysics Data System (ADS)

Dera, Przemyslaw; Zhuravlev, Kirill; Prakapenka, Vitali; Rivers, Mark L.; Finkelstein, Gregory J.; Grubor-Urosevic, Ognjen; Tschauner, Oliver; Clark, Simon M.; Downs, Robert T.

2013-08-01

GSE_ADA/RSV is a free software package for custom analysis of single-crystal micro X-ray diffraction (SCμXRD) data, developed with particular emphasis on data from samples enclosed in diamond anvil cells and subject to high pressure conditions. The package has been in extensive use at the high pressure beamlines of Advanced Photon Source (APS), Argonne National Laboratory and Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. The software is optimized for processing of wide-rotation images and includes a variety of peak intensity corrections and peak filtering features, which are custom-designed to make processing of high pressure SCμXRD easier and more reliable.

Connecting heterogeneous single slip to diffraction peak evolution in high-energy monochromatic X-ray experiments

PubMed Central

Pagan, Darren C.; Miller, Matthew P.

2014-01-01

A forward modeling diffraction framework is introduced and employed to identify slip system activity in high-energy diffraction microscopy (HEDM) experiments. In the framework, diffraction simulations are conducted on virtual mosaic crystals with orientation gradients consistent with Nye’s model of heterogeneous single slip. Simulated diffraction peaks are then compared against experimental measurements to identify slip system activity. Simulation results compared against diffraction data measured in situ from a silicon single-crystal specimen plastically deformed under single-slip conditions indicate that slip system activity can be identified during HEDM experiments. PMID:24904242

Growth and characterization of 4-chloro-3-nitrobenzophenone single crystals using vertical Bridgman technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aravinth, K., E-mail: anandcgc@gmail.com; Babu, G. Anandha, E-mail: anandcgc@gmail.com; Ramasamy, P., E-mail: anandcgc@gmail.com

2014-04-24

4-chloro-3-nitrobenzophenone (4C3N) has been grown by using vertical Bridgman technique. The grown crystal was confirmed by Powder X-ray diffraction analysis. The crystalline perfection of the grown crystal was examined by high-resolution X-ray diffraction study. The fluorescence spectra of grown 4C3N single crystals exhibit emission peak at 575 nm. The micro hardness measurements were used to analyze the mechanical property of the grown crystal.

FT-IR and Zeta potential measurements on TiO nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Jaiveer; Rathore, Ravi; Kaurav, Netram, E-mail: netramkaurav@yahoo.co.uk

2016-05-23

In the present investigation, ultrafine TiO particles have been synthesized successfully by thermal decomposition method. The sample was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. As-synthesized TiO nanoparticles have a cubic structure as characterized by power X-ray diffraction (XRD), which shows that TiO nanoparticles have narrow size distribution with particle size 11.5 nm. FTIR data shows a strong peak at 1300 cm{sup −1}, assignable to the Ti-O stretching vibrations mode.

X-ray peak profile analysis of zinc oxide nanoparticles formed by simple precipitation method

NASA Astrophysics Data System (ADS)

Pelicano, Christian Mark; Rapadas, Nick Joaquin; Magdaluyo, Eduardo

2017-12-01

Zinc oxide (ZnO) nanoparticles were successfully synthesized by a simple precipitation method using zinc acetate and tetramethylammonium hydroxide. The synthesized ZnO nanoparticles were characterized by X-ray Diffraction analysis (XRD) and Transmission Electron Microscopy (TEM). The XRD result revealed a hexagonal wurtzite structure for the ZnO nanoparticles. The TEM image showed spherical nanoparticles with an average crystallite size of 6.70 nm. For x-ray peak analysis, Williamson-Hall (W-H) and Size-Strain Plot (SSP) methods were applied to examine the effects of crystallite size and lattice strain on the peak broadening of the ZnO nanoparticles. Based on the calculations, the estimated crystallite sizes and lattice strains obtained are in good agreement with each other.

Defect structure of epitaxial layers of III nitrides as determined by analyzing the shape of X-ray diffraction peaks

NASA Astrophysics Data System (ADS)

Kyutt, R. T.

2017-04-01

The shape of X-ray diffraction epitaxial layers with high dislocation densities has been studied experimentally. Measurements with an X-ray diffractometer were performed in double- and triple-crystal setups with both Cu K α and Mo K α radiation. Epitaxial layers (GaN, AlN, AlGaN, ZnO, etc.) with different degrees of structural perfection grown by various methods on sapphire, silicon, and silicon carbide substrates have been examined. The layer thickness varied in the range of 0.5-30 μm. It has been found that the center part of peaks is well approximated by the Voigt function with different Lorentz fractions, while the wing intensity drops faster and may be represented by a power function (with the index that varies from one structure to another). A well-marked dependence on the ordering of dislocations was observed. The drop in intensity in the majority of structures with a regular system and regular threading dislocations was close to the theoretically predicted law Δθ-3; the intensity in films with a chaotic distribution decreased much faster. The dependence of the peak shape on the order of reflection, the diffraction geometry, and the epitaxial layer thickness was also examined.

Simultaneous, single-pulse, synchrotron x-ray imaging and diffraction under gas gun loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, D.; Luo, S. N., E-mail: sluo@pims.ac.cn; Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031

We develop a mini gas gun system for simultaneous, single-pulse, x-ray diffraction and imaging under high strain-rate loading at the beamline 32-ID of the Advanced Photon Source. In order to increase the reciprocal space covered by a small-area detector, a conventional target chamber is split into two chambers: a narrowed measurement chamber and a relief chamber. The gas gun impact is synchronized with synchrotron x-ray pulses and high-speed cameras. Depending on a camera’s capability, multiframe imaging and diffraction can be achieved. The proof-of-principle experiments are performed on single-crystal sapphire. The diffraction spots and images during impact are analyzed to quantifymore » lattice deformation and fracture; fracture is dominated by splitting cracks followed by wing cracks, and diffraction peaks are broadened likely due to mosaic spread. Our results demonstrate the potential of such multiscale measurements for studying high strain-rate phenomena at dynamic extremes.« less

In situ X-ray powder diffraction studies of the synthesis of graphene oxide and formation of reduced graphene oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Storm, Mie Møller, E-mail: mmst@dtu.dk; Johnsen, Rune E.; Norby, Poul

2016-08-15

Graphene oxide (GO) and reduced graphene oxide (rGO) are important materials in a wide range of fields. The modified Hummers methods, for synthesizing GO, and subsequent thermal reduction to rGO, are often employed for production of rGO. However, the mechanism behinds these syntheses methods are still unclear. We present an in situ X-ray diffraction study of the synthesis of GO and thermal reduction of GO. The X-ray diffraction revealed that the Hummers method includes an intercalation state and finally formation of additional crystalline material. The formation of GO is observed during both the intercalation and the crystallization stage. During thermalmore » reduction of GO three stages were observed: GO, a disordered stage, and the rGO stage. The appearance of these stages depends on the heating ramp. The aim of this study is to provide deeper insight into the chemical and physical processes during the syntheses. - Graphical abstract: In situ X-ray diffraction results for of the modified Hummers synthesis and the thermal reduction of graphene oxide, revealing three stages for both syntheses as well as new GO diffraction peaks and unidentified crystalline material for the Hummers synthesis and a disordered stage for the thermal reduction of graphene oxide. Display Omitted - Highlights: • Hummers synthesis consists of three stages: dissolution, intercalation and crystal. • GO is produced early on during the synthesis and display new diffraction peaks. • An unidentified triclinic phase is observed for the Hummers synthesis. • Thermal reduction of GO display three stages: GO, a disordered stage and rGO. • In situ XRD indicate reformation of rGO even for fast heated thermal reduction.« less

Nondestructive strain depth profiling with high energy X-ray diffraction: System capabilities and limitations

NASA Astrophysics Data System (ADS)

Zhang, Zhan; Wendt, Scott; Cosentino, Nicholas; Bond, Leonard J.

2018-04-01

Limited by photon energy, and penetration capability, traditional X-ray diffraction (XRD) strain measurements are only capable of achieving a few microns depth due to the use of copper (Cu Kα1) or molybdenum (Mo Kα1) characteristic radiation. For deeper strain depth profiling, destructive methods are commonly necessary to access layers of interest by removing material. To investigate deeper depth profiles nondestructively, a laboratory bench-top high-energy X-ray diffraction (HEXRD) system was previously developed. This HEXRD method uses an industrial 320 kVp X-Ray tube and the Kα1 characteristic peak of tungsten, to produces a higher intensity X-ray beam which enables depth profiling measurement of lattice strain. An aluminum sample was investigated with deformation/load provided using a bending rig. It was shown that the HEXRD method is capable of strain depth profiling to 2.5 mm. The method was validated using an aluminum sample where both the HEXRD method and the traditional X-ray diffraction method gave data compared with that obtained using destructive etching layer removal, performed by a commercial provider. The results demonstrate comparable accuracy up to 0.8 mm depth. Nevertheless, higher attenuation capabilities in heavier metals limit the applications in other materials. Simulations predict that HEXRD works for steel and nickel in material up to 200 µm, but experiment results indicate that the HEXRD strain profile is not practical for steel and nickel material, and the measured diffraction signals are undetectable when compared to the noise.

Minimization of spurious strains by using a Si bent-perfect-crystal monochromator: neutron surface strain scanning of a shot-peened sample

NASA Astrophysics Data System (ADS)

Rebelo Kornmeier, Joana; Gibmeier, Jens; Hofmann, Michael

2011-06-01

Neutron strain measurements are critical at the surface. When scanning close to a sample surface, aberration peak shifts arise due to geometrical and divergence effects. These aberration peak shifts can be of the same order as the peak shifts related to residual strains. In this study it will be demonstrated that by optimizing the horizontal bending radius of a Si (4 0 0) monochromator, the aberration peak shifts from surface effects can be strongly reduced. A stress-free sample of fine-grained construction steel, S690QL, was used to find the optimal instrumental conditions to minimize aberration peak shifts. The optimized Si (4 0 0) monochromator and instrument settings were then applied to measure the residual stress depth gradient of a shot-peened SAE 4140 steel sample to validate the effectiveness of the approach. The residual stress depth profile is in good agreement with results obtained by x-ray diffraction measurements from an international round robin test (BRITE-EURAM-project ENSPED). The results open very promising possibilities to bridge the gap between x-ray diffraction and conventional neutron diffraction for non-destructive residual stress analysis close to surfaces.

Ultrafast X-Ray Diffraction Studies of the Phase Transitions and Equation of State of Scandium Shock Compressed to 82 GPa

DOE PAGES

Briggs, R.; Gorman, M. G.; Coleman, A. L.; ...

2017-01-09

Using x-ray diffraction at the Linac Coherent Light Source x-ray free-electron laser, we have determined simultaneously and self-consistently the phase transitions and equation of state (EOS) of the lightest transition metal, scandium, under shock compression. On compression scandium undergoes a structural phase transition between 32 and 35 GPa to the same bcc structure seen at high temperatures at ambient pressures, and then a further transition at 46 GPa to the incommensurate host-guest polymorph found above 21 GPa in static compression at room temperature. Furthermore, shock melting of the host-guest phase is observed between 53 and 72 GPa with the disappearancemore » of Bragg scattering and the growth of a broad asymmetric diffraction peak from the high-density liquid.« less

Ultrafast X-Ray Diffraction Studies of the Phase Transitions and Equation of State of Scandium Shock Compressed to 82 GPa.

PubMed

Briggs, R; Gorman, M G; Coleman, A L; McWilliams, R S; McBride, E E; McGonegle, D; Wark, J S; Peacock, L; Rothman, S; Macleod, S G; Bolme, C A; Gleason, A E; Collins, G W; Eggert, J H; Fratanduono, D E; Smith, R F; Galtier, E; Granados, E; Lee, H J; Nagler, B; Nam, I; Xing, Z; McMahon, M I

2017-01-13

Using x-ray diffraction at the Linac Coherent Light Source x-ray free-electron laser, we have determined simultaneously and self-consistently the phase transitions and equation of state (EOS) of the lightest transition metal, scandium, under shock compression. On compression scandium undergoes a structural phase transition between 32 and 35 GPa to the same bcc structure seen at high temperatures at ambient pressures, and then a further transition at 46 GPa to the incommensurate host-guest polymorph found above 21 GPa in static compression at room temperature. Shock melting of the host-guest phase is observed between 53 and 72 GPa with the disappearance of Bragg scattering and the growth of a broad asymmetric diffraction peak from the high-density liquid.

Nanox: a miniature mechanical stress rig designed for near-field X-ray diffraction imaging techniques.

PubMed

Gueninchault, N; Proudhon, H; Ludwig, W

2016-11-01

Multi-modal characterization of polycrystalline materials by combined use of three-dimensional (3D) X-ray diffraction and imaging techniques may be considered as the 3D equivalent of surface studies in the electron microscope combining diffraction and other imaging modalities. Since acquisition times at synchrotron sources are nowadays compatible with four-dimensional (time lapse) studies, suitable mechanical testing devices are needed which enable switching between these different imaging modalities over the course of a mechanical test. Here a specifically designed tensile device, fulfilling severe space constraints and permitting to switch between X-ray (holo)tomography, diffraction contrast tomography and topotomography, is presented. As a proof of concept the 3D characterization of an Al-Li alloy multicrystal by means of diffraction contrast tomography is presented, followed by repeated topotomography characterization of one selected grain at increasing levels of deformation. Signatures of slip bands and sudden lattice rotations inside the grain have been shown by means of in situ topography carried out during the load ramps, and diffraction spot peak broadening has been monitored throughout the experiment.

Nanox: a miniature mechanical stress rig designed for near-field X-ray diffraction imaging techniques

PubMed Central

Gueninchault, N.; Proudhon, H.; Ludwig, W.

2016-01-01

Multi-modal characterization of polycrystalline materials by combined use of three-dimensional (3D) X-ray diffraction and imaging techniques may be considered as the 3D equivalent of surface studies in the electron microscope combining diffraction and other imaging modalities. Since acquisition times at synchrotron sources are nowadays compatible with four-dimensional (time lapse) studies, suitable mechanical testing devices are needed which enable switching between these different imaging modalities over the course of a mechanical test. Here a specifically designed tensile device, fulfilling severe space constraints and permitting to switch between X-ray (holo)tomography, diffraction contrast tomography and topotomography, is presented. As a proof of concept the 3D characterization of an Al–Li alloy multicrystal by means of diffraction contrast tomography is presented, followed by repeated topotomography characterization of one selected grain at increasing levels of deformation. Signatures of slip bands and sudden lattice rotations inside the grain have been shown by means of in situ topography carried out during the load ramps, and diffraction spot peak broadening has been monitored throughout the experiment. PMID:27787253

Quantitative analysis of crystalline pharmaceuticals in powders and tablets by a pattern-fitting procedure using X-ray powder diffraction data.

PubMed

Yamamura, S; Momose, Y

2001-01-16

A pattern-fitting procedure for quantitative analysis of crystalline pharmaceuticals in solid dosage forms using X-ray powder diffraction data is described. This method is based on a procedure for pattern-fitting in crystal structure refinement, and observed X-ray scattering intensities were fitted to analytical expressions including some fitting parameters, i.e. scale factor, peak positions, peak widths and degree of preferred orientation of the crystallites. All fitting parameters were optimized by the non-linear least-squares procedure. Then the weight fraction of each component was determined from the optimized scale factors. In the present study, well-crystallized binary systems, zinc oxide-zinc sulfide (ZnO-ZnS) and salicylic acid-benzoic acid (SA-BA), were used as the samples. In analysis of the ZnO-ZnS system, the weight fraction of ZnO or ZnS could be determined quantitatively in the range of 5-95% in the case of both powders and tablets. In analysis of the SA-BA systems, the weight fraction of SA or BA could be determined quantitatively in the range of 20-80% in the case of both powders and tablets. Quantitative analysis applying this pattern-fitting procedure showed better reproducibility than other X-ray methods based on the linear or integral intensities of particular diffraction peaks. Analysis using this pattern-fitting procedure also has the advantage that the preferred orientation of the crystallites in solid dosage forms can be also determined in the course of quantitative analysis.

Time Resolved X-Ray Diffraction Study of Acoustoelectrically Amplified Phonons.

NASA Astrophysics Data System (ADS)

Chapman, Leroy Dean

X-rays diffracted by nearly perfect crystals of n-type InSb have been investigated in the presence of intense acoustoelectrically (A.E.) amplified phonons. The fact that these phonons are nearly monochromatic and have a well defined propagation and polarization direction presents an excellent opportunity to investigate the nature of x -ray photon-phonon scattering in a diffracting crystal. The Debye-Waller factor which accounts for the attenuation of diffracted x-ray intensities due to thermal phonons is reflection dependent owing to its sin (theta)/(lamda) dependence. We have performed experiments comparing the (004) and (008) anomalously transmitted intensities as a function of A.E. amplified flux. The attenuation of both reflections due to the amplified phonons was the same in direct contradiction to an expected sin (theta)/(lamda) dependence. Some possible reasons for this failure are discussed. In a Bragg reflection scattering geometry, the intense monochromatic amplified phonons give rise to satellite peaks symmetrically located about the central elastic Brag peak in a rocking profile. We report in this thesis on the first observation of satellites in a thin crystal Laue transmission geometry. We have theoretically simulated the rocking profiles with some success. The A.E. amplification process in InSb is strongly favored for {110} propagation fast transverse (FT) phonons. In earlier experiments it was found that non-{110} FT phonons were also produced during the amplification process. We have developed a time resolved x-ray counting system which, in conjunction with a spatially resolved x-ray beam and a localized, traveling A.E. phonon distribution, allow the time evolution of the amplified distribution to be followed. We report on time resolved measurements for both the symmetric Bragg and Laue geometries from which we can determine when and where non-{110 } FT flux is generated and restrict the possible mechanisms for its generation.

Probing multi-scale mechanical damage in connective tissues using X-ray diffraction.

PubMed

Bianchi, Fabio; Hofmann, Felix; Smith, Andrew J; Thompson, Mark S

2016-11-01

The accumulation of microstructural collagen damage following repetitive loading is linked to painful and debilitating tendon injuries. As a hierarchical, semi-crystalline material, collagen mechanics can be studied using X-ray diffraction. The aim of the study was to describe multi-structural changes in tendon collagen following controlled plastic damage (5% permanent strain). We used small angle X-ray scattering (SAXS) to interrogate the spacing of collagen molecules within a fibril, and wide angle X-ray scattering (WAXS) to measure molecular strains under macroscopic loading. Simultaneous recordings of SAXS and WAXS patterns, together with whole-tissue strain in physiologically hydrated rat-tail tendons were made during increments of in situ tensile loading. Results showed that while tissue level modulus was unchanged, fibril modulus decreased significantly, and molecular modulus significantly increased. Further, analysis of higher order SAXS peaks suggested structural changes in the gap and overlap regions, possibly localising the damage to molecular cross-links. Our results provide new insight into the fundamental damage processes at work in collagenous tissues and point to new directions for their mitigation and repair. This article reports the first in situ loading synchrotron studies on mechanical damage in collagenous tissues. We provide new insight into the nano- and micro-structural mechanisms of damage processes. Pre-damaged tendons showed differential alteration of moduli at macro, micro and nano-scales as measured using X-ray scattering techniques. Detailed analysis of higher order diffraction peaks suggested damage is localised to molecular cross-links. The results are consistent with previous X-ray scattering studies of tendons and also with recent thermal stability studies on damaged material. Detailed understanding of damage mechanisms is essential in the development of new therapies promoting tissue repair. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Negative thermal expansion and magnetoelastic coupling in the breathing pyrochlore lattice material LiGaCr4S8

NASA Astrophysics Data System (ADS)

Pokharel, G.; May, A. F.; Parker, D. S.; Calder, S.; Ehlers, G.; Huq, A.; Kimber, S. A. J.; Arachchige, H. Suriya; Poudel, L.; McGuire, M. A.; Mandrus, D.; Christianson, A. D.

2018-04-01

The physical properties of the spinel LiGaCr4S8 have been studied with neutron diffraction, x-ray diffraction, magnetic susceptibility, and heat capacity measurements. The neutron diffraction and synchrotron x-ray diffraction data reveal negative thermal expansion (NTE) below 111(4) K. The magnetic susceptibility deviates from Curie-Weiss behavior with the onset of NTE. At low temperature a broad peak in the magnetic susceptibility at 10.3(3) K is accompanied by the return of normal thermal expansion. First-principles calculations find a strong coupling between the lattice and the simulated magnetic ground state. These results indicate strong magnetoelastic coupling in LiGaCr4S8 .

Microstructural characterisation of proton irradiated niobium using X-ray diffraction technique

NASA Astrophysics Data System (ADS)

Dutta, Argha; Gayathri, N.; Neogy, S.; Mukherjee, P.

2018-04-01

The microstructural parameters in pure Nb, irradiated with 5 MeV proton beam have been evaluated as a function of dose using X-ray diffraction line profile analysis. In order to assess the microstructural changes in the homogeneous region and in the peak damage region of the damage energy deposition profile, X-ray diffraction patterns have been collected using two different geometries (Bragg-Brentano and parallel beam geometries). Different X-ray line profile analysis like Williamson-Hall (W-H) analysis, modified W-H analysis, double-Voigt analysis, modified Rietveld technique and convolutional multiple whole profile fitting have been employed to extract the microstructural parameters like coherent domain size, microstrain within the domain, dislocation density and arrangement of dislocations. The coherent domain size decreases drastically along with increase in microstrain and dislocation density in the first dose for both the geometries. With increasing dose, a decreasing trend in microstrain associated with decrease in dislocation density is observed for both the geometries. This is attributed to the formation of defect clusters due to irradiation which with increasing dose collapse to dislocation loops to minimise the strain in the matrix. This is corroborated with the observation of black dots and loops in the TEM images. No significant difference is observed in the trend of microstructural parameters between the homogeneous and peak damage region of the damage profile.

Interaction of dipalmitoyl phosphatidylcholine (DPPC) liposomes and insulin

NASA Astrophysics Data System (ADS)

Mady, Mohsen M.; Elshemey, Wael M.

2011-06-01

Insulin, a peptide that has been used for decades in the treatment of diabetes, has well-defined properties and delivery requirements. Liposomes, which are lipid bilayer vesicles, have gained increasing attention as drug carriers which reduce the toxicity and increase the pharmacological activity of various drugs. The molecular interaction between (uncharged lipid) dipalmitoyl phosphatidylcholine (DPPC) liposomes and insulin has been characterized by using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. The characteristic protein absorption band peaks, Amide I (at about 1660 cm-1) and Amide II band (at about 1546 cm-1) are potentially reduced in the liposome insulin complex. Wide-angle x-ray scattering measurements showed that the association of insulin with DPPC lipid of liposomes still maintains the characteristic DPPC diffraction peaks with almost no change in relative intensities or change in peak positions. The absence of any shift in protein peak positions after insulin being associated with DPPC liposomes indicates that insulin is successfully forming complex with DPPC liposomes with possibly no pronounced alterations in the structure of insulin molecule.

Coded diffraction system in X-ray crystallography using a boolean phase coded aperture approximation

NASA Astrophysics Data System (ADS)

Pinilla, Samuel; Poveda, Juan; Arguello, Henry

2018-03-01

Phase retrieval is a problem present in many applications such as optics, astronomical imaging, computational biology and X-ray crystallography. Recent work has shown that the phase can be better recovered when the acquisition architecture includes a coded aperture, which modulates the signal before diffraction, such that the underlying signal is recovered from coded diffraction patterns. Moreover, this type of modulation effect, before the diffraction operation, can be obtained using a phase coded aperture, just after the sample under study. However, a practical implementation of a phase coded aperture in an X-ray application is not feasible, because it is computationally modeled as a matrix with complex entries which requires changing the phase of the diffracted beams. In fact, changing the phase implies finding a material that allows to deviate the direction of an X-ray beam, which can considerably increase the implementation costs. Hence, this paper describes a low cost coded X-ray diffraction system based on block-unblock coded apertures that enables phase reconstruction. The proposed system approximates the phase coded aperture with a block-unblock coded aperture by using the detour-phase method. Moreover, the SAXS/WAXS X-ray crystallography software was used to simulate the diffraction patterns of a real crystal structure called Rhombic Dodecahedron. Additionally, several simulations were carried out to analyze the performance of block-unblock approximations in recovering the phase, using the simulated diffraction patterns. Furthermore, the quality of the reconstructions was measured in terms of the Peak Signal to Noise Ratio (PSNR). Results show that the performance of the block-unblock phase coded apertures approximation decreases at most 12.5% compared with the phase coded apertures. Moreover, the quality of the reconstructions using the boolean approximations is up to 2.5 dB of PSNR less with respect to the phase coded aperture reconstructions.

USAF Summer Research Program - 1993 High School Apprenticeship Program Final Reports, Volume 15, Wright Laboratory

DTIC Science & Technology

1993-12-01

of the films. One is x - ray diffraction which is used to determine the crystallographic orientation of the films. No phases other than the YBa 2Cu3O 7...x were observed in any of the films. The x - ray data for the films with high critical current densities show strong peaks of reflections indicating a...Solving for x ca = (p/2 Now, if we look at a close-up of the prism face at the input ray (FIGURE 7), we want to solve for the angle between the rays

Glass transition in ferroic glass K x (ND4)1-x D2PO4: a complete x-ray diffraction line shape analysis

NASA Astrophysics Data System (ADS)

Ranjan Choudhury, Rajul; Chitra, R.; Jayakrishnan, V. B.

2016-03-01

Quenching of dynamic disorder in glassy systems is termed as the glass transition. Ferroic glasses belong to the class of paracrystalline materials having crystallographic order in-between that of a perfect crystal and amorphous material, a classic example of ferroic glass is the solid solution of ferroelectric deuterated potassium dihydrogen phosphate and antiferroelectric deuterated ammonium dihydrogen phosphate. Lowering temperature of this ferroic glass can lead to a glass transition to a quenched disordered state. The subtle atomic rearrangement that takes place at such a glass transition can be revealed by careful examination of the temperature induced changes occurring in the x-ray powder diffraction (XRD) patterns of these materials. Hence we report here results of a complete diffraction line shape analysis of the XRD patterns recorded at different temperatures from deuterated mixed crystals DK x A1-x DP with mixing concentration x ranging as 0 < x < 1. Changes observed in diffraction peak shapes have been explained on the basis of structural rearrangements induced by changing O-D-O hydrogen bond dynamics in these paracrystals.

X-ray and neutron diffraction anomalies preceding martensitic phase transformation in AuCuZn2 alloys

NASA Astrophysics Data System (ADS)

Nagasawa, A.; Makita, T.; Nakanishi, N.; Iizumi, M.; Morii, Y.

1988-04-01

The present paper gives the results obtained by the X-ray and neutron diffraction studies on the single crystals of the beta-1 AuCuZn2 alloys. As precursor phenomena, the dispersion relation of the [110] TA1 phonon exhibits significant dip near 2/3 [110] q max position and anomalous peaks appear around 1/3 and 2/3 [110] q max positions. Characteristics of the interplanar force constants, obtained by the analysis of the dispersion relation, and the positions of the anomalous peaks predict the martensite structures to be formed in the beta phase alloys. In the present case, both the 6R and 18R martensites will be formed by cooling and/or under the stress field.

Analysis of energy dispersive x-ray diffraction profiles for material identification, imaging and system control

NASA Astrophysics Data System (ADS)

Cook, Emily Jane

2008-12-01

This thesis presents the analysis of low angle X-ray scatter measurements taken with an energy dispersive system for substance identification, imaging and system control. Diffraction measurements were made on illicit drugs, which have pseudo- crystalline structures and thus produce diffraction patterns comprising a se ries of sharp peaks. Though the diffraction profiles of each drug are visually characteristic, automated detection systems require a substance identification algorithm, and multivariate analysis was selected as suitable. The software was trained with measured diffraction data from 60 samples covering 7 illicit drugs and 5 common cutting agents, collected with a range of statistical qual ities and used to predict the content of 7 unknown samples. In all cases the constituents were identified correctly and the contents predicted to within 15%. Soft tissues exhibit broad peaks in their diffraction patterns. Diffraction data were collected from formalin fixed breast tissue samples and used to gen erate images. Maximum contrast between healthy and suspicious regions was achieved using momentum transfer windows 1.04-1.10 and 1.84-1.90 nm_1. The resulting images had an average contrast of 24.6% and 38.9% compared to the corresponding transmission X-ray images (18.3%). The data was used to simulate the feedback for an adaptive imaging system and the ratio of the aforementioned momentum transfer regions found to be an excellent pa rameter. Investigation into the effects of formalin fixation on human breast tissue and animal tissue equivalents indicated that fixation in standard 10% buffered formalin does not alter the diffraction profiles of tissue in the mo mentum transfer regions examined, though 100% unbuffered formalin affects the profile of porcine muscle tissue (a substitute for glandular and tumourous tissue), though fat is unaffected.

Component analyses of urinary nanocrystallites of uric acid stone formers by combination of high-resolution transmission electron microscopy, fast Fourier transformation, energy dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy.

PubMed

Sun, Xin-Yuan; Xue, Jun-Fa; Xia, Zhi-Yue; Ouyang, Jian-Ming

2015-06-01

This study aimed to analyse the components of nanocrystallites in urines of patients with uric acid (UA) stones. X-ray diffraction (XRD), Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy (HRTEM), fast Fourier transformation (FFT) of HRTEM, and energy dispersive X-ray spectroscopy (EDS) were performed to analyse the components of these nanocrystallites. XRD and FFT showed that the main component of urinary nanocrystallites was UA, which contains a small amount of calcium oxalate monohydrate and phosphates. EDS showed the characteristic absorption peaks of C, O, Ca and P. The formation of UA stones was closely related to a large number of UA nanocrystallites in urine. A combination of HRTEM, FFT, EDS and XRD analyses could be performed accurately to analyse the components of urinary nanocrystallites.

Diamond sensors and polycapillary lenses for X-ray absorption spectroscopy.

PubMed

Ravel, B; Attenkofer, K; Bohon, J; Muller, E; Smedley, J

2013-10-01

Diamond sensors are evaluated as incident beam monitors for X-ray absorption spectroscopy experiments. These single crystal devices pose a challenge for an energy-scanning experiment using hard X-rays due to the effect of diffraction from the crystalline sensor at energies which meet the Bragg condition. This problem is eliminated by combination with polycapillary lenses. The convergence angle of the beam exiting the lens is large compared to rocking curve widths of the diamond. A ray exiting one capillary from the lens meets the Bragg condition for any reflection at a different energy from the rays exiting adjacent capillaries. This serves to broaden each diffraction peak over a wide energy range, allowing linear measurement of incident intensity over the range of the energy scan. Extended X-ray absorption fine structure data are measured with a combination of a polycapillary lens and a diamond incident beam monitor. These data are of comparable quality to data measured without a lens and with an ionization chamber monitoring the incident beam intensity.

X-ray free electron laser: opportunities for drug discovery.

PubMed

Cheng, Robert K Y; Abela, Rafael; Hennig, Michael

2017-11-08

Past decades have shown the impact of structural information derived from complexes of drug candidates with their protein targets to facilitate the discovery of safe and effective medicines. Despite recent developments in single particle cryo-electron microscopy, X-ray crystallography has been the main method to derive structural information. The unique properties of X-ray free electron laser (XFEL) with unmet peak brilliance and beam focus allow X-ray diffraction data recording and successful structure determination from smaller and weaker diffracting crystals shortening timelines in crystal optimization. To further capitalize on the XFEL advantage, innovations in crystal sample delivery for the X-ray experiment, data collection and processing methods are required. This development was a key contributor to serial crystallography allowing structure determination at room temperature yielding physiologically more relevant structures. Adding the time resolution provided by the femtosecond X-ray pulse will enable monitoring and capturing of dynamic processes of ligand binding and associated conformational changes with great impact to the design of candidate drug compounds. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Negative thermal expansion and magnetoelastic coupling in the breathing pyrochlore lattice material LiGaCr 4 S 8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pokharel, G.; May, A. F.; Parker, D. S.

In this paper, the physical properties of the spinel LiGaCr 4S 8 have been studied with neutron diffraction, x-ray diffraction, magnetic susceptibility, and heat capacity measurements. The neutron diffraction and synchrotron x-ray diffraction data reveal negative thermal expansion (NTE) below 111(4) K. The magnetic susceptibility deviates from Curie-Weiss behavior with the onset of NTE. At low temperature a broad peak in the magnetic susceptibility at 10.3(3) K is accompanied by the return of normal thermal expansion. First-principles calculations find a strong coupling between the lattice and the simulated magnetic ground state. Finally, these results indicate strong magnetoelastic coupling in LiGaCrmore » 4S 8.« less

Negative thermal expansion and magnetoelastic coupling in the breathing pyrochlore lattice material LiGaCr 4 S 8

DOE PAGES

Pokharel, G.; May, A. F.; Parker, D. S.; ...

2018-04-30

In this paper, the physical properties of the spinel LiGaCr 4S 8 have been studied with neutron diffraction, x-ray diffraction, magnetic susceptibility, and heat capacity measurements. The neutron diffraction and synchrotron x-ray diffraction data reveal negative thermal expansion (NTE) below 111(4) K. The magnetic susceptibility deviates from Curie-Weiss behavior with the onset of NTE. At low temperature a broad peak in the magnetic susceptibility at 10.3(3) K is accompanied by the return of normal thermal expansion. First-principles calculations find a strong coupling between the lattice and the simulated magnetic ground state. Finally, these results indicate strong magnetoelastic coupling in LiGaCrmore » 4S 8.« less

X-ray diffraction studies of shocked lunar analogs

NASA Technical Reports Server (NTRS)

Hanss, R. E.

1979-01-01

The X-ray diffraction experiments on shocked rock and mineral analogs of particular significance to lunar geology are described. Materials naturally shocked by meteorite impact, nuclear-shocked, or artificially shocked in a flat plate accelerator were utilized. Four areas were outlined for investigation: powder diffractometer studies of shocked single crystal silicate minerals (quartz, orthoclase, oligoclase, pyroxene), powder diffractometer studies of shocked polycrystalline monomineralic samples (dunite), Debye-Scherrer studies of single grains of shocked granodiorite, and powder diffractometer studies of shocked whole rock samples. Quantitative interpretation of peak shock pressures experienced by materials found in lunar or terrestrial impact structures is presented.

Growth and characterization of organic NLO material: Clobetasol propionate

NASA Astrophysics Data System (ADS)

Purusothaman, R.; Rajesh, P.; Ramasamy, P.

2015-06-01

Single crystals of clobetasol propionate (CP) have been grown by slow evaporation solution technique using mixed solvent of methanol-acetone. The grown crystals were subjected to single crystal X-ray diffraction analysis to confirm their lattice parameter and space group. The powder X-ray diffraction pattern of the grown CP has been indexed. Thermal analysis was performed to study the thermal stability of the grown crystals. Photoluminescence spectrum shows broad emission peak observed at 421 nm. Nonlinear optical studies were carried out for the grown crystal and second harmonic generation (SHG) efficiency was found in the crystal.

Application of powder X-ray diffraction in studying the compaction behavior of bulk pharmaceutical powders.

PubMed

Bandyopadhyay, Rebanta; Selbo, Jon; Amidon, Gregory E; Hawley, Michael

2005-11-01

This study investigates the effects of crystal lattice deformation on the powder X-ray diffraction (PXRD) patterns of compressed polycrystalline specimen (compacts/tablets) made from molecular, crystalline powders. The displacement of molecules and the corresponding adjustment of interplanar distances (d-spacings) between diffracting planes of PNU-288034 and PNU-177553, which have crystal habits with a high aspect ratio favoring preferred orientation during tableting, are demonstrated by shifts in the diffracted peak positions. The direction of shift in diffracted peak positions suggests a reduction of interplanar d-spacing in the crystals of PNU-288034 and PNU-177553 following compaction. There is also a general reduction of peak intensities following compression at the different compressive loads. The lattice strain representing the reduction in d-spacing is proportional to the original d-spacing of the uncompressed sample suggesting that, as with systems that obey a simple Hooke's law relationship, the further apart the planes of atoms/molecules within the lattice are, the easier it is for them to approach each other under compressive stresses. For a third model compound comprising more equant-shaped crystals of PNU-141659, the shift in diffracted peak positions are consistent with an expansion of lattice spacing after compression. This apparent anomaly is supported by the PXRD studies of the bulk powder consisting of fractured crystals where also, the shift in peak position suggests expansion of the lattice planes. Thus the crystals of PNU-141659 may be fracturing under the compressive loads used to produce the compacts. Additional studies are underway to relate the PXRD observations with the bulk tableting properties of these model compounds.

Cellulose polymorphy, crystallite size, and the Segal crystallinity index

USDA-ARS?s Scientific Manuscript database

The X-ray diffraction-based Segal Crystallinity Index (CI) was calculated for simulated different sizes of crystallites for cellulose I' and II. The Mercury software was used, and different crystallite sizes were based on different input peak widths at half of the maximum peak intensity (pwhm). The ...

In-situ synchrotron wide-angle X-ray diffraction as a rapid method for cocrystal/salt screening.

PubMed

Dong, Pin; Lin, Ling; Li, Yongcheng; Huang, Zhengwei; Lang, Tianqun; Wu, Chuanbin; Lu, Ming

2015-12-30

The purpose of this work was to explore in-situ synchrotron wide-angle X-ray diffraction (WAXD) as a rapid and accurate tool to screen and monitor the formation of cocrystal/salts during heating. The active pharmaceutical ingredients (caffeine, carbamazepine and lamotrigine) were respectively mixed with the coformer (saccharin), and then heated by the hot stage. Real-time process monitoring was performed using synchrotron WAXD to assess cocrystal formation and subsequently compared to differential scanning calorimetry (DSC) measurements. The effect of heating rates and cocrystal growth behavior were investigated. Synchrotron WAXD was fast and sensitive to detect cocrystal formation with the appearance of characteristic diffraction rings, even at the heating rate of 30°C/min, while DSC curves showed overlapped peaks. Unlike the indirect characterization of DSC on endo/exothermic peaks, synchrotron WAXD can directly and qualitatively determine cocrystal by diffraction peaks. The diffraction intensity-temperature curves and the corresponding first-derivative curves clearly exhibited the growth behavior of cocrystal upon heating, providing useful information to optimize the process temperature of hot melt extrusion to continuously manufacture cocrystal. The study suggests that in-situ synchrotron WAXD could provide a one-step process to screen cocrystal at high efficiency and reveal the details of cocrystal/salts growth behavior. Copyright © 2015 Elsevier B.V. All rights reserved.

Replacement of segmental bone defects using porous bioceramic cylinders: a biomechanical and X-ray diffraction study.

PubMed

Zhang, C; Wang, J; Feng, H; Lu, B; Song, Z; Zhang, X

2001-03-05

A porous ceramic material [hydroxyapatitetricalcium phosphate (HA-TCP)] was implanted in the femora of 30 dogs to investigate the possibility of using this material to repair segmental bone defects. A bone segment, 1.5 cm in length, was removed from the diaphysis of one femur in each dog to create the defect. Cylinders of corresponding size were inserted into the defects. The animals were divided into three groups with recovery times of 2 months, 4 months, and 6 months, respectively. The implants were harvested and subjected to biomechanic tests (bending strength) and X-ray diffraction analysis. The bending strengths of the implant construct increased gradually over time postoperatively. The values of strength for the three different time groups had significant variations (p < 0.05). The X-ray diffraction analysis indicated that the peaks of the TCP included in the cylinders decreased in intensity after implantation and tended to be similar to those of natural bone by 6 months after operation. Conversely, the peaks for the HA had fewer changes compared with preimplantation values. Based on the results of this experiment it was concluded that the porous HA-TCP ceramic cylinders have potential for repair of segmental bone defects if assisted by adequate stabilizing fixtures during the early postoperative period.

Extremely asymmetric diffraction as a method of determining magneto-optical constants for X-rays near absorption edges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreeva, M. A., E-mail: Mandreeva1@yandex.ru; Repchenko, Yu. L., E-mail: kent160@mail.ru; Smekhova, A. G.

2015-06-15

The spectral dependence of the Bragg peak position under conditions of extremely asymmetric diffraction has been analyzed in the kinematical and dynamical approximations of the diffraction theory. Simulations have been performed for the L{sub 3} absorption edge of yttrium in a single-crystal YFe{sub 2} film; they have shown that the magneto-optical constants (or, equivalently, the dispersion corrections to the atomic scattering factor) for hard X-rays can be determined from this dependence. Comparison with the experimental data obtained for a Nb(4 nm)/YFe{sub 2}(40 nm〈110〉)/Fe(1.5 nm)/Nb(50 nm)/sapphire sample at the European Synchrotron Radiation Facility has been made.

Surface-treated self-standing curved crystals as high-efficiency elements for X- and γ-ray optics: theory and experiment.

PubMed

Bonnini, Elisa; Buffagni, Elisa; Zappettini, Andrea; Doyle, Stephen; Ferrari, Claudio

2015-06-01

The efficiency of a Laue lens for X- and γ-ray focusing in the energy range 60-600 keV is closely linked to the diffraction efficiency of the single crystals composing the lens. A powerful focusing system is crucial for applications like medical imaging and X-ray astronomy where wide beams must be focused. Mosaic crystals with a high density, such as Cu or Au, and bent crystals with curved diffracting planes (CDPs) are considered for the realization of a focusing system for γ-rays, owing to their high diffraction efficiency in a predetermined angular range. In this work, a comparison of the efficiency of CDP crystals and Cu and Au mosaic crystals was performed on the basis of the theory of X-ray diffraction. Si, GaAs and Ge CDP crystals with optimized thicknesses and moderate radii of curvature of several tens of metres demonstrate comparable or superior performance with respect to the higher atomic number mosaic crystals generally used. In order to increase the efficiency of the lens further, a stack of several CDP crystals is proposed as an optical element. CDP crystals were obtained by a surface-damage method, and a stack of two surface-damaged bent Si crystals was prepared and tested. Rocking curves of the stack were performed with synchrotron radiation at 19 keV to check the lattice alignment: they exhibited only one diffraction peak.

Three-dimensional full-field X-ray orientation microscopy

PubMed Central

Viganò, Nicola; Tanguy, Alexandre; Hallais, Simon; Dimanov, Alexandre; Bornert, Michel; Batenburg, Kees Joost; Ludwig, Wolfgang

2016-01-01

A previously introduced mathematical framework for full-field X-ray orientation microscopy is for the first time applied to experimental near-field diffraction data acquired from a polycrystalline sample. Grain by grain tomographic reconstructions using convex optimization and prior knowledge are carried out in a six-dimensional representation of position-orientation space, used for modelling the inverse problem of X-ray orientation imaging. From the 6D reconstruction output we derive 3D orientation maps, which are then assembled into a common sample volume. The obtained 3D orientation map is compared to an EBSD surface map and local misorientations, as well as remaining discrepancies in grain boundary positions are quantified. The new approach replaces the single orientation reconstruction scheme behind X-ray diffraction contrast tomography and extends the applicability of this diffraction imaging technique to material micro-structures exhibiting sub-grains and/or intra-granular orientation spreads of up to a few degrees. As demonstrated on textured sub-regions of the sample, the new framework can be extended to operate on experimental raw data, thereby bypassing the concept of orientation indexation based on diffraction spot peak positions. This new method enables fast, three-dimensional characterization with isotropic spatial resolution, suitable for time-lapse observations of grain microstructures evolving as a function of applied strain or temperature. PMID:26868303

Advanced Spectral Analysis Program (ASAP) for High-Pressure X-ray Diffraction

NASA Astrophysics Data System (ADS)

Montgomery, Jeffrey

A program for analyzing large powder diffraction data sets has been developed. This tool enables the user to fit any type of crystal structure by indexing peaks in multiple files simultaneously by manually selecting them from a 2D plot of peak positions. The program has tools for automatic peak fitting and pressure determination using various equations of state. The interface is useful for correlating information from various types of spectral data, and so tools have been added for analyzing common fluorescence markers such as ruby, strontium tetraborate, and diamond. The program operation is demonstrated by the analysis of high-pressure powder x-ray diffraction data taken on a sample of vanadium metal at the Advanced Photon Source 16-BMD beamline. Samples were compressed in three runs to a pressure of 70 GPa in an attempt to measure the phase transition from bcc to orthorhombic in hydrostatic and non-hydrostatic conditions. Using ASAP to analyze this data provides a fast and accurate tool for observation of such a subtle transition, which is characterized primarily by a narrow splitting of the bcc 110 and 112 peaks. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

X-ray diffraction analysis of Nb-3Ge and NbGe alloys

NASA Technical Reports Server (NTRS)

Davis, J. H.; House, K. W.

1983-01-01

Of all the A-15 samples of NbGe alloy examined, DT 094 is unique in that it was at least 99% pure A-15 phase. Also its diffraction peaks were noisy as if there were about a one percent compositional variation on this phase. DT 094, however, was only a large fragment of the drop tube drop, and thus its small sample size may have reduced the intensity, thus enhancing fluctuations enough to explain some of the loss of peak resolution.

Mesoscale Science with High Energy X-ray Diffraction Microscopy at the Advanced Photon Source

NASA Astrophysics Data System (ADS)

Suter, Robert

2014-03-01

Spatially resolved diffraction of monochromatic high energy (> 50 keV) x-rays is used to map microstructural quantities inside of bulk polycrystalline materials. The non-destructive nature of High Energy Diffraction Microscopy (HEDM) measurements allows tracking of responses as samples undergo thermo-mechanical or other treatments. Volumes of the order of a cubic millimeter are probed with micron scale spatial resolution. Data sets allow direct comparisons to computational models of responses that frequently involve long-ranged, multi-grain interactions; such direct comparisons have only become possible with the development of HEDM and other high energy x-ray methods. Near-field measurements map the crystallographic orientation field within and between grains using a computational reconstruction method that simulates the experimental geometry and matches orientations in micron sized volume elements to experimental data containing projected grain images in large numbers of Bragg peaks. Far-field measurements yield elastic strain tensors through indexing schemes that sort observed diffraction peaks into sets associated with individual crystals and detect small radial motions in large numbers of such peaks. Combined measurements, facilitated by a new end station hutch at Advanced Photon Source beamline 1-ID, are mutually beneficial and result in accelerated data reduction. Further, absorption tomography yields density contrast that locates secondary phases, void clusters, and cracks, and tracks sample shape during deformation. A collaboration led by the Air Force Research Laboratory and including the Advanced Photon Source, Lawrence Livermore National Laboratory, Carnegie Mellon University, Petra-III, and Cornell University and CHESS is developing software and hardware for combined measurements. Examples of these capabilities include tracking of grain boundary migrations during thermal annealing, tensile deformation of zirconium, and combined measurements of nickel superalloys and a titanium alloy under tensile forces. Work supported by NSF grant DMR-1105173

Crystal growth, structural, low temperature thermoluminescence and mechanical properties of cubic fluoroperovskite single crystal (LiBaF3)

NASA Astrophysics Data System (ADS)

Daniel, D. Joseph; Ramasamy, P.; Ramaseshan, R.; Kim, H. J.; Kim, Sunghwan; Bhagavannarayana, G.; Cheon, Jong-Kyu

2017-10-01

Polycrystalline compounds of LiBaF3 were synthesized using conventional solid state reaction route and the phase purity was confirmed using powder X-ray diffraction technique. Using vertical Bridgman technique single crystal was grown from melt. Rocking curve measurements have been carried out to study the structural perfection of the grown crystal. The single peak of diffraction curve clearly reveals that the grown crystal was free from the structural grain boundaries. The low temperature thermoluminescence of the X-ray irradiated sample has been analyzed and found four distinguishable peaks having maximum temperatures at 18, 115, 133 and 216 K. Activation energy (E) and frequency factor (s) for the individual peaks have been studied using Peak shape method and the computerized curve fitting method combining with the Tmax- TStop procedure. Nanoindentation technique was employed to study the mechanical behaviour of the crystal. The indentation modulus and Vickers hardness of the grown crystal have values of 135.15 GPa and 680.81 respectively, under the maximum indentation load of 10 mN.

Chemical and morphological characterization of III-V strained layered heterostructures

NASA Astrophysics Data System (ADS)

Gray, Allen Lindsay

This dissertation describes investigations into the chemical and morphological characterization of III-V strained layered heterostructures by high-resolution x-ray diffraction. The purpose of this work is two-fold. The first was to use high-resolution x-ray diffraction coupled with transmission electron microscopy to characterize structurally a quaternary AlGaAsSb/InGaAsSb multiple quantum well heterostructure laser device. A method for uniquely determining the chemical composition of the strain quaternary quantum well, information previously thought to be unattainable using high resolution x-ray diffraction is thoroughly described. The misconception that high-resolution x-ray diffraction can separately find the well and barrier thickness of a multi-quantum well from the pendellosung fringe spacing is corrected, and thus the need for transmission electron microscopy is motivated. Computer simulations show that the key in finding the well composition is the intensity of the -3rd order satellite peaks in the diffraction pattern. The second part of this work addresses the evolution of strain relief in metastable multi-period InGaAs/GaAs multi-layered structures by high-resolution x-ray reciprocal space maps. Results are accompanied by transmission electron and differential contrast microscopy. The evolution of strain relief is tracked from a coherent "pseudomorphic" growth to a dislocated state as a function of period number by examining the x-ray diffuse scatter emanating from the average composition (zeroth-order) of the multi-layer. Relaxation is determined from the relative positions of the substrate with respect to the zeroth-order peak. For the low period number, the diffuse scatter from the multi-layer structure region arises from periodic, coherent crystallites. For the intermediate period number, the displacement fields around the multi-layer structure region transition to random coherent crystallites. At the higher period number, displacement fields of overlapping dislocations from relaxation of the random crystallites cause the initial stages of relaxation of the multi-layer structure. At the highest period number studied, relaxation of the multi-layer structure becomes bi-modal characterized by overlapping dislocations caused by mosaic block relaxation and periodically spaced misfit dislocations formed by 60°-type dislocations. The relaxation of the multi-layer structure has an exponential dependence on the diffuse scatter length-scale, which is shown to be a sensitive measure of the onset of relaxation.

Depth profiling of ion-induced damage in D9 alloy using X-ray diffraction

NASA Astrophysics Data System (ADS)

Dey, S.; Gayathri, N.; Mukherjee, P.

2018-04-01

The ion-induced depthwise damage profile in 35 MeV α-irradiated D9 alloy samples with doses of 5 × 1015 He2+/cm2, 6.4 × 1016 He2+/cm2 and 2 × 1017 He2+/cm2 has been assessed using X-ray diffraction technique. The microstructural characterisation has been done along the depth from beyond the stopping region (peak damage region) to the homogeneous damage region (surface) as simulated from SRIM. The parameters such as domain size and microstrain have been evaluated using two different X-ray diffraction line profile analysis techniques. The results indicate that at low dose the damage profile shows a prominent variation as a function of depth but, with increasing dose, it becomes more homogeneous along the depth. This suggests that enhanced defect diffusion and their annihilation in pre-existing and newly formed sinks play a significant role in deciding the final microstructure of the irradiated sample as a function of depth.

Effects of Kapton Sample Cell Windows on the Detection Limit of Smectite: Implications for CheMin on the Mars Science Laboratory Mission

NASA Technical Reports Server (NTRS)

Achilles, C. N.; Ming, Douglas W.; Morris, R. V.; Blake, D. F.

2012-01-01

The CheMin instrument on the Mars Science Laboratory (MSL) rover Curiosity is an X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument capable of providing the mineralogical and chemical compositions of rocks and soils on the surface of Mars. CheMin uses a microfocus X-ray tube with a Co target, transmission geometry, and an energy-discriminating X-ray sensitive CCD to produce simultaneous 2-D XRD patterns and energy-dispersive X-ray histograms from powdered samples. CheMin has two different window materials used for sample cells -- Mylar and Kapton. Instrument details are provided elsewhere. Fe/Mg-smectite (e.g., nontronite) has been identified in Gale Crater, the MSL future landing site, by CRISM spectra. While large quantities of phyllosilicate minerals will be easily detected by CheMin, it is important to establish detection limits of such phases to understand capabilities and limitations of the instrument. A previous study indicated that the (001) peak of smectite at 15 Ang was detectable in a mixture of 1 wt.% smectite with olivine when Mylar is the window material for the sample cell. Complications arise when Kapton is the window material because Kapton itself also has a diffraction peak near 15 Ang (6.8 deg 2 Theta). This study presents results of mineral mixtures of smectite and olivine to determine smectite detection limits for Kapton sample cells. Because the intensity and position of the smectite (001) peak depends on the hydration state, we also analyzed mixtures with "hydrated" and "dehydrated"h smectite to examine the effects of hydration state on detection limits.

Oxidized nanocrystalline Fe-Cu pseudoalloy subjected to high pressure and electrodischarge pulses: Mössbauer and x-ray investigations

NASA Astrophysics Data System (ADS)

Gavriliuk, A. G.; Voitkovsky, V. S.; Sidorov, V. A.; Filonenko, V. P.; Tsiok, O. B.; Khvostantsev, L. G.

1998-05-01

Nanocrystalline Fe15Cu85 pseudoalloy has been subjected to pulsed heating up to 1500 K at high pressure (8 GPa). Two regimes were studied: the direct heating using electrodischarge through the sample and indirect heating with the use of cylindrical heater around the sample. The temperature and time conditions in both types of experiments were adjusted to be equivalent. The discharge parameters (stored energy, discharge time, and magnitude of current pulse) were sufficient to move defects by conduction electrons, but insufficient to melt the sample. The properties of treated samples were studied using Mössbauer absorption spectra and x-ray diffraction for three types of samples: (a) primary powder treated by high pressure up to 8 GPa, (b) powder subjected to indirect pulsed heating at 8 GPa, (c) powder treated by electrical pulses at 8 GPa. The x-ray diffraction pattern of primary powder exhibits peaks of copper, iron, and copper oxide (CuO). The Mössbauer spectrum of primary powder exhibits six peaks of alpha iron and some peaks near zero velocity due to the small iron clusters in the copper matrix and ultrafine clusters of paramagnetic phase x-Fe2O3. The transformation of CuO to Cu2O takes place in the course of indirect heating, the Mössbauer spectrum being almost unchanged. The direct electrodischarge heating causes the appearance of new magnetic phase with the magnetic field on iron nucleus 505 kOe, which corresponds to α-Fe2O3. The formation of α-Fe2O3 was confirmed by x-ray diffraction. At the same time the transformation of CuO to Cu2O is incomplete. These experiments demonstrate that high density current pulses, causing the electron wind, can be a useful tool to influence the structure of nanocrystalline powder.

Crystallization and X-ray diffraction of crystals formed in water-plasticized amorphous lactose.

PubMed

Jouppila, K; Kansikas, J; Roos, Y H

1998-01-01

Effects of storage time and relative humidity on crystallization and crystal forms produced from amorphous lactose were investigated. Crystallization was observed from time-dependent loss of sorbed water and increasing intensities of peaks in X-ray diffraction patterns. The rate of crystallization increased with increasing storage relative humidity. Lactose crystallized mainly as alpha-lactose monohydrate and anhydrous crystals with alpha- and beta-lactose in a molar ratio of 5:3. The results suggested that the crystal form was defined by the early nucleation process. The crystallization data are important in modeling of crystallization phenomena and prediction of stability of lactose-containing food and pharmaceutical materials.

53 W average power few-cycle fiber laser system generating soft x rays up to the water window.

PubMed

Rothhardt, Jan; Hädrich, Steffen; Klenke, Arno; Demmler, Stefan; Hoffmann, Armin; Gotschall, Thomas; Eidam, Tino; Krebs, Manuel; Limpert, Jens; Tünnermann, Andreas

2014-09-01

We report on a few-cycle laser system delivering sub-8-fs pulses with 353 μJ pulse energy and 25 GW of peak power at up to 150 kHz repetition rate. The corresponding average output power is as high as 53 W, which represents the highest average power obtained from any few-cycle laser architecture so far. The combination of both high average and high peak power provides unique opportunities for applications. We demonstrate high harmonic generation up to the water window and record-high photon flux in the soft x-ray spectral region. This tabletop source of high-photon flux soft x rays will, for example, enable coherent diffractive imaging with sub-10-nm resolution in the near future.

X-ray diffraction diagnostic design for the National Ignition Facility

NASA Astrophysics Data System (ADS)

Ahmed, Maryum F.; House, Allen; Smith, R. F.; Ayers, Jay; Lamb, Zachary S.; Swift, David W.

2013-09-01

This paper describes the design considerations for Target Diffraction In-Situ (TARDIS), an x-ray diffraction diagnostic at the National Ignition Facility. A crystal sample is ramp-compressed to peak pressures between 10 and 30 Mbar and, during a pressure hold period, is probed with quasi-monochromatic x-rays emanating from a backlighter source foil. The crystal spectrography diffraction lines are recorded onto image plates. The crystal sample, filter, and image plates are packaged into one assembly, allowing for accurate and repeatable target to image plate registration. Unconverted laser light impinges upon the device, generating debris, the effects of which have been mitigated. Dimpled blast shields, high strength steel alloy, and high-z tungsten are used to shield and protect the image plates. A tapered opening was designed to provide adequate thickness of shielding materials without blocking the drive beams or x-ray source from reaching the crystal target. The high strength steel unit serves as a mount for the crystal target and x-ray source foil. A tungsten body contains the imaging components. Inside this sub-assembly, there are three image plates: a 160 degree field of view curved plate directly opposite the target opening and two flat plates for the top and bottom. A polycarbonate frame, coated with the appropriate filter material and embedded with registration features for image plate location, is inserted into the diagnostic body. The target assembly is metrologized and then the diagnostic assembly is attached.

Vibrational spectra, powder X-ray diffractions and physical properties of cyanide complexes with 1-ethylimidazole

NASA Astrophysics Data System (ADS)

Kürkçüoğlu, Güneş Süheyla; Kiraz, Fulya Çetinkaya; Sayın, Elvan

2015-10-01

The heteronuclear tetracyanonickelate(II) complexes of the type [M(etim)Ni(CN)4]n (hereafter, abbreviated as M-Ni-etim, M = Mn(II), Fe(II) or Co(II); etim = 1-ethylimidazole, C5H8N2) were prepared in powder form and characterized by FT-IR and Raman spectroscopy, powder X-ray diffraction (PXRD), thermal (TG; DTG and DTA), and elemental analysis techniques. The structures of these complexes were elucidated using vibrational spectra and powder X-ray diffraction patterns with the peak assignment to provide a better understanding of the structures. It is shown that the spectra are consistent with a proposed crystal structure for these compounds derived from powder X-ray diffraction measurements. Vibrational spectra of the complexes were presented and discussed with respect to the internal modes of both the etim and the cyanide ligands. The C, H and N analyses were carried out for all the complexes. Thermal behaviors of these complexes were followed using TG, DTG and DTA curves in the temperature range 30-700 °C in the static air atmosphere. The FT-IR, Raman spectra, thermal and powder X-ray analyses revealed no significant differences between the single crystal and powder forms. Additionally, electrical and magnetic properties of the complexes were investigated. The FT-IR and Raman spectroscopy, PXRD, thermal and elemental analyses results propose that these complexes are similar in structure to the Hofmann-type complexes.

Crystalline Stratification in Semiconducting Polymer Thin Film Quantified by Grazing Incidence X-ray Scattering

NASA Astrophysics Data System (ADS)

Gann, Eliot; Caironi, Mario; Noh, Yong-Young; Kim, Yun-Hi; McNeill, Christopher R.

The depth dependence of crystalline structure within thin films is critical for many technological applications, but has been impossible to measure directly using common techniques. In this work, by monitoring diffraction peak intensity and location and utilizing the highly angle-dependent waveguiding effects of X-rays near grazing incidence we quantitatively measure the thickness, roughness and orientation of stratified crystalline layers within thin films of a high-performance semiconducting polymer. In particular, this diffractive X-ray waveguiding reveals a self-organized 5-nm-thick crystalline surface layer with crystalline orientation orthogonal to the underlying 65-nm-thick layer. While demonstrated for an organic semiconductor film, this approach is applicable to any thin film material system where stratified crystalline structure and orientation can influence important interfacial processes such as charge injection and field-effect transport.

Structural changes in shock compressed silicon observed using time-resolved x-ray diffraction at the Dynamic Compression Sector

NASA Astrophysics Data System (ADS)

Turneaure, Stefan; Zdanowicz, E.; Sinclair, N.; Graber, T.; Gupta, Y. M.

2015-06-01

Structural changes in shock compressed silicon were observed directly using time-resolved x-ray diffraction (XRD) measurements at the Dynamic Compression Sector at the Advanced Photon Source. The silicon samples were impacted by polycarbonate impactors accelerated to velocities greater than 5 km/s using a two-stage light gas gun resulting in impact stresses of about 25 GPa. The 23.5 keV synchrotron x-ray beam passed through the polycarbonate impactor, the silicon sample, and an x-ray window (polycarbonate or LiF) at an angle of 30 degrees relative to the impact plane. Four XRD frames (~ 100 ps snapshots) were obtained with 153.4 ns between frames near the time of impact. The XRD measurements indicate that in the peak shocked state, the silicon samples completely transformed to a high-pressure phase. XRD results for both shocked polycrystalline silicon and single crystal silicon will be presented and compared. Work supported by DOE/NNSA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amaya, Andrew J.; Pathak, Harshad; Modak, Viraj P.

Using an X-ray laser, we investigated the crystal structure of ice formed by homogeneous ice nucleation in deeply supercooled water nanodrops (r ≈ 10 nm) at ~225 K. The nanodrops were formed by condensation of vapor in a supersonic nozzle, and the ice was probed within 100 μs of freezing using femtosecond wide-angle X-ray scattering at the Linac Coherent Light Source free-electron X-ray laser. The X-ray diffraction spectra indicate that this ice has a metastable, predominantly cubic structure; the shape of the first ice diffraction peak suggests stacking-disordered ice with a cubicity value, χ, in the range of 0.78 ±more » 0.05. The cubicity value determined here is higher than those determined in experiments with micron-sized drops but comparable to those found in molecular dynamics simulations. Lastly, the high cubicity is most likely caused by the extremely low freezing temperatures and by the rapid freezing, which occurs on a ~1 μs time scale in single nanodroplets.« less

How Cubic Can Ice Be?

DOE PAGES

Amaya, Andrew J.; Pathak, Harshad; Modak, Viraj P.; ...

2017-06-28

Using an X-ray laser, we investigated the crystal structure of ice formed by homogeneous ice nucleation in deeply supercooled water nanodrops (r ≈ 10 nm) at ~225 K. The nanodrops were formed by condensation of vapor in a supersonic nozzle, and the ice was probed within 100 μs of freezing using femtosecond wide-angle X-ray scattering at the Linac Coherent Light Source free-electron X-ray laser. The X-ray diffraction spectra indicate that this ice has a metastable, predominantly cubic structure; the shape of the first ice diffraction peak suggests stacking-disordered ice with a cubicity value, χ, in the range of 0.78 ±more » 0.05. The cubicity value determined here is higher than those determined in experiments with micron-sized drops but comparable to those found in molecular dynamics simulations. Lastly, the high cubicity is most likely caused by the extremely low freezing temperatures and by the rapid freezing, which occurs on a ~1 μs time scale in single nanodroplets.« less

Trichoderma koningii assisted biogenic synthesis of silver nanoparticles and evaluation of their antibacterial activity

NASA Astrophysics Data System (ADS)

Tripathi, R. M.; Gupta, Rohit Kumar; Shrivastav, Archana; Singh, M. P.; Shrivastav, B. R.; Singh, Priti

2013-09-01

The present study demonstrates the biosynthesis of silver nanoparticles using Trichoderma koningii and evaluation of their antibacterial activity. Trichoderma koningii secretes proteins and enzymes that act as reducing and capping agent. The biosynthesized silver nanoparticles (AgNPs) were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and x-ray diffraction (XRD). UV-Vis spectra showed absorbance peak at 413 nm corresponding to the surface plasmon resonance of silver nanoparticles. DLS was used to find out the size distribution profile. The size and morphology of the AgNPs was determined by TEM, which shows the formation of spherical nanoparticles in the size range of 8-24 nm. X-ray diffraction showed intense peaks corresponding to the crystalline silver. The antibacterial activity of biosynthesized AgNPs was evaluated by growth curve and inhibition zone and it was found that the AgNPs show potential effective antibacterial activity.

Growth, characterization and estimation of lattice strain and size in CdS nanoparticles: X-ray peak profile analysis

NASA Astrophysics Data System (ADS)

Solanki, Rekha Garg; Rajaram, Poolla; Bajpai, P. K.

2018-05-01

This work is based on the growth, characterization and estimation of lattice strain and crystallite size in CdS nanoparticles by X-ray peak profile analysis. The CdS nanoparticles were synthesized by a non-aqueous solvothermal method and were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and UV-visible spectroscopy. XRD confirms that the CdS nanoparticles have the hexagonal structure. The Williamson-Hall (W-H) method was used to study the X-ray peak profile analysis. The strain-size plot (SSP) was used to study the individual contributions of crystallite size and lattice strain from the X-rays peaks. The physical parameters such as strain, stress and energy density values were calculated using various models namely, isotropic strain model, anisotropic strain model and uniform deformation energy density model. The particle size was estimated from the TEM images to be in the range of 20-40 nm. The Raman spectrum shows the characteristic optical 1LO and 2LO vibrational modes of CdS. UV-visible absorption studies show that the band gap of the CdS nanoparticles is 2.48 eV. The results show that the crystallite size estimated from Scherrer's formula, W-H plots, SSP and the particle size calculated by TEM images are approximately similar.

X-ray Diffraction as a Means to Assess Fatigue Performance of Shot-Peened Materials

DTIC Science & Technology

2012-06-01

titanium 6 - 4 fatigue data exhibited similar trends to the 9310 steel material. Low shot- peening intensities (4A and 8A) improved fatigue performance... 6 Figure 4 ...7 Figure 4 . Residual stress and diffraction peak width data from the beta-STOA titanium 6Al-4V disks. attributed to the hardness of the

Modeling and measurements of XRD spectra of extended solids under high pressure

NASA Astrophysics Data System (ADS)

Batyrev, I. G.; Coleman, S. P.; Stavrou, E.; Zaug, J. M.; Ciezak-Jenkins, J. A.

2017-06-01

We present results of evolutionary simulations based on density functional calculations of various extended solids: N-Si and N-H using variable and fixed concentration methods of USPEX. Predicted from the evolutionary simulations structures were analyzed in terms of thermo-dynamical stability and agreement with experimental X-ray diffraction spectra. Stability of the predicted system was estimated from convex-hull plots. X-ray diffraction spectra were calculated using a virtual diffraction algorithm which computes kinematic diffraction intensity in three-dimensional reciprocal space before being reduced to a two-theta line profile. Calculations of thousands of XRD spectra were used to search for a structure of extended solids at certain pressures with best fits to experimental data according to experimental XRD peak position, peak intensity and theoretically calculated enthalpy. Comparison of Raman and IR spectra calculated for best fitted structures with available experimental data shows reasonable agreement for certain vibration modes. Part of this work was performed by LLNL, Contract DE-AC52-07NA27344. We thank the Joint DoD / DOE Munitions Technology Development Program, the HE C-II research program at LLNL and Advanced Light Source, supported by BES DOE, Contract No. DE-AC02-05CH112.

Ostwald ripening and interparticle-diffraction effects for illite crystals

USGS Publications Warehouse

Eberl, D.D.; Srodon, J.

1988-01-01

The Warren-Averbach method, an X-ray diffraction (XRD) method used to measure mean particle thickness and particle-thickness distribution, is used to restudy sericite from the Silverton caldera. Apparent particle-thickness distributions indicate that the clays may have undergone Ostwald ripening and that this process has modified the K-Ar ages of the samples. The mechanism of Ostwald ripening can account for many of the features found for the hydrothermal alteration of illite. Expandabilities measured by the XRD peak-position method for illite/smectites (I/S) from various locations are smaller than expandabilities measured by transmission electron microscopy (TEM) and by the Warren-Averbach (W-A) method. This disparity is interpreted as being related to the presence of nonswelling basal surfaces that form the ends of stacks of illite particles (short-stack effect), stacks that, according to the theory of interparticle diffraction, diffract as coherent X-ray scattering domains. -from Authors

Diffraction leveraged modulation of X-ray pulses using MEMS-based X-ray optics

DOEpatents

Lopez, Daniel; Shenoy, Gopal; Wang, Jin; Walko, Donald A.; Jung, Il-Woong; Mukhopadhyay, Deepkishore

2016-08-09

A method and apparatus are provided for implementing Bragg-diffraction leveraged modulation of X-ray pulses using MicroElectroMechanical systems (MEMS) based diffractive optics. An oscillating crystalline MEMS device generates a controllable time-window for diffraction of the incident X-ray radiation. The Bragg-diffraction leveraged modulation of X-ray pulses includes isolating a particular pulse, spatially separating individual pulses, and spreading a single pulse from an X-ray pulse-train.

Pressure dependence of the monoclinic phase in (1–x)Pb(Mg 1/3Nb 2/3)O 3-xPbTiO₃ solid solutions

DOE PAGES

Ahart, Muhtar; Sinogeikin, Stanislav; Shebanova, Olga; ...

2012-12-26

We combine high-pressure x-ray diffraction, high-pressure Raman scattering, and optical microscopy to investigate a series of (1–x)Pb(Mg 1/3Nb 2/3)O 3-xPbTiO₃ (PMN-xPT) solid solutions (x=0.2, 0.3, 0.33, 0.35, 0.37, 0.4) in diamond anvil cells up to 20 GPa at 300 K. The Raman spectra show a peak centered at 380 cm⁻¹ starting above 6 GPa for all samples, in agreement with previous observations. X-ray diffraction measurements are consistent with this spectral change indicating a structural phase transition; we find that the triplet at the pseudocubic (220) Bragg peak merges into a doublet above 6 GPa. Our results indicate that the morphotropicmore » phase boundary region (x=0.33–0.37) with the presence of monoclinic symmetry persists up to 7 GPa. The pressure dependence of ferroelectric domains in PMN-0.32PT single crystals was observed using a polarizing optical microscope. The domain wall density decreases with pressure and the domains disappear at a modest pressure of 3 GPa. We propose a pressure-composition phase diagram for PMN-xPT solid solutions.« less

Effect of processing on the microstructure of finger millet by X-ray diffraction and scanning electron microscopy.

PubMed

Dharmaraj, Usha; Parameswara, P; Somashekar, R; Malleshi, Nagappa G

2014-03-01

Finger millet is one of the important minor cereals, and carbohydrates form its major chemical constituent. Recently, the millet is processed to prepare hydrothermally treated (HM), decorticated (DM), expanded (EM) and popped (PM) products. The present research aims to study the changes in the microstructure of carbohydrates using X-ray diffraction and scanning electron microscopy. Processing the millet brought in significant changes in the carbohydrates. The native millet exhibited A-type pattern of X-ray diffraction with major peaks at 2θ values of 15.3, 17.86 and 23.15°, whereas, all other products showed V-type pattern with single major peak at 2θ values ranging from 19.39 to 19.81°. The corresponding lattice spacing and the number of unit cells in a particular direction of reflection also reduced revealing that crystallinity of starch has been decreased depending upon the processing conditions. Scanning electron microscopic studies also revealed that the orderly pattern of starch granules changed into a coherent mass due to hydrothermal treatment, while high temperature short time treatment rendered a honey-comb like structure to the product. However, the total carbohydrates and non-starch polysaccharide contents almost remained the same in all the products except for DM and EM, but the individual carbohydrate components changed significantly depending on the type of processing.

Rietveld analysis of X-ray powder diffraction patterns as a potential tool for the identification of impact-deformed carbonate rocks

NASA Astrophysics Data System (ADS)

Huson, S. A.; Foit, F. F.; Watkinson, A. J.; Pope, M. C.

2009-12-01

Previous X-ray powder diffraction (XRD) studies revealed that shock deformed carbonates and quartz have broader XRD patterns than those of unshocked samples. Entire XRD patterns, single peak profiles and Rietveld refined parameters of carbonate samples from the Sierra Madera impact crater, west Texas, unshocked equivalent samples from 95 miles north of the crater and the Mission Canyon Formation of southwest Montana and western Wyoming were used to evaluate the use of X-ray powder diffraction as a potential tool for distinguishing impact deformed rocks from unshocked and tectonically deformed rocks. At Sierra Madera dolostone and limestone samples were collected from the crater rim (lower shock intensity) and the central uplift (higher shock intensity). Unshocked equivalent dolostone samples were collected from well cores drilled outside of the impact crater. Carbonate rocks of the Mission Canyon Formation were sampled along a transect across the tectonic front of the Sevier and Laramide orogenic belts. Whereas calcite subjected to significant shock intensities at the Sierra Madera impact crater can be differentiated from tectonically deformed calcite from the Mission Canyon Formation using Rietveld refined peak profiles, weakly shocked calcite from the crater rim appears to be indistinguishable from the tectonically deformed calcite. In contrast, Rietveld analysis readily distinguishes shocked Sierra Madera dolomite from unshocked equivalent dolostone samples from outside the crater and tectonically deformed Mission Canyon Formation dolomite.

Mitigation of X-ray damage in macromolecular crystallography by submicrometre line focusing.

PubMed

Finfrock, Y Zou; Stern, Edward A; Alkire, R W; Kas, Joshua J; Evans-Lutterodt, Kenneth; Stein, Aaron; Duke, Norma; Lazarski, Krzysztof; Joachimiak, Andrzej

2013-08-01

Reported here are measurements of the penetration depth and spatial distribution of photoelectron (PE) damage excited by 18.6 keV X-ray photons in a lysozyme crystal with a vertical submicrometre line-focus beam of 0.7 µm full-width half-maximum (FWHM). The experimental results determined that the penetration depth of PEs is 5 ± 0.5 µm with a monotonically decreasing spatial distribution shape, resulting in mitigation of diffraction signal damage. This does not agree with previous theoretical predication that the mitigation of damage requires a peak of damage outside the focus. A new improved calculation provides some qualitative agreement with the experimental results, but significant errors still remain. The mitigation of radiation damage by line focusing was measured experimentally by comparing the damage in the X-ray-irradiated regions of the submicrometre focus with the large-beam case under conditions of equal exposure and equal volumes of the protein crystal, and a mitigation factor of 4.4 ± 0.4 was determined. The mitigation of radiation damage is caused by spatial separation of the dominant PE radiation-damage component from the crystal region of the line-focus beam that contributes the diffraction signal. The diffraction signal is generated by coherent scattering of incident X-rays (which introduces no damage), while the overwhelming proportion of damage is caused by PE emission as X-ray photons are absorbed.

High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector

PubMed Central

Giewekemeyer, Klaus; Philipp, Hugh T.; Wilke, Robin N.; Aquila, Andrew; Osterhoff, Markus; Tate, Mark W.; Shanks, Katherine S.; Zozulya, Alexey V.; Salditt, Tim; Gruner, Sol M.; Mancuso, Adrian P.

2014-01-01

Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 108 8-keV photons pixel−1 s−1, and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 1010 photons µm−2 s−1 within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while ‘still’ images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described. PMID:25178008

High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector.

PubMed

Giewekemeyer, Klaus; Philipp, Hugh T; Wilke, Robin N; Aquila, Andrew; Osterhoff, Markus; Tate, Mark W; Shanks, Katherine S; Zozulya, Alexey V; Salditt, Tim; Gruner, Sol M; Mancuso, Adrian P

2014-09-01

Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 10(8) 8-keV photons pixel(-1) s(-1), and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 10(10) photons µm(-2) s(-1) within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while `still' images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described.

Rare earth substitution on structural and optical behaviour of CdSe thin films

NASA Astrophysics Data System (ADS)

Singh, Sarika; Shrivastava, A. K.; Tapdiya, Swati

2018-05-01

A series of Sm2+,Gd2+ doped with Cadmium selenide CdSe (x =0.01) has been prepared by using Chemical bath deposition technique. Structural, Optical and Morphological studies were performed using X-ray diffraction (XRD), UV-Visible spectrometer, Raman Studies and Scanning Electron Microscopy (SEM). XRD patterns confirm the samples with Sm,Gd ions, some diffraction peaks appeared which belongs to the cubic phase structure. The values of lattice parameter (a) decreased and particle size decrease on doping. Morphology of the grown films reveals that surface are homogeneous and uniformly spread on the substrates. The elemental analysis of CdSe doped Sm and Gd (1%) different composition was analyzed by Energy Dispersive X-Rays (EDX). The optical values of some important parameters of the studied films were calculated by UVstudy are determined from transmission spectra at wavelength 200 to 900nm. Optical band gap Eg was calculated by tauc relation. Energy band gap of CdSe doped with Sm and Gd varies at 1.8eV and 1.9eV respectively. Bandgap In Raman analysis, a prominent peak shows that confirmation of nano crystalline phase. And intensity of peaks was decreasing after doping.

Controlled vapor crystal growth of N a4I r3O8 : A three-dimensional quantum spin liquid candidate

NASA Astrophysics Data System (ADS)

Zheng, Hong; Zhang, Junjie; Stoumpos, Constantinos C.; Ren, Yang; Chen, Yu-Sheng; Dally, Rebecca; Wilson, Stephen D.; Islam, Zahirul; Mitchell, J. F.

2018-04-01

We report the successful bulk single-crystal growth of the hyperkagome lattice iridate N a4I r3O8 (Na438) by vapor transport using a sealed aluminum oxide tube as a container. Crystals were characterized by magnetization, x-ray diffraction, and energy-dispersive x-ray measurements, confirming their identity and properties. Single-crystal x-ray diffraction experiments revealed superlattice peaks indexed on a propagation vector q =(1 /3 ,1 /3 ,1 /3 ) based on the cubic substructure with cell parameter a =8.986 (1 )Å . This superlattice is three-dimensional and fully coherent. Polarization analysis rules out spin and/or orbital order as the underlying origin of the modulation and points to long-range ordering of Na ions at the notionally disordered Na sites as a plausible origin for the observed superlattice.

Controlled vapor crystal growth of N a 4 I r 3 O 8 : A three-dimensional quantum spin liquid candidate

DOE PAGES

Zheng, Hong; Zhang, Junjie; Stoumpos, Constantinos C.; ...

2018-04-24

In this work, we report the successful bulk single-crystal growth of the hyperkagome lattice iridate Na 4Ir 3O 8 (Na438) by vapor transport using a sealed aluminum oxide tube as a container. Crystals were characterized by magnetization, x-ray diffraction, and energy-dispersive x-ray measurements, confirming their identity and properties. Single-crystal x-ray diffraction experiments revealed superlattice peaks indexed on a propagation vector q=(1/3,1/3,1/3) based on the cubic substructure with cell parameter a=8.986(1)Å. This superlattice is three-dimensional and fully coherent. Polarization analysis rules out spin and/or orbital order as the underlying origin of the modulation and points to long-range ordering of Na ionsmore » at the notionally disordered Na sites as a plausible origin for the observed superlattice.« less

Controlled vapor crystal growth of N a 4 I r 3 O 8 : A three-dimensional quantum spin liquid candidate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Hong; Zhang, Junjie; Stoumpos, Constantinos C.

In this work, we report the successful bulk single-crystal growth of the hyperkagome lattice iridate Na 4Ir 3O 8 (Na438) by vapor transport using a sealed aluminum oxide tube as a container. Crystals were characterized by magnetization, x-ray diffraction, and energy-dispersive x-ray measurements, confirming their identity and properties. Single-crystal x-ray diffraction experiments revealed superlattice peaks indexed on a propagation vector q=(1/3,1/3,1/3) based on the cubic substructure with cell parameter a=8.986(1)Å. This superlattice is three-dimensional and fully coherent. Polarization analysis rules out spin and/or orbital order as the underlying origin of the modulation and points to long-range ordering of Na ionsmore » at the notionally disordered Na sites as a plausible origin for the observed superlattice.« less

The hydrothermal decomposition of calcium monosulfoaluminate 14-hydrate to katoite hydrogarnet and β-anhydrite: An in-situ synchrotron X-ray diffraction study

NASA Astrophysics Data System (ADS)

Meller, Nicola; Kyritsis, Konstantinos; Hall, Christopher

2009-10-01

We apply in-situ synchrotron X-ray diffraction to study the transformation of calcium monosulfoaluminate 14-hydrate Ca 4Al 2O 6(SO 4)·14H 2O [monosulfate-14] to hydrogarnet Ca 3Al 2(OH) 12 on the saturated water vapor pressure curve up to 250 °C. We use an aqueous slurry of synthetic ettringite Ca 6Al 2(SO 4) 3(OH) 12·26H 2O as the starting material; on heating, this decomposes at about 115 °C to form monosulfate-14 and bassanite CaSO 4·0.5H 2O. Above 170 °C monosulfate-14 diffraction peaks slowly diminish in intensity, perhaps as a result of loss of crystallinity and the formation of an X-ray amorphous meta-monosulfate. Hydrogarnet nucleates only at temperatures above 210 °C. Bassanite transforms to β-anhydrite (insoluble anhydrite) at about 230 °C and this transformation is accompanied by a second burst of hydrogarnet growth. The transformation pathway is more complex than previously thought. The mapping of the transformation pathway shows the value of rapid in-situ time-resolved synchrotron diffraction.

In operando X-ray diffraction strain measurement in Ni3Sn2 - Coated inverse opal nanoscaffold anodes for Li-ion batteries

NASA Astrophysics Data System (ADS)

Glazer, Matthew P. B.; Wang, Junjie; Cho, Jiung; Almer, Jonathan D.; Okasinski, John S.; Braun, Paul V.; Dunand, David C.

2017-11-01

Volume changes associated with the (de)lithiation of a nanostructured Ni3Sn2 coated nickel inverse opal scaffold anode create mismatch stresses and strains between the Ni3Sn2 anode material and its mechanically supporting Ni scaffold. Using in operando synchrotron x-ray diffraction measurements, elastic strains in the Ni scaffold are determined during cyclic (dis)charging of the Ni3Sn2 anode. These strains are characterized using both the center position of the Ni diffraction peaks, to quantify the average strain, and the peak breadth, which describes the distribution of strain in the measured volume. Upon lithiation (half-cell discharging) or delithiation (half-cell charging), compressive strains and peak breadth linearly increase or decrease, respectively, with charge. The evolution of the average strains and peak breadths suggests that some irreversible plastic deformation and/or delamination occurs during cycling, which can result in capacity fade in the anode. The strain behavior associated with cycling of the Ni3Sn2 anode is similar to that observed in recent studies on a Ni inverse-opal supported amorphous Si anode and demonstrates that the (de)lithiation-induced deformation and damage mechanisms are likely equivalent in both anodes, even though the magnitude of mismatch strain in the Ni3Sn2 is lower due to the lower (de)lithiation-induced contraction/expansion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frølich, S.; Leemreize, H.; Jakus, A.

A model sample consisting of two different hydroxyapatite (hAp) powders was used as a bone phantom to investigate the extent to which X-ray diffraction tomography could map differences in hAp lattice constants and crystallite size. The diffraction data were collected at beamline 1-ID, the Advanced Photon Source, using monochromatic 65 keV X-radiation, a 25 × 25 µm pinhole beam and translation/rotation data collection. The diffraction pattern was reconstructed for each volume element (voxel) in the sample, and Rietveld refinement was used to determine the hAp lattice constants. The crystallite size for each voxel was also determined from the 00.2 hApmore » diffraction peak width. The results clearly show that differences between hAp powders could be measured with diffraction tomography.« less

In Situ X-ray Diffraction Studies of Li(sub x)Mn(sub 2)O(sub 4) Cathode Materials by Synchrotron X-ray Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, X. Q.; Sun, X.; Lee, S. J.

In Situ x-ray diffraction studies on Li{sub x}Mn{sub 2}O{sub 4} spinel cathode materials during charge-discharge cycles were carried out by using a synchrotron as x-ray source. Lithium rich (x = 1.03-1.06) spinel materials obtained from two different sources were studied. Three cubic phases with different lattice constants were observed during charge-discharge cycles in all the samples when a Sufficiently low charge-discharge rate (C/10) was used. There are two regions of two-phase coexistence between these three phases, indicating that both phase transitions are first order. The separation of the Bragg peaks representing these three phases varies from sample to sample andmore » also depends on the charge-discharge rate. These results show that the de-intercalation of lithium in lithium-rich spinel cathode materials proceeds through a series of phase transitions from a lithium-rich phase to a lithium-poor phase and finally to a {lambda}-MnO{sub 2} like cubic phase, rather than through a continuous lattice constant contraction in a single phase.« less

Measuring Three-Dimensional Strain and Structural Defects in a Single InGaAs Nanowire Using Coherent X-ray Multiangle Bragg Projection Ptychography

DOE PAGES

Hill, Megan O.; Calvo-Almazan, Irene; Allain, Marc; ...

2018-01-08

III - As nanowires are candidates for near-infrared light emitters and detectors that can be directly integrated onto silicon. However, nanoscale to microscale variations in structure, composition, and strain within a given nanowire, as well as variations between nanowires, pose challenges to correlating microstructure with device performance. In this work, we utilize coherent nanofocused X-rays to characterize stacking defects and strain in a single InGaAs nanowire supported on Si. By reconstructing diffraction patterns from the 2110 Bragg peak, we show that the lattice orientation varies along the length of the wire, while the strain field along the cross-section is largelymore » unaffected, leaving the band structure unperturbed. Diffraction patterns from the 0110 Bragg peak are reproducibly reconstructed to create three-dimensional images of stacking defects and associated lattice strains, revealing sharp planar boundaries between different crystal phases of wurtzite (WZ) structure that contribute to charge carrier scattering. Phase retrieval is made possible by developing multiangle Bragg projection ptychography (maBPP) to accommodate coherent nanodiffraction patterns measured at arbitrary overlapping positions at multiple angles about a Bragg peak, eliminating the need for scan registration at different angles. The penetrating nature of X-ray radiation, together with the relaxed constraints of maBPP, will enable the in operando imaging of nanowire devices.« less

Measuring Three-Dimensional Strain and Structural Defects in a Single InGaAs Nanowire Using Coherent X-ray Multiangle Bragg Projection Ptychography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, Megan O.; Calvo-Almazan, Irene; Allain, Marc

III - As nanowires are candidates for near-infrared light emitters and detectors that can be directly integrated onto silicon. However, nanoscale to microscale variations in structure, composition, and strain within a given nanowire, as well as variations between nanowires, pose challenges to correlating microstructure with device performance. In this work, we utilize coherent nanofocused X-rays to characterize stacking defects and strain in a single InGaAs nanowire supported on Si. By reconstructing diffraction patterns from the 2110 Bragg peak, we show that the lattice orientation varies along the length of the wire, while the strain field along the cross-section is largelymore » unaffected, leaving the band structure unperturbed. Diffraction patterns from the 0110 Bragg peak are reproducibly reconstructed to create three-dimensional images of stacking defects and associated lattice strains, revealing sharp planar boundaries between different crystal phases of wurtzite (WZ) structure that contribute to charge carrier scattering. Phase retrieval is made possible by developing multiangle Bragg projection ptychography (maBPP) to accommodate coherent nanodiffraction patterns measured at arbitrary overlapping positions at multiple angles about a Bragg peak, eliminating the need for scan registration at different angles. The penetrating nature of X-ray radiation, together with the relaxed constraints of maBPP, will enable the in operando imaging of nanowire devices.« less

Protein crystal structure from non-oriented, single-axis sparse X-ray data

DOE PAGES

Wierman, Jennifer L.; Lan, Ti-Yen; Tate, Mark W.; ...

2016-01-01

X-ray free-electron lasers (XFELs) have inspired the development of serial femtosecond crystallography (SFX) as a method to solve the structure of proteins. SFX datasets are collected from a sequence of protein microcrystals injected across ultrashort X-ray pulses. The idea behind SFX is that diffraction from the intense, ultrashort X-ray pulses leaves the crystal before the crystal is obliterated by the effects of the X-ray pulse. The success of SFX at XFELs has catalyzed interest in analogous experiments at synchrotron-radiation (SR) sources, where data are collected from many small crystals and the ultrashort pulses are replaced by exposure times that aremore » kept short enough to avoid significant crystal damage. The diffraction signal from each short exposure is so `sparse' in recorded photons that the process of recording the crystal intensity is itself a reconstruction problem. Using theEMCalgorithm, a successful reconstruction is demonstrated here in a sparsity regime where there are no Bragg peaks that conventionally would serve to determine the orientation of the crystal in each exposure. In this proof-of-principle experiment, a hen egg-white lysozyme (HEWL) crystal rotating about a single axis was illuminated by an X-ray beam from an X-ray generator to simulate the diffraction patterns of microcrystals from synchrotron radiation. Millions of these sparse frames, typically containing only ~200 photons per frame, were recorded using a fast-framing detector. It is shown that reconstruction of three-dimensional diffraction intensity is possible using theEMCalgorithm, even with these extremely sparse frames and without knowledge of the rotation angle. Further, the reconstructed intensity can be phased and refined to solve the protein structure using traditional crystallographic software. In conclusion, this suggests that synchrotron-based serial crystallography of micrometre-sized crystals can be practical with the aid of theEMCalgorithm even in cases where the data are sparse.« less

Protein crystal structure from non-oriented, single-axis sparse X-ray data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wierman, Jennifer L.; Lan, Ti-Yen; Tate, Mark W.

X-ray free-electron lasers (XFELs) have inspired the development of serial femtosecond crystallography (SFX) as a method to solve the structure of proteins. SFX datasets are collected from a sequence of protein microcrystals injected across ultrashort X-ray pulses. The idea behind SFX is that diffraction from the intense, ultrashort X-ray pulses leaves the crystal before the crystal is obliterated by the effects of the X-ray pulse. The success of SFX at XFELs has catalyzed interest in analogous experiments at synchrotron-radiation (SR) sources, where data are collected from many small crystals and the ultrashort pulses are replaced by exposure times that aremore » kept short enough to avoid significant crystal damage. The diffraction signal from each short exposure is so `sparse' in recorded photons that the process of recording the crystal intensity is itself a reconstruction problem. Using theEMCalgorithm, a successful reconstruction is demonstrated here in a sparsity regime where there are no Bragg peaks that conventionally would serve to determine the orientation of the crystal in each exposure. In this proof-of-principle experiment, a hen egg-white lysozyme (HEWL) crystal rotating about a single axis was illuminated by an X-ray beam from an X-ray generator to simulate the diffraction patterns of microcrystals from synchrotron radiation. Millions of these sparse frames, typically containing only ~200 photons per frame, were recorded using a fast-framing detector. It is shown that reconstruction of three-dimensional diffraction intensity is possible using theEMCalgorithm, even with these extremely sparse frames and without knowledge of the rotation angle. Further, the reconstructed intensity can be phased and refined to solve the protein structure using traditional crystallographic software. In conclusion, this suggests that synchrotron-based serial crystallography of micrometre-sized crystals can be practical with the aid of theEMCalgorithm even in cases where the data are sparse.« less

Structural and optical properties of CuS thin films deposited by Thermal co-evaporation

NASA Astrophysics Data System (ADS)

Sahoo, A. K.; Mohanta, P.; Bhattacharyya, A. S.

2015-02-01

Copper sulfide (CuS) thin films with thickness 100, 150 and 200 nm have been deposited on glass substrates by thermal co-evaporation of Copper and Sulphur. The effect of CuS film thickness on the structural and optical properties have investigated and discussed. Structural and optical investigations of the films were carried out by X-ray diffraction, atomic force microscopy, high-resolution transmission electron microscopy and UV spectroscopy. XRD and selected area electron diffraction conforms that polycrystalline in nature with hexagonal crystal structure. AFM studies revealed a smooth surface morphology with root mean-square roughness values increases from 24 nm to 42 nm as the film thickness increase from 100 nm to 200 nm. AFM image showed that grain size increases with thickness of film increases and good agreement with the calculated from full width half maximum of the X-ray diffraction peak using Scherrer's formula and Williamson-Hall plot. The absorbance of the thin films were absorbed decreases with wavelength through UV-visible regions but showed a increasing in the near-infrared regions. The reflectance spectra also showed lower reflectance peak (25% to 32%) in visible region and high reflectance peak (49 % to 54 %) in near-infrared region. These high absorbance films made them for photo-thermal conversion of solar energy.

Merging single-shot XFEL diffraction data from inorganic nanoparticles: a new approach to size and orientation determination

DOE PAGES

Li, Xuanxuan; Spence, John C. H.; Hogue, Brenda G.; ...

2017-09-22

X-ray free-electron lasers (XFELs) provide new opportunities for structure determination of biomolecules, viruses and nanomaterials. With unprecedented peak brilliance and ultra-short pulse duration, XFELs can tolerate higher X-ray doses by exploiting the femtosecond-scale exposure time, and can thus go beyond the resolution limits achieved with conventional X-ray diffraction imaging techniques. Using XFELs, it is possible to collect scattering information from single particles at high resolution, however particle heterogeneity and unknown orientations complicate data merging in three-dimensional space. Using the Linac Coherent Light Source (LCLS), synthetic inorganic nanocrystals with a core–shell architecture were used as a model system for proof-of-principle coherentmore » diffractive single-particle imaging experiments. To deal with the heterogeneity of the core–shell particles, new computational methods have been developed to extract the particle size and orientation from the scattering data to assist data merging. The size distribution agrees with that obtained by electron microscopy and the merged data support a model with a core–shell architecture.« less

Merging single-shot XFEL diffraction data from inorganic nanoparticles: a new approach to size and orientation determination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xuanxuan; Spence, John C. H.; Hogue, Brenda G.

X-ray free-electron lasers (XFELs) provide new opportunities for structure determination of biomolecules, viruses and nanomaterials. With unprecedented peak brilliance and ultra-short pulse duration, XFELs can tolerate higher X-ray doses by exploiting the femtosecond-scale exposure time, and can thus go beyond the resolution limits achieved with conventional X-ray diffraction imaging techniques. Using XFELs, it is possible to collect scattering information from single particles at high resolution, however particle heterogeneity and unknown orientations complicate data merging in three-dimensional space. Using the Linac Coherent Light Source (LCLS), synthetic inorganic nanocrystals with a core–shell architecture were used as a model system for proof-of-principle coherentmore » diffractive single-particle imaging experiments. To deal with the heterogeneity of the core–shell particles, new computational methods have been developed to extract the particle size and orientation from the scattering data to assist data merging. The size distribution agrees with that obtained by electron microscopy and the merged data support a model with a core–shell architecture.« less

Examining the ground layer of St. Anthony from Padua 19th century oil painting by Raman spectroscopy, scanning electron microscopy and X-ray diffraction

NASA Astrophysics Data System (ADS)

Vančo, Ľubomír; Kadlečíková, Magdaléna; Breza, Juraj; Čaplovič, Ľubomír; Gregor, Miloš

2013-01-01

In this paper we studied the material composition of the ground layer of a neoclassical painting. We used Raman spectroscopy (RS) as a prime method. Thereafter scanning electron microscopy combined with energy dispersive spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD) were employed as complementary techniques. The painting inspected was of the side altar in King St. Stephen's Church in Galanta (Slovakia), signed and dated by Jos. Chr. Mayer 1870. Analysis was carried out on both covered and uncovered ground layers. Four principal compounds (barite, lead white, calcite, dolomite) and two minor compounds (sphalerite, quartz) were identified. This ground composition is consistent with the 19th century painting technique used in Central Europe consisting of white pigments and white fillers. Transformation of lead white occurred under laser irradiation. Subdominant Raman peaks of the components were measured. The observed results elucidate useful partnership of RS and SEM-EDS measurements supported by X-ray powder diffraction as well as possibilities and limitations of non-destructive analysis of covered lower layers by RS.

Time-resolved structural studies at synchrotrons and X-ray free electron lasers: opportunities and challenges

PubMed Central

Neutze, Richard; Moffat, Keith

2012-01-01

X-ray free electron lasers (XFELs) are potentially revolutionary X-ray sources because of their very short pulse duration, extreme peak brilliance and high spatial coherence, features that distinguish them from today’s synchrotron sources. We review recent time-resolved Laue diffraction and time-resolved wide angle X-ray scattering (WAXS) studies at synchrotron sources, and initial static studies at XFELs. XFELs have the potential to transform the field of time-resolved structural biology, yet many challenges arise in devising and adapting hardware, experimental design and data analysis strategies to exploit their unusual properties. Despite these challenges, we are confident that XFEL sources are poised to shed new light on ultrafast protein reaction dynamics. PMID:23021004

Photoinduced coherent acoustic phonon dynamics inside Mott insulator Sr2IrO4 films observed by femtosecond X-ray pulses

NASA Astrophysics Data System (ADS)

Zhang, Bing-Bing; Liu, Jian; Wei, Xu; Sun, Da-Rui; Jia, Quan-Jie; Li, Yuelin; Tao, Ye

2017-04-01

We investigate the transient photoexcited lattice dynamics in a layered perovskite Mott insulator Sr2IrO4 film by femtosecond X-ray diffraction using a laser plasma-based X-ray source. The ultrafast structural dynamics of Sr2IrO4 thin films are determined by observing the shift and broadening of (0012) Bragg diffraction after excitation by 1.5 eV and 3.0 eV pump photons for films with different thicknesses. The observed transient lattice response can be well interpreted as a distinct three-step dynamics due to the propagation of coherent acoustic phonons generated by photoinduced quasiparticles (QPs). Employing a normalized phonon propagation model, we found that the photoinduced angular shifts of the Bragg peak collapse into a universal curve after introducing normalized coordinates to account for different thicknesses and pump photon energies, pinpointing the origin of the lattice distortion and its early evolution. In addition, a transient photocurrent measurement indicates that the photoinduced QPs are charge neutral excitons. Mapping the phonon propagation and correlating its dynamics with the QP by ultrafast X-ray diffraction (UXRD) establish a powerful way to study electron-phonon coupling and uncover the exotic physics in strongly correlated systems under nonequilibrium conditions.

Compositional dependence of magnetic anisotropy in chemically synthesized Co3- x Fe x O4 (0 ≤ x ≤ 2)

NASA Astrophysics Data System (ADS)

Hayashi, Kensuke; Yamada, Keisuke; Shima, Mutsuhiro

2018-01-01

Magnetic anisotropy of Co3- x Fe x O4 (CFO, 0 ≤ x ≤ 2) thin-film and powder samples prepared by a sol-gel method has been investigated as a function of Fe composition x. Structural analyses by X-ray diffraction show that CFO powder samples exhibit diffraction peaks associated with the spinel structure when x < 2, while CFO thin-film samples with thickness of 130-510 nm yield the peaks when 0 ≤ x ≤ 2. CFO thin-film samples are highly (111)-oriented with the Lotgering factor greater than 0.9 when 0.6 ≤ x ≤ 1.3. The magnetic anisotropy constant K 1 of CFO powder samples estimated from their room-temperature hysteresis loops yields a minimum when x = 0.9. Relatively large in-plane magnetic anisotropy (K eff = 5.7 × 105 erg/cm3) is observed for the CFO thin-film sample when x = 1.3. With increasing x, the magnetic easy axis of the spinel CFO changes from 〈111〉 to 〈100〉 when x = 0.9.

Factors Influencing Ferrihydrite Crystallinity In Natural And Synthetic Systems

EPA Science Inventory

Recent investigations of the structure of the mineral ferrihydrite indicate that disparities in the number of peaks observed in powder x-ray diffraction patterns can be attributed to differences in crystallite size. This has lead to the conclusion that specimens previously refer...

Ultrafast molecular processes mapped by femtosecond x-ray diffraction

NASA Astrophysics Data System (ADS)

Elsaesser, Thomas

2012-02-01

X-ray diffraction with a femtosecond time resolution allows for mapping photoinduced structural dynamics on the length scale of a chemical bond and in the time domain of atomic and molecular motion. In a pump-probe approach, a femtosecond excitation pulse induces structural changes which are probed by diffracting a femtosecond hard x-ray pulse from the excited sample. The transient angular positions and intensities of diffraction peaks give insight into the momentary atomic or molecular positions and into the distribution of electronic charge density. The simultaneous measurement of changes on different diffraction peaks is essential for determining atom positions and charge density maps with high accuracy. Recent progress in the generation of ultrashort hard x-ray pulses (Cu Kα, wavelength λ=0.154 nm) in laser-driven plasma sources has led to the implementation of the powder diffraction and the rotating crystal method with a time resolution of 100 fs. In this contribution, we report new results from powder diffraction studies of molecular materials. A first series of experiments gives evidence of a so far unknown concerted transfer of electrons and protons in ammonium sulfate [(NH4)2SO4], a centrosymmetric structure. Charge transfer from the sulfate groups results in the sub-100 fs generation of a confined electron channel along the c-axis of the unit cell which is stabilized by transferring protons from the adjacent ammonium groups into the channel. Time-dependent charge density maps display a periodic modulation of the channel's charge density by low-frequency lattice motions with a concerted electron and proton motion between the channel and the initial proton binding site. A second study addresses atomic rearrangements and charge dislocations in the non-centrosymmetric potassium dihydrogen phosphate [KH2PO4, KDP]. Photoexcitation generates coherent low-frequency motions along the LO and TO phonon coordinates, leaving the average atomic positions unchanged. The time-dependent maps of electron density demonstrate a concomitant oscillatory relocation of electronic charge with a spatial amplitude of the order of a chemical bond length, two orders of magnitude larger than the vibrational amplitudes. The coherent phonon motions drive the charge relocation, similar to a soft mode driven phase transition between the ferro- and paraelectric phase of KDP.

Insights into the dominant factors of porous gold for CO oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kameoka, Satoshi, E-mail: kameoka@tagen.tohoku.ac.jp; Miyamoto, Kanji; Tanabe, Toyokazu

2016-01-21

Three different porous Au catalysts that exhibit high catalytic activity for CO oxidation were prepared by the leaching of Al from an intermetallic compound, Al{sub 2}Au, with 10 wt. %-NaOH, HNO{sub 3}, or HCl aqueous solutions. The catalysts were investigated using Brunauer-Emmett-Teller measurements, synchrotron X-ray powder diffraction, hard X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy (TEM). Broad diffraction peaks generated during the leaching process correlated with high activity for all the porous Au catalysts. CO oxidation catalyzed by porous Au leached with NaOH and HNO{sub 3} is considered to be dominated by different mechanisms atmore » low (< 320 K) and high (> 370 K) temperatures. Activity in the low-temperature region is mainly attributed to the perimeter interface between residual Al species (AlO{sub x}) and porous Au, whereas activity in the high-temperature region results from a high density of lattice defects such as twins and dislocations, which were evident from diffraction peak broadening and were observed with high-resolution TEM in the porous Au leached with NaOH. It is proposed that atoms located at lattice defects on the surfaces of porous Au are the active sites for catalytic reactions.« less

Micro X-ray diffraction analysis of thin films using grazing-exit conditions.

PubMed

Noma, T; Iida, A

1998-05-01

An X-ray diffraction technique using a hard X-ray microbeam for thin-film analysis has been developed. To optimize the spatial resolution and the surface sensitivity, the X-ray microbeam strikes the sample surface at a large glancing angle while the diffracted X-ray signal is detected with a small (grazing) exit angle. Kirkpatrick-Baez optics developed at the Photon Factory were used, in combination with a multilayer monochromator, for focusing X-rays. The focused beam size was about 10 x 10 micro m. X-ray diffraction patterns of Pd, Pt and their layered structure were measured. Using a small exit angle, the signal-to-background ratio was improved due to a shallow escape depth. Under the grazing-exit condition, the refraction effect of diffracted X-rays was observed, indicating the possibility of surface sensitivity.

Compressibility of Cs2SnBr6 by X-ray diffraction and Raman spectroscopy

NASA Astrophysics Data System (ADS)

Yuan, Guan; Huang, Shengxuan; Niu, Jingjing; Qin, Shan; Wu, Xiang; Ding, Hongrui; Lu, Anhuai

2018-07-01

Cs2SnBr6, one promising material applied in perovskite solar cells, has been investigated up to 20 GPa by synchrotron X-ray diffraction and Raman spectroscopy. Both experimental data demonstrate that no phase transition occurs up to 20 GPa. By fitting the third-order Birch-Murnaghan equation of state, we have obtained V0 = 1288 (14) Å3, K0 = 11 (1) GPa and K0‧ = 7 (1). The ultralow value of bulk modulus K0 demonstrates the soft nature of Cs2SnBr6. Combining calculated values with experimental results, we find that x coordinate of Sn (x,0,0) atoms increases and Snsbnd Br bond lengths get shortened on compression. We have assigned vibrational peaks of Cs2SnBr6 in Raman measurements, and all the three Raman bands present nonlinear correlations with pressure.

Enhanced model for determining the number of graphene layers and their distribution from X-ray diffraction data

PubMed Central

Ademi, Abdulakim; Grozdanov, Anita; Paunović, Perica; Dimitrov, Aleksandar T

2015-01-01

Summary A model consisting of an equation that includes graphene thickness distribution is used to calculate theoretical 002 X-ray diffraction (XRD) peak intensities. An analysis was performed upon graphene samples produced by two different electrochemical procedures: electrolysis in aqueous electrolyte and electrolysis in molten salts, both using a nonstationary current regime. Herein, the model is enhanced by a partitioning of the corresponding 2θ interval, resulting in significantly improved accuracy of the results. The model curves obtained exhibit excellent fitting to the XRD intensities curves of the studied graphene samples. The employed equation parameters make it possible to calculate the j-layer graphene region coverage of the graphene samples, and hence the number of graphene layers. The results of the thorough analysis are in agreement with the calculated number of graphene layers from Raman spectra C-peak position values and indicate that the graphene samples studied are few-layered. PMID:26665083

Validation of powder X-ray diffraction following EN ISO/IEC 17025.

PubMed

Eckardt, Regina; Krupicka, Erik; Hofmeister, Wolfgang

2012-05-01

Powder X-ray diffraction (PXRD) is used widely in forensic science laboratories with the main focus of qualitative phase identification. Little is found in literature referring to the topic of validation of PXRD in the field of forensic sciences. According to EN ISO/IEC 17025, the method has to be tested for several parameters. Trueness, specificity, and selectivity of PXRD were tested using certified reference materials or a combination thereof. All three tested parameters showed the secure performance of the method. Sample preparation errors were simulated to evaluate the robustness of the method. These errors were either easily detected by the operator or nonsignificant for phase identification. In case of the detection limit, a statistical evaluation of the signal-to-noise ratio showed that a peak criterion of three sigma is inadequate and recommendations for a more realistic peak criterion are given. Finally, the results of an international proficiency test showed the secure performance of PXRD. © 2012 American Academy of Forensic Sciences.

A hydrous Ca-bearing magnesium carbonate from playa lake sediments, Salines Lake, Spain

USGS Publications Warehouse

Queralt, I.; Julia, R.; Plana, F.; Bischoff, J.L.

1997-01-01

Sediments of playa Lake Salines, SE, Spain, contain a carbonate mineral characterized by X-ray diffraction peaks very similar to, but systematically shifted from those of pure magnesite. Analyses (SEM, IR and Raman spectroscopy, DTA, TGA, and ICP) indicate the mineral is a hydrous Ca-bearing magnesium carbonate with the chemical formula (Mg0.92,Ca0.08)CO3??3H2O. Thermal characteristics of the mineral are similar to those of other known hydrated magnesium carbonates. X-ray and electron diffraction data suggests a monoclinic system (P21/n space group) with unit-cell parameters of a = 6.063(6), b = 10.668(5), and c = 6.014(4) A?? and ?? = 107.28??.

Structural and spectral properties of MgZnO2:Sm3+ phosphor

NASA Astrophysics Data System (ADS)

Rajput, Preasha; Sharma, Pallavi; Biswas, Pankaj; Kamni

2018-05-01

The samarium doped MgZnO2 phosphor was synthesized by the low-cost combustion method. The powder X-ray diffraction (XRD) analysis confirmed the crystallinity and phase purity of the phosphor. The lattice parameters were determined by indexing the diffraction peaks. The photoluminescence (PL) study revealed that the phosphor exhibited a broad excitation band in the UV region ranging between 200 to 350 nm. The 601 nm emission was ascribed to 4G5/2 to 6H7/2 transitions of the Sm3+ ion. The optical bandgap of MgZnO2:Sm3+ was obtained to be 3.56 eV. The phosphor can be projected as a useful material in X- and gamma-ray scintillators.

Structure Evolution of BaTiO3 on Co Doping: X-ray diffraction and Raman study

NASA Astrophysics Data System (ADS)

Mansuri, Amantulla; Mishra, Ashutosh

2016-10-01

In the present study, we have synthesize polycrystalline samples of BaTi1-xCoxO3 (x = 0, 0.05 and 0.1) with standard solid state reaction technique. The obtained samples are characterized by X-ray diffraction (XRD) and Raman spectroscopy. The detail structural analysis has been performed by Rietveld refinement using Fullprof program. The structural analysis reveal the samples are chemical pure and crystallize in tetragonal phase with space group Pm3m. We observe an increase in lattice parameters which results due to substitution of Co2+ with large ionic radii (0.9) for smaller ionic radii (0.6) Ti4+. Moreover peak at 45.5° shift to 45° on Co doping, which is due to structure phase transition from tetragonal to cubic. Raman study infers that the intensity of characteristic peaks decreases and linewidth increases with Co doping. The bands linked with the tetragonal structure (307 cm1) decreased due to the tetragonal-towards-cubic phase transition with Co doping. Our structural study reveals the expansion of BTO unit cell and tetragonal-to-cubic phase transformation takes place, results from different characterization techniques are conclusive and show structural evolution with Co doping.

Investigation of the optical property and photocatalytic activity of mixed phase nanocrystalline titania

NASA Astrophysics Data System (ADS)

Paul, Susmita; Choudhury, Amarjyoti

2014-10-01

Mixed phase nanocrystalline titania are prepared by simple sol-gel method. The physico-chemical characteristics of the prepared nanoparticles are studied with X-ray diffraction, high-resolution transmission electron microscopy, RAMAN, BET, UV-Vis, steady state and time resolved photoluminescence. X-ray diffraction and Raman spectra clearly demarcate the anatase and rutile phase as both the phases give different diffraction patterns and Raman peaks. A comparison in the band gap indicates that pure anatase and rutile phase have band gap in the UV region, whereas a mixture of these phases has lower band gap and corresponds to the visible region. Steady state and time resolved photoluminescence are employed to understand the emissivity and carrier lifetime. The photocatalytic activity is evaluated by monitoring the degradation of phenol under visible light illumination. Due to the synergistic effect of mixed anatase and rutile phases, mixed phase nanocrystalline titania exhibit superior photocatalytic activity.

Characterization of high energy Xe ion irradiation effects in single crystal molybdenum with depth-resolved synchrotron microbeam diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yun, Di; Miao, Yinbin; Xu, Ruqing

2016-04-01

Microbeam X-ray diffraction experiments were conducted at beam line 34-ID of the Advanced Photon Source (APS) on fission fragment energy Xe heavy ion irradiated single crystal Molybdenum (Mo). Lattice strain measurements were obtained with a depth resolution of 0.7 mu m, which is critical in resolving the peculiar heterogeneity of irradiation damage associated with heavy ion irradiation. Q-space diffraction peak shift measurements were correlated with lattice strain induced by the ion irradiations. Transmission electron microscopy (TEM) characterizations were performed on the as-irradiated materials as well. Nanometer sized Xe bubble microstructures were observed via TEM. Molecular Dynamics (MD) simulations were performedmore » to help interpret the lattice strain measurement results from the experiment. This study showed that the irradiation effects by fission fragment energy Xe ion irradiations can be collaboratively understood with the depth resolved X-ray diffraction and TEM measurements under the assistance of MD simulations. (c) 2015 Elsevier B.V. All rights reserved.« less

Characterization of individual stacking faults in a wurtzite GaAs nanowire by nanobeam X-ray diffraction.

PubMed

Davtyan, Arman; Lehmann, Sebastian; Kriegner, Dominik; Zamani, Reza R; Dick, Kimberly A; Bahrami, Danial; Al-Hassan, Ali; Leake, Steven J; Pietsch, Ullrich; Holý, Václav

2017-09-01

Coherent X-ray diffraction was used to measure the type, quantity and the relative distances between stacking faults along the growth direction of two individual wurtzite GaAs nanowires grown by metalorganic vapour epitaxy. The presented approach is based on the general property of the Patterson function, which is the autocorrelation of the electron density as well as the Fourier transformation of the diffracted intensity distribution of an object. Partial Patterson functions were extracted from the diffracted intensity measured along the [000\\bar{1}] direction in the vicinity of the wurtzite 00\\bar{1}\\bar{5} Bragg peak. The maxima of the Patterson function encode both the distances between the fault planes and the type of the fault planes with the sensitivity of a single atomic bilayer. The positions of the fault planes are deduced from the positions and shapes of the maxima of the Patterson function and they are in excellent agreement with the positions found with transmission electron microscopy of the same nanowire.

Characterization of individual stacking faults in a wurtzite GaAs nanowire by nanobeam X-ray diffraction

PubMed Central

Davtyan, Arman; Lehmann, Sebastian; Zamani, Reza R.; Dick, Kimberly A.; Bahrami, Danial; Al-Hassan, Ali; Leake, Steven J.; Pietsch, Ullrich; Holý, Václav

2017-01-01

Coherent X-ray diffraction was used to measure the type, quantity and the relative distances between stacking faults along the growth direction of two individual wurtzite GaAs nanowires grown by metalorganic vapour epitaxy. The presented approach is based on the general property of the Patterson function, which is the autocorrelation of the electron density as well as the Fourier transformation of the diffracted intensity distribution of an object. Partial Patterson functions were extracted from the diffracted intensity measured along the direction in the vicinity of the wurtzite Bragg peak. The maxima of the Patterson function encode both the distances between the fault planes and the type of the fault planes with the sensitivity of a single atomic bilayer. The positions of the fault planes are deduced from the positions and shapes of the maxima of the Patterson function and they are in excellent agreement with the positions found with transmission electron microscopy of the same nanowire. PMID:28862620

Neutron and X-ray diffraction of plasma-sprayed zirconia-yttria thermal barrier coatings

NASA Technical Reports Server (NTRS)

Shankar, N. R.; Herman, H.; Singhal, S. P.; Berndt, C. C.

1984-01-01

ZrO2-7.8mol. pct. YO1.5, a fused powder, and ZrO2-8.7mol. pct. YO1.5, a prereacted powder, were plasma-sprayed onto steel substrates. Neutron diffraction and X-ray diffraction of the as-received powder, the powder plasma sprayed into water, as-sprayed coatings, and coatings heat-treated for 10 and 100 h were carried out to study phase transformations and ordering of the oxygen ions on the oxygen sublattice. The as-received fused powder has a much lower monoclinic percentage than does the pre-reacted powder, this resulting in a much lower monoclinic percentage in the coating. Heat treatment increases the percentages of the cubic and monoclinic phases, while decreasing the tetragonal content. An ordered tetragonal phase is detected by the presence of extra neutron diffraction peaks. These phase transformations and ordering will result in volume changes. The implications of these transformations on the performance of partially stabilized zirconia thermal barrier coatings is discussed.

A new theory for X-ray diffraction.

PubMed

Fewster, Paul F

2014-05-01

This article proposes a new theory of X-ray scattering that has particular relevance to powder diffraction. The underlying concept of this theory is that the scattering from a crystal or crystallite is distributed throughout space: this leads to the effect that enhanced scatter can be observed at the `Bragg position' even if the `Bragg condition' is not satisfied. The scatter from a single crystal or crystallite, in any fixed orientation, has the fascinating property of contributing simultaneously to many `Bragg positions'. It also explains why diffraction peaks are obtained from samples with very few crystallites, which cannot be explained with the conventional theory. The intensity ratios for an Si powder sample are predicted with greater accuracy and the temperature factors are more realistic. Another consequence is that this new theory predicts a reliability in the intensity measurements which agrees much more closely with experimental observations compared to conventional theory that is based on `Bragg-type' scatter. The role of dynamical effects (extinction etc.) is discussed and how they are suppressed with diffuse scattering. An alternative explanation for the Lorentz factor is presented that is more general and based on the capture volume in diffraction space. This theory, when applied to the scattering from powders, will evaluate the full scattering profile, including peak widths and the `background'. The theory should provide an increased understanding of the reliability of powder diffraction measurements, and may also have wider implications for the analysis of powder diffraction data, by increasing the accuracy of intensities predicted from structural models.

Anisotropic pyrochemical microetching of poly(tetrafluoroethylene) initiated by synchrotron radiation-induced scission of molecule bonds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamaguchi, Akinobu, E-mail: yamaguti@lasti.u-hyogo.ac.jp, E-mail: utsumi@lasti.u-hyogo.ac.jp; Kido, Hideki; Utsumi, Yuichi, E-mail: yamaguti@lasti.u-hyogo.ac.jp, E-mail: utsumi@lasti.u-hyogo.ac.jp

2016-02-01

We developed a process for micromachining polytetrafluoroethylene (PTFE): anisotropic pyrochemical microetching induced by synchrotron X-ray irradiation. X-ray irradiation was performed at room temperature. Upon heating, the irradiated PTFE substrates exhibited high-precision features. Both the X-ray diffraction peak and Raman signal from the irradiated areas of the substrate decreased with increasing irradiation dose. The etching mechanism is speculated as follows: X-ray irradiation caused chain scission, which decreased the number-average degree of polymerization. The melting temperature of irradiated PTFE decreased as the polymer chain length decreased, enabling the treated regions to melt at a lower temperature. The anisotropic pyrochemical etching process enabledmore » the fabrication of PTFE microstructures with higher precision than simultaneously heating and irradiating the sample.« less

In operando X-ray diffraction strain measurement in Ni 3Sn 2 – Coated inverse opal nanoscaffold anodes for Li-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glazer, Matthew P. B.; Wang, Junjie; Cho, Jiung

Volume changes associated with the (de)lithiation of a nanostructured Ni 3Sn 2 coated nickel inverse opal scaffold anode create mismatch stresses and strains between the Ni 3Sn 2 anode material and its mechanically supporting Ni scaffold. By using in operando synchrotron x-ray diffraction measurements, elastic strains in the Ni scaffold are determined during cyclic (dis)charging of the Ni 3Sn 2 anode. These strains are characterized using both the center position of the Ni diffraction peaks, to quantify the average strain, and the peak breadth, which describes the distribution of strain in the measured volume. Upon lithiation (half-cell discharging) or delithiationmore » (half-cell charging), compressive strains and peak breadth linearly increase or decrease, respectively, with charge. The evolution of the average strains and peak breadths suggests that some irreversible plastic deformation and/or delamination occurs during cycling, which can result in capacity fade in the anode. The strain behavior associated with cycling of the Ni 3Sn 2 anode is similar to that observed in recent studies on a Ni inverse-opal supported amorphous Si anode and demonstrates that the (de)lithiation-induced deformation and damage mechanisms are likely equivalent in both anodes, even though the magnitude of mismatch strain in the Ni 3Sn 2 is lower due to the lower (de)lithiation-induced contraction/expansion.« less

In operando X-ray diffraction strain measurement in Ni 3Sn 2 – Coated inverse opal nanoscaffold anodes for Li-ion batteries

DOE PAGES

Glazer, Matthew P. B.; Wang, Junjie; Cho, Jiung; ...

2017-11-01

Volume changes associated with the (de)lithiation of a nanostructured Ni 3Sn 2 coated nickel inverse opal scaffold anode create mismatch stresses and strains between the Ni 3Sn 2 anode material and its mechanically supporting Ni scaffold. By using in operando synchrotron x-ray diffraction measurements, elastic strains in the Ni scaffold are determined during cyclic (dis)charging of the Ni 3Sn 2 anode. These strains are characterized using both the center position of the Ni diffraction peaks, to quantify the average strain, and the peak breadth, which describes the distribution of strain in the measured volume. Upon lithiation (half-cell discharging) or delithiationmore » (half-cell charging), compressive strains and peak breadth linearly increase or decrease, respectively, with charge. The evolution of the average strains and peak breadths suggests that some irreversible plastic deformation and/or delamination occurs during cycling, which can result in capacity fade in the anode. The strain behavior associated with cycling of the Ni 3Sn 2 anode is similar to that observed in recent studies on a Ni inverse-opal supported amorphous Si anode and demonstrates that the (de)lithiation-induced deformation and damage mechanisms are likely equivalent in both anodes, even though the magnitude of mismatch strain in the Ni 3Sn 2 is lower due to the lower (de)lithiation-induced contraction/expansion.« less

Probing Photoinduced Structural Phase Transitions by Fast or Ultra-Fast Time-Resolved X-Ray Diffraction

NASA Astrophysics Data System (ADS)

Cailleau, Hervé Collet, Eric; Buron-Le Cointe, Marylise; Lemée-Cailleau, Marie-Hélène Koshihara, Shin-Ya

A new frontier in the field of structural science is the emergence of the fast and ultra-fast X-ray science. Recent developments in time-resolved X-ray diffraction promise direct access to the dynamics of electronic, atomic and molecular motions in condensed matter triggered by a pulsed laser irradiation, i.e. to record "molecular movies" during the transformation of matter initiated by light pulse. These laser pump and X-ray probe techniques now provide an outstanding opportunity for the direct observation of a photoinduced structural phase transition as it takes place. The use of X-ray short-pulse of about 100ps around third-generation synchrotron sources allows structural investigations of fast photoinduced processes. Other new X-ray sources, such as laser-produced plasma ones, generate ultra-short pulses down to 100 fs. This opens the way to femtosecond X-ray crystallography, but with rather low X-ray intensities and more limited experimental possibilities at present. However this new ultra-fast science rapidly progresses around these sources and new large-scale projects exist. It is the aim of this contribution to overview the state of art and the perspectives of fast and ultra-fast X-ray scattering techniques to study photoinduced phase transitions (here, the word ultra-fast is used for sub-picosecond time resolution). In particular we would like to largely present the contribution of crystallographic methods in comparison with optical methods, such as pump-probe reflectivity measurements, the reader being not necessary familiar with X-ray scattering. Thus we want to present which type of physical information can be obtained from the positions of the Bragg peaks, their intensity and their shape, as well as from the diffuse scattering beyond Bragg peaks. An important physical feature is to take into consideration the difference in nature between a photoinduced phase transition and conventional homogeneous photoinduced chemical or biochemical processes where molecules transform in an independent way each other. Actually the photoinduced phase transition with the establishment of the new electronic and structural oscopic order is preceded by precursor co-operative phenomena due to the formation of nano-scale correlated objects. These are the counterpart of pre-transitional fluctuations at thermal equilibrium which take place above the transition temperature (short range order preceding long range one). Moreover ultra-fast X-ray scattering will play a central role within the fascinating field of manipulating coherence, for instance to directly observe coherent atomic motions induced by a light pulse, such as optical phonons. In the first part of this contribution we present what experimental features are accessible by X-ray scattering to describe the physical picture for a photoinduced structural phase transition. The second part shows how a time-resolved X-ray scattering experiment can be performed with regards to the different pulsed X-ray sources. The first time-resolved X-ray diffraction experiments on photoinduced phase transitions are described and discussed in the third part. Finally some challenges for future are briefly indicated in the conclusion.

Microyielding of core-shell crystal dendrites in a bulk-metallic-glass matrix composite

DOE PAGES

Huang, E. -Wen; Qiao, Junwei; Winiarski, Bartlomiej; ...

2014-03-18

In-situ synchrotron x-ray experiments have been used to follow the evolution of the diffraction peaks for crystalline dendrites embedded in a bulk metallic glass matrix subjected to a compressive loading-unloading cycle. We observe irreversible diffraction-peak splitting even though the load does not go beyond half of the bulk yield strength. The chemical analysis coupled with the transmission electron microscopy mapping suggests that the observed peak splitting originates from the chemical heterogeneity between the core (major peak) and the stiffer shell (minor peak) of the dendrites. A molecular dynamics model has been developed to compare the hkl-dependent microyielding of the bulkmore » metallic-glass matrix composite. As a result, the complementary diffraction measurements and the simulation results suggest that the interfaces between the amorphous matrix and the (211) crystalline planes relax under prolonged load that causes a delay in the reload curve which ultimately catches up with the original path.« less

Experimental evidences for molecular origin of low-Q peak in neutron/x-ray scattering of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ionic liquids

NASA Astrophysics Data System (ADS)

Fujii, Kenta; Kanzaki, Ryo; Takamuku, Toshiyuki; Kameda, Yasuo; Kohara, Shinji; Kanakubo, Mitsuhiro; Shibayama, Mitsuhiro; Ishiguro, Shin-ichi; Umebayashi, Yasuhiro

2011-12-01

Short- and long-range liquid structures of [CnmIm+][TFSA-] with n = 2, 4, 6, 8, 10, and 12 have been studied by high-energy x-ray diffraction (HEXRD) and small-angle neutron scattering (SANS) experiments with the aid of MD simulations. Observed x-ray structure factor, S(Q), for the ionic liquids with the alkyl-chain length n > 6 exhibited a characteristic peak in the low-Q range of 0.2-0.4 Å -1, indicating the heterogeneity of their ionic liquids. SANS profiles IH(Q) and ID(Q) for the normal and the alkyl group deuterated ionic liquids, respectively, showed significant peaks for n = 10 and 12 without no form factor component for large spherical or spheroidal aggregates like micelles in solution. The peaks for n = 10 and 12 evidently disappeared in the difference SANS profiles ΔI(Q) [=ID(Q) - IH(Q)], although that for n = 12 slightly remained. This suggests that the long-range correlations originated from the alkyl groups hardly contribute to the low-Q peak intensity in SANS. To reveal molecular origin of the low-Q peak, we introduce here a new function; x-ray structure factor intensity at a given Q as a function of r, SQpeak(r). The SQpeak(r) function suggests that the observed low-Q peak intensity depending on n is originated from liquid structures at two r-region of 5-8 and 8-15 Å for all ionic liquids examined except for n = 12. Atomistic MD simulations are consistent with the HEXRD and SANS experiments, and then we discussed the relationship between both variations of low-Q peak and real-space structure with lengthening the alkyl group of the CnmIm.

Digital Image Correlation of 2D X-ray Powder Diffraction Data for Lattice Strain Evaluation

PubMed Central

Zhang, Hongjia; Sui, Tan; Daisenberger, Dominik; Fong, Kai Soon

2018-01-01

High energy 2D X-ray powder diffraction experiments are widely used for lattice strain measurement. The 2D to 1D conversion of diffraction patterns is a necessary step used to prepare the data for full pattern refinement, but is inefficient when only peak centre position information is required for lattice strain evaluation. The multi-step conversion process is likely to lead to increased errors associated with the ‘caking’ (radial binning) or fitting procedures. A new method is proposed here that relies on direct Digital Image Correlation analysis of 2D X-ray powder diffraction patterns (XRD-DIC, for short). As an example of using XRD-DIC, residual strain values along the central line in a Mg AZ31B alloy bar after 3-point bending are calculated by using both XRD-DIC and the conventional ‘caking’ with fitting procedures. Comparison of the results for strain values in different azimuthal angles demonstrates excellent agreement between the two methods. The principal strains and directions are calculated using multiple direction strain data, leading to full in-plane strain evaluation. It is therefore concluded that XRD-DIC provides a reliable and robust method for strain evaluation from 2D powder diffraction data. The XRD-DIC approach simplifies the analysis process by skipping 2D to 1D conversion, and opens new possibilities for robust 2D powder diffraction data analysis for full in-plane strain evaluation. PMID:29543728

Diversity of band gap and photoluminescence properties of lead halide perovskite: A halogen-dependent spectroscopic study

NASA Astrophysics Data System (ADS)

Yu, Wenlei; Jiang, Yunfeng; Zhu, Xiuwei; Luo, Chunhua; Jiang, Kai; Chen, Liangliang; Zhang, Juan

2018-05-01

The effects of halogen substitution on microstructure, optical absorption, and phonon modes for perovskite CH3NH3PbX3 (MAPbX3, X = I/Br/Cl) films grown on FTO substrates have been investigated. The X-ray diffraction analysis exhibited good crystallization, and the strong diffraction peak assigned to (1 0 0) c for X = Br/Cl shifted toward a higher angle compared to (1 1 0) t of MAPbI3. Band-gap tuning from 1.63 to 2.37 to 3.11 eV in the I-Br-Cl series can be found due to the halogen effects. These energy values closely match the positions of peak determined from photoluminescence experiments. The remarkable absorption dip and emission peak appear for the MAPbBr3, suggesting higher crystallinity under the same preparation conditions. The wavenumbers of main IR-vibrations slightly decrease with ionic radius of the halogen increasing (in the order of Cl-Br-I), which related to the increasing polarizability. These results provide important progress towards the understanding of the halide role in the realization of high performance MAPbX3-based solar cells.

Electric field dependent local structure of ( K x N a 1 - x ) 0.5 B i 0.5 Ti O 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goetzee-Barral, A. J.; Usher, T. -M.; Stevenson, T. J.

The in situ x-ray pair-distribution function (PDF) characterization technique has been used to study the behavior of (K xNa 1–x) 0.5Bi 0.5TiO 3, as a function of electric field. As opposed to conventional x-ray Bragg diffraction techniques, PDF is sensitive to local atomic displacements, detecting local structural changes at the angstrom to nanometer scale. Several field-dependent ordering mechanisms can be observed in x = 0.15, 0.18 and at the morphotropic phase boundary composition x = 0.20. X-ray total scattering shows suppression of diffuse scattering with increasing electric-field amplitude, indicative of an increase in structural ordering. Analysis of PDF peaks inmore » the 3–4-Å range shows ordering of Bi-Ti distances parallel to the applied electric field, illustrated by peak amplitude redistribution parallel and perpendicular to the electric-field vector. A transition from < 110 > to < 112 >-type off-center displacements of Bi relative to the neighboring Ti atoms is observable with increasing x. Analysis of PDF peak shift with electric field shows the effects of Bi-Ti redistribution and onset of piezoelectric lattice strain. Furthermore, the combination of these field-induced ordering mechanisms is consistent with local redistribution of Bi-Ti distances associated with domain reorientation and an overall increase in order of atomic displacements.« less

Electric field dependent local structure of ( K x N a 1 - x ) 0.5 B i 0.5 Ti O 3

DOE PAGES

Goetzee-Barral, A. J.; Usher, T. -M.; Stevenson, T. J.; ...

2017-07-31

The in situ x-ray pair-distribution function (PDF) characterization technique has been used to study the behavior of (K xNa 1–x) 0.5Bi 0.5TiO 3, as a function of electric field. As opposed to conventional x-ray Bragg diffraction techniques, PDF is sensitive to local atomic displacements, detecting local structural changes at the angstrom to nanometer scale. Several field-dependent ordering mechanisms can be observed in x = 0.15, 0.18 and at the morphotropic phase boundary composition x = 0.20. X-ray total scattering shows suppression of diffuse scattering with increasing electric-field amplitude, indicative of an increase in structural ordering. Analysis of PDF peaks inmore » the 3–4-Å range shows ordering of Bi-Ti distances parallel to the applied electric field, illustrated by peak amplitude redistribution parallel and perpendicular to the electric-field vector. A transition from < 110 > to < 112 >-type off-center displacements of Bi relative to the neighboring Ti atoms is observable with increasing x. Analysis of PDF peak shift with electric field shows the effects of Bi-Ti redistribution and onset of piezoelectric lattice strain. Furthermore, the combination of these field-induced ordering mechanisms is consistent with local redistribution of Bi-Ti distances associated with domain reorientation and an overall increase in order of atomic displacements.« less

X-ray diffraction from shock-loaded polycrystals.

PubMed

Swift, Damian C

2008-01-01

X-ray diffraction was demonstrated from shock-compressed polycrystalline metals on nanosecond time scales. Laser ablation was used to induce shock waves in polycrystalline foils of Be, 25-125 microm thick. A second laser pulse was used to generate a plasma x-ray source by irradiation of a Ti foil. The x-ray source was collimated to produce a beam of controllable diameter, which was directed at the Be sample. X-rays were diffracted from the sample, and detected using films and x-ray streak cameras. The diffraction angle was observed to change with shock pressure. The diffraction angles were consistent with the uniaxial (elastic) and isotropic (plastic) compressions expected for the loading conditions used. Polycrystalline diffraction will be used to measure the response of the crystal lattice to high shock pressures and through phase changes.

Comment on Sub-15 nm Hard X-Ray Focusing with a New Total-Reflection Zone Plate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Specht, Eliot D

2011-01-01

Takano et al. report the focusing of 10-keV X-rays to a size of 14.4 nm using a total-reflection zone plate (TRZP). This focal size is at the diffraction limit for the optic's aperture. This would be a noteworthy result, since the TRZP was fabricated using conventional lithography techniques. Alternative nanofocusing optics require more demanding fabrication methods. However, as I will discuss in this Comment, the intensity distribution presented by Takano et al. (Fig. 4 of ref. 1) is more consistent with the random speckle pattern produced by the scattering of a coherent incident beam by a distorted optic than withmore » a diffraction-limited focus. When interpreted in this manner, the true focal spot size is {approx}70 nm: 5 times the diffraction limit. When a coherent photon beam illuminates an optic containing randomly distributed regions which introduce different phase shifts, the scattered diffraction pattern consists of a speckle pattern. Each speckle will be diffraction-limited: the peak width of a single speckle depends entirely on the source coherence and gives no information about the optic. The envelope of the speckle distribution corresponds to the focal spot which would be observed using incoherent illumination. The width of this envelope is due to the finite size of the coherently-diffracting domains produced by slope and position errors in the optic. The focal intensity distribution in Fig. 4 of ref. 1 indeed contains a diffraction-limited peak, but this peak contains only a fraction of the power in the focused, and forms part of a distribution of sharp peaks with an envelope {approx}70 nm in width, just as expected for a speckle pattern. At the 4mm focal distance, the 70 nm width corresponds to a slope error of 18 {micro}rad. To reach the 14 nm diffraction limit, the slope error must be reduced to 3 {micro}rad. Takano et al. have identified a likely source of this error: warping due to stress as a result of zone deposition. It will be interesting to see whether the use of a more rigid substrate gives improved results.« less

Melting-solidification transition of Zn nanoparticles embedded in SiO2: Observation by synchrotron x-ray and ultraviolet-visible-near-infrared light

NASA Astrophysics Data System (ADS)

Amekura, H.; Tanaka, M.; Katsuya, Y.; Yoshikawa, H.; Ohnuma, M.; Matsushita, Y.; Kobayashi, K.; Kishimoto, N.

2010-11-01

Melting-solidification transition of Zn nanoparticles (NPs) with the mean diameter of 11.5 nm, embedded in silica glass, was investigated by glancing incident x-ray diffraction (GIXRD) at high temperatures using synchrotron radiation (SR). With increasing temperature, 101Zn diffraction peak gradually decreases up to ˜360 °C and then steeply decreases. This is due to the melting of Zn NPs, which completes around 420 °C. With decreasing temperature, the solidification of the NPs begins around ˜310 °C. The temperature hysteresis with a width of ˜110 °C was observed. With temperature, the diffraction angle shows a shift without hysteresis, which is ascribed to thermal expansion of Zn NP lattice. Thermal expansion coefficient of Zn NPs was determined as 24.4×10-6 K-1 along the ⟨101⟩ direction. Optical absorption spectroscopy shows a broad ultraviolet (UV) peak which was observed at even higher temperatures than the melting temperature but shifts to the low-energy side with the melting. The energy shift in the UV peak also shows the temperature hysteresis which resembles with the melting-solidification hysteresis recorded by SR-GIXRD. The melting-solidification transition is also detectable by the optical absorption spectroscopy in the UV-visible-near-infrared region.

CCD sensors in synchrotron X-ray detectors

NASA Astrophysics Data System (ADS)

Strauss, M. G.; Naday, I.; Sherman, I. S.; Kraimer, M. R.; Westbrook, E. M.; Zaluzec, N. J.

1988-04-01

The intense photon flux from advanced synchrotron light sources, such as the 7-GeV synchrotron being designed at Argonne, require integrating-type detectors. Charge-coupled devices (CCDs) are well suited as synchrotron X-ray detectors. When irradiated indirectly via a phosphor followed by reducing optics, diffraction patterns of 100 cm 2 can be imaged on a 2 cm 2 CCD. With a conversion efficiency of ˜ 1 CCD electron/X-ray photon, a peak saturation capacity of > 10 6 X-rays can be obtained. A programmable CCD controller operating at a clock frequency of 20 MHz has been developed. The readout rate is 5 × 10 6 pixels/s and the shift rate in the parallel registers is 10 6 lines/s. The test detector was evaluated in two experiments. In protein crystallography diffraction patterns have been obtained from a lysozyme crystal using a conventional rotating anode X-ray generator. Based on these results we expect to obtain at a synchrotron diffraction images at a rate of ˜ 1 frame/s or a complete 3-dimensional data set from a single crystal in ˜ 2 min. In electron energy-loss spectroscopy (EELS), the CCD was used in a parallel detection mode which is similar to the mode array detectors are used in dispersive EXAFS. With a beam current corresponding to 3 × 10 9 electron/s on the detector, a series of 64 spectra were recorded on the CCD in a continuous sequence without interruption due to readout. The frame-to-frame pixel signal fluctuations had σ = 0.4% from which DQE = 0.4 was obtained, where the detector conversion efficiency was 2.6 CCD electrons/X-ray photon. These multiple frame series also showed the time-resolved modulation of the electron microscope optics by stray magnetic fields.

Diffraction based Hanbury Brown and Twiss interferometry at a hard x-ray free-electron laser

DOE PAGES

Gorobtsov, O. Yu.; Mukharamova, N.; Lazarev, S.; ...

2018-02-02

X-ray free-electron lasers (XFELs) provide extremely bright and highly spatially coherent x-ray radiation with femtosecond pulse duration. Currently, they are widely used in biology and material science. Knowledge of the XFEL statistical properties during an experiment may be vitally important for the accurate interpretation of the results. Here, for the first time, we demonstrate Hanbury Brown and Twiss (HBT) interferometry performed in diffraction mode at an XFEL source. It allowed us to determine the XFEL statistical properties directly from the Bragg peaks originating from colloidal crystals. This approach is different from the traditional one when HBT interferometry is performed inmore » the direct beam without a sample. Our analysis has demonstrated nearly full (80%) global spatial coherence of the XFEL pulses and an average pulse duration on the order of ten femtoseconds for the monochromatized beam, which is significantly shorter than expected from the electron bunch measurements.« less

Synthesis of silver nanoparticles using leaves of Catharanthus roseus Linn. G. Don and their antiplasmodial activities

PubMed Central

Ponarulselvam, S; Panneerselvam, C; Murugan, K; Aarthi, N; Kalimuthu, K; Thangamani, S

2012-01-01

Objective To develop a novel approach for the green synthesis of silver nanoparticles using aqueous leaves extracts of Catharanthus roseus (C. roseus) Linn. G. Don which has been proven active against malaria parasite Plasmodium falciparum (P. falciparum). Methods Characterizations were determined by using ultraviolet-visible (UV-Vis) spectrophotometry, scanning electron microscopy (SEM), energy dispersive X-ray and X-ray diffraction. Results SEM showed the formation of silver nanoparticles with an average size of 35–55 nm. X-ray diffraction analysis showed that the particles were crystalline in nature with face centred cubic structure of the bulk silver with the broad peaks at 32.4, 46.4 and 28.0. Conclusions It can be concluded that the leaves of C. roseus can be good source for synthesis of silver nanoparticle which shows antiplasmodial activity against P. falciparum. The important outcome of the study will be the development of value added products from medicinal plants C. roseus for biomedical and nanotechnology based industries. PMID:23569974

In Situ XRD Studies of the Process Dynamics During Annealing in Cold-Rolled Copper

NASA Astrophysics Data System (ADS)

Dey, Santu; Gayathri, N.; Bhattacharya, M.; Mukherjee, P.

2016-12-01

The dynamics of the release of stored energy during annealing along two different crystallographic planes, i.e., {111} and {220}, in deformed copper have been investigated using in situ X-ray diffraction measurements at 458 K and 473 K (185 °C and 200 °C). The study has been carried out on 50 and 80 pct cold-rolled Cu sheets. The microstructures of the rolled samples have been characterized using optical microscopy and electron backscattered diffraction measurements. The microstructural parameters were evaluated from the X-ray diffractogram using the Scherrer equation and the modified Rietveld method. The stored energy along different planes was determined using the modified Stibitz formula from the X-ray peak broadening, and the bulk stored energy was evaluated using differential scanning calorimetry. The process dynamics of recovery and recrystallization as observed through the release of stored energy have been modeled as the second-order and first-order processes, respectively.

Diffraction based Hanbury Brown and Twiss interferometry at a hard x-ray free-electron laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorobtsov, O. Yu.; Mukharamova, N.; Lazarev, S.

X-ray free-electron lasers (XFELs) provide extremely bright and highly spatially coherent x-ray radiation with femtosecond pulse duration. Currently, they are widely used in biology and material science. Knowledge of the XFEL statistical properties during an experiment may be vitally important for the accurate interpretation of the results. Here, for the first time, we demonstrate Hanbury Brown and Twiss (HBT) interferometry performed in diffraction mode at an XFEL source. It allowed us to determine the XFEL statistical properties directly from the Bragg peaks originating from colloidal crystals. This approach is different from the traditional one when HBT interferometry is performed inmore » the direct beam without a sample. Our analysis has demonstrated nearly full (80%) global spatial coherence of the XFEL pulses and an average pulse duration on the order of ten femtoseconds for the monochromatized beam, which is significantly shorter than expected from the electron bunch measurements.« less

Structural analysis of bioceramic materials for denture application

NASA Astrophysics Data System (ADS)

Rauf, Nurlaela; Tahir, Dahlang; Arbiansyah, Muhammad

2016-03-01

Structural analysis has been performed on bioceramic materials for denture application by using X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscopy (SEM). XRF is using for analysis chemical composition of raw materials. XRF shows the ratio 1 : 1 : 1 : 1 between feldspar, quartz, kaolin and eggshell, respectively, resulting composition CaO content of 56.78 %, which is similar with natural tooth. Sample preparation was carried out on temperature of 800 °C, 900 °C and 1000 °C. X-ray diffraction result showed that the structure is crystalline with trigonal crystal system for SiO2 (a=b=4.9134 Å and c=5.4051 Å) and CaH2O2 (a=b=3.5925 Å and c=4.9082 Å). Based on the Scherrer's equation showed the crystallite size of the highest peak (SiO2) increase with increasing the temperature preparation. The highest hardness value (87 kg/mm2) and match with the standards of dentin hardness. The surface structure was observed by using SEM also discussed.

Single-pulse x-ray diffraction using polycapillary optics for in situ dynamic diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddox, B. R., E-mail: maddox3@llnl.gov; Akin, M. C., E-mail: akin1@llnl.gov; Teruya, A.

2016-08-15

Diagnostic use of single-pulse x-ray diffraction (XRD) at pulsed power facilities can be challenging due to factors such as the high flux and brightness requirements for diffraction and the geometric constraints of experimental platforms. By necessity, the x-ray source is usually positioned very close, within a few inches of the sample. On dynamic compression platforms, this puts the x-ray source in the debris field. We coupled x-ray polycapillary optics to a single-shot needle-and-washer x-ray diode source using a laser-based alignment scheme to obtain high-quality x-ray diffraction using a single 16 ns x-ray pulse with the source >1 m from themore » sample. The system was tested on a Mo sample in reflection geometry using 17 keV x-rays from a Mo anode. We also identified an anode conditioning effect that increased the x-ray intensity by 180%. Quantitative measurements of the x-ray focal spot produced by the polycapillary yielded a total x-ray flux on the sample of 3.3 ± 0.5 × 10{sup 7} molybdenum Kα photons.« less

Characterization and electron-energy-loss spectroscopy on NiV and NiMo superlattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahmood, S.H.

1986-01-01

NiV superlattices with periods (A) ranging from 15 to 80 A, and NiMo superlattices with from 14 to 110 A were studied using X-ray Diffraction (XRD), Electron Diffraction (ED), Energy-Dispersive X-Ray (EDX) microanalysis, and Electron Energy Loss Spectroscopy (EELS). Both of these systems have sharp superlattice-to-amorphous (S-A) transitions at about empty set = 17A. Superlattices with empty set around the S-A boundary were found to have large local variations in the in-plane grain sizes. Except for a few isolated regions, the chemical composition of the samples were found to be uniform. In samples prepared at Argonne National Laboratory (ANL), mostmore » places studied with EELS showed changes in the EELS spectrum with decreasing empty set. An observed growth in a plasmon peak at approx. 10ev in both NiV and NiMo as empty set decreased down to 19 A is attributed to excitation of interface plasmons. Consistent with this attribution, the peak height shrank in the amorphous samples. The width of this peak is consistent with the theory. The sift in this peak down to 9 ev with decreasing empty set in NiMo is not understood.« less

X-ray diffraction and infrared spectroscopy studies of Ba(Fe1/2Nb1/2)O3-(Na1/2Bi1/2)TiO3 ceramics

NASA Astrophysics Data System (ADS)

Chandra, K. P.; Yadav, Anjana; Prasad, K.

2018-05-01

Ceramics (1-x)Ba(Fe1/2Nb1/2)O3-x(Na1/2Bi1/2)TiO3; 0≤x≤1.0 were prepared by conventional ceramic synthesis technique. Rietveld refinements of X-ray diffraction data of these ceramics were carried out using FullProf software and determined their crystal symmetry, space group and unit cell dimensions. Rietveld refinement revealed that Ba(Fe1/2Nb1/2)O3 has cubic structure with space group Pm 3 ¯ m and Na1/2Bi1/2)TiO3 has rhombohedral structure with space group R3c. Addition of (Na1/2Bi1/2)TiO3 to Ba(Fe1/2Nb1/2)O3 resulted in the change of unit cell structure from cubic to tetragonal (P4/mmm) for x = 0.75 and the X-Ray diffraction peaks slightly shift towards higher Bragg's angle, suggesting slight decrease in unit cell volume. SEM studies were carried out in order to access the quality of the prepared ceramics which showed a change in grain shapes with the increase of (Na1/2Bi1/2)TiO3 content. FTIR spectra confirmed the formation of perovskite type solid solutions.

Effect of gamma-irradiation on thermal decomposition kinetics, X-ray diffraction pattern and spectral properties of tris(1,2-diaminoethane)nickel(II)sulphate

NASA Astrophysics Data System (ADS)

Jayashri, T. A.; Krishnan, G.; Rema Rani, N.

2014-12-01

Tris(1,2-diaminoethane)nickel(II)sulphate was prepared, and characterised by various chemical and spectral techniques. The sample was irradiated with 60Co gamma rays for varying doses. Sulphite ion and ammonia were detected and estimated in the irradiated samples. Non-isothermal decomposition kinetics, X-ray diffraction pattern, Fourier transform infrared spectroscopy, electronic, fast atom bombardment mass spectra, and surface morphology of the complex were studied before and after irradiation. Kinetic parameters were evaluated by integral, differential, and approximation methods. Irradiation enhanced thermal decomposition, lowering thermal and kinetic parameters. The mechanism of decomposition is controlled by R3 function. From X-ray diffraction studies, change in lattice parameters and subsequent changes in unit cell volume and average crystallite size were observed. Both unirradiated and irradiated samples of the complex belong to trigonal crystal system. Decrease in the intensity of the peaks was observed in the infrared spectra of irradiated samples. Electronic spectral studies revealed that the M-L interaction is unaffected by irradiation. Mass spectral studies showed that the fragmentation patterns of the unirradiated and irradiated samples are similar. The additional fragment with m/z 256 found in the irradiated sample is attributed to S8+. Surface morphology of the complex changed upon irradiation.

Research on the Treatment of Wastewater by Waste Ceramic Adsorption

NASA Astrophysics Data System (ADS)

He, Lingfeng; Zhang, Yongli; Shi, Liang

2018-03-01

The process of preparing porous ceramic with waste porcelain powder as aggregate was researched. The affect of assimilate time on cuprum removal efficiency in wastewater containing copper was investigated. The results show the water copper removal rate increased along with the augment of assimilate time, and the assimilate time is suitable for 35 min; XRD characterizations show the porous ceramic catalyst before and after calcination in active components of X ray diffraction peak position almost had no changes, and the diffraction intensity slightly changed with calcination and absorption, and diffraction peaks became sharper, and its crystallinity was improved. Baking leads to the growth of crystal particles, and the performance of porous ceramics is stable before and after adsorption.

Opportunities and challenges for time-resolved studies of protein structural dynamics at X-ray free-electron lasers.

PubMed

Neutze, Richard

2014-07-17

X-ray free-electron lasers (XFELs) are revolutionary X-ray sources. Their time structure, providing X-ray pulses of a few tens of femtoseconds in duration; and their extreme peak brilliance, delivering approximately 10(12) X-ray photons per pulse and facilitating sub-micrometre focusing, distinguish XFEL sources from synchrotron radiation. In this opinion piece, I argue that these properties of XFEL radiation will facilitate new discoveries in life science. I reason that time-resolved serial femtosecond crystallography and time-resolved wide angle X-ray scattering are promising areas of scientific investigation that will be advanced by XFEL capabilities, allowing new scientific questions to be addressed that are not accessible using established methods at storage ring facilities. These questions include visualizing ultrafast protein structural dynamics on the femtosecond to picosecond time-scale, as well as time-resolved diffraction studies of non-cyclic reactions. I argue that these emerging opportunities will stimulate a renaissance of interest in time-resolved structural biochemistry.

Emerging trends in X-ray spectroscopic studies of plasma produced by intense laser beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arora, V., E-mail: arora@rrcat.gov.in; Chakera, J. A.; Naik, P. A.

2015-07-31

X-ray line emission from hot dense plasmas, produced by ultra-short high intensity laser systems, has been studied experimentally in recent years for applications in materials science as well as for back-lighter applications. By virtue of the CPA technology, several laser facilities delivering pulses with peak powers in excess of one petawatt (focused intensities > 10{sup 20} W-cm{sup −2}) have either been commissioned across the globe during the last few years or are presently under construction. On the other hand, hard x-ray sources on table top, generating ultra-short duration x-rays at a repetition rate up to 10 kHz, are routinely available formore » time resolved x-ray diffraction studies. In this paper, the recent experiments on x-ray spectroscopic studies of plasma produced by 45 fs, Ti:sapphire laser pulses (focused iintensity > 10{sup 18} W-cm{sup −2}) at RRCAT Indore will be presented.« less

Quick measurement of crystal truncation rod profiles in simultaneous multi-wavelength dispersive mode

NASA Astrophysics Data System (ADS)

Matsushita, T.; Takahashi, T.; Shirasawa, T.; Arakawa, E.; Toyokawa, H.; Tajiri, H.

2011-11-01

To conduct time-resolved measurements in the wide momentum transfer (q = 4π sinθ/λ, θ: the glancing angle of the x-ray beam, λ: x-ray wavelength) range of interest, we developed a method that can simultaneously measure the whole profile of x-ray diffraction and crystal truncation rod scattering of interest with no need of rotation of the specimen, detector, and monochromator crystal during the measurement. With a curved crystal polychromator (Si 111 diffraction), a horizontally convergent x-ray beam having a one-to-one correlation between wavelength (energy: 16.24-23.0 keV) and direction is produced. The convergent x-ray beam components of different wavelengths are incident on the specimen in a geometry where θ is the same for all the x-ray components and are diffracted within corresponding vertical scattering planes by a specimen ([GaAs(12ML)/AlAs(8 ML)]50 on GaAs(001) substrate) placed at the focal point. Although θ is the same for all the directions, q continuously varies because λ changes as a function of direction. The normalized horizontal intensity distribution across the beam, as measured using a two-dimensional pixel array detector downstream of the specimen, represents the reflectivity curve profile both near to and far from the Bragg point. As for the crystal truncation rod scattering around the 002 reflection, the diffraction profile from the Bragg peak down to reflectivity of 1.0 × 10-9 was measured with a sufficient data collection time (1000-2000 s). With data collection times of 100, 10, 1.0, and 0.1 s, profiles down to a reflectivity of ˜6 × 10-9, ˜2 × 10-8, ˜8 × 10-8, and ˜8 × 10-7 were measured, respectively. To demonstrate the time-resolving capability of the system, reflectivity curves were measured with time resolutions of 1.0 s while rotating the specimen. We have also measured the diffraction profile around the 113 reflection in the non-specular reflection geometry.

Effect of different conventional melt quenching technique on purity of lithium niobate (LiNbO3) nano crystal phase formed in lithium borate glass

NASA Astrophysics Data System (ADS)

Kashif, Ismail; Soliman, Ashia A.; Sakr, Elham M.; Ratep, Asmaa

2012-01-01

The glass system (45Li2O + 45B2O3 + 10Nb2O5) was fabricated by the conventional melt quenching technique poured in water, at air, between two hot plates and droplets at the cooled surface. The glass and glass ceramics were studied by differential thermal analysis (DTA) and X-ray diffraction (XRD). The as quenched samples poured in water and between two hot plates were amorphous. The samples poured at air and on cooled surface were crystalline as established via X-ray powder diffraction (XRD) studies. Differential thermal analysis was measured. The glass transition temperature (Tg) and the crystallization temperatures were calculated. Lithium niobate (LiNbO3) was the main phase in glass ceramic poured at air, droplets at the cooled surface and the heat treated glass sample at 500, 540 and 580 °C in addition to traces from LiNb3O8. Crystallite size of the main phases determined from the X-ray diffraction peaks is in the range of <100 nm. The fraction of crystalline (LiNbO3) phase decreases with increase in the heat treatment temperature.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Bing-Bing; Liu, Jian; Wei, Xu

We investigate the transient photoexcited lattice dynamics in a layered perovskite Mott insulator Sr2IrO4 film by femtosecond X-ray diffraction using a laser plasma-based X-ray source. The ultrafast structural dynamics of Sr2IrO4 thin films are determined by observing the shift and broadening of (0012) Bragg diffraction after excitation by 1.5 eV and 3.0 eV pump photons for films with different thicknesses. The observed transient lattice response can be well interpreted as a distinct three-step dynamics due to the propagation of coherent acoustic phonons generated by photoinduced quasiparticles (QPs). Employing a normalized phonon propagation model, we found that the photoinduced angular shiftsmore » of the Bragg peak collapse into a universal curve after introducing normalizedn coordinates to account for different thicknesses and pump photon energies, pinpointing the origin of the lattice distortion and its early evolution. In addition, a transient photocurrent measurement indicates that the photoinduced QPs are charge neutral excitons. Mapping the phonon propagation and correlating its dynamics with the QP by ultrafast X-ray diffraction (UXRD) establish a powerful way to study electron-phonon coupling and uncover the exotic physics in strongly correlated systems under nonequilibrium conditions.« less

Study of gold nanoparticle synthesis by synchrotron x-ray diffraction and fluorescence

NASA Astrophysics Data System (ADS)

Yan, Zhongying; Wang, Xiao; Yu, Le; Moeendarbari, Sina; Hao, Yaowu; Cai, Zhonghou; Cheng, Xuemei

Gold nanoparticles have a wide range of potential applications, including therapeutic agent delivery, catalysis, and electronics. Recently a new process of hollow nanoparticle synthesis was reported, the mechanism of which was hypothesized to involve electroless deposition around electrochemically evolved hydrogen bubbles. However, the growth mechanism still needs experimental evidence. We report investigation of this synthesis process using synchrotron x-ray diffraction and fluorescence measurements performed at beamline 2-ID-D of the Advanced Photon Source (APS). A series of gold nanoparticle samples with different synthesis time (50-1200 seconds) were deposited using a mixture electrolyte solution of Na3Au(SO3)2 and H4N2NiO6S2 on anodic aluminum oxide (AAO) membranes. The 2D mapping of fluorescence intensity and comparison of x-ray diffraction peaks of the samples have provided valuable information on the growth mechanism. Work at Bryn Mawr College and University of Texas at Arlington is supported by NSF Grants (1207085 and 1207377) and use of the APS at Argonne National Laboratory is supported by the U. S. Department of Energy under Contract No. DE-AC02-06CH11357.

[Physicochemical properties of suplatast tosilate racemate and enantiomers].

PubMed

Ushio, T; Endo, K; Yamamoto, K

1996-11-01

The physicochemical properties of the enantiomer and racemates of suplatast tosilate (ST) were investigated by means of infrared spectroscopy, solid-state 13C CP/MAS NMR spectroscopy, thermal analysis, and X-ray diffraction analysis, and by measuring the solubility and hygroscopy. The infrared and NMR spectra and X-ray diffraction pattern of the enantiomer were distinctly different from those of the racemate. The melting point of the enantiomer was lower than that of the racemate by 5 degrees C, while the solubility of the enantiomer was 1.3 times higher than that of the racemate. The hygroscopic rate of the enantiomer was greater than that of the racemate. These results suggested that ST was classified into a racemic compound crystal. Furthermore, by comparing the relative peak intensity ratios on X-ray diffraction patterns of the crystals with various optical purities prepared by recrystallization, it was found that a mixture of racemic compound crystals and either of racemic mixture crystals or racemic solid solutions was obtained by recrystallization of ST in the content of 0 to 64%ee, while the recrystallization of ST in the content of more than 64%ee led to the formation of racemic mixture crystals or racemic solid solutions.

Measurement of fundamental illite particle thicknesses by X-ray diffraction using PVP-10 intercalation

USGS Publications Warehouse

Eberl, D.D.; Nüesch, R.; Šucha, Vladimír; Tsipursky, S.

1998-01-01

The thicknesses of fundamental illite particles that compose mixed-layer illite-smectite (I-S) crystals can be measured by X-ray diffraction (XRD) peak broadening techniques (Bertaut-Warren-Averbach [BWA] method and integral peak-width method) if the effects of swelling and XRD background noise are eliminated from XRD patterns of the clays. Swelling is eliminated by intercalating Na-saturated I-S with polyvinylpyrrolidone having a molecular weight of 10,000 (PVP-10). Background is minimized by using polished metallic silicon wafers cut perpendicular to (100) as a substrate for XRD specimens, and by using a single-crystal monochromator. XRD measurements of PVP-intercalated diagenetic, hydrothermal and low-grade metamorphic I-S indicate that there are at least 2 types of crystallite thickness distribution shapes for illite fundamental particles, lognormal and asymptotic; that measurements of mean fundamental illite particle thicknesses made by various techniques (Bertant-Warren-Averbach, integral peak width, fixed cation content, and transmission electron microscopy [TEM]) give comparable results; and that strain (small differences in layer thicknesses) generally has a Gaussian distribution in the log-normal-type illites, but is often absent in the asymptotic-type illites.

High-pressure polymorphism of the electrochemically active organic molecule tetrahydroxy-p-benzoquinone

DOE PAGES

Ciezak-Jenkins, Jennifer A.

2016-04-22

We have studied the structural and chemical response of tetrahydroxy-p-benzoquinone to isothermal compression to near 20 GPa using powder x-ray diffraction and vibrational spectroscopy. Compression beyond 11.5 GPa resulted in the appearance of several new peaks in the x-ray patterns, changes in the peak distribution and intensities, as well as the disappearance of features observed at lower pressures, which when coupled with concomitant changes in the infrared spectrum are indicative of a phase transition. Further analysis of the infrared spectra suggest this phase transition results in an increase in the anharmonicity of the system. Finally, Raman spectroscopic experiments indicate themore » high-pressure phase to be highly photosensitive and easily polymerized.« less

X-Ray Diffraction Apparatus

NASA Technical Reports Server (NTRS)

Blake, David F. (Inventor); Bryson, Charles (Inventor); Freund, Friedmann (Inventor)

1996-01-01

An x-ray diffraction apparatus for use in analyzing the x-ray diffraction pattern of a sample is introduced. The apparatus includes a beam source for generating a collimated x-ray beam having one or more discrete x-ray energies, a holder for holding the sample to be analyzed in the path of the beam, and a charge-coupled device having an array of pixels for detecting, in one or more selected photon energy ranges, x-ray diffraction photons produced by irradiating such a sample with said beam. The CCD is coupled to an output unit which receives input information relating to the energies of photons striking each pixel in the CCD, and constructs the diffraction pattern of photons within a selected energy range striking the CCD.

Structure of a two-dimensional crystal in a Langmuir monolayer: grazing incidence X-ray diffraction and macroscopic properties

NASA Astrophysics Data System (ADS)

Flament, C.; Gallet, F.; Graner, F.; Goldmann, M.; Peterson, I.; Renault, A.

1994-06-01

Grazing incidence X-ray diffraction is performed on a Langmuir monolayer made of pure fluorescent NBD-stearic acid, spread at the free surface of water. It shows several intense narrow peaks in the solid phase, at the same wavevectors as the brightest peaks observed earlier by electron diffraction, for a monolayer transferred onto an amorphous polymer substrate. Thus the solid phase has the same crystalline structure on water and on solid substrate. The relative peak intensities are comparable in both experiments, and in the proposed model for the molecular structure. This model also accounts for the very large anisotropy of the crystalline phase and its optical properties. This phase could be ferroelectric, as previously assumed in order to explain the elongated shape of the crystals. Une monocouche de Langmuir, composée d'acide NBD-stéarique fluorescent pur, déposée à la surface libre de l'eau, est analysée par diffraction de rayons X sous incidence rasante. On détecte plusieurs pics étroits et intenses dans la phase solide, aux mêmes vecteurs d'onde que les pics les plus brillants précédemment observés par diffraction électronique, pour une monocouche transférée sur un substrat de polymère amorphe. La phase solide a donc la même structure cristalline sur l'eau et sur substrat solide. Les intensités relatives des pics sont comparables dans les deux expériences, ainsi que dans le modèle proposé pour la structure moléculaire. Ce modèle rend également compte de l'anisotropie très importante de la phase cristalline et de ses propriétés optiques. Il pourrait s'agir d'une phase ferroélectrique, comme cela avait été précédemment supposé pour expliquer la forme allongée des cristaux.

An Improved X-ray Diffraction Method For Cellulose Crystallinity Measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ju, Xiaohui; Bowden, Mark E.; Brown, Elvie E.

2015-06-01

We show in this work a modified X-ray diffraction method to determine cellulose crystallinity index (CrI). Nanocrystalline cellulose (NCC) dervided from bleached wood pulp was used as a model substrate. Rietveld refinement was applied with consideration of March-Dollase preferred orientation at the (001) plane. In contrast to most previous methods, three distinct amorphous peaks identified from new model samples which are used to calculate CrI. A 2 theta range from 10° to 75° was found to be more suitable to determine CrI and crystallite structural parameters such as d-spacing and crystallite size. This method enables a more reliable measurement ofmore » CrI of cellulose and may be applicable to other types of cellulose polymorphs.« less

Raman validity for crystallite size La determination on reticulated vitreous carbon with different graphitization index

NASA Astrophysics Data System (ADS)

Baldan, M. R.; Almeida, E. C.; Azevedo, A. F.; Gonçalves, E. S.; Rezende, M. C.; Ferreira, N. G.

2007-11-01

The graphitization index provided by X-ray diffraction (XRD) and Raman spectrometry for reticulated vitreous carbon (RVC) substrates, carbonized at different heat treatment temperatures (HTT), is investigated. A systematic study of the dependence between the disorder-induced D and G Raman bands is presented. The crystallite size La was obtained for both X-ray diffraction and Raman spectrometry techniques. Particularly, the validity for La determination, from Raman spectra, is pointed out comparing the commonly used formula based on peaks amplitude ratio ( ID/ IG) and the recent proposed equation that uses the integrated intensities of D and G bands. The results discrepancy is discussed taken into account the strong contribution of the line broadening presented in carbon materials heat treated below 2000 °C.

Real-time X-ray Diffraction: Applications to Materials Characterization

NASA Technical Reports Server (NTRS)

Rosemeier, R. G.

1984-01-01

With the high speed growth of materials it becomes necessary to develop measuring systems which also have the capabilities of characterizing these materials at high speeds. One of the conventional techniques of characterizing materials was X-ray diffraction. Film, which is the oldest method of recording the X-ray diffraction phenomenon, is not quite adequate in most circumstances to record fast changing events. Even though conventional proportional counters and scintillation counters can provide the speed necessary to record these changing events, they lack the ability to provide image information which may be important in some types of experiment or production arrangements. A selected number of novel applications of using X-ray diffraction to characterize materials in real-time are discussed. Also, device characteristics of some X-ray intensifiers useful in instantaneous X-ray diffraction applications briefly presented. Real-time X-ray diffraction experiments with the incorporation of image X-ray intensification add a new dimension in the characterization of materials. The uses of real-time image intensification in laboratory and production arrangements are quite unlimited and their application depends more upon the ingenuity of the scientist or engineer.

Dolomite-II: A new high pressure polymorph of CaMg(CO3)2

NASA Astrophysics Data System (ADS)

Santillan, J.; Williams, Q.; Knittle, E.

2002-12-01

We have measured the infrared spectra and x-ray diffraction of CaMg(CO3)2-dolomite to pressures of 50 GPa at 300 K. We observe both splittings and disappearances of x-ray diffraction peaks between 15 and 20 GPa, as well as new bands in the infrared spectrum of dolomite. The onset of the changes in both the x-ray and infrared data appears to be gradual, and thus kinetically impeded: this is consistent with previous shock results. The infrared and x-ray data are consistent with dolomite adopting a calcite-III-like structure. The net volume change associated with the transition based on a calcite-III monoclinic unit cell is ~4 percent. We calculate that the high pressure phase of dolomite has a volume virtually indistinguishable from that of magnesite plus aragonite. Similarly, an assemblage of the high pressure phase of dolomite and magnesium silicate perovskite has an essentially volume to a magnesite plus calcium silicate perovskite assemblage. Our results thus indicate that high-pressure polymorphism in dolomite could stabilize CaMg(CO3)2 in the deep mantle, and thus that high-pressure polymorphs of dolomite could represent the main reservoir for carbon storage within Earth's lower mantle.

Electric field dependent local structure of (KxNa1-x) 0.5B i0.5Ti O3

NASA Astrophysics Data System (ADS)

Goetzee-Barral, A. J.; Usher, T.-M.; Stevenson, T. J.; Jones, J. L.; Levin, I.; Brown, A. P.; Bell, A. J.

2017-07-01

The in situ x-ray pair-distribution function (PDF) characterization technique has been used to study the behavior of (KxNa1-x) 0.5B i0.5Ti O3 , as a function of electric field. As opposed to conventional x-ray Bragg diffraction techniques, PDF is sensitive to local atomic displacements, detecting local structural changes at the angstrom to nanometer scale. Several field-dependent ordering mechanisms can be observed in x =0.15 , 0.18 and at the morphotropic phase boundary composition x =0.20 . X-ray total scattering shows suppression of diffuse scattering with increasing electric-field amplitude, indicative of an increase in structural ordering. Analysis of PDF peaks in the 3-4-Å range shows ordering of Bi-Ti distances parallel to the applied electric field, illustrated by peak amplitude redistribution parallel and perpendicular to the electric-field vector. A transition from <110 > to <112 > -type off-center displacements of Bi relative to the neighboring Ti atoms is observable with increasing x . Analysis of PDF peak shift with electric field shows the effects of Bi-Ti redistribution and onset of piezoelectric lattice strain. The combination of these field-induced ordering mechanisms is consistent with local redistribution of Bi-Ti distances associated with domain reorientation and an overall increase in order of atomic displacements.

The power of in situ pulsed laser deposition synchrotron characterization for the detection of domain formation during growth of Ba0.5Sr0.5TiO3 on MgO.

PubMed

Bauer, Sondes; Lazarev, Sergey; Molinari, Alan; Breitenstein, Andreas; Leufke, Philipp; Kruk, Robert; Hahn, Horst; Baumbach, Tilo

2014-03-01

A highly sophisticated pulsed laser deposition (PLD) chamber has recently been installed at the NANO beamline at the synchrotron facility ANKA (Karlsruhe, Germany), which allows for comprehensive studies on the PLD growth process of dielectric, ferroelectric and ferromagnetic thin films in epitaxial oxide heterostructures or even multilayer systems by combining in situ reflective high-energy diffraction with the in situ synchrotron high-resolution X-ray diffraction and surface diffraction methods. The modularity of the in situ PLD chamber offers the opportunity to explore the microstructure of the grown thin films as a function of the substrate temperature, gas pressure, laser fluence and target-substrate separation distance. Ba0.5Sr0.5TiO3 grown on MgO represents the first system that is grown in this in situ PLD chamber and studied by in situ X-ray reflectivity, in situ two-dimensional reciprocal space mapping of symmetric X-ray diffraction and acquisition of time-resolved diffraction profiles during the ablation process. In situ PLD synchrotron investigation has revealed the occurrence of structural distortion as well as domain formation and misfit dislocation which all depend strongly on the film thickness. The microstructure transformation has been accurately detected with a time resolution of 1 s. The acquisition of two-dimensional reciprocal space maps during the PLD growth has the advantage of simultaneously monitoring the changes of the crystalline structure as well as the formation of defects. The stability of the morphology during the PLD growth is demonstrated to be remarkably affected by the film thickness. A critical thickness for the domain formation in Ba0.5Sr0.5TiO3 grown on MgO could be determined from the acquisition of time-resolved diffraction profiles during the PLD growth. A splitting of the diffraction peak into two distinguishable peaks has revealed a morphology change due to modification of the internal strain during growth.

Radiation damage free ghost diffraction with atomic resolution

DOE PAGES

Li, Zheng; Medvedev, Nikita; Chapman, Henry N.; ...

2017-12-21

The x-ray free electron lasers can enable diffractive structural determination of protein nanocrystals and single molecules that are too small and radiation-sensitive for conventional x-ray diffraction. However the electronic form factor may be modified during the ultrashort x-ray pulse due to photoionization and electron cascade caused by the intense x-ray pulse. For general x-ray imaging techniques, the minimization of the effects of radiation damage is of major concern to ensure reliable reconstruction of molecular structure. Here in this paper, we show that radiation damage free diffraction can be achieved with atomic spatial resolution by using x-ray parametric down-conversion and ghostmore » diffraction with entangled photons of x-ray and optical frequencies. We show that the formation of the diffraction patterns satisfies a condition analogous to the Bragg equation, with a resolution that can be as fine as the crystal lattice length scale of several Ångstrom. Since the samples are illuminated by low energy optical photons, they can be free of radiation damage.« less

Radiation damage free ghost diffraction with atomic resolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zheng; Medvedev, Nikita; Chapman, Henry N.

The x-ray free electron lasers can enable diffractive structural determination of protein nanocrystals and single molecules that are too small and radiation-sensitive for conventional x-ray diffraction. However the electronic form factor may be modified during the ultrashort x-ray pulse due to photoionization and electron cascade caused by the intense x-ray pulse. For general x-ray imaging techniques, the minimization of the effects of radiation damage is of major concern to ensure reliable reconstruction of molecular structure. Here in this paper, we show that radiation damage free diffraction can be achieved with atomic spatial resolution by using x-ray parametric down-conversion and ghostmore » diffraction with entangled photons of x-ray and optical frequencies. We show that the formation of the diffraction patterns satisfies a condition analogous to the Bragg equation, with a resolution that can be as fine as the crystal lattice length scale of several Ångstrom. Since the samples are illuminated by low energy optical photons, they can be free of radiation damage.« less

Synchrotron Radiation X-ray Diffraction Techniques Applied to Insect Flight Muscle.

PubMed

Iwamoto, Hiroyuki

2018-06-13

X-ray fiber diffraction is a powerful tool used for investigating the molecular structure of muscle and its dynamics during contraction. This technique has been successfully applied not only to skeletal and cardiac muscles of vertebrates but also to insect flight muscle. Generally, insect flight muscle has a highly ordered structure and is often capable of high-frequency oscillations. The X-ray diffraction studies on muscle have been accelerated by the advent of 3rd-generation synchrotron radiation facilities, which can generate brilliant and highly oriented X-ray beams. This review focuses on some of the novel experiments done on insect flight muscle by using synchrotron radiation X-rays. These include diffraction recordings from single myofibrils within a flight muscle fiber by using X-ray microbeams and high-speed diffraction recordings from the flight muscle during the wing-beat of live insects. These experiments have provided information about the molecular structure and dynamic function of flight muscle in unprecedented detail. Future directions of X-ray diffraction studies on muscle are also discussed.

Characterization of SiGe thin films using a laboratory X-ray instrument

PubMed Central

Ulyanenkova, Tatjana; Myronov, Maksym; Benediktovitch, Andrei; Mikhalychev, Alexander; Halpin, John; Ulyanenkov, Alex

2013-01-01

The technique of reciprocal space mapping using X-rays is a recognized tool for the nondestructive characterization of epitaxial films. X-ray scattering from epitaxial Si0.4Ge0.6 films on Si(100) substrates using a laboratory X-ray source was investigated. It is shown that a laboratory source with a rotating anode makes it possible to investigate the material parameters of the super-thin 2–6 nm layers. For another set of partially relaxed layers, 50–200 nm thick, it is shown that from a high-resolution reciprocal space map, conditioned from diffuse scattering on dislocations, it is possible to determine quantitatively from the shape of a diffraction peak (possessing no thickness fringes) additional parameters such as misfit dislocation density and layer thickness as well as concentration and relaxation. PMID:24046495

Characterization of SiGe thin films using a laboratory X-ray instrument.

PubMed

Ulyanenkova, Tatjana; Myronov, Maksym; Benediktovitch, Andrei; Mikhalychev, Alexander; Halpin, John; Ulyanenkov, Alex

2013-08-01

The technique of reciprocal space mapping using X-rays is a recognized tool for the nondestructive characterization of epitaxial films. X-ray scattering from epitaxial Si 0.4 Ge 0.6 films on Si(100) substrates using a laboratory X-ray source was investigated. It is shown that a laboratory source with a rotating anode makes it possible to investigate the material parameters of the super-thin 2-6 nm layers. For another set of partially relaxed layers, 50-200 nm thick, it is shown that from a high-resolution reciprocal space map, conditioned from diffuse scattering on dislocations, it is possible to determine quantitatively from the shape of a diffraction peak (possessing no thickness fringes) additional parameters such as misfit dislocation density and layer thickness as well as concentration and relaxation.

Structural analysis of emerging ferrite: Doped nickel zinc ferrite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Rajinder; Kumar, Hitanshu; Singh, Ragini Raj

2015-08-28

Ni{sub 0.6-x}Zn{sub 0.4}Co{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.033, 0.264) nanoparticles were synthesized by sol-gel method and annealed at 900°C. Structural properties of all prepared samples were examined with X-ray diffraction (XRD). The partial formation of hematite (α-Fe{sub 2}O{sub 3}) secondary phase with spinel phase cubic structure of undoped and cobalt doped nickel zinc ferrite was found by XRD peaks. The variation in crystallite size and other structural parameters with cobalt doping has been calculated for most prominent peak (113) of XRD and has been explained on the basis of cations ionic radii difference.

Combining experiment and optical simulation in coherent X-ray nanobeam characterization of Si/SiGe semiconductor heterostructures

DOE PAGES

Tilka, J. A.; Park, J.; Ahn, Y.; ...

2016-07-06

Here, the highly coherent and tightly focused x-ray beams produced by hard x-ray light sources enable the nanoscale characterization of the structure of electronic materials but are accompanied by significant challenges in the interpretation of diffraction and scattering patterns. X-ray nanobeams exhibit optical coherence combined with a large angular divergence introduced by the x-ray focusing optics. The scattering of nanofocused x-ray beams from intricate semiconductor heterostructures produces a complex distribution of scattered intensity. We report here an extension of coherent xray optical simulations of convergent x-ray beam diffraction patterns to arbitrary x-ray incident angles to allow the nanobeam diffraction patternsmore » of complex heterostructures to be simulated faithfully. These methods are used to extract the misorientation of lattice planes and the strain of individual layers from synchrotron x-ray nanobeam diffraction patterns of Si/SiGe heterostructures relevant to applications in quantum electronic devices. The systematic interpretation of nanobeam diffraction patterns from semiconductor heterostructures presents a new opportunity in characterizing and ultimately designing electronic materials.« less

Effect of Boron Doping on High-Resolution X-Ray Diffraction Metrology

NASA Astrophysics Data System (ADS)

Faheem, M.; Zhang, Y.; Dai, X.

2018-03-01

The effect of boron (B) doping on high-resolution X-ray diffraction (HXRD) metrology has been investigated. Twelve samples of Si1-xGex films were epitaxially grown on Si (100) substrates with different thicknesses, germanium (Ge) concentrations and with/without B dopants. Secondary ion mass spectroscopy (SIMS) and HXRD were employed for measurements of B doping, Ge concentration, strain, and thickness of the layers. The SIMS results show the absence of B in two samples while the rest of the samples have B doping in the range of 8.40 × 1018-8.7 × 1020 atoms/cm3 with Ge concentration of 13.3-55.2 at.%. The HXRD measurements indicate the layers thickness of 7.07-108.13 nm along with Ge concentration of 12.82-49.09 at.%. The difference in the Ge concentration measured by SIMS and HXRD was found to deend on B doping. For the undoped samples, the difference is 0.5 at.% and increases with B doping but with no linear proportionality. The difference in the Ge concentration was 7.11 at.% for the highly B-doped (8.7 × 1020 atoms/cm3) sample. The B doping influences the Si1-xGex structure, causing a change in the lattice parameter and producing tensile strains shifting Si1-xGex peaks towards Si (100) substrate peaks in the HXRD diffraction patterns. As a result, Vegard's law is no longer effective and makes a high impact on the HXRD measurement. The comparison between symmetric (004) and asymmetric (+113, +224) reciprocal space mappings (RSM) showed a slight difference in Ge concentration between the undoped and lower B-doped samples. However, there is a change of 0.21 at.% observed for the highly doped Si1-xGex samples. RSM's (+113) demonstrate the small SiGe peak broadening as B doping increases, which indicates a minor crystal distortion.

Development of an X-ray prism for a combined diffraction enhanced imaging and fluorescence imaging system

NASA Astrophysics Data System (ADS)

Bewer, Brian E.

Analyzer crystal based imaging techniques such as diffraction enhanced imaging (DEI) and multiple imaging radiography (MIR) utilize the Bragg peak of perfect crystal diffraction to convert angular changes into intensity changes. These X-ray techniques extend the capability of conventional radiography, which derives image contrast from absorption, by providing a large change in intensity for a small angle change introduced by the X-ray beam traversing the sample. Objects that have very little absorption contrast may have considerable refraction and ultra small angle X-ray scattering (USAXS) contrast thus improving visualization and extending the utility of X-ray imaging. To improve on the current DEI technique this body of work describes the design of an X-ray prism (XRP) included in the imaging system which allows the analyzer crystal to be aligned anywhere on the rocking curve without moving the analyzer from the Bragg angle. By using the XRP to set the rocking curve alignment rather than moving the analyzer crystal physically the needed angle sensitivity is changed from muradians for direct mechanical movement of the analyzer crystal to milliradian control for movement the XRP angle. In addition to using an XRP for the traditional DEI acquisition method of two scans on opposite sides of the rocking curve preliminary tests will be presented showing the potential of using an XRP to scan quickly through the entire rocking curve. This has the benefit of collecting all the required data for image reconstruction in a single fast measurement thus removing the occurrence of motion artifacts for each point or line used during a scan. The XRP design is also intended to be compatible with combined imaging systems where more than one technique is used to investigate a sample. Candidates for complimentary techniques are investigated and measurements from a combined X-ray imaging system are presented.

An In-situ method for the study of strain broadening usingsynchrotronx-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Chiu C.; Lynch, Peter A.; Cheary, Robert W.

2006-12-15

A tensonometer for stretching metal foils has beenconstructed for the study of strain broadening in x-ray diffraction lineprofiles. This device, which is designed for use on the powderdiffractometer in Station 2.3 at Daresbury Laboratory, allows in-situmeasurements to be performed on samples under stress. It can be used fordata collection in either transmission or reflection modes using eithersymmetric or asymmetric diffraction geometries. As a test case,measurements were carried out on a 18mum thick copper foil experiencingstrain levels of up to 5 percent using both symmetric reflection andsymmetric transmission diffraction. All the diffraction profilesdisplayed peak broadening and asymmetry which increased with strain.more » Themeasured profiles were analysed by the fundamental parameters approachusing the TOPAS peak fitting software. All the observed broadenedprofiles were modelled by convoluting a refineable diffraction profile,representing the dislocation and crystallite size broadening, with afixed instrumental profile pre-determined usinghigh quality LaB6reference powder. The de-convolution process yielded "pure" sampleintegral breadths and asymmetry results which displayed a strongdependence on applied strain and increased almost linearly with appliedstrain. Assuming crystallite size broadening in combination withdislocation broadening arising from fcc a/2<110>111 dislocations,we have extracted the variation of mechanic al property with strain. Theobservation of both peak asymmetry and broadening has been interpreted asa manifestation of a cellular structure with cell walls and cellinteriors possessing high and low dislocation densities.« less

A new theory for X-ray diffraction

PubMed Central

Fewster, Paul F.

2014-01-01

This article proposes a new theory of X-ray scattering that has particular relevance to powder diffraction. The underlying concept of this theory is that the scattering from a crystal or crystallite is distributed throughout space: this leads to the effect that enhanced scatter can be observed at the ‘Bragg position’ even if the ‘Bragg condition’ is not satisfied. The scatter from a single crystal or crystallite, in any fixed orientation, has the fascinating property of contributing simultaneously to many ‘Bragg positions’. It also explains why diffraction peaks are obtained from samples with very few crystallites, which cannot be explained with the conventional theory. The intensity ratios for an Si powder sample are predicted with greater accuracy and the temperature factors are more realistic. Another consequence is that this new theory predicts a reliability in the intensity measurements which agrees much more closely with experimental observations compared to conventional theory that is based on ‘Bragg-type’ scatter. The role of dynamical effects (extinction etc.) is discussed and how they are suppressed with diffuse scattering. An alternative explanation for the Lorentz factor is presented that is more general and based on the capture volume in diffraction space. This theory, when applied to the scattering from powders, will evaluate the full scattering profile, including peak widths and the ‘background’. The theory should provide an increased understanding of the reliability of powder diffraction measurements, and may also have wider implications for the analysis of powder diffraction data, by increasing the accuracy of intensities predicted from structural models. PMID:24815975

Dynamical scattering in coherent hard x-ray nanobeam Bragg diffraction

NASA Astrophysics Data System (ADS)

Pateras, A.; Park, J.; Ahn, Y.; Tilka, J. A.; Holt, M. V.; Kim, H.; Mawst, L. J.; Evans, P. G.

2018-06-01

Unique intensity features arising from dynamical diffraction arise in coherent x-ray nanobeam diffraction patterns of crystals having thicknesses larger than the x-ray extinction depth or exhibiting combinations of nanoscale and mesoscale features. We demonstrate that dynamical scattering effects can be accurately predicted using an optical model combined with the Darwin theory of dynamical x-ray diffraction. The model includes the highly divergent coherent x-ray nanobeams produced by Fresnel zone plate focusing optics and accounts for primary extinction, multiple scattering, and absorption. The simulation accurately reproduces the dynamical scattering features of experimental diffraction patterns acquired from a GaAs/AlGaAs epitaxial heterostructure on a GaAs (001) substrate.

Coherent x-ray diffraction imaging with nanofocused illumination.

PubMed

Schroer, C G; Boye, P; Feldkamp, J M; Patommel, J; Schropp, A; Schwab, A; Stephan, S; Burghammer, M; Schöder, S; Riekel, C

2008-08-29

Coherent x-ray diffraction imaging is an x-ray microscopy technique with the potential of reaching spatial resolutions well beyond the diffraction limits of x-ray microscopes based on optics. However, the available coherent dose at modern x-ray sources is limited, setting practical bounds on the spatial resolution of the technique. By focusing the available coherent flux onto the sample, the spatial resolution can be improved for radiation-hard specimens. A small gold particle (size <100 nm) was illuminated with a hard x-ray nanobeam (E=15.25 keV, beam dimensions approximately 100 x 100 nm2) and is reconstructed from its coherent diffraction pattern. A resolution of about 5 nm is achieved in 600 s exposure time.

Development of an x-ray prism for analyzer based imaging systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bewer, Brian; Chapman, Dean

Analyzer crystal based imaging techniques such as diffraction enhanced imaging (DEI) and multiple imaging radiography (MIR) utilize the Bragg peak of perfect crystal diffraction to convert angular changes into intensity changes. These x-ray techniques extend the capability of conventional radiography, which derives image contrast from absorption, by providing large intensity changes for small angle changes introduced from the x-ray beam traversing the sample. Objects that have very little absorption contrast may have considerable refraction and ultrasmall angle x-ray scattering contrast improving visualization and extending the utility of x-ray imaging. To improve on the current DEI technique an x-ray prism (XRP)more » was designed and included in the imaging system. The XRP allows the analyzer crystal to be aligned anywhere on the rocking curve without physically moving the analyzer from the Bragg angle. By using the XRP to set the rocking curve alignment rather than moving the analyzer crystal physically the needed angle sensitivity is changed from submicroradians for direct mechanical movement of the analyzer crystal to tens of milliradians for movement of the XRP angle. However, this improvement in angle positioning comes at the cost of absorption loss in the XRP and depends on the x-ray energy. In addition to using an XRP for crystal alignment it has the potential for scanning quickly through the entire rocking curve. This has the benefit of collecting all the required data for image reconstruction in a single measurement thereby removing some problems with motion artifacts which remain a concern in current DEI/MIR systems especially for living animals.« less

Development of an x-ray prism for analyzer based imaging systems

NASA Astrophysics Data System (ADS)

Bewer, Brian; Chapman, Dean

2010-08-01

Analyzer crystal based imaging techniques such as diffraction enhanced imaging (DEI) and multiple imaging radiography (MIR) utilize the Bragg peak of perfect crystal diffraction to convert angular changes into intensity changes. These x-ray techniques extend the capability of conventional radiography, which derives image contrast from absorption, by providing large intensity changes for small angle changes introduced from the x-ray beam traversing the sample. Objects that have very little absorption contrast may have considerable refraction and ultrasmall angle x-ray scattering contrast improving visualization and extending the utility of x-ray imaging. To improve on the current DEI technique an x-ray prism (XRP) was designed and included in the imaging system. The XRP allows the analyzer crystal to be aligned anywhere on the rocking curve without physically moving the analyzer from the Bragg angle. By using the XRP to set the rocking curve alignment rather than moving the analyzer crystal physically the needed angle sensitivity is changed from submicroradians for direct mechanical movement of the analyzer crystal to tens of milliradians for movement of the XRP angle. However, this improvement in angle positioning comes at the cost of absorption loss in the XRP and depends on the x-ray energy. In addition to using an XRP for crystal alignment it has the potential for scanning quickly through the entire rocking curve. This has the benefit of collecting all the required data for image reconstruction in a single measurement thereby removing some problems with motion artifacts which remain a concern in current DEI/MIR systems especially for living animals.

Development of an x-ray prism for analyzer based imaging systems.

PubMed

Bewer, Brian; Chapman, Dean

2010-08-01

Analyzer crystal based imaging techniques such as diffraction enhanced imaging (DEI) and multiple imaging radiography (MIR) utilize the Bragg peak of perfect crystal diffraction to convert angular changes into intensity changes. These x-ray techniques extend the capability of conventional radiography, which derives image contrast from absorption, by providing large intensity changes for small angle changes introduced from the x-ray beam traversing the sample. Objects that have very little absorption contrast may have considerable refraction and ultrasmall angle x-ray scattering contrast improving visualization and extending the utility of x-ray imaging. To improve on the current DEI technique an x-ray prism (XRP) was designed and included in the imaging system. The XRP allows the analyzer crystal to be aligned anywhere on the rocking curve without physically moving the analyzer from the Bragg angle. By using the XRP to set the rocking curve alignment rather than moving the analyzer crystal physically the needed angle sensitivity is changed from submicroradians for direct mechanical movement of the analyzer crystal to tens of milliradians for movement of the XRP angle. However, this improvement in angle positioning comes at the cost of absorption loss in the XRP and depends on the x-ray energy. In addition to using an XRP for crystal alignment it has the potential for scanning quickly through the entire rocking curve. This has the benefit of collecting all the required data for image reconstruction in a single measurement thereby removing some problems with motion artifacts which remain a concern in current DEI/MIR systems especially for living animals.

DynAMITe: a prototype large area CMOS APS for breast cancer diagnosis using x-ray diffraction measurements

NASA Astrophysics Data System (ADS)

Konstantinidis, A.; Anaxagoras, T.; Esposito, M.; Allinson, N.; Speller, R.

2012-03-01

X-ray diffraction studies are used to identify specific materials. Several laboratory-based x-ray diffraction studies were made for breast cancer diagnosis. Ideally a large area, low noise, linear and wide dynamic range digital x-ray detector is required to perform x-ray diffraction measurements. Recently, digital detectors based on Complementary Metal-Oxide- Semiconductor (CMOS) Active Pixel Sensor (APS) technology have been used in x-ray diffraction studies. Two APS detectors, namely Vanilla and Large Area Sensor (LAS), were developed by the Multidimensional Integrated Intelligent Imaging (MI-3) consortium to cover a range of scientific applications including x-ray diffraction. The MI-3 Plus consortium developed a novel large area APS, named as Dynamically Adjustable Medical Imaging Technology (DynAMITe), to combine the key characteristics of Vanilla and LAS with a number of extra features. The active area (12.8 × 13.1 cm2) of DynaMITe offers the ability of angle dispersive x-ray diffraction (ADXRD). The current study demonstrates the feasibility of using DynaMITe for breast cancer diagnosis by identifying six breast-equivalent plastics. Further work will be done to optimize the system in order to perform ADXRD for identification of suspicious areas of breast tissue following a conventional mammogram taken with the same sensor.

SU-E-I-44: Some Preliminary Analysis of Angular Distribution of X-Ray Scattered On Soft Tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ganezer, K; Krmar, M; Cvejic, Z

2015-06-15

Purpose: The angular distribution of x-radiation scattered at small angles (up to 16 degrees) from several different animal soft tissue (skin, fat, muscle, retina, etc) were measured using standard equipment devoted to study of crystal structure which provides excellent geometry conditions of measurements. showed measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Methods: An x-ray scattering profilemore » usually consists of sharp diffraction peak; however some properties of the spatial profiles of scattered radiation as intensity, the peak position, height, area, FWHM, the ratio of peak heights, etc. Results: The data contained measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Measurements of different samples in the very preliminary phase showed that simple biological material used in study showed slightly different scattering pattern, especially at higher angles (around 10degrees). Intensity of radiation scattered from same tissue type is very dependent on water content and several more parameters. Conclusion: This preliminary study using animal soft tissues on the angular distributions of scattered x-rays suggests that angular distributions of X-rays scattered off of soft tissues might be useful in distinguishing healthy tissue from malignant soft tissue.« less

Resolution enhancement in coherent x-ray diffraction imaging by overcoming instrumental noise.

PubMed

Kim, Chan; Kim, Yoonhee; Song, Changyong; Kim, Sang Soo; Kim, Sunam; Kang, Hyon Chol; Hwu, Yeukuang; Tsuei, Ku-Ding; Liang, Keng San; Noh, Do Young

2014-11-17

We report that reference objects, strong scatterers neighboring weak phase objects, enhance the phase retrieval and spatial resolution in coherent x-ray diffraction imaging (CDI). A CDI experiment with Au nano-particles exhibited that the reference objects amplified the signal-to-noise ratio in the diffraction intensity at large diffraction angles, which significantly enhanced the image resolution. The interference between the diffracted x-ray from reference objects and a specimen also improved the retrieval of the phase of the diffraction signal. The enhancement was applied to image NiO nano-particles and a mitochondrion and confirmed in a simulation with a bacteria phantom. We expect that the proposed method will be of great help in imaging weakly scattering soft matters using coherent x-ray sources including x-ray free electron lasers.

[The spectrum studies of structure characteristics in magma contact metamorphic coal].

PubMed

Wu, Dun; Sun, Ruo-Yu; Liu, Gui-Jian; Yuan, Zi-Jiao

2013-10-01

The structural parameters evolution of coal due to the influence of intrusions of hot magma was investigated and analyzed. X-ray diffraction and laser confocal microscope Raman spectroscopy were used to test and analyze 4 coal samples undergoing varying contact-metamorphism by igneous magmas in borehole No. 13-4 of Zhuji coal mine, Huainan coalfield. The result showed that coal XRD spectrum showed higher background intensity, with the 26 degrees and 42 degrees nearby apparent graphite diffraction peak. Two significant vibration peaks of coal Raman spectra were observed in the 1 000-2 000 cm(-1) frequency range: broad "D" peak at 1 328-1 369 cm(-1) and sharp "G" peak at 1 564-1 599 cm(-1). With the influence of magma intrusion, the relationship between coal structural parameters and coal ranks was excellent.

3D Diffraction Microscope Provides a First Deep View

NASA Astrophysics Data System (ADS)

Miao, Jianwei

2005-03-01

When a coherent diffraction pattern is sampled at a spacing sufficiently finer than the Bragg peak frequency (i.e. the inverse of the sample size), the phase information is in principle encoded inside the diffraction pattern, and can be directly retrieved by using an iterative process. In combination of this oversampling phasing method with either coherent X-rays or electrons, a novel form of diffraction microscopy has recently been developed to image nanoscale materials and biological structures. In this talk, I will present the principle of the oversampling method, discuss the first experimental demonstration of this microscope, and illustrate some applications in nanoscience and biology.

Application of graphene oxide-poly (vinyl alcohol) polymer nanocomposite for memory devices

NASA Astrophysics Data System (ADS)

Kaushal, Jyoti; Kaur, Ravneet; Sharma, Jadab; Tripathi, S. K.

2018-05-01

Significant attention has been gained by polymer nanocomposites because of their possible demands in future electronic memory devices. In the present work, device based on Graphene Oxide (GO) and polyvinyl alcohol (PVA) has been made and examined for the memory device application. The prepared Graphene oxide (GO) and GO-PVA nanocomposite (NC) has been characterized by X-ray Diffraction (XRD). GO nanosheets show the diffraction peak at 2θ = 11.60° and the interlayer spacing of 0.761 nm. The XRD of GO-PVA NC shows the diffraction peak at 2θ =18.56°. The fabricated device shows bipolar switching behavior having ON/OFF current ratio ˜102. The Write-Read-Erase-Read (WRER) cycles test shows that the Al/GO-PVA/Ag device has good stability and repeatability.

Local and average structures of BaTiO 3-Bi(Zn 1/2Ti 1/2)O 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Usher, Tedi-Marie; Iamsasri, Thanakorn; Forrester, Jennifer S.

The complex crystallographic structures of (1-x)BaTiO 3-xBi(Zn 1/2Ti 1/2)O 3 (BT-xBZT) are examined using high resolution synchrotron X-ray diffraction, neutron diffraction, and neutron pair distribution function (PDF) analyses. The short-range structures are characterized from the PDFs, and a combined analysis of the X-ray and neutron diffraction patterns is used to determine the long-range structures. Our results demonstrate that the structure appears different when averaged over different length scales. In all compositions, the local structures determined from the PDFs show local tetragonal distortions (i.e., c/a > 1). But, a box-car fitting analysis of the PDFs reveals variations at different length scales.more » For 0.80BT-0.20BZT and 0.90BT-0.10BZT, the tetragonal distortions decrease at longer atom-atom distances (e.g., 30 vs. 5 ). When the longest distances are evaluated (r > 40 ), the lattice parameters approach cubic. Neutron and X-ray diffraction yield further information about the long-range structure. Compositions 0.80BT-0.20BZT and 0.90BT-0.10BZT appear cubic by Bragg diffraction (no peak splitting), consistent with the PDFs at long distances. However, these patterns cannot be adequately fit using a cubic lattice model; modeling their structures with the P4mm space group allows for a better fit to the patterns because the space group allows for c-axis atomic displacements that occur at the local scale. Furthermore, for the compositions 0.92BT-0.08BZT and 0.94BT-0.06BZT, strong tetragonal distortions are observed at the local scale and a less-distorted tetragonal structure is observed at longer length scales. In Rietveld refinements, the latter is modeled using a tetragonal phase. Since the peak overlap in these two-phase compositions limits the ability to model the local-scale structures as tetragonal, it is approximated in the refinements as a cubic phase. These results demonstrate that alloying BT with BZT results in increased disorder and disrupts the long-range ferroelectric symmetry present in BT, while the large tetragonal distortion present in BZT persists at the local scale.« less

Local and average structures of BaTiO 3-Bi(Zn 1/2Ti 1/2)O 3

DOE PAGES

Usher, Tedi-Marie; Iamsasri, Thanakorn; Forrester, Jennifer S.; ...

2016-11-11

The complex crystallographic structures of (1-x)BaTiO 3-xBi(Zn 1/2Ti 1/2)O 3 (BT-xBZT) are examined using high resolution synchrotron X-ray diffraction, neutron diffraction, and neutron pair distribution function (PDF) analyses. The short-range structures are characterized from the PDFs, and a combined analysis of the X-ray and neutron diffraction patterns is used to determine the long-range structures. Our results demonstrate that the structure appears different when averaged over different length scales. In all compositions, the local structures determined from the PDFs show local tetragonal distortions (i.e., c/a > 1). But, a box-car fitting analysis of the PDFs reveals variations at different length scales.more » For 0.80BT-0.20BZT and 0.90BT-0.10BZT, the tetragonal distortions decrease at longer atom-atom distances (e.g., 30 vs. 5 ). When the longest distances are evaluated (r > 40 ), the lattice parameters approach cubic. Neutron and X-ray diffraction yield further information about the long-range structure. Compositions 0.80BT-0.20BZT and 0.90BT-0.10BZT appear cubic by Bragg diffraction (no peak splitting), consistent with the PDFs at long distances. However, these patterns cannot be adequately fit using a cubic lattice model; modeling their structures with the P4mm space group allows for a better fit to the patterns because the space group allows for c-axis atomic displacements that occur at the local scale. Furthermore, for the compositions 0.92BT-0.08BZT and 0.94BT-0.06BZT, strong tetragonal distortions are observed at the local scale and a less-distorted tetragonal structure is observed at longer length scales. In Rietveld refinements, the latter is modeled using a tetragonal phase. Since the peak overlap in these two-phase compositions limits the ability to model the local-scale structures as tetragonal, it is approximated in the refinements as a cubic phase. These results demonstrate that alloying BT with BZT results in increased disorder and disrupts the long-range ferroelectric symmetry present in BT, while the large tetragonal distortion present in BZT persists at the local scale.« less

Antibacterial Carbon Nanotubes by Impregnation with Copper Nanostructures

NASA Astrophysics Data System (ADS)

Palza, Humberto; Saldias, Natalia; Arriagada, Paulo; Palma, Patricia; Sanchez, Jorge

2017-08-01

The addition of metal-based nanoparticles on carbon nanotubes (CNT) is a relevant method producing multifunctional materials. In this context, CNT were dispersed in an ethanol/water solution containing copper acetate for their impregnation with different copper nanostructures by either a non-thermal or a thermal post-synthesis treatment. Our simple method is based on pure CNT in an air atmosphere without any other reagents. Particles without thermal treatment were present as a well-dispersed layered copper hydroxide acetate nanostructures on CNT, as confirmed by scanning and transmission (TEM) electron microscopies, and showing a characteristic x-ray diffraction peak at 6.6°. On the other hand, by thermal post-synthesis treatment at 300°C, these layered nanostructures became Cu2O nanoparticles of around 20 nm supported on CNT, as confirmed by TEM images and x-ray diffraction peaks. These copper nanostructures present on the CNT surface rendered antibacterial behavior to the resulting hybrid materials against both Staphylococcus aureus and Escherichia coli. These findings present for the first time a simple method for producing antibacterial CNT by direct impregnation of copper nanostructures.

In-situ cyclic pulse annealing of InN on AlN/Si during IR-lamp-heated MBE growth

NASA Astrophysics Data System (ADS)

Suzuki, Akira; Bungi, Yu; Araki, Tsutomu; Nanishi, Yasushi; Mori, Yasuaki; Yamamoto, Hiroaki; Harima, Hiroshi

2009-05-01

To improve crystal quality of InN, an in-situ cyclic rapid pulse annealing during growth was carried out using infrared-lamp-heated molecular beam epitaxy. A cycle of 4 min growth of InN at 400 °C and 3 s pulse annealing at a higher temperature was repeated 15 times on AlN on Si substrate. Annealing temperatures were 550, 590, 620, and 660 °C. The back of Si was directly heated by lamp irradiation through a quartz rod. A total InN film thickness was about 200 nm. With increasing annealing temperature up to 620 °C, crystal grain size by scanning electron microscope showed a tendency to increase, while widths of X-ray diffraction rocking curve of (0 0 0 2) reflection and E 2 (high) mode peak of Raman scattering spectra decreased. A peak of In (1 0 1) appeared in X-ray diffraction by annealing higher than 590 °C, and In droplets were found on the surface by annealing at 660 °C.

Tomography with energy dispersive diffraction

NASA Astrophysics Data System (ADS)

Stock, S. R.; Okasinski, J. S.; Woods, R.; Baldwin, J.; Madden, T.; Quaranta, O.; Rumaiz, A.; Kuczewski, T.; Mead, J.; Krings, T.; Siddons, P.; Miceli, A.; Almer, J. D.

2017-09-01

X-ray diffraction can be used as the signal for tomographic reconstruction and provides a cross-sectional map of the crystallographic phases and related quantities. Diffraction tomography has been developed over the last decade using monochromatic x-radiation and an area detector. This paper reports tomographic reconstruction with polychromatic radiation and an energy sensitive detector array. The energy dispersive diffraction (EDD) geometry, the instrumentation and the reconstruction process are described and related to the expected resolution. Results of EDD tomography are presented for two samples containing hydroxyapatite (hAp). The first is a 3D-printed sample with an elliptical crosssection and contains synthetic hAp. The second is a human second metacarpal bone from the Roman-era cemetery at Ancaster, UK and contains bio-hAp which may have been altered by diagenesis. Reconstructions with different diffraction peaks are compared. Prospects for future EDD tomography are also discussed.

Macromolecular diffractive imaging using imperfect crystals

PubMed Central

Ayyer, Kartik; Yefanov, Oleksandr; Oberthür, Dominik; Roy-Chowdhury, Shatabdi; Galli, Lorenzo; Mariani, Valerio; Basu, Shibom; Coe, Jesse; Conrad, Chelsie E.; Fromme, Raimund; Schaffer, Alexander; Dörner, Katerina; James, Daniel; Kupitz, Christopher; Metz, Markus; Nelson, Garrett; Lourdu Xavier, Paulraj; Beyerlein, Kenneth R.; Schmidt, Marius; Sarrou, Iosifina; Spence, John C. H.; Weierstall, Uwe; White, Thomas A.; Yang, Jay-How; Zhao, Yun; Liang, Mengning; Aquila, Andrew; Hunter, Mark S.; Robinson, Joseph S.; Koglin, Jason E.; Boutet, Sébastien; Fromme, Petra; Barty, Anton; Chapman, Henry N.

2016-01-01

The three-dimensional structures of macromolecules and their complexes are predominantly elucidated by X-ray protein crystallography. A major limitation is access to high-quality crystals, to ensure X-ray diffraction extends to sufficiently large scattering angles and hence yields sufficiently high-resolution information that the crystal structure can be solved. The observation that crystals with shrunken unit-cell volumes and tighter macromolecular packing often produce higher-resolution Bragg peaks1,2 hints that crystallographic resolution for some macromolecules may be limited not by their heterogeneity but rather by a deviation of strict positional ordering of the crystalline lattice. Such displacements of molecules from the ideal lattice give rise to a continuous diffraction pattern, equal to the incoherent sum of diffraction from rigid single molecular complexes aligned along several discrete crystallographic orientations and hence with an increased information content3. Although such continuous diffraction patterns have long been observed—and are of interest as a source of information about the dynamics of proteins4 —they have not been used for structure determination. Here we show for crystals of the integral membrane protein complex photosystem II that lattice disorder increases the information content and the resolution of the diffraction pattern well beyond the 4.5 Å limit of measurable Bragg peaks, which allows us to directly phase5 the pattern. With the molecular envelope conventionally determined at 4.5 Å as a constraint, we then obtain a static image of the photosystem II dimer at 3.5 Å resolution. This result shows that continuous diffraction can be used to overcome long-supposed resolution limits of macromolecular crystallography, with a method that puts great value in commonly encountered imperfect crystals and opens up the possibility for model-free phasing6,7. PMID:26863980

Effect of chemical pressure on competition and cooperation between polar and antiferrodistortive distortions in sodium niobate

NASA Astrophysics Data System (ADS)

Jauhari, Mrinal; Mishra, S. K.; Mittal, R.; Sastry, P. U.; Chaplot, S. L.

2017-12-01

We present results obtained from a combination of dielectric and x-ray diffraction measurements for compositional design of (1 -x )NaNb O3-x BaTi O3(NNBT x ) , which can induce interferroelectric phase transitions. Anomalies are observed in dielectric measurements performed for various compositions at 300 K, as well as at different temperatures for NNBT03. We observed the appearance(disappearance) of the superlattice reflections along with change in the intensities of the main perovskite peaks in the powder x-ray diffraction data, which provide clear evidences for structural phase transitions with composition and temperature. We found that increasing the concentration of BaTi O3 leads to the suppression of out-of-phase rotation of octahedra and an increment in tetragonality (c /a ratio), which promotes the polar mode at room temperature. The temperature-dependent powder diffraction study shows that the ferroelectric rhombohedral phase of pure sodium niobate gets suppressed for the composition x =0.03 , and the monoclinic phase C c gets stabilized at low temperature. The monoclinic phase is believed to provide for a flexible polarization rotation and is considered to be directly linked to the high-performance piezoelectricity in materials due to presence of more easy axes for spontaneous polarizations than the rhombohedral phase.

Detection of nanoscale embedded layers using laboratory specular X-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beekman, Matt, E-mail: matt.beekman@oit.edu; Rodriguez, Gabriel; Atkins, Ryan

Unusual specular X-ray diffraction patterns have been observed from certain thin film intergrowths of metal monochalcogenide (MX) and transition metal dichalcogenide (TX{sub 2}) structures. These patterns exhibit selective “splitting” or broadening of selected (00l) diffraction peaks, while other (00l) reflections remain relatively unaffected [Atkins et al., Chem. Mater. 24, 4594 (2012)]. Using a simplified optical model in the kinematic approximation, we illustrate that these peculiar and somewhat counterintuitive diffraction features can be understood in terms of additional layers of one of the intergrowth components, MX or TX{sub 2}, interleaved between otherwise “ideal” regions of MX-TX{sub 2} intergrowth. The interpretation ismore » in agreement with scanning transmission electron microscope imaging, which reveals the presence of such stacking “defects” in films prepared from non-ideal precursors. In principle, the effect can be employed as a simple, non-destructive laboratory probe to detect and characterize ultrathin layers of one material, e.g., 2-dimensional crystals, embedded between two slabs of a second material, effectively using the two slabs as a highly sensitive interferometer of their separation distance.« less

Local terahertz field enhancement for time-resolved x-ray diffraction

DOE PAGES

Kozina, M.; Pancaldi, M.; Bernhard, C.; ...

2017-02-20

We report local field strength enhancement of single-cycle terahertz (THz) pulses in an ultrafast time-resolved x-ray diffraction experiment. We show that patterning the sample with gold microstructures increases the THz field without changing the THz pulse shape or drastically affecting the quality of the x-ray diffraction pattern. Lastly, we find a five-fold increase in THz-induced x-ray diffraction intensity change in the presence of microstructures on a SrTiO 3 thin-film sample.

Local terahertz field enhancement for time-resolved x-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozina, M.; Pancaldi, M.; Bernhard, C.

We report local field strength enhancement of single-cycle terahertz (THz) pulses in an ultrafast time-resolved x-ray diffraction experiment. We show that patterning the sample with gold microstructures increases the THz field without changing the THz pulse shape or drastically affecting the quality of the x-ray diffraction pattern. Lastly, we find a five-fold increase in THz-induced x-ray diffraction intensity change in the presence of microstructures on a SrTiO 3 thin-film sample.

Optical and structural properties in type-II InAlAs/AlGaAs quantum dots observed by photoluminescence, X-ray diffraction and transmission electron microscopy

NASA Astrophysics Data System (ADS)

Ben Daly, A.; Craciun, D.; Laura Ursu, E.; Lemaître, A.; Maaref, M. A.; Iacomi, F.; Vasile, B. S.; Craciun, V.

2017-10-01

We present the effects of AlGaAs alloy composition on InAlAs quantum dots (QDs) optical and structural properties. Photoluminescence (PL) analysis of samples having a variety of aluminium composition values covering type-II transitions clearly in QDs showed the presence of two transitions X-Sh and X-Ph. High-resolution X-ray diffraction (HRXRD) investigations showed that the layers grew epitaxially on the GaAs substrate, with no relaxation regardless the Al content of AlGaAs layer. From the reciprocal space map (RSM) investigation around (004) and (115) diffraction peaks, it was shown that the InAlAs layer is fully strained, the in-plane lattice parameters (a and b, a = b) being identical to those of GaAs substrate, while the c lattice parameter was dependent on the In and Al concentrations, being larger than that of the substrate. High-resolution transmission electronic microscopy (HRTEM) investigations confirmed that films grew epitaxially on the GaAs substrate with no visible dislocations or other major defects within the InAlAs/GaAlAs QDs structure.

Thermal x-ray diffraction and near-field phase contrast imaging

NASA Astrophysics Data System (ADS)

Li, Zheng; Classen, Anton; Peng, Tao; Medvedev, Nikita; Wang, Fenglin; Chapman, Henry N.; Shih, Yanhua

2017-10-01

Using higher-order coherence of thermal light sources, the resolution power of standard x-ray imaging techniques can be enhanced. In this work, we applied the higher-order measurement to far-field x-ray diffraction and near-field phase contrast imaging (PCI), in order to achieve superresolution in x-ray diffraction and obtain enhanced intensity contrast in PCI. The cost of implementing such schemes is minimal compared to the methods that achieve similar effects by using entangled x-ray photon pairs.

Thermal x-ray diffraction and near-field phase contrast imaging

DOE PAGES

Li, Zheng; Classen, Anton; Peng, Tao; ...

2017-12-27

Using higher-order coherence of thermal light sources, the resolution power of standard x-ray imaging techniques can be enhanced. Here in this work, we applied the higher-order measurement to far-field x-ray diffraction and near-field phase contrast imaging (PCI), in order to achieve superresolution in x-ray diffraction and obtain enhanced intensity contrast in PCI. The cost of implementing such schemes is minimal compared to the methods that achieve similar effects by using entangled x-ray photon pairs.

Room Temperature Ferromagnetism of Fe Doped Indium Tin Oxide Based on Dispersed Fe3O4 Nanoparticles

NASA Astrophysics Data System (ADS)

Okada, Koichi; Kohiki, Shigemi; Nishi, Sachio; Shimooka, Hirokazu; Deguchi, Hiroyuki; Mitome, Masanori; Bando, Yoshio; Shishido, Toetsu

2007-09-01

Transmission electron microscopy revealed that Fe3O4 nanoparticles with diameter of ≈200 nm dispersed in Fe doped indium tin oxide (Fe@ITO) powders exhibiting co-occurrence of room temperature ferromagnetism and superparamagnetism. Although we observed no X-ray diffraction peak from Fe related compounds for Fe0.19@ITO (ITO: In1.9Sn0.1O3) powders, the powders showed both hysteresis loop in field dependent magnetization at 300 K and divergence of zero-field-cooled magnetization from field-cooled magnetization. Scanning transmission electron microscopy with energy dispersive X-ray spectroscopy demonstrated that the nanoparticle with diameter of ≈200 nm consists of Fe and oxygen. Transmission electron diffraction revealed that crystal structure of the nanoparticle is inverse spinel type Fe3O4. The Fe3O4 crystalline phase by electron diffraction is consistent with the saturation magnetization of 1.3 μB/Fe and magnetic anomaly at ≈110 K observed for the powders.

In Situ Observation of High-Pressure Phase Transitions in SiO2 Under Shock Loading Using Time Resolved X-Ray Diffraction

NASA Astrophysics Data System (ADS)

Tracy, S. J.; Turneaure, S.; Duffy, T. S.

2016-12-01

Quartz is one of the most abundant minerals in Earth's crust and serves as an archetype for silicate minerals generally. The shock metamorphism of silica is important for understanding and interpreting meteorite impact events. Shock compression of quartz is characterized by a phase transition occurring over a broad mixed-phase region ( 10-40 GPa). Despite decades of study, the nature of this transformation and the structure of the high-pressure phase remain poorly understood. In situ x-ray diffraction data on shock-compressed SiO2 was collected at the Dynamic Compression Sector at the Advanced Photon Source. The behavior both single crystal alpha-quartz and fused silica was investigated under dynamic loading through a series real-time synchrotron x-ray diffraction measurements during peak stresses up to 65 GPa. A two-stage light gas gun was used to accelerate LiF flyer plates that impacted the SiO2 samples resulting in a propagating step-like increase in pressure and temperature behind the shock front. Four consecutive x-ray frames, separated by 153 ns, were collected during the transient loading and unloading. These measurements allow for the determination of time-dependent atomic arrangements, demonstrating that both amorphous silica as well as crystalline alpha-quartz transform to stishovite above 36 GPa. These measurements reveal important information about the role of kinetics as well texture development and potential defect structures in the transformed material.

Interactions that know no boundaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wall, Michael E.

Deviations from an ideal crystal lead to diffuse scattering (DS) intensity, both between and beneath the Bragg peaks in diffraction patterns (Guinier, 1963). First characterized using simple ionic crystals in early studies of X-ray diffraction (Lonsdale, 1942), DS has a rich history (Welberry & Weber, 2016) and is a well established technique in smallmolecule crystallography (Welberry, 2004). DS studies in macromolecular crystallography began more recently (Phillips et al., 1980) and now the potential for obtaining information about protein motions is fueling the growing interest in DS (Meisburger et al., 2017).

Interactions that know no boundaries

DOE PAGES

Wall, Michael E.

2018-03-01

Deviations from an ideal crystal lead to diffuse scattering (DS) intensity, both between and beneath the Bragg peaks in diffraction patterns (Guinier, 1963). First characterized using simple ionic crystals in early studies of X-ray diffraction (Lonsdale, 1942), DS has a rich history (Welberry & Weber, 2016) and is a well established technique in smallmolecule crystallography (Welberry, 2004). DS studies in macromolecular crystallography began more recently (Phillips et al., 1980) and now the potential for obtaining information about protein motions is fueling the growing interest in DS (Meisburger et al., 2017).

Structural and spectroscopic study of mechanically synthesized SnO2 nanostructures

NASA Astrophysics Data System (ADS)

Vij, Ankush; Kumar, Ravi

2016-05-01

We report the single step synthesis of SnO2 nanostructures using high energy mechanical attrition method. X-ray diffraction (XRD) pattern reveals the single phase rutile structure with appreciable broadening of diffraction peaks, which is a signature of nanostructure formation. The average crystallite size of SnO2 nanostructures has been calculated to be ~15 nm. The micro-Raman study reveals the shifting of A1g Raman mode towards lower wave number, which is correlated with the nanostructure formation.

Supercritical carbon dioxide treatment as a method for polymorph preparation of deoxycholic acid.

PubMed

Tozuka, Yuichi; Kawada, Dai; Oguchi, Toshio; Yamamoto, Keiji

2003-09-16

A new polymorph of deoxycholic acid (DCA) was formed by using a supercritical carbon dioxide treatment. Deoxycholic acid crystals were stored in a pressure vessel purged with carbon dioxide at 12MPa, 60 degrees C for definite intervals. After storage for 1h in supercritical carbon dioxide (SC-CO2), new X-ray diffraction (XRD) peaks, not found in the bulk DCA crystal, were observed at 2theta = 7.4 degrees, 9.7 degrees and 14.0 degrees. The intensities of the new diffraction peaks increased with an increase in storage time, whereas the intensities of the diffraction peaks due to bulk DCA crystal decreased. On the DSC curves, the crystals obtained showed an exothermic peak at around 155 degrees C followed by the melting peak of bulk DCA crystal at 175 degrees C. By the temperature-controlled powder XRD measurement, the crystals obtained were found to be a metastable form of DCA. The polymorphs of DCA have not been reported; therefore, the SC-CO2 treatment would be a peculiar method to obtain a DCA polymorph.

An image focusing means by using an opaque object to diffract x-rays

DOEpatents

Sommargren, Gary E.; Weaver, H. Joseph

1991-01-01

The invention provides a method and apparatus for focusing and imaging x-rays. An opaque sphere is used as a diffractive imaging element to diffract x-rays from an object so that the divergent x-ray wavefronts are transformed into convergent wavefronts and are brought to focus to form an image of the object with a large depth of field.

Focal Spot and Wavefront Sensing of an X-Ray Free Electron laser using Ronchi shearing interferometry

DOE PAGES

Nagler, Bob; Aquila, Andrew; Boutet, Sebastien; ...

2017-10-20

The Linac Coherent Light Source (LCLS) is an X-ray source of unmatched brilliance, that is advancing many scientific fields at a rapid pace. The highest peak intensities that are routinely produced at LCLS take place at the Coherent X-ray Imaging (CXI) instrument, which can produce spotsize at the order of 100 nm, and such spotsizes and intensities are crucial for experiments ranging from coherent diffractive imaging, non-linear x-ray optics and high field physics, and single molecule imaging. Nevertheless, a full characterisation of this beam has up to now not been performed. In this paper we for the first time characterisemore » this nanofocused beam in both phase and intensity using a Ronchi Shearing Interferometric technique. The method is fast, in-situ, uses a straightforward optimization algoritm, and is insensitive to spatial jitter.« less

A chemical reduction approach to the synthesis of copper nanoparticles

NASA Astrophysics Data System (ADS)

Khan, Ayesha; Rashid, Audil; Younas, Rafia; Chong, Ren

2016-11-01

Development of improved methods for the synthesis of copper nanoparticles is of high priority for the advancement of material science and technology. Herein, starch-protected zero-valent copper (Cu) nanoparticles have been successfully synthesized by a novel facile route. The method is based on the chemical reduction in aqueous copper salt using ascorbic acid as reducing agent at low temperature (80 °C). X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy measurements were taken to investigate the size, structure and composition of synthesized Cu nanocrystals, respectively. Average crystallite size of Cu nanocrystals calculated from the major diffraction peaks using the Scherrer formula is about 28.73 nm. It is expected that the outcomes of the study take us a step closer toward designing rational strategies for the synthesis of nascent Cu nanoparticles without inert gas protection.

Structure, magnetic, and electrical properties of Zn1-xMnxO material

NASA Astrophysics Data System (ADS)

Sebayang, P.; Hulu, S. F.; Nasruddin, Aryanto, D.; Kurniawan, C.; Subhan, A.; Sudiro, T.; Ginting, M.

2017-07-01

ZnO and MnO2 powder were synthesized using solid state reaction method to produce Zn1-xMnxO materials. Effect of dopant concentrations at the material of Zn1-xMnxO (x = 0.015, 0.02, 0.025) to the change of crystal structure, electrical and magnetic properties was studied. The X-ray diffraction (XRD) result of the samples that were doped with Mn showed a hexagonal wurtzite polycrystalline structure. The addition of Mn dopant resulting the decrease of lattice parameters and peaks intensity. The significant increase of the peak intensity occurred at x = 0.02, which also indicated an increase in the crystal quality of ZnO. The change of the ZnO structure affected the electrical and magnetic properties of the samples.

Soft X-Ray Diffraction Microscopy of a Frozen Hydrated Yeast Cell

DOE PAGES

Huang, Xiaojing; Nelson, Johanna; Kirz, Janos; ...

2009-11-01

We report the first image of an intact, frozen hydrated eukaryotic cell using x-ray diffraction microscopy, or coherent x-ray diffraction imaging. By plunge freezing the specimen in liquid ethane and maintaining it below -170 °C, artifacts due to dehydration, ice crystallization, and radiation damage are greatly reduced. In this example, coherent diffraction data using 520 eV x rays were recorded and reconstructed to reveal a budding yeast cell at a resolution better than 25 nm. This demonstration represents an important step towards high resolution imaging of cells in their natural, hydrated state, without limitations imposed by x-ray optics.

Structural, thermal, dielectric spectroscopic and AC impedance properties of SiC nanoparticles doped PVK/PVC blend

NASA Astrophysics Data System (ADS)

Alghunaim, Naziha Suliman

2018-06-01

Nanocomposite films based on poly (N-vinylcarbazole)/polyvinylchloride (PVK/PVC) blend doped with different concentrations of Silicon Carbide (SiC) nanoparticles have been prepared. The X-ray diffraction, Ultra violet-visible spectroscopy, thermogravimetric analysis and electrical spectroscopic has been used to characterize these nanocomposites. The X-ray analysis confirms the semi-crystalline nature of the films. The intensity of the main X-ray peak is decreased due to the interaction between the PVK/PVC and SiC. The main SiC peaks are absent due to complete dissolution of SiC in polymeric matrices. The UV-Vis spectra indicated that the band gap optical energy is affected by adding SiC nanoparticles because the charges transfer complexes between PVK/PVC with amount of SiC. The thermal stability is improved and the estimated values of ε‧ and ε″ are increased with increasing for SiC content due to the free charge carriers which in turn increase the ionic conductivity of the doped samples. The plots of tan δ with frequency are studied. A single peak from the plot between tan δ and Log (f) is appeared and shifted towards the higher frequency confirmed the presence of relaxing dipoles moment.

Application of focused-beam flat-sample method to synchrotron powder X-ray diffraction with anomalous scattering effect

NASA Astrophysics Data System (ADS)

Tanaka, M.; Katsuya, Y.; Matsushita, Y.

2013-03-01

The focused-beam flat-sample method (FFM), which is a method for high-resolution and rapid synchrotron X-ray powder diffraction measurements by combination of beam focusing optics, a flat shape sample and an area detector, was applied for diffraction experiments with anomalous scattering effect. The advantages of FFM for anomalous diffraction were absorption correction without approximation, rapid data collection by an area detector and good signal-to-noise ratio data by focusing optics. In the X-ray diffraction experiments of CoFe2O4 and Fe3O4 (By FFM) using X-rays near the Fe K absorption edge, the anomalous scattering effect between Fe/Co or Fe2+/Fe3+ can be clearly detected, due to the change of diffraction intensity. The change of observed diffraction intensity as the incident X-ray energy was consistent with the calculation. The FFM is expected to be a method for anomalous powder diffraction.

Rietveld analysis using powder diffraction data with anomalous scattering effect obtained by focused beam flat sample method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Masahiko, E-mail: masahiko@spring8.or.jp; Katsuya, Yoshio, E-mail: katsuya@spring8.or.jp; Sakata, Osami, E-mail: SAKATA.Osami@nims.go.jp

2016-07-27

Focused-beam flat-sample method (FFM) is a new trial for synchrotron powder diffraction method, which is a combination of beam focusing optics, flat shape powder sample and area detectors. The method has advantages for X-ray diffraction experiments applying anomalous scattering effect (anomalous diffraction), because of 1. Absorption correction without approximation, 2. High intensity X-rays of focused incident beams and high signal noise ratio of diffracted X-rays 3. Rapid data collection with area detectors. We applied the FFM to anomalous diffraction experiments and collected synchrotron X-ray powder diffraction data of CoFe{sub 2}O{sub 4} (inverse spinel structure) using X-rays near Fe K absorptionmore » edge, which can distinguish Co and Fe by anomalous scattering effect. We conducted Rietveld analyses with the obtained powder diffraction data and successfully determined the distribution of Co and Fe ions in CoFe{sub 2}O{sub 4} crystal structure.« less

Growth, crystalline perfection, spectral, thermal and theoretical studies on imidazolium L-tartrate crystals.

PubMed

Meena, K; Muthu, K; Meenatchi, V; Rajasekar, M; Bhagavannarayana, G; Meenakshisundaram, S P

2014-04-24

Transparent optical quality single crystals of imidazolium L-tartrate (IMLT) were grown by conventional slow evaporation solution growth technique. Crystal structure of the as-grown IMLT was determined by single crystal X-ray diffraction analysis. Thermal analysis reveals the purity of the crystal and the sample is stable up to the melting point. Good transmittance in the visible region is observed and the band gap energy is estimated using diffuse reflectance data by the application of Kubelka-Munk algorithm. The powder X-ray diffraction study reveals the crystallinity of the as-grown crystal and it is compared with that of the experimental one. An additional peak in high resolution X-ray diffraction (HRXRD) indicates the presence of an internal structural low angle boundary. Second harmonic generation (SHG) activity of IMLT is significant as estimated by Kurtz and Perry powder technique. HOMO-LUMO energies and first-order molecular hyperpolarizability of IMLT have been evaluated using density functional theory (DFT) employing B3LYP functional and 6-31G(d,p) basis set. The optimized geometry closely resembles the ORTEP. The vibrational patterns present in the molecule are confirmed by FT-IR coinciding with theoretical patterns. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and characterization of Ce, Cu co-doped ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Harish, G. S.; Sreedhara Reddy, P.

2015-09-01

Ce, Cu co-doped ZnS nanoparticles were prepared at room temperature using a chemical co-precipitation method. The prepared nanoparticles were characterized by X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and high resolution Raman spectroscopic techniques. Transmission electron microscopy (TEM) and X-ray diffraction studies showed that the diameter of the particles was around 2-3 nm. Broadened XRD peaks revealed the formation of nanoparticles with a face centered cubic (fcc) structure. DRS studies confirmed that the band gap increased with an increase in the dopant concentration. The Raman spectra of undoped and Ce, Cu ions co-doped ZnS nanoparticles showed longitudinal optical mode and transverse optical mode. Compared with the Raman modes (276 and 351 cm-1) of undoped ZnS nanoparticles, the Raman modes of Ce, Cu co- doped ZnS nanoparticles were slightly shifted towards lower frequency. PL spectra of the samples showed remarkable enhancement in the intensity upon doping.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rauf, Nurlaela, E-mail: n-rauf@fmipa.unhas.ac.id; Tahir, Dahlang; Arbiansyah, Muhammad

Structural analysis has been performed on bioceramic materials for denture application by using X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscopy (SEM). XRF is using for analysis chemical composition of raw materials. XRF shows the ratio 1 : 1 : 1 : 1 between feldspar, quartz, kaolin and eggshell, respectively, resulting composition CaO content of 56.78 %, which is similar with natural tooth. Sample preparation was carried out on temperature of 800 °C, 900 °C and 1000 °C. X-ray diffraction result showed that the structure is crystalline with trigonal crystal system for SiO{sub 2} (a=b=4.9134 Å and c=5.4051more » Å) and CaH{sub 2}O{sub 2} (a=b=3.5925 Å and c=4.9082 Å). Based on the Scherrer’s equation showed the crystallite size of the highest peak (SiO{sub 2}) increase with increasing the temperature preparation. The highest hardness value (87 kg/mm{sup 2}) and match with the standards of dentin hardness. The surface structure was observed by using SEM also discussed.« less

Thermoluminescence, ESR and x-ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature thermal treatment

NASA Astrophysics Data System (ADS)

Bakshi, A. K.; Patwe, S. J.; Bhide, M. K.; Sanyal, B.; Natarajan, V.; Tyagi, A. K.; Kher, R. K.

2008-01-01

Thermoluminescence (TL), electron spin resonance (ESR) and x ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature treatment were carried out. Analysis of the TL glow curve indicated that the dosimetric glow peak at 240 °C reduces, whereas the low temperature satellite peak increases with the increase in the annealing temperature in the range 650-1000 °C. The influence of the annealing atmosphere on the TL glow curve structure was also observed. Reduction of the photoluminescence intensity of the annealed phosphor indicated that the environment of Dy3+ ions might have undergone some change due to high temperature treatment. Reduction in the ESR signal intensity corresponding to O_{3}^{-} and SO_{3}^{-} radicals was observed initially with the increase in the annealing temperaure; subsequently their intensity increased with temperature. Signals due to the SO_{4}^{-} radical vanished, when the phosphor was annealed beyond 800 °C. A signal corresponding to SH2- radicals was also observed in the ESR spectra for samples subjected to annealing in the temperature regime 800-1000 °C. XRD of the in situ annealed phosphor showed a change in the unit cell parameters. An endothermic peak at 860 °C in the DTA spectrum was observed.

Ion beam modification of the structure and properties of hexagonal boron nitride: An infrared and X-ray diffraction study

NASA Astrophysics Data System (ADS)

Aradi, E.; Naidoo, S. R.; Billing, D. G.; Wamwangi, D.; Motochi, I.; Derry, T. E.

2014-07-01

The vibrational mode for the cubic symmetry of boron nitride (BN) has been produced by boron ion implantation of hexagonal boron nitride (h-BN). The optimum fluence at 150 keV was found to be 5 × 1014 ions/cm2. The presence of the c-BN phase was inferred using glancing incidence XRD (GIXRD) and Fourier Transform Infrared Spectroscopy (FTIR). After implantation, Fourier Transform Infrared Spectroscopy indicated a peak at 1092 cm-1 which corresponds to the vibrational mode for nanocrystalline BN (nc-BN). The glancing angle XRD pattern after implantation exhibited c-BN diffraction peaks relative to the implantation depth of 0.4 μm.

Crystalline structure analysis of cellulose treated with sodium hydroxide and carbon dioxide by means of X-ray diffraction and FTIR spectroscopy.

PubMed

Oh, Sang Youn; Yoo, Dong Il; Shin, Younsook; Kim, Hwan Chul; Kim, Hak Yong; Chung, Yong Sik; Park, Won Ho; Youk, Ji Ho

2005-10-31

Crystalline structures of cellulose (named as Cell 1), NaOH-treated cellulose (Cell 2), and subsequent CO2-treated cellulose (Cell 2-C) were analyzed by wide-angle X-ray diffraction and FTIR spectroscopy. Transformation from cellulose I to cellulose II was observed by X-ray diffraction for Cell 2 treated with 15-20 wt% NaOH. Subsequent treatment with CO2 also transformed the Cell 2-C treated with 5-10 wt% NaOH. Many of the FTIR bands including 2901, 1431, 1282, 1236, 1202, 1165, 1032, and 897 cm(-1) were shifted to higher wave number (by 2-13 cm(-1)). However, the bands at 3352, 1373, and 983 cm(-1) were shifted to lower wave number (by 3-95 cm(-1)). In contrast to the bands at 1337, 1114, and 1058 cm(-1), the absorbances measured at 1263, 993, 897, and 668 cm(-1) were increased. The FTIR spectra of hydrogen-bonded OH stretching vibrations at around 3352 cm(-1) were resolved into three bands for cellulose I and four bands for cellulose II, assuming that all the vibration modes follow Gaussian distribution. The bands of 1 (3518 cm(-1)), 2 (3349 cm(-1)), and 3 (3195 cm(-1)) were related to the sum of valence vibration of an H-bonded OH group and an intramolecular hydrogen bond of 2-OH ...O-6, intramolecular hydrogen bond of 3-OH...O-5 and the intermolecular hydrogen bond of 6-O...HO-3', respectively. Compared with the bands of cellulose I, a new band of 4 (3115 cm(-1)) related to intermolecular hydrogen bond of 2-OH...O-2' and/or intermolecular hydrogen bond of 6-OH...O-2' in cellulose II appeared. The crystallinity index (CI) was obtained by X-ray diffraction [CI(XD)] and FTIR spectroscopy [CI(IR)]. Including absorbance ratios such as A1431,1419/A897,894 and A1263/A1202,1200, the CI(IR) was evaluated by the absorbance ratios using all the characteristic absorbances of cellulose. The CI(XD) was calculated by the method of Jayme and Knolle. In addition, X-ray diffraction curves, with and without amorphous halo correction, were resolved into portions of cellulose I and cellulose II lattice. From the ratio of the peak area, that is, peak area of cellulose I (or cellulose II)/total peak area, CI(XD) were divided into CI(XD-CI) for cellulose I and CI(XD-CII) for cellulose II. The correlation between CI(XD-CI) (or CI(XD-CII)) and CI(IR) was evaluated, and the bands at 2901 (2802), 1373 (1376), 897 (894), 1263, 668 cm(-1) were good for the internal standard (or denominator) of CI(IR), which increased the correlation coefficient. Both fraction of the absorbances showing peak shift were assigned as the alternate components of CI(IR). The crystallite size was decreased to constant value for Cell 2 treated at >or= 15 wt% NaOH. The crystallite size of Cell 2-C (cellulose II) was smaller than that of Cell 2 (cellulose I) treated at 5-10 wt% NaOH. But the crystallite size of Cell 2-C (cellulose II) was larger than that of Cell 2 (cellulose II) treated at 15-20 wt% NaOH.

Dynamical effects in Bragg coherent x-ray diffraction imaging of finite crystals

NASA Astrophysics Data System (ADS)

Shabalin, A. G.; Yefanov, O. M.; Nosik, V. L.; Bushuev, V. A.; Vartanyants, I. A.

2017-08-01

We present simulations of Bragg coherent x-ray diffractive imaging (CXDI) data from finite crystals in the frame of the dynamical theory of x-ray diffraction. The developed approach is based on a numerical solution of modified Takagi-Taupin equations and can be applied for modeling of a broad range of x-ray diffraction experiments with finite three-dimensional crystals of arbitrary shape also in the presence of strain. We performed simulations for nanocrystals of a cubic and hemispherical shape of different sizes and provided a detailed analysis of artifacts in the Bragg CXDI reconstructions introduced by the dynamical diffraction. Based on our theoretical analysis we developed an analytical procedure to treat effects of refraction and absorption in the reconstruction. Our results elucidate limitations for the kinematical approach in the Bragg CXDI and suggest a natural criterion to distinguish between kinematical and dynamical cases in coherent x-ray diffraction on a finite crystal.

YAlO3:Ce3+ powders: Synthesis, characterization, thermoluminescence and optical studies

NASA Astrophysics Data System (ADS)

Parganiha, Yogita; Kaur, Jagjeet; Dubey, Vikas; Shrivastava, Ravi

2015-09-01

Yttrium aluminum perovskite (YAP) is a promising high temperature ceramic material, known for its mechanical, structural and optical properties. YAP's also known as an ideal host material for solid-state lasers and phosphors. In this work, Ce3+ doped YAlO3 phosphors were synthesized by solid state reaction method, which is very suitable technique for large scale production. A prepared phosphor was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Photoluminescence spectra and Thermoluminescence (TL) glow curve study. The starting reagents used for sample preparation are Y2O3, Al2O3 and CeO2, boric acid used as a flux. Ratio of Y:Al was 1:1 which shows perovskite structure confirmed by the X-ray diffraction (XRD) study. The entire prepared sample was studied by PL excitation and emission spectra. Prominent peak at 446 nm (blue emission) which shows broad emission spectra of photoluminescence. It proves that prepared phosphor can act as a single host for blue emission of light and can be used for display applications. Commission Internationale de I'Eclairage (CIE) techniques proves the blue emission of light (x = .148, y = .117). TL glow curve analysis of prepared phosphor shows the prominent peak at 189 °C for the variable UV exposure time and high temperature peak shows the more stability and less fading in the prepared phosphor. Kinetic data of prepared phosphor were evaluated by peak shape method for variable UV exposure time (5-25 min).

Characterization of Limestone as Raw Material to Hydrated Lime

NASA Astrophysics Data System (ADS)

Salem Hwidi, Rajeb; Nuraiti Tengku Izhar, Tengku; Saad, Farah Naemah Mohd

2018-03-01

In Malaysia, limestone is essentially important for the economic growth as raw materials in the industry sector. Nevertheless, a little attention was paid to the physical, chemical, mineralogical, and morphological properties of the limestone using X-ray fluorescence (X-RF), X-ray diffraction (X-RD), Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy / energy dispersive x-ray spectroscopy (SEM-EDS) respectively. Raw materials (limestone rocks) were collected from Bukit Keteri area, Chuping, Kangar, Perlis, Malaysia. Lab crusher and lab sieved were utilized to prepare five different size of ground limestone at (75 µm, 150 µm, 225 µm, 300, and 425 µm) respectively. It is found that the main chemical composition of bulk limestone was Calcium oxide (CaO) at 97.58 wt.% and trace amount of MnO, Al2O3, and Fe2O3 at 0.02%, 0.35%, and 0.396% respectively. XRD diffractograms showed characteristic peaks of calcite and quartz. Furthermore, main FTIR absorption bands at 1,419, 874.08 and 712.20 cm-1 indicated the presence of calcite. The micrographs showed clearly the difference of samples particle size. Furthermore, EDS peaks of Ca, O, and C elements confirmed the presence of CaCO3 in the samples.

Thermoluminescence (TL) properties and x-ray diffraction (XRD) analysis of high purity CaSO4:Dy TL material

NASA Astrophysics Data System (ADS)

Kamarudin, Nadira; Abdullah, Wan Saffiey Wan; Hamid, Muhammad Azmi Abdul; Dollah, Mohd Taufik

2014-09-01

This paper presents the characterization and TL properties of dysprosium (Dy) doped calcium sulfate (CaSO4) TL material produced by co-precipitation technique with 0.5mol% concentration of dopant. The morphology of the produced TL material was studied using scanning electron microscope (SEM) and the micrograph shows that rectangular parallelepiped shaped crystal with the average of 150 μm in length were produced. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectra show that the TL material produced is high purity anhydrite CaSO4 with average crystallite size of 74 nm with orthorhombic crystal system. The TL behavior of produced CaSO4:Dy was studied using a TLD reader after exposure to gamma ray by Co60 source with the doses of 1,5 and 10 Gy. The glow curve shows linear response with glow peak around 230°C which is desired development in the field of radiation dosimetry.

Remote analysis of planetary soils: X-ray diffractometer development

NASA Technical Reports Server (NTRS)

Gregory, J. C.

1973-01-01

A system is described suitable for remote low power mineralogical analysis of lunar, planetary, or asteroid soils. It includes an X-ray diffractometer, fluorescence spectrometer, and sample preparation system. A one Curie Fe-55 source provides a monochromatic X-ray beam of 5.9 keV. Seeman-Bohlin or focusing geometry is employed in the camera, allowing peak detection to proceed simultaneously at all angles and obviating the need for moving parts. The detector system is an array of 500-600 proportional counters with a wire-spacing of 1 mm. An electronics unit comprising preamplifier, postamplifier, window discriminators, and storage flipflops requiring only 3.5 milliwatts was designed and tested. Total instrument power is less than 5 watts. Powder diffraction patterns using a flat breadboard multiwire counter were recorded.

Instrument and method for X-ray diffraction, fluorescence, and crystal texture analysis without sample preparation

NASA Technical Reports Server (NTRS)

Gendreau, Keith (Inventor); Martins, Jose Vanderlei (Inventor); Arzoumanian, Zaven (Inventor)

2010-01-01

An X-ray diffraction and X-ray fluorescence instrument for analyzing samples having no sample preparation includes a X-ray source configured to output a collimated X-ray beam comprising a continuum spectrum of X-rays to a predetermined coordinate and a photon-counting X-ray imaging spectrometer disposed to receive X-rays output from an unprepared sample disposed at the predetermined coordinate upon exposure of the unprepared sample to the collimated X-ray beam. The X-ray source and the photon-counting X-ray imaging spectrometer are arranged in a reflection geometry relative to the predetermined coordinate.

Intrinsic ferromagnetism in nanocrystalline Mn-doped ZnO depending on Mn concentration.

PubMed

Subramanian, Munisamy; Tanemura, Masaki; Hihara, Takehiko; Soga, Tetsuo; Jimbo, Takashi

2011-04-01

The physical properties of Zn(1-x)Mn(x)O nanoparticles synthesized by thermal decomposition are extensively investigated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman light scattering and Hysteresis measurements. XRD and XPS spectra reveal the absence of secondary phase in nanocrystalline ZnO doped with 5% or less Mn; and, later confirms that the valance state of Mn to be 2+ for all the samples. Raman spectra exhibit a peak at 660 cm(-1) which we attribute to the intrinsic lattice defects of ZnO with increasing Mn concentration. Overall, our results demonstrate that ferromagnetic properties can be realized while Mn-doped ZnO obtained in the nanocrystalline form.

Amorphous tantala and its relationship with the molten state

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alderman, Oliver L.G.; Benmore, C. J.; Neuefeind, Joerg C.

The structure factors of molten Ta 2O 5 and Nb 2O 5 have been measured by high-energy x-ray and pulsed neutron diffraction. These are compared to transmission-mode x-ray diffraction through a self-supported 15-μm ion-beam sputtered amorphous tantala film. Atomistic models derived from the diffraction data by means of empirical potential structure refinement reveal that tantala and niobia liquids are very close to isomorphous, as confirmed by measurement of a molten mixture, Ta 0.8Nb 1.2O 5. Nonetheless, peak Nb-O bond lengths are about 1% shorter than those for Ta-O, at temperatures, T*=T/T melt, scaled to the melting points. Mean coordination numbersmore » are n MO≃5.6(1),n OM≃2.23(4) in the liquid state, and n TaO≃6.6(2),n OTa≃2.63(8) in the solid. The liquids are built from five- and six-fold M-O polyhedra which connect principally by corner sharing, with a minority of edge sharing; a-Ta 2O 5 on the other hand has a local structure more akin to the crystalline polymorphs, built primarily from six- and seven-fold polyhedra, with a larger degree of edge sharing. The structural differences between liquid and amorphous Ta 2O 5, coupled with observations of increasing peak bond lengths upon cooling, are consistent with the interpretation that the amorphous film reaches a supercooled liquidlike metastable equilibrium during deposition. In other words, the amorphous film shares a common progenitor state with a hypothetical glass quenched from a fragile melt. In addition, we show that recent classical interatomic potentials do not fully reproduce the diffraction data, and infer that inclusion of attractive (non-Coulombic) Ta-Ta interactions is important, particularly for obtaining the correct degree of edge sharing, coordination numbers, and densities. In conclusion, nanoscale inhomogeneity of the amorphous film is confirmed by the observation of small-angle x-ray scattering.« less

Amorphous tantala and its relationship with the molten state

NASA Astrophysics Data System (ADS)

Alderman, O. L. G.; Benmore, C. J.; Neuefeind, J.; Coillet, E.; Mermet, A.; Martinez, V.; Tamalonis, A.; Weber, R.

2018-04-01

The structure factors of molten T a2O5 and N b2O5 have been measured by high-energy x-ray and pulsed neutron diffraction. These are compared to transmission-mode x-ray diffraction through a self-supported 15-μm ion-beam sputtered amorphous tantala film. Atomistic models derived from the diffraction data by means of empirical potential structure refinement reveal that tantala and niobia liquids are very close to isomorphous, as confirmed by measurement of a molten mixture, T a0.8N b1.2O5 . Nonetheless, peak Nb-O bond lengths are about 1 % shorter than those for Ta-O, at temperatures, T*=T /Tmelt , scaled to the melting points. Mean coordination numbers are nM O≃5.6 (1 ) ,nO M≃2.23 (4 ) in the liquid state, and nTaO≃6.6 (2 ) ,nOTa≃2.63 (8 ) in the solid. The liquids are built from five- and six-fold M -O polyhedra which connect principally by corner sharing, with a minority of edge sharing; a-T a2O5 on the other hand has a local structure more akin to the crystalline polymorphs, built primarily from six- and seven-fold polyhedra, with a larger degree of edge sharing. The structural differences between liquid and amorphous T a2O5 , coupled with observations of increasing peak bond lengths upon cooling, are consistent with the interpretation that the amorphous film reaches a supercooled liquidlike metastable equilibrium during deposition. In other words, the amorphous film shares a common progenitor state with a hypothetical glass quenched from a fragile melt. In addition, we show that recent classical interatomic potentials do not fully reproduce the diffraction data, and infer that inclusion of attractive (non-Coulombic) Ta-Ta interactions is important, particularly for obtaining the correct degree of edge sharing, coordination numbers, and densities. Nanoscale inhomogeneity of the amorphous film is confirmed by the observation of small-angle x-ray scattering.

Amorphous tantala and its relationship with the molten state

DOE PAGES

Alderman, Oliver L.G.; Benmore, C. J.; Neuefeind, Joerg C.; ...

2018-04-01

The structure factors of molten Ta 2O 5 and Nb 2O 5 have been measured by high-energy x-ray and pulsed neutron diffraction. These are compared to transmission-mode x-ray diffraction through a self-supported 15-μm ion-beam sputtered amorphous tantala film. Atomistic models derived from the diffraction data by means of empirical potential structure refinement reveal that tantala and niobia liquids are very close to isomorphous, as confirmed by measurement of a molten mixture, Ta 0.8Nb 1.2O 5. Nonetheless, peak Nb-O bond lengths are about 1% shorter than those for Ta-O, at temperatures, T*=T/T melt, scaled to the melting points. Mean coordination numbersmore » are n MO≃5.6(1),n OM≃2.23(4) in the liquid state, and n TaO≃6.6(2),n OTa≃2.63(8) in the solid. The liquids are built from five- and six-fold M-O polyhedra which connect principally by corner sharing, with a minority of edge sharing; a-Ta 2O 5 on the other hand has a local structure more akin to the crystalline polymorphs, built primarily from six- and seven-fold polyhedra, with a larger degree of edge sharing. The structural differences between liquid and amorphous Ta 2O 5, coupled with observations of increasing peak bond lengths upon cooling, are consistent with the interpretation that the amorphous film reaches a supercooled liquidlike metastable equilibrium during deposition. In other words, the amorphous film shares a common progenitor state with a hypothetical glass quenched from a fragile melt. In addition, we show that recent classical interatomic potentials do not fully reproduce the diffraction data, and infer that inclusion of attractive (non-Coulombic) Ta-Ta interactions is important, particularly for obtaining the correct degree of edge sharing, coordination numbers, and densities. In conclusion, nanoscale inhomogeneity of the amorphous film is confirmed by the observation of small-angle x-ray scattering.« less

Crystal structure determination of new antimitotic agent bis(p-fluorobenzyl)trisulfide.

PubMed

An, Haoyun; Hu, Xiurong; Gu, Jianming; Chen, Linshen; Xu, Weiming; Mo, Xiaopeng; Xu, Wanhong; Wang, Xiaobo; Xu, Xiao

2008-01-01

The purpose of this research was to investigate the physical characteristics and crystalline structure of bis(p-fluorobenzyl)trisulfide, a new anti-tumor agent. Methods used included X-ray single crystal diffraction, X-ray powder diffraction (XRPD), Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetric (DSC) and thermogravimetric (TG) analyses. The findings obtained with X-ray single crystal diffraction showed that a monoclinic unit cell was a = 12.266(1) A, b = 4.7757(4) A, c = 25.510(1) A, beta = 104.25(1) degrees ; cell volume = 1,448.4(2) A(3), Z = 4, and space group C2/c. The XRPD studies of the four crystalline samples, obtained by recrystallization from four different solvents, indicated that they had the same diffraction patterns. The diffraction pattern stimulated from the crystal structure data is in excellent agreement with the experimental results. In addition, the identical FT-IR spectra of the four crystalline samples revealed absorption bands corresponding to S-S and C-S stretching as well as the characteristic aromatic substitution. Five percent weight loss at 163.3 degrees C was observed when TG was used to study the decomposition process in the temperature range of 20-200 degrees C. DSC also allowed for the determination of onset temperatures at 60.4(1)-60.7(3) degrees C and peak temperatures at 62.1(3)-62.4(3) degrees C for the four crystalline samples studied. The results verified that the single crystal structure shared the same crystal form with the four crystalline samples investigated.

Structural ordering and interface morphology in symmetrically strained(GaIn)As/Ga(PAs) superlattices grown on off-oriented GaAs(100)

NASA Astrophysics Data System (ADS)

Giannini, C.; Tapfer, L.; Zhuang, Y.; de Caro, L.; Marschner, T.; Stolz, W.

1997-02-01

In this work we investigate the structural properties of symmetrically strained (GaIn)As/GaAs/Ga(PAs)/GaAs superlattices by means of x-ray diffraction, reciprocal-space mapping, and x-ray reflectivity. The multilayers were grown by metalorganic vapor-phase epitaxy on (001) GaAs substrates intentionally off-oriented towards one of the nearest <110> directions. High-resolution triple-crystal reciprocal-space maps recorded for different azimuth angles in the vicinity of the (004) Bragg diffraction clearly show a double periodicity of the x-ray peak intensity that can be ascribed to a lateral and a vertical periodicity occurring parallel and perpendicular to the growth surface. Moreover, from the intensity modulation of the satellite peaks, a lateral-strain gradient within the epilayer unit cell is found, varying from a tensile to a compressive strain. Thus, the substrate off-orientation promotes a lateral modulation of the layer thickness (ordered interface roughness) and of the lattice strain, giving rise to laterally ordered macrosteps. In this respect, contour maps of the specular reflected beam in the vicinity of the (000) reciprocal lattice point were recorded in order to inspect the vertical and lateral interface roughness correlation. A semiquantitative analysis of our results shows that the interface morphology and roughness is greatly influenced by the off-orientation angle and the lateral strain distribution. Two mean spatial wavelengths can be determined, one corresponding exactly to the macrostep periodicity and the other indicating a further interface waviness along the macrosteps. The same spatial periodicities were found on the surface by atomic-force-microscopy images confirming the x-ray results and revealing a strong vertical correlation of the interfaces up to the outer surface.

Philip A. Parilla | NREL

Science.gov Websites

atomic layer deposition for applications. He also manages the majority of X-ray characterization equipment at NREL, specifically X-ray diffraction and X-ray fluorescence instrumentation. Additionally, he for EERE's Hydrogen Storage program. He is also an expert in X-ray diffraction and X-ray fluorescence

Three-dimensional distribution of polymorphs and magnesium in a calcified underwater attachment system by diffraction tomography

PubMed Central

Leemreize, Hanna; Almer, Jonathan D.; Stock, Stuart R.; Birkedal, Henrik

2013-01-01

Biological materials display complicated three-dimensional hierarchical structures. Determining these structures is essential in understanding the link between material design and properties. Herein, we show how diffraction tomography can be used to determine the relative placement of the calcium carbonate polymorphs calcite and aragonite in the highly mineralized holdfast system of the bivalve Anomia simplex. In addition to high fidelity and non-destructive mapping of polymorphs, we use detailed analysis of X-ray diffraction peak positions in reconstructed powder diffraction data to determine the local degree of Mg substitution in the calcite phase. These data show how diffraction tomography can provide detailed multi-length scale information on complex materials in general and of biomineralized tissues in particular. PMID:23804437

Simulations of X-ray diffraction of shock-compressed single-crystal tantalum with synchrotron undulator sources.

PubMed

Tang, M X; Zhang, Y Y; E, J C; Luo, S N

2018-05-01

Polychromatic synchrotron undulator X-ray sources are useful for ultrafast single-crystal diffraction under shock compression. Here, simulations of X-ray diffraction of shock-compressed single-crystal tantalum with realistic undulator sources are reported, based on large-scale molecular dynamics simulations. Purely elastic deformation, elastic-plastic two-wave structure, and severe plastic deformation under different impact velocities are explored, as well as an edge release case. Transmission-mode diffraction simulations consider crystallographic orientation, loading direction, incident beam direction, X-ray spectrum bandwidth and realistic detector size. Diffraction patterns and reciprocal space nodes are obtained from atomic configurations for different loading (elastic and plastic) and detection conditions, and interpretation of the diffraction patterns is discussed.

Simulations of X-ray diffraction of shock-compressed single-crystal tantalum with synchrotron undulator sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, M. X.; Zhang, Y. Y.; E, J. C.

Polychromatic synchrotron undulator X-ray sources are useful for ultrafast single-crystal diffraction under shock compression. Here, simulations of X-ray diffraction of shock-compressed single-crystal tantalum with realistic undulator sources are reported, based on large-scale molecular dynamics simulations. Purely elastic deformation, elastic–plastic two-wave structure, and severe plastic deformation under different impact velocities are explored, as well as an edge release case. Transmission-mode diffraction simulations consider crystallographic orientation, loading direction, incident beam direction, X-ray spectrum bandwidth and realistic detector size. Diffraction patterns and reciprocal space nodes are obtained from atomic configurations for different loading (elastic and plastic) and detection conditions, and interpretation of themore » diffraction patterns is discussed.« less

Synthesis of cerium oxide (CeO 2) by co-precipitation for application as a reference material for X-ray powder diffraction peak widths

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Lima Batista, Anderson Márcio; Miranda, Marcus Aurélio Ribeiro; Martins, Fátima Itana Chaves Custódio

Several methods can be used to obtain, from powder diffraction patterns, crystallite size and lattice strain of polycrystalline samples. Some examples are the Scherrer equation, Williamson–Hall plots, Warren/Averbach Fourier decomposition, Whole Powder Pattern Modeling, and Debye function analysis. To apply some of these methods, it is necessary to remove the contribution of the instrument to the widths of the diffraction peaks. Nowadays, one of the main samples used for this purpose is the LaB6 SRM660b commercialized by the National Institute of Standard Technology; the width of the diffraction peak of this sample is caused only by the instrumental apparatus. However,more » this sample can be expensive for researchers in developing countries. In this work, the authors present a simple route to obtain micron-sized polycrystalline CeO 2that have a full width at half maximum comparable with the SRM660b and therefore it can be used to remove instrumental broadening.« less

Coherent X-ray diffraction imaging of nanoengineered polymeric capsules

NASA Astrophysics Data System (ADS)

Erokhina, S.; Pastorino, L.; Di Lisa, D.; Kiiamov, A. G.; Faizullina, A. R.; Tayurskii, D. A.; Iannotta, S.; Erokhin, V.

2017-10-01

For the first time, nanoengineered polymeric capsules and their architecture have been studied with coherent X-ray diffraction imaging technique. The use of coherent X-ray diffraction imaging technique allowed us to analyze the samples immersed in a liquid. We report about the significant difference between polymeric capsule architectures under dry and liquid conditions.

A high-transparency, micro-patternable chip for X-ray diffraction analysis of microcrystals under native growth conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, Thomas D.; Johns Hopkins University School of Medicine, Baltimore, MD 21205; Lyubimov, Artem Y.

A highly X-ray-transparent, silicon nitride-based device has been designed and fabricated to harvest protein microcrystals for high-resolution X-ray diffraction data collection using microfocus beamlines and XFELs. Microcrystals present a significant impediment to the determination of macromolecular structures by X-ray diffraction methods. Although microfocus synchrotron beamlines and X-ray free-electron lasers (XFELs) can enable the collection of interpretable diffraction data from microcrystals, there is a need for efficient methods of harvesting small volumes (<2 µl) of microcrystals grown under common laboratory formats and delivering them to an X-ray beam source under native growth conditions. One approach that shows promise in overcoming themore » challenges intrinsic to microcrystal analysis is to pair so-called ‘fixed-target’ sample-delivery devices with microbeam-based X-ray diffraction methods. However, to record weak diffraction patterns it is necessary to fabricate devices from X-ray-transparent materials that minimize background scattering. Presented here is the design of a new micro-diffraction device consisting of three layers fabricated from silicon nitride, photoresist and polyimide film. The chip features low X-ray scattering and X-ray absorption properties, and uses a customizable blend of hydrophobic and hydrophilic surface patterns to help localize microcrystals to defined regions. Microcrystals in their native growth conditions can be loaded into the chips with a standard pipette, allowing data collection at room temperature. Diffraction data collected from hen egg-white lysozyme microcrystals (10–15 µm) loaded into the chips yielded a complete, high-resolution (<1.6 Å) data set sufficient to determine a high-quality structure by molecular replacement. The features of the chip allow the rapid and user-friendly analysis of microcrystals grown under virtually any laboratory format at microfocus synchrotron beamlines and XFELs.« less

X-Ray diffraction and resonance shear measurement of nano-confined ionic liquids.

PubMed

Tomita, Kazuhito; Mizukami, Masashi; Nakano, Shinya; Ohta, Noboru; Yagi, Naoto; Kurihara, Kazue

2018-05-23

X-ray diffraction measurement at the SPring-8 synchrotron was employed to investigate the structures of two types of imidazolium-based ionic liquids (ILs), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTF2]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]), confined between silica surfaces by varying the surface separation distances of ca. 500 nm (bulk liquid), ca. 10 nm, and ca. 2 nm (hard wall thickness). The obtained diffraction profiles and intensities were discussed by considering the structures and properties of the nano-confined ILs between the silica surfaces investigated by resonance shear measurement (RSM) and molecular dynamics simulation (MD) in our previous reports. [C4mim][NTf2] showed two diffraction peaks at q = 8.8 nm-1 (spacing d = 0.71 nm) and at q = 14.0 nm-1 (spacing d = 0.45 nm) at the greatest distance (D = ca. 500 nm), which were assigned to the interval between the same ions (anion-anion or cation-cation) within the polar network of [C4mim][NTf2] and the interval between the neighboring anion-cation, respectively. The positions of these two peaks remained the same at D = ca. 10 nm and at the hard wall (D = ca. 2 nm) and their intensity factor increased, indicating that both the cation and anion existed in the same layer. This result was consistent with the checkerboard structure of [C4mim][NTf2] on the silica surface computer simulated in our previous studies. On the other hand, [C4mim][BF4] showed a peak at q = 15.4 nm-1 (spacing d = 0.41 nm) corresponding to the anion-cation interval at the greatest distance (D = ca. 500 nm). This peak became broader and weaker at D = ca. 12 nm and at D = ca. 2 nm.

X-Ray Structure determination of the Glycine Cleavage System Protein H of Mycobacterium tuberculosis Using An Inverse Compton Synchrotron X-Ray Source

PubMed Central

Abendroth, Jan; McCormick, Michael S.; Edwards, Thomas E.; Staker, Bart; Loewen, Roderick; Gifford, Martin; Rifkin, Jeff; Mayer, Chad; Guo, Wenjin; Zhang, Yang; Myler, Peter; Kelley, Angela; Analau, Erwin; Hewitt, Stephen Nakazawa; Napuli, Alberto J.; Kuhn, Peter; Ruth, Ronald D.; Stewart, Lance J.

2010-01-01

Structural genomics discovery projects require ready access to both X-ray and NMR instrumentation which support the collection of experimental data needed to solve large numbers of novel protein structures. The most productive X-ray crystal structure determination laboratories make extensive frequent use of tunable synchrotron X-ray light to solve novel structures by anomalous diffraction methods. This requires that frozen cryo-protected crystals be shipped to large government-run synchrotron facilities for data collection. In an effort to eliminate the need to ship crystals for data collection, we have developed the first laboratory-scale synchrotron light source capable of performing many of the state-of-the-art synchrotron applications in X-ray science. This Compact Light Source is a first-in-class device that uses inverse Compton scattering to generate X-rays of sufficient flux, tunable wavelength and beam size to allow high-resolution X-ray diffraction data collection from protein crystals. We report on benchmarking tests of X-ray diffraction data collection with hen egg white lysozyme, and the successful high-resolution X-ray structure determination of the Glycine cleavage system protein H from Mycobacterium tuberculosis using diffraction data collected with the Compact Light Source X-ray beam. PMID:20364333

Anti-contamination device for cryogenic soft X-ray diffraction microscopy

DOE PAGES

Huang, Xiaojing; Miao, Huijie; Nelson, Johanna; ...

2011-05-01

Cryogenic microscopy allows one to view frozen hydrated biological and soft matter specimens with good structural preservation and a high degree of stability against radiation damage. We describe a liquid nitrogen-cooled anti-contamination device for cryogenic X-ray diffraction microscopy. The anti-contaminator greatly reduces the buildup of ice layers on the specimen due to condensation of residual water vapor in the experimental vacuum chamber. We show by coherent X-ray diffraction measurements that this leads to fivefold reduction of background scattering, which is important for far-field X-ray diffraction microscopy of biological specimens.

Ca2 Al2 SiO7 :Ce3+ phosphors for mechanoluminescence dosimetry.

PubMed

Tiwari, Geetanjali; Brahme, Nameeta; Sharma, Ravi; Bisen, D P; Sao, Sanjay Kumar; Sahu, Ishwar Prasad

2016-12-01

A series of Ce 3+ ion single-doped Ca 2 Al 2 SiO 7 phosphors was synthesized by a combustion-assisted method at an initiating temperature of 600 °C. The samples were annealed at 1100 °C for 3 h and their X-ray diffraction patterns confirmed a tetragonal structure. The phase structure, particle size, surface morphology and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy techniques. Thermoluminescence (TL) intensity increased with increase in ultraviolet (UV) light exposure time up to 15 min. With further increase in the UV irradiation time the TL intensity decreases. The increase in TL intensity indicates that trap concentration increased with UV exposure time. A broad peak at 121 °C suggested the existence of a trapping level. The peak of mechanoluminescence (ML) intensity versus time curve increased linearly with increasing impact velocity of the moving piston. Mechanoluminescence intensity increased with increase in UV irradiation time up to 15 min. Under UV-irradiation excitation, the TL and ML emission spectra of Ca 2 Al 2 SiO 7 :Ce 3+ phosphor showed the characteristic emission of Ce 3+ peaking at 400 nm (UV-violet) and originating from the Ce 3+ transitions of 5d-4f ( 2 F 5/2 and 2 F 7/2 ). The photoluminescence (PL) emission spectra for Ca 2 Al 2 SiO 7 :Ce 3+ were similar to the ML/TL emission spectra. The mechanism of ML excitation and the suitability of the Ca 2 Al 2 SiO 7 :Ce 3+ phosphor for radiation dosimetry are discussed. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Low temperature dielectric relaxation in ordinary perovskite ferroelectrics: enlightenment from high-energy x-ray diffraction

NASA Astrophysics Data System (ADS)

Ochoa, D. A.; Levit, R.; Fancher, C. M.; Esteves, G.; Jones, J. L.; E García, J.

2017-05-01

Ordinary ferroelectrics exhibit a second order phase transition that is characterized by a sharp peak in the dielectric permittivity at a frequency-independent temperature. Furthermore, these materials show a low temperature dielectric relaxation that appears to be a common behavior of perovskite systems. Tetragonal lead zirconate titanate is used here as a model system in order to explore the origin of such an anomaly, since there is no consensus about the physical phenomenon involved in it. Crystallographic and domain structure studies are performed from temperature dependent synchrotron x-ray diffraction measurement. Results indicate that the dielectric relaxation cannot be associated with crystallographic or domain configuration changes. The relaxation process is then parameterized by using the Vogel-Fulcher-Tammann phenomenological equation. Results allow us to hypothesize that the observed phenomenon is due to changes in the dynamic behavior of the ferroelectric domains related to the fluctuation of the local polarization.

X-Ray diffraction, spectroscopy and thermochemical characterization of the pharmaceutical paroxetine nitrate salt

NASA Astrophysics Data System (ADS)

Carvalho, Paulo S.; de Melo, Cristiane C.; Ayala, Alejandro P.; Ellena, Javier

2016-08-01

A comprehensive solid state study of Paroxetine nitrate hydrate, (PRX+·NO3-)H2O, is reported. This salt was characterized by a combination of methods, including Single crystal X-ray diffraction, Thermal analysis, Fourier transform infrared spectroscopy (FTIR) and Solubility measurements. (PRX+·NO3-)H2O crystallizes in the monoclinic C2 space group (Z‧ = 1) and its packing was analyzed in details, showing that the main supramolecular motif consists in a C22(4) chain formed by charge-assisted N+-H⋯O- hydrogen bonds. The salt formation and conformation features were also accuracy established via FTIR spectra. In comparison with the pharmaceutical approved (PRX+ṡCl-)ṡ0.5H2O, (PRX+ṡNO3-)ṡH2O showed a decrease of 24 °C in the drug melting peak and a slight reduction in its water solubility value.

Enhancement in surface area and magnetization of CoFe2O4 nanoparticles for targeted drug delivery application

NASA Astrophysics Data System (ADS)

Kale, Swati B.; Somvanshi, Sandeep B.; Sarnaik, M. N.; More, S. D.; Shukla, S. J.; Jadhav, K. M.

2018-05-01

This paper reports facile synthesis, characterizations by X-ray diffraction and scanning electron microscopy and magnetic behaviour of cobalt ferrite nanoparticles. Cobalt ferrite nanoparticles were prepared by sol-gel auto combustion technique using glycine as a fuel. Phase purity and nanocrystalline nature of the prepared sample was confirmed through X-ray diffraction technique. No extra peak other than cubic spinel structure was observed in the XRD pattern. The crystallite size calculated by using Scherrer's formula is of the order of 21.6 nm indicating the nanocrystalline nature of the prepared cobalt ferrite sample. The surface morphological studies were carried out using scanning electron microscope (SEM). SEM image shows homogeneous, agglomerated particles with sponge-like form. The saturation magnetization, coercivity and remenance magnetization obtained by hysteresis curve clearly gives the evidence of excellent and enhanced magnetic behaviour.

Structural correlation of the chalcogenide Ge40Se60 glass

NASA Astrophysics Data System (ADS)

Moharram, A. H.

2017-01-01

Binary Ge40Se60 glass was prepared using the melt-quench technique. The total structure factors, S( K), are obtained using the X-ray diffraction in the wave vector interval 0.28 ≤ K ≤ 6.5 Å-1. The appearance of the first sharp diffraction peak (FSDP) in the structure factor indicates the presence of the intermediate range order. Radial distribution functions, RDF( r), have been obtained using either the conventional (Fourier) transformation or the Monte Carlo simulation of the experimental X-ray data. The short range order parameters deduced from the Monte Carlo total correlation, T( r), functions are better than those obtained from the conventional (Fourier) T( r) data. Gaussian analyses of the total correlation function show that Ge2(Se1/2)6 molecular units are the basic structural units for the investigated Ge40Se60 glass.

Crystal Structure of the Caged Magnetic Compound DyFe2Zn20 at Low Temperature Magnetic Ordering State

NASA Astrophysics Data System (ADS)

Kishii, Nobuya; Tateno, Shota; Ohashi, Masashi; Isikawa, Yosikazu

We have carried out X-ray powder diffraction and thermal expansion measurements of the caged magnetic compound DyFe2Zn20. Even though a strong magnetic anisotropy exists in the magnetization and magnetic susceptibility due to strong exchange interaction between Fe and Dy, almost all X-ray powder diffraction peaks at 14 K correspond to Bragg reflections of the cubic structural models not only at room temperature paramagnetic state but also at low temperature magnetic ordering state. Although the temperature change of the lattice constant is isotropic, an anomalous behavior was observed in the thermal expansion coefficient around 15 K, while the anomaly around TC = 53 K is not clear. The results indicate that the volume change is not caused by the ferromagnetic interaction between Fe and Dy but by the exchange interaction between two Dy ions.

Synthesis, characterization, photoluminescence, and electrochemical studies of novel mononuclear Cu(II) and Zn(II) complexes with the 1-benzylimidazolium ligand

NASA Astrophysics Data System (ADS)

Bibi, Sherino; Mohammad, Sharifah; Manan, Ninie Suhana Abdul; Ahmad, Jimmy; Kamboh, Muhammad Afzal; Khor, Sook Mei; Yamin, Bohari M.; Abdul Halim, Siti Nadiah

2017-08-01

Two new mononuclear coordination complexes [Cu(bim)4Cl2]ṡ2H2O (1) and [Zn(bim)2Cl2] (2) containing the 1-benzylimidazole (bim) ligand were successfully synthesized. Both complexes were characterized by IR, UV-vis, and fluorescence spectroscopies, single crystal and powder X-ray diffraction measurements, and thermogravimetric analysis. Self-assembly during the recrystallization process resulted in the formation of octahedral and tetrahedral Cu(II) and Zn(II) complexes, respectively. The single crystals obtained are representative of the bulk material, as shown by the powder X-ray diffraction patterns. Cyclic voltammetry measurements showed that complex 1 undergoes a quasi-reversible redox reaction, while complex 2 undergoes reduction alone, and no oxidation peak was observed; this is due to the stability of the reduced form of complex 2.

Structural analysis of polymer thin films using GISAXS in the tender X-ray region: Concept and design of GISAXS experiments using the tender X-ray energy at BL-15A2 at the Photon Factory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takagi, H., E-mail: takagih@post.kek.jp; Igarashi, N.; Mori, T.

If small angle X-ray scattering (SAXS) utilizing the soft X-ray region is available, advanced and unique experiments, which differ from traditional SAXS methods, can be realized. For example, grazing-incidence small angle X-ray scattering (GISAXS) using hard X-ray is a powerful tool for understanding the nanostructure in both vertical and lateral directions of thin films, while GISAXS utilizing the tender X-ray region (SX-GISAXS) enables depth-resolved analysis as well as a standard GISAXS analysis in thin films. Thus, at BL-15A2 at the Photon Factory, a dedicated diffractometer for SX-GISAXS (above 2.1 keV) was constructed. This diffractometer is composed of four vacuum chambers andmore » can be converted into the vacuum state from the sample chamber in front of the detector surface. Diffractions are clearly observed until 12th peak when measuring collagen by SAXS with an X-ray energy of 2.40 keV and a camera length of 825 mm. Additionally, we conducted the model experiment using SX-GISAXS with an X-ray energy of 2.40 keV to confirm that a poly(methyl methacrylate)-poly(n-butyl acrylate) block copolymer thin film has a microphase-separated structure in the thin film, which is composed of lamellae aligned both parallel and perpendicular to the substrate surface. Similarly, in a polystyrene-poly(methyl methacrylate) block copolymer thin film, SX-GISAXS with 3.60 keV and 5.73 keV revealed that hexagonally packed cylinders are aligned parallel to the substrate surface. The incident angle dependence of the first order peak position of the q{sub z} direction obtained from experiments at various incident X-ray energies agrees very well with the theoretical one calculated from the distorted wave Born approximation.« less

Observation of electromigration in a Cu thin line by in situ coherent x-ray diffraction microscopy

NASA Astrophysics Data System (ADS)

Takahashi, Yukio; Nishino, Yoshinori; Furukawa, Hayato; Kubo, Hideto; Yamauchi, Kazuto; Ishikawa, Tetsuya; Matsubara, Eiichiro

2009-06-01

Electromigration (EM) in a 1-μm-thick Cu thin line was investigated by in situ coherent x-ray diffraction microscopy (CXDM). Characteristic x-ray speckle patterns due to both EM-induced voids and thermal deformation in the thin line were observed in the coherent x-ray diffraction patterns. Both parts of the voids and the deformation were successfully visualized in the images reconstructed from the diffraction patterns. This result not only represents the first demonstration of the visualization of structural changes in metallic materials by in situ CXDM but is also an important step toward studying the structural dynamics of nanomaterials using x-ray free-electron lasers in the near future.

Note: application of a pixel-array area detector to simultaneous single crystal X-ray diffraction and X-ray absorption spectroscopy measurements.

PubMed

Sun, Cheng-Jun; Zhang, Bangmin; Brewe, Dale L; Chen, Jing-Sheng; Chow, G M; Venkatesan, T; Heald, Steve M

2014-04-01

X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are two main x-ray techniques in synchrotron radiation facilities. In this Note, we present an experimental setup capable of performing simultaneous XRD and XAS measurements by the application of a pixel-array area detector. For XRD, the momentum transfer in specular diffraction was measured by scanning the X-ray energy with fixed incoming and outgoing x-ray angles. By selecting a small fixed region of the detector to collect the XRD signal, the rest of the area was available for collecting the x-ray fluorescence for XAS measurements. The simultaneous measurement of XRD and X-ray absorption near edge structure for Pr0.67Sr0.33MnO3 film was demonstrated as a proof of principle for future time-resolved pump-probe measurements. A static sample makes it easy to maintain an accurate overlap of the X-ray spot and laser pump beam.

Time-resolved x-ray diffraction and calorimetric studies at low scan rates

PubMed Central

Yao, Haruhiko; Hatta, Ichiro; Koynova, Rumiana; Tenchov, Boris

1992-01-01

The phase transitions of dipalmitoylphosphatidylethanolamine (DPPE) in excess water have been examined by low-angle time-resolved x-ray diffraction and calorimetry at low scan rates. The lamellar subgel/lamellar liquid-crystalline (Lc → Lα), lamellar gel/lamellar liquid-crystalline (Lβ → Lα), and lamellar liquid-crystalline/lamellar gel (Lα → Lβ) phase transitions proceed via coexistence of the initial and final phases with no detectable intermediates at scan rates 0.1 and 0.5°C/min. At constant temperature within the region of the Lβ → Lα transition the ratio of the two coexisting phases was found to be stable for over 30 min. The state of stable phase coexistence was preceded by a 150-s relaxation taking place at constant temperature after termination of the heating scan in the transition region. While no intermediate structures were present in the coexistence region, a well reproducible multipeak pattern, with at least four prominent heat capacity peaks separated in temperature by 0.4-0.5°C, has been observed in the cooling transition (Lα → Lβ) by calorimetry. The multipeak pattern became distinct with an increase of incubation time in the liquid-crystalline phase. It was also clearly resolved in the x-ray diffraction intensity versus temperature plots recorded at slow cooling rates. These data suggest that the equilibrium state of the Lα phase of hydrated DPPE is represented by a mixture of domains that differ in thermal behavior, but cannot be distinguished structurally by x-ray scattering. Imagesp689-aFIGURE 9 PMID:19431820

Gas gun shock experiments with single-pulse x-ray phase contrast imaging and diffraction at the Advanced Photon Source

NASA Astrophysics Data System (ADS)

Luo, S. N.; Jensen, B. J.; Hooks, D. E.; Fezzaa, K.; Ramos, K. J.; Yeager, J. D.; Kwiatkowski, K.; Shimada, T.

2012-07-01

The highly transient nature of shock loading and pronounced microstructure effects on dynamic materials response call for in situ, temporally and spatially resolved, x-ray-based diagnostics. Third-generation synchrotron x-ray sources are advantageous for x-ray phase contrast imaging (PCI) and diffraction under dynamic loading, due to their high photon fluxes, high coherency, and high pulse repetition rates. The feasibility of bulk-scale gas gun shock experiments with dynamic x-ray PCI and diffraction measurements was investigated at the beamline 32ID-B of the Advanced Photon Source. The x-ray beam characteristics, experimental setup, x-ray diagnostics, and static and dynamic test results are described. We demonstrate ultrafast, multiframe, single-pulse PCI measurements with unprecedented temporal (<100 ps) and spatial (˜2 μm) resolutions for bulk-scale shock experiments, as well as single-pulse dynamic Laue diffraction. The results not only substantiate the potential of synchrotron-based experiments for addressing a variety of shock physics problems, but also allow us to identify the technical challenges related to image detection, x-ray source, and dynamic loading.

Indium vacancy induced d0 ferromagnetism in Li-doped In2O3 nanoparticles

NASA Astrophysics Data System (ADS)

Cao, Haiming; Xing, Pengfei; Zhou, Wei; Yao, Dongsheng; Wu, Ping

2018-04-01

Li-doped In2O3 nanoparticles with room temperature d0 ferromagnetism were prepared by a sol-gel method. X-ray diffraction, X-ray photoelectron spectroscopy and photoluminescence were carried out to investigate the effects of Li incorporation on the lattice defects. As the content of Li increases, non-monotonic changes in shifts of XRD peak (2 2 2) and the intensity ratios of indium vacancies related photoluminescence peak (PII) with respect to oxygen vacancies related peak (PI) are observed. Results show that at low doping level (≤2 at.%) Li prefers to occupy In sites, while with further doping the interstitial sites are more favorable for Li. Combined with the consistent non-monotonic change in saturation magnetization, we think that indium vacancies resulting from Li-doping play an important role in inducing d0 ferromagnetism in our Li-doped In2O3 nanoparticles, and the FM coupling is mainly mediated by the LiIn-ONN-VIn-ONN-LiIn chains.

Resonant x-ray scattering from a skyrmion lattice

NASA Astrophysics Data System (ADS)

Roy, S.; Langner, M. C.; Mishra, S. K.; Lee, J. C. T.; Shi, X. W.; Hossain, M. A.; Chuang, Y.-D.; Kevan, S. D.; Schoenlein, R. W.; Seki, S.; Tokura, Y.

2014-03-01

Topologically protected novel phases in condensed matter systems are a current research topic of tremendous interest due to both the unique physics and their potential in device applications. Skyrmions are a topological phase that in magnetic systems manifest as a hexagonal lattice of spin-swirls. We report the first observation of the skyrmion lattice using resonant soft x-ray diffraction in Cu2OSeO3, a cubic insulator that exhibits degenerate helical magnetic structures along <100> axes in zero magnetic field. Within a narrow window of temperature and applied magnetic field we observed the six fold symmetric satellite peaks due to the skyrmion lattice around the (001) lattice Bragg peak. As a function of incident photon energy a rotational splitting of the skyrmion satellite peaks was observed that we ascribe to the two Cu sublattices of Cu2OSeO3, with different magnetically active orbitals. The splitting implies a long wavelength modulation of the skyrmion lattice. Work supported by U.S. DOE.

Synthesis and Photoluminescence of Single-Crystalline Fe(III)-Doped CdS Nanobelts.

PubMed

Kamran, Muhammad Arshad; Zou, Bingsuo; Majid, A; Alharbil, Thamer; Saeed, M A; Abdullah, Ali; Javed, Qurat-ul-ain

2016-04-01

In this paper, we report the synthesis and optical properties of Fe(III) doped CdS nanobelts (NBs) via simple Chemical Vapor Deposition (CVD) technique to explore their potential in nano-optics. The energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analysis manifested the presence of Fe(III) ions in the NBs subsequently confirmed by the peak shifting to lower phonon energies as recorded by Raman spectra and shorter lifetime in ns. Photoluminescence (PL) spectrum investigations of the single Fe(III)-doped CdS NBs depicted an additional PL peak centered at 573 nm (orange emission) in addition to the bandedge(BE) emission. The redshift and decrease in the BE intensity of the PL peaks, as compared to the bulk CdS, confirmed the quenching of spectra upon Fe doping. The synthesis and orange emission for Fe-doped CdS NBs have been observed for the first time and point out their potential in nanoscale devices.

Preparation of TiN films by reactive high-power pulsed sputtering Penning discharges

NASA Astrophysics Data System (ADS)

Kimura, Takashi; Yoshida, Ryo; Mishima, Toshihiko; Azuma, Kingo; Nakao, Setsuo

2018-06-01

Titanium nitride (TiN) films are prepared by reactive high-power pulsed sputtering Penning discharges at a total pressure of 0.7 Pa and an average power of 60 W, where the nitrogen fraction is varied up to 15%. The peak value of the instantaneous power ranges between 3 and 14 kW, and the peak power density ranges between 0.3 and 1.2 kW cm‑2. The hardness of TiN films is higher than 22 GPa at the nitrogen fractions lower than 10% and it reaches 31 GPa at a nitrogen fraction of 5%. The X-ray diffraction peak of TiN(111) texture is observed for all prepared films, showing the grain size of about 10 nm. In X-ray photoelectron spectroscopy, oxygen is mainly bonded to titanium, but the intensity of the TiN bond is dominant in the entire Ti 2p spectrum. The intensity ratio of N 1s to Ti 2p ranges between 0.85 and 0.95.

X-ray and neutron diffraction studies of crystallinity in hydroxyapatite coatings.

PubMed

Girardin, E; Millet, P; Lodini, A

2000-02-01

To standardize industrial implant production and make comparisons between different experimental results, we have to be able to quantify the crystallinity of hydroxyapatite. Methods of measuring crystallinity ratio were developed for various HA samples before and after plasma spraying. The first series of methods uses X-ray diffraction. The advantage of these methods is that X-ray diffraction equipment is used widely in science and industry. In the second series, a neutron diffraction method is developed and the results recorded are similar to those obtained by the modified X-ray diffraction methods. The advantage of neutron diffraction is the ability to obtain measurements deep inside a component. It is a nondestructive method, owing to the very low absorption of neutrons in most materials. Copyright 2000 John Wiley & Sons, Inc.

X-ray Diffraction Gratings for Astrophysics

NASA Astrophysics Data System (ADS)

Paerels, Frits

2010-12-01

Over the past year, we have celebrated the tenth anniversary of the Chandra and XMM-Newton X-ray observatories. Both carry powerful, novel diffraction grating spectrometers, which have opened true X-ray spectroscopy for astrophysics. I will describe the design and operation of these instruments, as the background to some of the beautiful results they have produced. But these designs do not exhaust the versatility and essential simplicity of diffraction grating spectrometers, and I will discuss applications for the International X-ray Observatory IXO.

Cadmium effect on structural properties of Cu{sub 2}Zn{sub 1-x}Cd{sub x}SnS{sub 4} quinternary alloys nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ibraheam, A. S.; Al-Douri, Y., E-mail: yaldouri@yahoo.com; Hashim, U.

The study report novel sensing plat of extended quinternart materials, Cu{sub 2}Zn{sub 1-x}d{sub x}SnS{sub 4} quinternary alloy nanostructures were fabricated onto oxidized silicon substrate by sol-gel method and characterized were synthesized by X-ray diffraction (XRD). The XRD peaks were shifted towered the lower angle side with increasing cadmium content. The practical size average of the Cu{sub 2}Zn{sub 1-x}d{sub x}SnS{sub 4} quinternary alloy nanostructures between 34.55 to 63.30 nm.

X-ray diffraction investigations of structural modifications in In-doped tin pyrophosphates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Botez, Cristian E.; Martinez, Heber; Morris, Joshua L.

2017-08-01

Laboratory and synchrotron x-ray powder diffraction were used to investigate the structural modifications that occur upon indium doping of tin pyrophosphate. The data collected under air, vacuum, and inert gas sample environments at temperatures (T) from 50 °C to 300 °C show that regardless of the In-doping level (0 ≤ x ≤ 0.18) all InxSn1-xP2O7 samples are isomorphic (have the same P a -3 cubic crystal structure) at all temperatures and under all the conditions investigated. The cubic lattice parameter (a) increases linearly with T at all doping levels, but the “a vs. x|T“ isotherms exhibit a robust peak atmore » x = 0.1 when data are collected on samples measured in air. On the other hand, Rietveld refinements against data collected on InxSn1-xP2O7 samples yield values of OO bond lengths and POP bond angles that show no major changes at x = 0.1 at any temperature. This is significant, as the Sn0.9In0.1P2O7 (x = 0.1) compound is known to exhibit the highest proton conductivity within the series, but the microscopic details responsible for the increased proton conductivity are not understood. Finally, the peak observed in the “a vs. x|T“ curves vanishes if the measurements are taken on samples kept either under vacuum or in an inert gas environment. This is a remarkable behavior as it lends further support to our hypothesis that a key microscopic feature responsible for the large proton conductivity of the Sn0.9In0.1P2O7 compound is the enlargement of the lattice constant at x = 0.1.« less

Tailoring growth conditions for efficient tuning of band edge of CdS nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Susha, N.; Nair, Swapna S., E-mail: swapna.s.nair@gmail.com; Aravind, P. B.

2015-06-24

CdS nanoparticles are successively synthesized by chemical precipitation method. The samples prepared at different reaction time and temperature are characterized by X-ray diffraction, Diffuse reflectance spectroscopy, Photoluminescence spectroscopy ans Energy dispersive x-ray analysis. Visible color variation is noted from light yellow to orange, indicates the quantum confinement effect and the results are again got confirmed from the optical studies. A shift in absorption peak is observed towards the lower region of the visible spectra - the “blue shift”- upon decrease in reaction time and temperature. Blue emission observed in the photoluminescence spectrum confirms the grain size induced confinement.

Effect of annealing temperature on the stress and structural properties of Ge core fibre

NASA Astrophysics Data System (ADS)

Zhao, Ziwen; Cheng, Xueli; Xue, Fei; He, Ting; Wang, Tingyun

2017-09-01

Effect of annealing temperature on the stress and structural properties of a Ge core fibre via the molten core drawing (MCD) method is investigated using Raman spectroscopy, Scanning electronic microscopy (SEM), and X-ray diffraction. The experimental results showed that the Raman peak position of the Ge fibre shifted from 297.6 cm-1 to 300.5 cm-1, and the FWHM value decreased from 4.53 cm-1 to 4.31 cm-1, when the annealing is carried out at 700 °C, 800 °C, and 900 °C, respectively. For the Ge core annealed at 900 °C, an apparent crystal grain can be seen in the SEM image, and the diffraction peaks of the (3 3 1) plane are generated in the X-ray diffraction spectra. These results show that optimising the annealing temperature allows the release of the residual stress in the Ge core. When the Ge core fibre is annealed at 900 °C, it exhibits the lowest residual stress and the highest crystal quality, and the quality improvement relative to that of the sample annealed at 800 °C is significant. Hence, annealing at around 900 °C can greatly improve the quality of a Ge core fibre. Further performance improvement of the Ge core fibre by annealing techniques can be anticipated.

Detecting rare, abnormally large grains by x-ray diffraction

DOE PAGES

Boyce, Brad L.; Furnish, Timothy Allen; Padilla, H. A.; ...

2015-07-16

Bimodal grain structures are common in many alloys, arising from a number of different causes including incomplete recrystallization and abnormal grain growth. These bimodal grain structures have important technological implications, such as the well-known Goss texture which is now a cornerstone for electrical steels. Yet our ability to detect bimodal grain distributions is largely confined to brute force cross-sectional metallography. The present study presents a new method for rapid detection of unusually large grains embedded in a sea of much finer grains. Traditional X-ray diffraction-based grain size measurement techniques such as Scherrer, Williamson–Hall, or Warren–Averbach rely on peak breadth andmore » shape to extract information regarding the average crystallite size. However, these line broadening techniques are not well suited to identify a very small fraction of abnormally large grains. The present method utilizes statistically anomalous intensity spikes in the Bragg peak to identify regions where abnormally large grains are contributing to diffraction. This needle-in-a-haystack technique is demonstrated on a nanocrystalline Ni–Fe alloy which has undergone fatigue-induced abnormal grain growth. In this demonstration, the technique readily identifies a few large grains that occupy <0.00001 % of the interrogation volume. Finally, while the technique is demonstrated in the current study on nanocrystalline metal, it would likely apply to any bimodal polycrystal including ultrafine grained and fine microcrystalline materials with sufficiently distinct bimodal grain statistics.« less

High power, high beam quality regenerative amplifier

DOEpatents

Hackel, L.A.; Dane, C.B.

1993-08-24

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

High power, high beam quality regenerative amplifier

DOEpatents

Hackel, Lloyd A.; Dane, Clifford B.

1993-01-01

A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gargarella, P., E-mail: piter@ufscar.br; Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rodovia Washington Luiz, Km 235, 13565-905 São Carlos, São Paulo; Pauly, S.

The structural evolution of Ti{sub 50}Cu{sub 43}Ni{sub 7} and Ti{sub 55}Cu{sub 35}Ni{sub 10} metallic glasses during heating was investigated by in-situ synchrotron X-ray diffraction. The width of the most intense diffraction maximum of the glassy phase decreases slightly during relaxation below the glass transition temperature. Significant structural changes only occur above the glass transition manifesting in a change in the respective peak positions. At even higher temperatures, nanocrystals of the shape memory B2-Ti(Cu,Ni) phase precipitate, and their small size hampers the occurrence of a martensitic transformation.

Structural and spectroscopic study of mechanically synthesized SnO{sub 2} nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vij, Ankush, E-mail: vij-anx@yahoo.com; Kumar, Ravi; Presently at Beant College of Engineering and Technology, Gurdaspur-143521

2016-05-23

We report the single step synthesis of SnO{sub 2} nanostructures using high energy mechanical attrition method. X-ray diffraction (XRD) pattern reveals the single phase rutile structure with appreciable broadening of diffraction peaks, which is a signature of nanostructure formation. The average crystallite size of SnO{sub 2} nanostructures has been calculated to be ~15 nm. The micro-Raman study reveals the shifting of A{sub 1g} Raman mode towards lower wave number, which is correlated with the nanostructure formation.

X-Ray Sum Frequency Diffraction for Direct Imaging of Ultrafast Electron Dynamics

NASA Astrophysics Data System (ADS)

Rouxel, Jérémy R.; Kowalewski, Markus; Bennett, Kochise; Mukamel, Shaul

2018-06-01

X-ray diffraction from molecules in the ground state produces an image of their charge density, and time-resolved x-ray diffraction can thus monitor the motion of the nuclei. However, the density change of excited valence electrons upon optical excitation can barely be monitored with regular diffraction techniques due to the overwhelming background contribution of the core electrons. We present a nonlinear x-ray technique made possible by novel free electron laser sources, which provides a spatial electron density image of valence electron excitations. The technique, sum frequency generation carried out with a visible pump and a broadband x-ray diffraction pulse, yields snapshots of the transition charge densities, which represent the electron density variations upon optical excitation. The technique is illustrated by ab initio simulations of transition charge density imaging for the optically induced electronic dynamics in a donor or acceptor substituted stilbene.

Part II: diffraction from two-dimensional cholera toxin crystals bound to their receptors in a lipid monolayer.

PubMed

Miller, C E; Majewski, J; Watkins, E B; Weygand, M; Kuhl, T L

2008-07-01

The structure of cholera toxin (CTAB(5)) bound to its putative ganglioside receptor, galactosyl-N-acetylgalactosaminyl (N-acetyl-neuraminyl) galactosylglucosylceramide (GM(1)), in a lipid monolayer at the air-water interface has been studied utilizing grazing incidence x-ray diffraction. Cholera toxin is one of very few proteins to be crystallized in two dimensions and characterized in a fully hydrated state. The observed grazing incidence x-ray diffraction Bragg peaks indicated cholera toxin was ordered in a hexagonal lattice and the order extended 600-800 A. The pentameric binding portion of cholera toxin (CTB(5)) improved in-plane ordering over the full toxin (CTAB(5)) especially at low pH. Disulfide bond reduction (activation of the full toxin) also increased the protein layer ordering. These findings are consistent with A-subunit flexibility and motion, which cause packing inefficiencies and greater disorder of the protein layer. Corroborative out-of-plane diffraction (Bragg rod) analysis indicated that the scattering units in the cholera layer with CTAB(5) shortened after disulfide bond reduction of the A subunit. These studies, together with Part I results, revealed key changes in the structure of the cholera toxin-lipid system under different pH conditions.

High energy cathode material

DOEpatents

Li, Bin; Caldwell, Marissa; Tong, Wei; Kaye, Steven; Bhat, Vinay

2015-09-01

A composition for use in a battery electrode comprising a compound including lithium, manganese, nickel, and oxygen. The composition is characterized by a powder X-ray diffraction pattern having peaks including 18.6.+-.0.2, 35.0.+-.0.2, 36.4.+-.0.2, 37.7.+-.0.2, 42.1.+-.0.2, and 44.5.+-.0.2 degrees 2.theta. as measured using Cu K.sub..alpha. radiation.

Structural, spectroscopic and theoretical studies on 3,4,7,8-tetramethyl-1,10-phenantroline complex with picric acid

NASA Astrophysics Data System (ADS)

Bator, G.; Sobczyk, L.; Sawka-Dobrowolska, W.; Wuttke, J.; Pawlukojć, A.; Grech, E.; Nowicka-Scheibe, J.

2013-01-01

The almost planar molecular complex, formed by 3,4,7,8-tetramethyl-phenantroline (Me4phen) and picric acid (2,4,6-trinitrophenol, PA), has been investigated by using X-ray diffraction, vibrational spectroscopy, tunnel splitting and theoretical analysis. In the crystal of Me4phen·PA two short bifurcated hydrogen bonds N+-H···O- [2.6238(14) Å] and N+-H···N [2.6898(15) Å] are created. Infra-red spectra show the hydrogen bonds are short. The neutron backscattering spectrum of Me4phenṡPA at 3 K shows two tunneling peaks at ca. 1 and 3 μeV. The number of the peaks is consistent with X-ray diffraction studies, which disclosed the inequivalence of methyl groups in the crystal structure. The comparison of the tunnel splitting for neat Me4phen and for its complex with picric acid indicates that in the latter case the methyl groups are more strongly engaged in the intermolecular interactions, particularly with nitro group oxygen atoms of picric acid, leading to an increase of the CH3 rotational barrier height.

Fungal Melanins Differ in Planar Stacking Distances

PubMed Central

Casadevall, Arturo; Nakouzi, Antonio; Crippa, Pier R.; Eisner, Melvin

2012-01-01

Melanins are notoriously difficult to study because they are amorphous, insoluble and often associated with other biological materials. Consequently, there is a dearth of structural techniques to study this enigmatic pigment. Current models of melanin structure envision the stacking of planar structures. X ray diffraction has historically been used to deduce stacking parameters. In this study we used X ray diffraction to analyze melanins derived from Cryptococcus neoformans, Aspergillus niger, Wangiella dermatitides and Coprinus comatus. Analysis of melanin in melanized C. neoformans encapsulated cells was precluded by the fortuitous finding that the capsular polysaccharide had a diffraction spectrum that was similar to that of isolated melanin. The capsular polysaccharide spectrum was dominated by a broad non-Bragg feature consistent with origin from a repeating structural motif that may arise from inter-molecular interactions and/or possibly gel organization. Hence, we isolated melanin from each fungal species and compared diffraction parameters. The results show that the inferred stacking distances of fungal melanins differ from that reported for synthetic melanin and neuromelanin, occupying intermediate position between these other melanins. These results suggest that all melanins have a fundamental diffracting unit composed of planar graphitic assemblies that can differ in stacking distance. The stacking peak appears to be a distinguishing universal feature of melanins that may be of use in characterizing these enigmatic pigments. PMID:22359541

Development of an adaptable coherent x-ray diffraction microscope with the emphasis on imaging hydrated specimens.

PubMed

Nam, Daewoong; Park, Jaehyun; Gallagher-Jones, Marcus; Shimada, Hiroki; Kim, Sangsoo; Kim, Sunam; Kohmura, Yoshiki; Ishikawa, Tetsuya; Song, Changyong

2013-11-01

This paper describes the development of a versatile coherent x-ray diffraction microscope capable of imaging biological specimens in solution. The microscope is a flexible platform accommodating various conditions, from low vacuum (10(-2) Pa) to helium gas filled ambient pressure. This flexibility greatly expands the application area, from in situ materials science to biology systems in their native state, by significantly relaxing restrictions to the sample environment. The coherent diffraction microscope has been used successfully to image a yeast cell immersed in buffer solution. We believe that the design of this coherent diffraction microscope can be directly adapted to various platforms such as table top soft x-ray laser, synchrotron x-ray sources, and x-ray free electron laser with minor relevant adjustments.

Development of an adaptable coherent x-ray diffraction microscope with the emphasis on imaging hydrated specimens

NASA Astrophysics Data System (ADS)

Nam, Daewoong; Park, Jaehyun; Gallagher-Jones, Marcus; Shimada, Hiroki; Kim, Sangsoo; Kim, Sunam; Kohmura, Yoshiki; Ishikawa, Tetsuya; Song, Changyong

2013-11-01

This paper describes the development of a versatile coherent x-ray diffraction microscope capable of imaging biological specimens in solution. The microscope is a flexible platform accommodating various conditions, from low vacuum (10-2 Pa) to helium gas filled ambient pressure. This flexibility greatly expands the application area, from in situ materials science to biology systems in their native state, by significantly relaxing restrictions to the sample environment. The coherent diffraction microscope has been used successfully to image a yeast cell immersed in buffer solution. We believe that the design of this coherent diffraction microscope can be directly adapted to various platforms such as table top soft x-ray laser, synchrotron x-ray sources, and x-ray free electron laser with minor relevant adjustments.

Thin Film Research. Volume 1

DTIC Science & Technology

1985-05-30

Order (FECO) ......... 23 3. X -Ray Diffraction ............................... 26 4. Transmission Electron Microscopy (TEM) ............... 26 5...remained amorphous after bombardment, as evidenced by X - ray diffraction, and showed no other changes. 0 (2) For Sb203, the crystallite size was reduced...main effect on MgF2 was the reduction in crystallite size. The films were too thir. for meaningful x - ray diffraction analysis. Durability and

X-Ray Diffraction and the Discovery of the Structure of DNA

ERIC Educational Resources Information Center

Crouse, David T.

2007-01-01

A method is described for teaching the analysis of X-ray diffraction of DNA through a series of steps utilizing the original methods used by James Watson, Francis Crick, Maurice Wilkins and Rosalind Franklin. The X-ray diffraction pattern led to the conclusion of the basic helical structure of DNA and its dimensions while basic chemical principles…

High Resolution X-Ray Diffraction of Macromolecules with Synchrotron Radiation

NASA Technical Reports Server (NTRS)

Stojanoff, Vivian; Boggon, Titus; Helliwell, John R.; Judge, Russell; Olczak, Alex; Snell, Edward H.; Siddons, D. Peter; Rose, M. Franklin (Technical Monitor)

2000-01-01

We recently combined synchrotron-based monochromatic X-ray diffraction topography methods with triple axis diffractometry and rocking curve measurements: high resolution X-ray diffraction imaging techniques, to better understand the quality of protein crystals. We discuss these methods in the light of results obtained on crystals grown under different conditions. These non destructive techniques are powerful tools in the characterization of the protein crystals and ultimately will allow to improve, develop, and understand protein crystal growth. High resolution X-ray diffraction imaging methods will be discussed in detail in light of recent results obtained on Hen Egg White Lysozyme crystals and other proteins.

Phase coexistence and magnetic behavior in the low-dimensional hexagonal cobaltites BaxA1-xCoO3-δ (A = Mg or Ca and 0 ⩽ x ⩽ 0.20)

NASA Astrophysics Data System (ADS)

Oliveira, M. P.; Mercena, S. G.; Meneses, C. T.; Jesus, C. B. R.; Pagliuso, P. G.; Duque, J. G. S.

2018-04-01

In this work, we report on X-ray diffraction and magnetization measurements carried out in the low-dimensional hexagonal cobaltites BaxA1-xCoO3-δ (A = Mg or Ca, 0 ⩽ x ⩽ 0.20 and δ = 0 or 0.4). Polycrystalline samples have been synthesized by solid-state reaction. The Rietveld refinements of the X-ray diffraction patterns show clearly a phase coexistence of both BaCoO2.6 and BaCoO3 hexagonal polytype structures (space group: P63/mmc), which is dependent on both the dopant ion and doping level. At low temperatures (T < 50K), the ZFC-FC data recorded at H = 1 kOe for Ca-doped (x < 0.15) and Ba0.80Mg0.20CoO3-δ samples present a broad peak and strong thermal hysteresis. Besides, a second anomaly around room temperature is also observed in susceptibility curves for all samples. Further increasing in the Ca-doping produces a continuous decreasing of magnetization and for the samples with x > 0.10 the low temperature hysteresis is not observed anymore. The field-dependence of ZFC-FC curves taken for the sample grown with x = 0 show a displacement of the peak position into low temperature region. Except for the sample grown with x = 0.20, the MvsH loops taken at T = 2 K show multiple steps in the field region ranging - 15 ⩽ H ⩽ 15 kOe . Finally, the saturation magnetization values are consistent with a low-spin state for the Co2+ or Co4+ ions.

Hard X-ray polarizer to enable simultaneous three-dimensional nanoscale imaging of magnetic structure and lattice strain

DOE PAGES

Logan, Jonathan; Harder, Ross; Li, Luxi; ...

2016-01-01

Recent progress in the development of dichroic Bragg coherent diffractive imaging, a new technique for simultaneous three-dimensional imaging of strain and magnetization at the nanoscale, is reported. This progress includes the installation of a diamond X-ray phase retarder at beamline 34-ID-C of the Advanced Photon Source. Here, the performance of the phase retarder for tuning X-ray polarization is demonstrated with temperature-dependent X-ray magnetic circular dichroism measurements on a gadolinium foil in transmission and on a Gd 5Si 2Ge 2crystal in diffraction geometry with a partially coherent, focused X-ray beam. Feasibility tests for dichroic Bragg coherent diffractive imaging are presented. Thesemore » tests include (1) using conventional Bragg coherent diffractive imaging to determine whether the phase retarder introduces aberrations using a nonmagnetic gold nanocrystal as a control sample, and (2) collecting coherent diffraction patterns of a magnetic Gd 5Si 2Ge 2nanocrystal with left- and right-circularly polarized X-rays. Future applications of dichroic Bragg coherent diffractive imaging for the correlation of strain and lattice defects with magnetic ordering and inhomogeneities are considered.« less

Synthesis and Characterization of Nd(3+)-Doped CaF2 Nanoparticles.

PubMed

Yuan, Dan; Li, Weiwei; Mei, Bingchu; Song, Jinghong

2015-12-01

The Ca(1-x)F(2+x):Nd(x) nanoparticles were synthesized by chemical direct precipitation method. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Image analyzer, absorption spectrum and transmittance were taken to characterization the phases, morphologies, sizes, size distribution and optical properties of the samples. The results indicate that the Ca(1-x)F(2+x):Nd(x) samples can be rationally modified in size and morphology by altering the Nd3+ ions doping concentration. With increasing concentration of Nd3+ ions, the particle size decreased from 24 to 14 nm, the intensity of the diffraction peaks decreased, the Ca(1-x)F(2+x):Nd(x) particles aggregated ion of the formed clusters which should have an effect on both speed and orientation of the particles growth. The transmittance of ceramics with a thickness of 2 mm showed that the transmittance can reach 90% when the doping concentration was 5%, which should be profitable for LD pumping.

Effect of Cu2+ substitution on the structural, optical and magnetic behaviour ofchemically derived manganese ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Vasuki, G.; Balu, T.

2018-06-01

Mixed spinel copper manganese ferrite (CuXMn1‑XFe2O4, X = 0, 0.25, 0.5, 0.75, 1) nanoparticles were synthesized by chemical co-precipitation technique. From the powder x-ray diffraction analysis the lattice constant, volume of unit cell, x-ray density, hopping lengths, crystallite size, surface area, dislocation density and microstrain were calculated. The substitution of Cu2+ ions shows a considerable reduction in the crystallite size of manganese ferrite from 34 nm to 22 nm. Further a linear fit of Williamson-Hall plot has been drawn to determine the microstrain and crystallite size. The crystallite size and morphology were further observed through high resolution transmission electron microscope and scanning electron microscope. The diffraction rings observed from selected area electron diffraction pattern exhibits the crystalline nature of all the samples. The energy dispersive x-ray analysis shows the composition of all the elements incorporated in the synthesized nanomaterials. FTIR studies reveal the absorption peaks that correspond to the metal-oxygen vibrations in the tetrahedral and octahedral sites. From the UV–vis absorption spectra the band gap energy, refractive index and optical dielectric constant were determined. Magnetic studies carried out using vibrating sample magnetometer shows interesting behaviour in the variation of magnetisation and coercivity. Peculiar magnetic behaviour is observed when Cu2+ ions are substituted in manganese ferrites. All the synthesized materials have very low value of squareness ratio which attributes to the superparamagnetic behaviour.

Three Dimensional Variable-Wavelength X-Ray Bragg Coherent Diffraction Imaging

DOE PAGES

Cha, W.; Ulvestad, A.; Allain, M.; ...

2016-11-23

Here, we present and demonstrate a formalism by which three-dimensional (3D) Bragg x-ray coherent diffraction imaging (BCDI) can be implemented without moving the sample by scanning the energy of the incident x-ray beam. This capability is made possible by introducing a 3D Fourier transform that accounts for x-ray wavelength variability. We also demonstrate the approach by inverting coherent Bragg diffraction patterns from a gold nanocrystal measured with an x-ray energy scan. Furthermore, variable-wavelength BCDI will expand the breadth of feasible in situ 3D strain imaging experiments towards more diverse materials environments, especially where sample manipulation is difficult.

Synchrotron X-Ray Diffraction Analysis of Meteorites in Thin Section: Preliminary Results

NASA Technical Reports Server (NTRS)

Treiman, A. H.; Lanzirotti, A.; Xirouchakis, D.

2004-01-01

X-ray diffraction is the pre-eminent technique for mineral identification and structure determination, but is difficult to apply to grains in thin section, the standard meteorite preparation. Bright focused X-ray beams from synchrotrons have been used extensively in mineralogy and have been applied to extraterrestrial particles. The intensity and small spot size achievable in synchrotron X-ray beams makes them useful for study of materials in thin sections. Here, we describe Synchrotron X-ray Diffraction (SXRD) in thin section as done at the National Synchrotron Light Source, and cite examples of its value for studies of meteorites in thin section.

Three Dimensional Variable-Wavelength X-Ray Bragg Coherent Diffraction Imaging

NASA Astrophysics Data System (ADS)

Cha, W.; Ulvestad, A.; Allain, M.; Chamard, V.; Harder, R.; Leake, S. J.; Maser, J.; Fuoss, P. H.; Hruszkewycz, S. O.

2016-11-01

We present and demonstrate a formalism by which three-dimensional (3D) Bragg x-ray coherent diffraction imaging (BCDI) can be implemented without moving the sample by scanning the energy of the incident x-ray beam. This capability is made possible by introducing a 3D Fourier transform that accounts for x-ray wavelength variability. We demonstrate the approach by inverting coherent Bragg diffraction patterns from a gold nanocrystal measured with an x-ray energy scan. Variable-wavelength BCDI will expand the breadth of feasible in situ 3D strain imaging experiments towards more diverse materials environments, especially where sample manipulation is difficult.

Three Dimensional Variable-Wavelength X-Ray Bragg Coherent Diffraction Imaging.

PubMed

Cha, W; Ulvestad, A; Allain, M; Chamard, V; Harder, R; Leake, S J; Maser, J; Fuoss, P H; Hruszkewycz, S O

2016-11-25

We present and demonstrate a formalism by which three-dimensional (3D) Bragg x-ray coherent diffraction imaging (BCDI) can be implemented without moving the sample by scanning the energy of the incident x-ray beam. This capability is made possible by introducing a 3D Fourier transform that accounts for x-ray wavelength variability. We demonstrate the approach by inverting coherent Bragg diffraction patterns from a gold nanocrystal measured with an x-ray energy scan. Variable-wavelength BCDI will expand the breadth of feasible in situ 3D strain imaging experiments towards more diverse materials environments, especially where sample manipulation is difficult.

Physicochemical, rheological and structural characteristics of starch in maize tortillas.

PubMed

Hernández-Uribe, Juan P; Ramos-López, Gonzalo; Yee-Madeira, Hernani; Bello-Pérez, Luis A

2010-06-01

Fresh and stored maize (white and blue) tortillas were evaluated for physicochemical, rheological and structural characteristics assessed by calorimetry, x-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, dynamic viscoelastic tests, and high-performance size-exclusion chromatography. Two endotherms were found in studies of fresh and stored tortillas. The low temperature endotherm (50-56 degrees C) was due to reorganized (retrograded) amylopectin, while the high temperature endotherm (105-123 degrees C) was attributed to retrograded amylose. The enthalpy value for the lower temperature transition was minor than that of the high temperature transition. Fresh tortillas showed an amorphous starch arrangement by x-ray diffraction study. Stored samples showed the presence of peaks at 2theta = 17 masculine and 23 masculine, indicating re-crystallization of starch components. FTIR results confirmed the development of higher levels of starch crystals during storage. Differences in the viscoelastic parameters were also observed between fresh and stored samples. At the longest storage times, white tortillas were more rigid than blue tortillas. Molar mass values for starch increased for both white and blue tortillas as storage time progressed, though relatively higher values were obtained for white tortillas. More starch reorganization occurred in white tortillas, in accordance to calorimetric, x-ray diffraction, FTIR and rheological results. These results corroborate that changes occurring in tortillas during storage are related to reorganization of starch components, and the maize variety more than the color plays an important role.

Digital model for X-ray diffraction with application to composition and strain determination in strained InAs/GaSb superlattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Yifei; Kim, Honggyu; Zuo, Jian-Min

2014-07-07

We propose a digital model for high quality superlattices by including fluctuations in the superlattice periods. The composition and strain profiles are assumed to be coherent and persist throughout the superlattice. Using this model, we have significantly improved the fit with experimental X-ray diffraction data recorded from the nominal InAs/GaSb superlattice. The lattice spacing of individual layers inside the superlattice and the extent of interfacial intermixing are refined by including both (002) and (004) and their satellite peaks in the fitting. For the InAs/GaSb strained layer superlattice, results show: (i) the GaSb-on-InAs interface is chemically sharper than the InAs-on-GaSb interface,more » (ii) the GaSb layers experience compressive strain with In incorporation, (iii) there are interfacial strain associated with InSb-like bonds in GaSb and GaAs-like bonds in InAs, (iv) Sb substitutes a significant amount of In inside InAs layer near the InAs-on-GaSb interface. For support, we show that the composition profiles determined by X-ray diffraction are in good agreement with those obtained from atom probe tomography measurement. Comparison with the kinetic growth model shows a good agreement in terms of the composition profiles of anions, while the kinetic model underestimates the intermixing of cations.« less

[Structure and luminescence properties of Ga2O3 : Cr3+ by Al doping].

PubMed

Wang, Xian-Sheng; Wan, Min-Hua; Wang, Yin-Hai; Zhao, Hui; Hu, Zheng-Fa; Li, Hai-Ling

2013-11-01

The Al doping gallate phosphor (Ga(1-x)Al(x))2O3 : Cr3+ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) was synthesized by a high temperature solid-state reaction method. The X-ray diffractions show that the phase of the phosphors remains to be Ga2 O3 structure with increase in the contents of Al3+ ion. Beside, the fact that the X-ray diffraction peak shifts towards big angles with increasing Al3+ ions content shows that Al3+ ions entered the Ga2 O3 lattice. The peaks of the excitation spectra located at 258, 300, 410 and 550 nm are attributed to the band to band transition of the matrix, charge transfer band transition, and 4A2 --> 4T1 and 4A2 --> 4T2 transition of Cr3+ ions, respectively. Those excitation spectrum peak positions show different degrees of blue shift with the increase in the Al3+ ions content. The blue shift of the first two peaks are due to the band gap energy of substrate and the electronegativity between Cr3+ ions and ligands increasing, respectively. The blue shift of the energy level transition of Cr3+ ion is attributed to crystal field strength increasing. The Cr3+ ion luminescence changes from a broadband emission to a narrow-band emission with Al3+ doping, because the emission of Cr3+ ion changed from 4 T2 --> 4A2 to 2E --> 4A2 transition with the crystal field change after Al3+ ions doping. The Al3+ ions doping improved the long afterglow luminescence properties of samples, and the sample showed a longer visible near infrared when Al3+ ions content reaches 0.5. The thermoluminescence curve shows the sample with suitable trap energy level, and this is also the cause of the long afterglow luminescence materials.

In-situ X-ray diffraction system using sources and detectors at fixed angular positions

DOEpatents

Gibson, David M [Voorheesville, NY; Gibson, Walter M [Voorheesville, NY; Huang, Huapeng [Latham, NY

2007-06-26

An x-ray diffraction technique for measuring a known characteristic of a sample of a material in an in-situ state. The technique includes using an x-ray source for emitting substantially divergent x-ray radiation--with a collimating optic disposed with respect to the fixed source for producing a substantially parallel beam of x-ray radiation by receiving and redirecting the divergent paths of the divergent x-ray radiation. A first x-ray detector collects radiation diffracted from the sample; wherein the source and detector are fixed, during operation thereof, in position relative to each other and in at least one dimension relative to the sample according to a-priori knowledge about the known characteristic of the sample. A second x-ray detector may be fixed relative to the first x-ray detector according to the a-priori knowledge about the known characteristic of the sample, especially in a phase monitoring embodiment of the present invention.

Synthesis and characterization of graphene oxide using modified Hummer's method

NASA Astrophysics Data System (ADS)

Kaur, Manpreet; Kaur, Harsimran; Kukkar, Deepak

2018-05-01

In the present study, a simple approach has been followed for the synthesis of graphene oxide (GO) using modified Hummers method in which graphite powder was oxidized in the presence of concentrated H2SO4 and KMnO4. The amount of NaNO3 and KMnO4 was varied to produce sheet like structure. The varied concentrations of NaNO3 and KMnO4 resulted in yielding large amount of the product. Structural, morphological and physicochemical features of the product were studied using UV-Visible spectrophotometer, Fourier Transform infrared spectroscopy (FTIR), and crystal structure was determined using X-ray powder diffraction (XRD). UV-Vis spectra of GO was observed at a maximum absorption of 230 nm due to (π-π*) transition of atomic carbon-carbon bonds. FTIR spectra revealed the presence of oxygen containing functional groups which ensures the complete exfoliation of graphite into graphene oxide X-ray powder diffraction pattern of the product showed the diffraction peak at (2θ = 26.7°) with an interlayer spacing of 0.334 nm. All the above characterizations successfully confirmed the formation of GO.

The effect of exit beam phase aberrations on parallel beam coherent x-ray reconstructions

NASA Astrophysics Data System (ADS)

Hruszkewycz, S. O.; Harder, R.; Xiao, X.; Fuoss, P. H.

2010-12-01

Diffraction artifacts from imperfect x-ray windows near the sample are an important consideration in the design of coherent x-ray diffraction measurements. In this study, we used simulated and experimental diffraction patterns in two and three dimensions to explore the effect of phase imperfections in a beryllium window (such as a void or inclusion) on the convergence behavior of phasing algorithms and on the ultimate reconstruction. A predictive relationship between beam wavelength, sample size, and window position was derived to explain the dependence of reconstruction quality on beryllium defect size. Defects corresponding to this prediction cause the most damage to the sample exit wave and induce signature error oscillations during phasing that can be used as a fingerprint of experimental x-ray window artifacts. The relationship between x-ray window imperfection size and coherent x-ray diffractive imaging reconstruction quality explored in this work can play an important role in designing high-resolution in situ coherent imaging instrumentation and will help interpret the phasing behavior of coherent diffraction measured in these in situ environments.

The effect of exit beam phase aberrations on parallel beam coherent x-ray reconstructions.

PubMed

Hruszkewycz, S O; Harder, R; Xiao, X; Fuoss, P H

2010-12-01

Diffraction artifacts from imperfect x-ray windows near the sample are an important consideration in the design of coherent x-ray diffraction measurements. In this study, we used simulated and experimental diffraction patterns in two and three dimensions to explore the effect of phase imperfections in a beryllium window (such as a void or inclusion) on the convergence behavior of phasing algorithms and on the ultimate reconstruction. A predictive relationship between beam wavelength, sample size, and window position was derived to explain the dependence of reconstruction quality on beryllium defect size. Defects corresponding to this prediction cause the most damage to the sample exit wave and induce signature error oscillations during phasing that can be used as a fingerprint of experimental x-ray window artifacts. The relationship between x-ray window imperfection size and coherent x-ray diffractive imaging reconstruction quality explored in this work can play an important role in designing high-resolution in situ coherent imaging instrumentation and will help interpret the phasing behavior of coherent diffraction measured in these in situ environments.

Femtosecond X-ray Diffraction From Two-Dimensional Protein Crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frank, Matthias; Carlson, David B.; Hunter, Mark

2014-02-28

Here we present femtosecond x-ray diffraction patterns from two-dimensional (2-D) protein crystals using an x-ray free electron laser (XFEL). To date it has not been possible to acquire x-ray diffraction from individual 2-D protein crystals due to radiation damage. However, the intense and ultrafast pulses generated by an XFEL permits a new method of collecting diffraction data before the sample is destroyed. Utilizing a diffract-before-destroy methodology at the Linac Coherent Light Source, we observed Bragg diffraction to better than 8.5 Å resolution for two different 2-D protein crystal samples that were maintained at room temperature. These proof-of-principle results show promisemore » for structural analysis of both soluble and membrane proteins arranged as 2-D crystals without requiring cryogenic conditions or the formation of three-dimensional crystals.« less

Structural characterization of precious-mean quasiperiodic Mo/V single-crystal superlattices grown by dual-target magnetron sputtering

NASA Astrophysics Data System (ADS)

Birch, J.; Severin, M.; Wahlström, U.; Yamamoto, Y.; Radnoczi, G.; Riklund, R.; Sundgren, J.-E.; Wallenberg, L. R.

1990-05-01

A class of quasiperiodic superlattice structures, which can be generated by the concurrent inflation rule A-->AmB and B-->A (where m=positive integer), has been studied both theoretically and experimentally. Given that the ratios between the thicknesses of the two superlattice building blocks, A and B, are chosen to be γ(m)=[m+(m2+4)1/2]/2 (known as the ``precious means''), then the x-ray- and electron-diffraction peak positions are analytically found to be located at the wave vectors q=2πΛ-1r[γ(m)]k, where r and k are integers and Λ is an average superlattice wavelength. The analytically obtained results have been compared to experimental results from single-crystalline Mo/V superlattice structures, generated with m=1, 2, and 3. The superlattices were grown by dual-target dc-magnetron sputtering on MgO(001) substrates kept at 700 °C. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) showed that the analytical model mentioned above predicts the peak positions of the experimental XRD and SAED spectra with a very high accuracy. Furthermore, numerical calculations of the diffraction intensities based on a kinematical model of diffraction showed good agreement with the experimental data for all three cases. In addition to a direct verification of the quasiperiodic modulation, both conventional and high-resolution cross-sectional transmission electron microscopy (XTEM) showed that the superlattices are of high crystalline quality with sharp interfaces. Based on lattice resolution images, the width of the interfaces was determined to be less than two (002) lattice-plane spacings (~=0.31 nm).

Large-surface-area diamond (111) crystal plates for applications in high-heat-load wavefront-preserving X-ray crystal optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoupin, Stanislav; Antipov, Sergey; Butler, James E.

Fabrication and results of high-resolution X-ray topography characterization of diamond single-crystal plates with large surface area (10 mm × 10 mm) and (111) crystal surface orientation for applications in high-heat-load X-ray crystal optics are reported. The plates were fabricated by laser-cutting of the (111) facets of diamond crystals grown using high-pressure high-temperature methods. The intrinsic crystal quality of a selected 3 mm × 7 mm crystal region of one of the studied samples was found to be suitable for applications in wavefront-preserving high-heat-load crystal optics. Wavefront characterization was performed using sequential X-ray diffraction topography in the pseudo plane wave configurationmore » and data analysis using rocking-curve topography. In conclusion, the variations of the rocking-curve width and peak position measured with a spatial resolution of 13 µm × 13 µm over the selected region were found to be less than 1 µrad.« less

Large-surface-area diamond (111) crystal plates for applications in high-heat-load wavefront-preserving X-ray crystal optics.

PubMed

Stoupin, Stanislav; Antipov, Sergey; Butler, James E; Kolyadin, Alexander V; Katrusha, Andrey

2016-09-01

Fabrication and results of high-resolution X-ray topography characterization of diamond single-crystal plates with large surface area (10 mm × 10 mm) and (111) crystal surface orientation for applications in high-heat-load X-ray crystal optics are reported. The plates were fabricated by laser-cutting of the (111) facets of diamond crystals grown using high-pressure high-temperature methods. The intrinsic crystal quality of a selected 3 mm × 7 mm crystal region of one of the studied samples was found to be suitable for applications in wavefront-preserving high-heat-load crystal optics. Wavefront characterization was performed using sequential X-ray diffraction topography in the pseudo plane wave configuration and data analysis using rocking-curve topography. The variations of the rocking-curve width and peak position measured with a spatial resolution of 13 µm × 13 µm over the selected region were found to be less than 1 µrad.

Large-surface-area diamond (111) crystal plates for applications in high-heat-load wavefront-preserving X-ray crystal optics

DOE PAGES

Stoupin, Stanislav; Antipov, Sergey; Butler, James E.; ...

2016-08-10

Fabrication and results of high-resolution X-ray topography characterization of diamond single-crystal plates with large surface area (10 mm × 10 mm) and (111) crystal surface orientation for applications in high-heat-load X-ray crystal optics are reported. The plates were fabricated by laser-cutting of the (111) facets of diamond crystals grown using high-pressure high-temperature methods. The intrinsic crystal quality of a selected 3 mm × 7 mm crystal region of one of the studied samples was found to be suitable for applications in wavefront-preserving high-heat-load crystal optics. Wavefront characterization was performed using sequential X-ray diffraction topography in the pseudo plane wave configurationmore » and data analysis using rocking-curve topography. In conclusion, the variations of the rocking-curve width and peak position measured with a spatial resolution of 13 µm × 13 µm over the selected region were found to be less than 1 µrad.« less

High Power Optical Coatings by Atomic Layer Deposition and Signatures of Laser-Induced Damage

DTIC Science & Technology

2012-08-28

diffraction angle 0 into crystal lattice spacing d by the Bragg condition, mX = 2d sin 0. Here X is the x - ray wavelength... angle x - ray diffraction (GAXRD) measurements, which were made at a fixed shallow incidence angle of 0.5°. Detector scans were done to measure the...was finished with 200 hafnia cycles m the fmal half period rather than 400. Crystallinity was measured by x - ray diffraction (XRD) with

Materials identification using a small-scale pixellated x-ray diffraction system

NASA Astrophysics Data System (ADS)

O'Flynn, D.; Crews, C.; Drakos, I.; Christodoulou, C.; Wilson, M. D.; Veale, M. C.; Seller, P.; Speller, R. D.

2016-05-01

A transmission x-ray diffraction system has been developed using a pixellated, energy-resolving detector (HEXITEC) and a small-scale, mains operated x-ray source (Amptek Mini-X). HEXITEC enables diffraction to be measured without the requirement of incident spectrum filtration, or collimation of the scatter from the sample, preserving a large proportion of the useful signal compared with other diffraction techniques. Due to this efficiency, sufficient molecular information for material identification can be obtained within 5 s despite the relatively low x-ray source power. Diffraction data are presented from caffeine, hexamine, paracetamol, plastic explosives and narcotics. The capability to determine molecular information from aspirin tablets inside their packaging is demonstrated. Material selectivity and the potential for a sample classification model is shown with principal component analysis, through which each different material can be clearly resolved.

Fixture for supporting and aligning a sample to be analyzed in an x-ray diffraction apparatus

DOEpatents

Green, L.A.; Heck, J.L. Jr.

1985-04-23

A fixture is provided for supporting and aligning small samples of material on a goniometer for x-ray diffraction analysis. A sample-containing capillary is accurately positioned for rotation in the x-ray beam by selectively adjusting the fixture to position the capillary relative to the x and y axes thereof to prevent wobble and position the sample along the z axis or the axis of rotation. By employing the subject fixture relatively small samples of materials can be analyzed in an x-ray diffraction apparatus previously limited to the analysis of much larger samples.

Fixture for supporting and aligning a sample to be analyzed in an X-ray diffraction apparatus

DOEpatents

Green, Lanny A.; Heck, Jr., Joaquim L.

1987-01-01

A fixture is provided for supporting and aligning small samples of material on a goniometer for X-ray diffraction analysis. A sample-containing capillary is accurately positioned for rotation in the X-ray beam by selectively adjusting the fixture to position the capillary relative to the x and y axes thereof to prevent wobble and position the sample along the z axis or the axis of rotation. By employing the subject fixture relatively small samples of materials can be analyzed in an X-ray diffraction apparatus previously limited to the analysis of much larger samples.

Direct Observation of Active Material Concentration Gradients and Crystallinity Breakdown in LiFePO4 Electrodes During Charge/Discharge Cycling of Lithium Batteries.

PubMed

Roberts, Matthew R; Madsen, Alex; Nicklin, Chris; Rawle, Jonathan; Palmer, Michael G; Owen, John R; Hector, Andrew L

2014-04-03

The phase changes that occur during discharge of an electrode comprised of LiFePO 4 , carbon, and PTFE binder have been studied in lithium half cells by using X-ray diffraction measurements in reflection geometry. Differences in the state of charge between the front and the back of LiFePO 4 electrodes have been visualized. By modifying the X-ray incident angle the depth of penetration of the X-ray beam into the electrode was altered, allowing for the examination of any concentration gradients that were present within the electrode. At high rates of discharge the electrode side facing the current collector underwent limited lithium insertion while the electrode as a whole underwent greater than 50% of discharge. This behavior is consistent with depletion at high rate of the lithium content of the electrolyte contained in the electrode pores. Increases in the diffraction peak widths indicated a breakdown of crystallinity within the active material during cycling even during the relatively short duration of these experiments, which can also be linked to cycling at high rate.

Improved electrochemical properties of a coin cell using LiMn 1.5Ni 0.5O 4 as cathode in the 5 V range

NASA Astrophysics Data System (ADS)

Singhal, Rahul; Das, Suprem R.; Oviedo, Osbert; Tomar, Maharaj S.; Katiyar, Ram S.

Phase pure LiMn 1.5Ni 0.5O 4 powders were synthesized by a chemical synthesis route and were subsequently characterized as cathode materials in a Li-ion coin cell comprising a Li anode and lithium hexafluorophosphate (LiPF 6), dissolved in dimethyl carbonate (DMC) + ethylene carbonate (EC) [1:1, v/v ratio] as electrolyte. The spinel structure and phase purity of the powders were characterized using X-ray diffraction and micro-Raman spectroscopy. The presence of both oxidation and reduction peaks in the cyclic voltammogram revealed Li + extraction and insertion from the spinel structure. The charge-discharge characteristics of the coin cell were performed in the 3.0-4.8 V range. An initial discharge capacity of ∼140 mAh g -1 was obtained with 94% initial discharge capacity retention after 50 repeated cycles. The microstructures and compositions of the cathode before and after electrochemistry were investigated using scanning electron microscopy and energy-dispersive analysis by X-ray analysis, respectively. Using X-ray diffraction, Raman spectroscopy and electrochemical analysis, we correlated the structural stability and the electrochemical performance of this cathode.

Direct Observation of Active Material Concentration Gradients and Crystallinity Breakdown in LiFePO4 Electrodes During Charge/Discharge Cycling of Lithium Batteries

PubMed Central

2014-01-01

The phase changes that occur during discharge of an electrode comprised of LiFePO4, carbon, and PTFE binder have been studied in lithium half cells by using X-ray diffraction measurements in reflection geometry. Differences in the state of charge between the front and the back of LiFePO4 electrodes have been visualized. By modifying the X-ray incident angle the depth of penetration of the X-ray beam into the electrode was altered, allowing for the examination of any concentration gradients that were present within the electrode. At high rates of discharge the electrode side facing the current collector underwent limited lithium insertion while the electrode as a whole underwent greater than 50% of discharge. This behavior is consistent with depletion at high rate of the lithium content of the electrolyte contained in the electrode pores. Increases in the diffraction peak widths indicated a breakdown of crystallinity within the active material during cycling even during the relatively short duration of these experiments, which can also be linked to cycling at high rate. PMID:24790684

Reaction of Pb(II) and Zn(II) with Ethyl Linoleate To Form Structured Hybrid Inorganic–Organic Complexes: A Model for Degradation in Historic Paint Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacDonald, Margaret G.; Palmer, Michael R.; Suchomel, Matthew R.

To investigate soap formation in drying oils in historic paints, the reaction between metal acetates (K +, Zn 2+, Pb 2+) and ethyl linoleate (EL) was studied using optical microscopy, X-ray powder diffraction, and electron microscopy. Pb(II) and Zn(II) react rapidly with EL to form highly structured, spherulitic, luminescent crystallites that aggregate. Evidence from Fourier transform infrared (FTIR) and scanning electron microscopy/energy dispersive X-ray analysis and high-resolution synchrotron powder X-ray diffraction indicates that these are organic-inorganic hybrid complexes or coordination polymers. FTIR absorbance peaks at ca. 1540 cm -1 for Pb(II) and ca. 1580 cm -1 for Zn(II) are consistentmore » with the formation of carboxylate complexes. The complexes formed offer insight into the degradation processes observed in oil paint films, suggesting that soap formation is rapid when metal ions are solubilized and can occur with unsaturated fatty acids that are present in fresh oils. Finally, these complexes may account for the atypical luminescence observed in lead-containing cured oil paint films.« less

Reaction of Pb(II) and Zn(II) with Ethyl Linoleate To Form Structured Hybrid Inorganic–Organic Complexes: A Model for Degradation in Historic Paint Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacDonald, Margaret G.; Palmer, Michael R.; Suchomel, Matthew R.

To investigate soap formation in drying oils in historic paints, the reaction between metal acetates (K +, Zn 2+, Pb 2+) and ethyl linoleate (EL) was studied using optical microscopy, X-ray powder diffraction, and electron microscopy. Pb(II) and Zn(II) react rapidly with EL to form highly structured, spherulitic, luminescent crystallites that aggregate. Evidence from Fourier transform infrared (FTIR) and scanning electron microscopy/energy dispersive X-ray analysis and high-resolution synchrotron powder X-ray diffraction indicates that these are organic–inorganic hybrid complexes or coordination polymers. FTIR absorbance peaks at ca. 1540 cm –1 for Pb(II) and ca. 1580 cm –1 for Zn(II) are consistentmore » with the formation of carboxylate complexes. The complexes formed offer insight into the degradation processes observed in oil paint films, suggesting that soap formation is rapid when metal ions are solubilized and can occur with unsaturated fatty acids that are present in fresh oils. These complexes may account for the atypical luminescence observed in lead-containing cured oil paint films.« less

Reaction of Pb(II) and Zn(II) with Ethyl Linoleate To Form Structured Hybrid Inorganic–Organic Complexes: A Model for Degradation in Historic Paint Films

DOE PAGES

MacDonald, Margaret G.; Palmer, Michael R.; Suchomel, Matthew R.; ...

2016-09-07

To investigate soap formation in drying oils in historic paints, the reaction between metal acetates (K +, Zn 2+, Pb 2+) and ethyl linoleate (EL) was studied using optical microscopy, X-ray powder diffraction, and electron microscopy. Pb(II) and Zn(II) react rapidly with EL to form highly structured, spherulitic, luminescent crystallites that aggregate. Evidence from Fourier transform infrared (FTIR) and scanning electron microscopy/energy dispersive X-ray analysis and high-resolution synchrotron powder X-ray diffraction indicates that these are organic-inorganic hybrid complexes or coordination polymers. FTIR absorbance peaks at ca. 1540 cm -1 for Pb(II) and ca. 1580 cm -1 for Zn(II) are consistentmore » with the formation of carboxylate complexes. The complexes formed offer insight into the degradation processes observed in oil paint films, suggesting that soap formation is rapid when metal ions are solubilized and can occur with unsaturated fatty acids that are present in fresh oils. Finally, these complexes may account for the atypical luminescence observed in lead-containing cured oil paint films.« less

Green biosynthesis of silver nanoparticles using Curcuma longa tuber powder

PubMed Central

Shameli, Kamyar; Ahmad, Mansor Bin; Zamanian, Ali; Sangpour, Parvanh; Shabanzadeh, Parvaneh; Abdollahi, Yadollah; Zargar, Mohsen

2012-01-01

Green synthesis of noble metal nanoparticles is a vastly developing area of research. Metallic nanoparticles have received great attention from chemists, physicists, biologists, and engineers who wish to use them for the development of a new-generation of nanodevices. In this study, silver nanoparticles were biosynthesized from aqueous silver nitrate through a simple and eco-friendly route using Curcuma longa tuber-powder extracts, which acted as a reductant and stabilizer simultaneously. Characterizations of nanoparticles were done using different methods, which included ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray fluorescence spectrometry, and Fourier-transform infrared spectroscopy. The ultraviolet-visible spectrum of the aqueous medium containing silver nanoparticles showed an absorption peak at around 415 nm. Transmission electron microscopy showed that mean diameter and standard deviation for the formation of silver nanoparticles was 6.30 ± 2.64 nm. Powder X-ray diffraction showed that the particles are crystalline in nature, with a face-centered cubic structure. The most needed outcome of this work will be the development of value-added products from C. longa for biomedical and nanotechnology-based industries. PMID:23341739

Structural, Optical, and Vibrational Properties of ZnO Microrods Deposited on Silicon Substrate

NASA Astrophysics Data System (ADS)

Lahlouh, Bashar I.; Ikhmayies, Shadia J.; Juwhari, Hassan K.

2018-03-01

Zinc oxide (ZnO) microrod films deposited by spray pyrolysis on silicon substrate at 350 ± 5°C have been studied and evaluated, and compared with thin films deposited by electron beam to confirm the identity of the studied samples. The films were characterized using different techniques. The microrod structure was studied and confirmed by scanning electron microscopy. Fourier-transform infrared (FTIR) spectroscopy and x-ray diffraction analysis confirmed successful deposition of ZnO thin films with the expected wurtzite structure. Reflectance data showed a substantial drop across the whole studied wavelength range. The photoluminescence (PL) spectra of the studied samples showed a peak at ˜ 360 nm, representing a signature of ZnO. The shift in the PL peak position is due to defects and other species present in the films, as confirmed by FTIR and energy-dispersive x-ray spectroscopy results.

Effect of substrate temperature in the synthesis of BN nanostructures

NASA Astrophysics Data System (ADS)

Sajjad, M.; Zhang, H. X.; Peng, X. Y.; Feng, P. X.

2011-06-01

Boron nitride (BN) nanostructures were grown on molybdenum discs at different substrate temperatures using the short-pulse laser plasma deposition technique. Large numbers of randomly oriented nanorods of fiber-like structures were obtained. The variation in the length and diameter of the nanorods as a function of the substrate temperature was systematically studied. The surface morphologies of the samples were studied using scanning electron microscopy. Energy dispersive x-ray spectroscopy confirmed that both the elements boron and nitrogen are dominant in the nanostructure. The x-ray diffraction (XRD) technique was used to analyse BN phases. The XRD peak that appeared at 26° showed the presence of hexagonal BN phase, whereas the peak at 44° was related to cubic BN content in the samples. Raman spectroscopic analysis showed vibrational modes of sp2- and sp3-type bonding in the sample. The Raman spectra agreed well with XRD results.

Explanation of the photocurrent generation of Cu2O quantum dots (QDs) sensitized p-CuSCN stable photoelectrochemical cells

NASA Astrophysics Data System (ADS)

Karunarathna, P. G. D. C. K.; Samarakoon, S. P. A. U. K.; Fernando, C. A. N.

2018-01-01

Fabrication of Cu2O quantum dots (QDs) sensitized p-CuSCN photoelectrode provides a significant photocurrent enhancement in photoelectrochemical medium for the first time. The variation of photocurrent quantum efficiency (Ф%) with Cu2O amount formed on p-CuSCN was presented. Here, two maxima of photocurrent could be observed in Cu/p-CuSCN/Cu2O photoelectrodes. The first photocurrent peak was due to the Cu2O QDs sensitization on p-CuSCN layer, and the second photocurrent peak was due to the formation of p-n junction. Time development of the photocurrent for Cu/p-CuSCN/n-Cu2O photoelectrodes and material characterization from Fourier transform infrared (FTIR) spectra, scanning electron microscope (SEM) images, energy dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD) were done in this study in detailed.

Investigation of the nanoscale two-component ZnS-ZnO heterostructures by means of HR-TEM and X-ray based analysis

NASA Astrophysics Data System (ADS)

Pankin, I. A.; Polozhentsev, O. E.; Soldatov, M. A.; Bugaev, A. L.; Tsaturyan, A.; Lomachenko, K. A.; Guda, A. A.; Budnyk, A. P.; Lamberti, C.; Soldatov, A. V.

2018-06-01

This article is devoted to the spectroscopic characterization of ZnS-ZnO nanoscale heterostructures synthesized by the microwave-assisted solvothermal method. The synthesized samples were investigated by means of X-ray powder diffraction (XRPD), high energy resolution fluorescence detected X-ray absorption near-edge-structure (HERFD-XANES) spectroscopy, valence-to-core X-ray emission spectroscopy (VtC-XES) and high resolution transmission electron microscopy (HR-TEM) as well as energy dispersive X-ray spectroscopy (EDX). The average crystallite size estimated by the broadening of XRPD peaks increases from 2.7 nm to 3.7 nm in the temperature range from 100 °C to 150 °C. HR-TEM images show that nanoparticles are arranged in aggregates with the 60-200 nm size. Theoretical estimation shows that the systems synthesized at higher temperatures more prone to the agglomeration. The full profile Reitveld analysis of XRPD data reveals the formation of hexagonal zinc sulfide structure, whereas electron diffraction data reveal also the formation of cubic zinc sulfide and claim the polymorphous character of the system. High energy resolution Zn K-edge XANES data unambiguously demonstrate the presence of a certain amount of the zinc oxide which is likely to have an amorphous structure and could not be detected by XRPD. Qualitative analysis of XANES data allows deriving ZnS/ZnO ratio as a function of synthesis temperature. EDX analysis depicts homogeneous distribution of ZnS and amorphous ZnO phases across the conglomerates. A complementary element-selective valence to core X-ray emission spectroscopy evidences formation of two-component system and confirms estimations of ZnS/ZnO fractions obtained by linear combination fit of XANES data.

When is one layer complete? Using simultaneous in-situ RHEED and x-ray reflectivity to map layer-by-layer thin-film oxide growth

NASA Astrophysics Data System (ADS)

Sullivan, M. C.; Ward, M. J.; Joress, H.; Gutierrez-Llorente, A.; White, A. E.; Woll, A.; Brock, J. D.

2014-03-01

The most popular tool for characterizing in situ layer-by-layer growth is Reflection High-Energy Electron Diffraction (RHEED). X-ray reflectivity can also be used to study layer-by-layer growth, as long as the incident angle of the x-rays is far from a Bragg peak. During layer-by-layer homoepitaxial growth, both the RHEED intensity and the reflected x-ray intensity will oscillate, and each complete oscillation indicates the addition of one layer of material. However, it is well documented, but not well understood, that the maxima in the RHEED intensity oscillations do not necessarily occur at the completion of a layer. In contrast, the maxima in the x-ray intensity oscillations do occur at the completion of a layer, thus the RHEED and x-ray oscillations are rarely in phase. We present our results on simultaneous in situ x-ray reflectivity and RHEED during layer-by-layer growth of SrTiO3 and discuss how to determine the completion of a layer for RHEED oscillations independent of the phase of the RHEED oscillation. Supported by DOE Office of Basic Energy Sciences Award DE-SC0001086, CHESS is supported by the NSF & NIH/NIGMS via NSF award DMR-0936384.

JMFA2—a graphically interactive Java program that fits microfibril angle X-ray diffraction data

Treesearch

Steve P. Verrill; David E. Kretschmann; Victoria L. Herian

2006-01-01

X-ray diffraction techniques have the potential to decrease the time required to determine microfibril angles dramatically. In this paper, we discuss the latest version of a curve-fitting toll that permits us to reduce the time required to evaluate MFA X-ray diffraction patterns. Further, because this tool reflects the underlying physics more accurately than existing...

A high-transparency, micro-patternable chip for X-ray diffraction analysis of microcrystals under native growth conditions

DOE PAGES

Murray, Thomas D.; Lyubimov, Artem Y.; Ogata, Craig M.; ...

2015-08-11

Microcrystals present a significant impediment to the determination of macromolecular structures by X-ray diffraction methods. Although microfocus synchrotron beamlines and X-ray free-electron lasers (XFELs) can enable the collection of interpretable diffraction data from microcrystals, there is a need for efficient methods of harvesting small volumes (<2 µl) of microcrystals grown under common laboratory formats and delivering them to an X-ray beam source under native growth conditions. One approach that shows promise in overcoming the challenges intrinsic to microcrystal analysis is to pair so-called `fixed-target' sample-delivery devices with microbeam-based X-ray diffraction methods. However, to record weak diffraction patterns it is necessarymore » to fabricate devices from X-ray-transparent materials that minimize background scattering. Presented here is the design of a new micro-diffraction device consisting of three layers fabricated from silicon nitride, photoresist and polyimide film. The chip features low X-ray scattering and X-ray absorption properties, and uses a customizable blend of hydrophobic and hydrophilic surface patterns to help localize microcrystals to defined regions. Microcrystals in their native growth conditions can be loaded into the chips with a standard pipette, allowing data collection at room temperature. Diffraction data collected from hen egg-white lysozyme microcrystals (10–15 µm) loaded into the chips yielded a complete, high-resolution (<1.6 Å) data set sufficient to determine a high-quality structure by molecular replacement. In addition, the features of the chip allow the rapid and user-friendly analysis of microcrystals grown under virtually any laboratory format at microfocus synchrotron beamlines and XFELs.« less

A high-transparency, micro-patternable chip for X-ray diffraction analysis of microcrystals under native growth conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, Thomas D.; Lyubimov, Artem Y.; Ogata, Craig M.

Microcrystals present a significant impediment to the determination of macromolecular structures by X-ray diffraction methods. Although microfocus synchrotron beamlines and X-ray free-electron lasers (XFELs) can enable the collection of interpretable diffraction data from microcrystals, there is a need for efficient methods of harvesting small volumes (<2 µl) of microcrystals grown under common laboratory formats and delivering them to an X-ray beam source under native growth conditions. One approach that shows promise in overcoming the challenges intrinsic to microcrystal analysis is to pair so-called `fixed-target' sample-delivery devices with microbeam-based X-ray diffraction methods. However, to record weak diffraction patterns it is necessarymore » to fabricate devices from X-ray-transparent materials that minimize background scattering. Presented here is the design of a new micro-diffraction device consisting of three layers fabricated from silicon nitride, photoresist and polyimide film. The chip features low X-ray scattering and X-ray absorption properties, and uses a customizable blend of hydrophobic and hydrophilic surface patterns to help localize microcrystals to defined regions. Microcrystals in their native growth conditions can be loaded into the chips with a standard pipette, allowing data collection at room temperature. Diffraction data collected from hen egg-white lysozyme microcrystals (10–15 µm) loaded into the chips yielded a complete, high-resolution (<1.6 Å) data set sufficient to determine a high-quality structure by molecular replacement. In addition, the features of the chip allow the rapid and user-friendly analysis of microcrystals grown under virtually any laboratory format at microfocus synchrotron beamlines and XFELs.« less

A high-transparency, micro-patternable chip for X-ray diffraction analysis of microcrystals under native growth conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, Thomas D.; Lyubimov, Artem Y.; Ogata, Craig M.

Microcrystals present a significant impediment to the determination of macromolecular structures by X-ray diffraction methods. Although microfocus synchrotron beamlines and X-ray free-electron lasers (XFELs) can enable the collection of interpretable diffraction data from microcrystals, there is a need for efficient methods of harvesting small volumes (<2µl) of microcrystals grown under common laboratory formats and delivering them to an X-ray beam source under native growth conditions. One approach that shows promise in overcoming the challenges intrinsic to microcrystal analysis is to pair so-called `fixed-target' sample-delivery devices with microbeam-based X-ray diffraction methods. However, to record weak diffraction patterns it is necessary tomore » fabricate devices from X-ray-transparent materials that minimize background scattering. Presented here is the design of a new micro-diffraction device consisting of three layers fabricated from silicon nitride, photoresist and polyimide film. The chip features low X-ray scattering and X-ray absorption properties, and uses a customizable blend of hydrophobic and hydrophilic surface patterns to help localize microcrystals to defined regions. Microcrystals in their native growth conditions can be loaded into the chips with a standard pipette, allowing data collection at room temperature. Diffraction data collected from hen egg-white lysozyme microcrystals (10–15µm) loaded into the chips yielded a complete, high-resolution (<1.6Å) data set sufficient to determine a high-quality structure by molecular replacement. The features of the chip allow the rapid and user-friendly analysis of microcrystals grown under virtually any laboratory format at microfocus synchrotron beamlines and XFELs.« less

A high-transparency, micro-patternable chip for X-ray diffraction analysis of microcrystals under native growth conditions

PubMed Central

Murray, Thomas D.; Lyubimov, Artem Y.; Ogata, Craig M.; Vo, Huy; Uervirojnangkoorn, Monarin; Brunger, Axel T.; Berger, James M.

2015-01-01

Microcrystals present a significant impediment to the determination of macromolecular structures by X-ray diffraction methods. Although microfocus synchrotron beamlines and X-ray free-electron lasers (XFELs) can enable the collection of interpretable diffraction data from microcrystals, there is a need for efficient methods of harvesting small volumes (<2 µl) of microcrystals grown under common laboratory formats and delivering them to an X-ray beam source under native growth conditions. One approach that shows promise in overcoming the challenges intrinsic to microcrystal analysis is to pair so-called ‘fixed-target’ sample-delivery devices with microbeam-based X-ray diffraction methods. However, to record weak diffraction patterns it is necessary to fabricate devices from X-ray-transparent materials that minimize background scattering. Presented here is the design of a new micro-diffraction device consisting of three layers fabricated from silicon nitride, photoresist and polyimide film. The chip features low X-ray scattering and X-ray absorption properties, and uses a customizable blend of hydrophobic and hydrophilic surface patterns to help localize microcrystals to defined regions. Microcrystals in their native growth conditions can be loaded into the chips with a standard pipette, allowing data collection at room temperature. Diffraction data collected from hen egg-white lysozyme microcrystals (10–15 µm) loaded into the chips yielded a complete, high-resolution (<1.6 Å) data set sufficient to determine a high-quality structure by molecular replacement. The features of the chip allow the rapid and user-friendly analysis of microcrystals grown under virtually any laboratory format at microfocus synchrotron beamlines and XFELs. PMID:26457423

Interaction between U/UO2 bilayers and hydrogen studied by in-situ X-ray diffraction

NASA Astrophysics Data System (ADS)

Darnbrough, J. E.; Harker, R. M.; Griffiths, I.; Wermeille, D.; Lander, G. H.; Springell, R.

2018-04-01

This paper reports experiments investigating the reaction of H2 with uranium metal-oxide bilayers. The bilayers consist of ≤ 100 nm of epitaxial α-U (grown on a Nb buffer deposited on sapphire) with a UO2 overlayer of thicknesses of between 20 and 80 nm. The oxides were made either by depositing via reactive magnetron sputtering, or allowing the uranium metal to oxidise in air at room temperature. The bilayers were exposed to hydrogen, with sample temperatures between 80 and 200 C, and monitored via in-situ x-ray diffraction and complimentary experiments conducted using Scanning Transmission Electron Microscopy - Electron Energy Loss Spectroscopy (STEM-EELS). Small partial pressures of H2 caused rapid consumption of the U metal and lead to changes in the intensity and position of the diffraction peaks from both the UO2 overlayers and the U metal. There is an orientational dependence in the rate of U consumption. From changes in the lattice parameter we deduce that hydrogen enters both the oxide and metal layers, contracting the oxide and expanding the metal. The air-grown oxide overlayers appear to hinder the H2-reaction up to a threshold dose, but then on heating from 80 to 140 C the consumption is more rapid than for the as-deposited overlayers. STEM-EELS establishes that the U-hydride layer lies at the oxide-metal interface, and that the initial formation is at defects or grain boundaries, and involves the formation of amorphous and/or nanocrystalline UH3. This explains why no diffraction peaks from UH3 are observed.

High-resolution x-ray diffraction microscopy of specifically labeled yeast cells

PubMed Central

Nelson, Johanna; Huang, Xiaojing; Steinbrener, Jan; Shapiro, David; Kirz, Janos; Marchesini, Stefano; Neiman, Aaron M.; Turner, Joshua J.; Jacobsen, Chris

2010-01-01

X-ray diffraction microscopy complements other x-ray microscopy methods by being free of lens-imposed radiation dose and resolution limits, and it allows for high-resolution imaging of biological specimens too thick to be viewed by electron microscopy. We report here the highest resolution (11–13 nm) x-ray diffraction micrograph of biological specimens, and a demonstration of molecular-specific gold labeling at different depths within cells via through-focus propagation of the reconstructed wavefield. The lectin concanavalin A conjugated to colloidal gold particles was used to label the α-mannan sugar in the cell wall of the yeast Saccharomyces cerevisiae. Cells were plunge-frozen in liquid ethane and freeze-dried, after which they were imaged whole using x-ray diffraction microscopy at 750 eV photon energy. PMID:20368463

High-resolution x-ray diffraction microscopy of specifically labeled yeast cells

DOE PAGES

Nelson, Johanna; Huang, Xiaojing; Steinbrener, Jan; ...

2010-04-20

X-ray diffraction microscopy complements other x-ray microscopy methods by being free of lens-imposed radiation dose and resolution limits, and it allows for high-resolution imaging of biological specimens too thick to be viewed by electron microscopy. We report here the highest resolution (11-13 nm) x-ray diffraction micrograph of biological specimens, and a demonstration of molecular-specific gold labeling at different depths within cells via through-focus propagation of the reconstructed wavefield. The lectin concanavalin A conjugated to colloidal gold particles was used to label the α-mannan sugar in the cell wall of the yeast Saccharomyces cerevisiae. Cells were plunge-frozen in liquid ethane andmore » freeze-dried, after which they were imaged whole using x-ray diffraction microscopy at 750 eV photon energy.« less

Coherent x-ray zoom condenser lens for diffractive and scanning microscopy.

PubMed

Kimura, Takashi; Matsuyama, Satoshi; Yamauchi, Kazuto; Nishino, Yoshinori

2013-04-22

We propose a coherent x-ray zoom condenser lens composed of two-stage deformable Kirkpatrick-Baez mirrors. The lens delivers coherent x-rays with a controllable beam size, from one micrometer to a few tens of nanometers, at a fixed focal position. The lens is suitable for diffractive and scanning microscopy. We also propose non-scanning coherent diffraction microscopy for extended objects by using an apodized focused beam produced by the lens with a spatial filter. The proposed apodized-illumination method will be useful in highly efficient imaging with ultimate storage ring sources, and will also open the way to single-shot coherent diffraction microscopy of extended objects with x-ray free-electron lasers.

Scanning force microscope for in situ nanofocused X-ray diffraction studies

PubMed Central

Ren, Zhe; Mastropietro, Francesca; Davydok, Anton; Langlais, Simon; Richard, Marie-Ingrid; Furter, Jean-Jacques; Thomas, Olivier; Dupraz, Maxime; Verdier, Marc; Beutier, Guillaume; Boesecke, Peter; Cornelius, Thomas W.

2014-01-01

A compact scanning force microscope has been developed for in situ combination with nanofocused X-ray diffraction techniques at third-generation synchrotron beamlines. Its capabilities are demonstrated on Au nano-islands grown on a sapphire substrate. The new in situ device allows for in situ imaging the sample topography and the crystallinity by recording simultaneously an atomic force microscope (AFM) image and a scanning X-ray diffraction map of the same area. Moreover, a selected Au island can be mechanically deformed using the AFM tip while monitoring the deformation of the atomic lattice by nanofocused X-ray diffraction. This in situ approach gives access to the mechanical behavior of nanomaterials. PMID:25178002

Investigations on Cu2+-substituted Ni-Zn ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Amarjeet; Kumar, Vinod

2016-11-01

CuxNi(1-x)/2Zn(1-x)/2Fe2O4 (x = 0.1, 0.3 and 0.5) nanoparticles were prepared by chemical co-precipitation method. The developed nanoparticles were characterized for structural properties by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Peak position in the X-ray diffraction pattern confirmed the single spinel phase of the developed particles. Infrared (IR) spectroscopy in mid-IR range showed the presence of characteristic absorption bands corresponding to octahedral and tetrahedral bonds in the spinel structure of prepared samples. Thermo-gravimetric analysis (TGA) measurements showed a considerable weight loss in the developed samples above 700∘C. Frequency dependence of the electrical properties of the developed material pellets was studied in the frequency range of 1 kHz-5 MHz. Temperature dependence of the dielectric constant of Cu0.1Ni0.45Zn0.45Fe2O4 was studied at different temperatures, i.e. at 425, 450 and 475 K, in the frequency range of 1 kHz-5 MHz. It was found that the electrical conductivity decreases with increasing Cu2+ ion content while it increases with the increase in temperature.

Influence of Nb Doping Concentration on Bolometric Properties of RF Magnetron Sputtered Nb:TiO2- x Films

NASA Astrophysics Data System (ADS)

Reddy, Y. Ashok Kumar; Shin, Young Bong; Kang, In-Ku; Lee, Hee Chul

2018-03-01

The present study directly addresses the improved bolometric properties by means of different Nb doping concentrations into TiO2- x films. The x-ray diffraction patterns do not display any obvious diffraction peaks, suggesting that all the films deposited at room temperature had an amorphous structure. A small binding energy shift was observed in x-ray photo electron spectroscopy due to the change of chemical composition with Nb doping concentration. All the device samples exhibit linear I- V characteristics, which attests to the formation of good ohmic contact with low contact resistance between the Nb:TiO2- x (TNO) film and the electrode (Ti) material. The performance of the bolometric material can be evaluated through the temperature coefficient of resistance (TCR), and the absolute value of TCR was found to be increased from 2.54% to 2.78% with increasing the Nb doping concentration. The voltage spectral density of 1/ f noise was measured in the frequency range of 1-60 Hz and found to be decreased with increase of Nb doping concentration. As a result, for 1 at.% Nb-doped TNO sample exhibits improved bolometric properties towards the good infrared image sensor device.

Effect of Sn Composition in Ge1- x Sn x Layers Grown by Using Rapid Thermal Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Kil, Yeon-Ho; Kang, Sukill; Jeong, Tae Soo; Shim, Kyu-Hwan; Kim, Dae-Jung; Choi, Yong-Dae; Kim, Mi Joung; Kim, Taek Sung

2018-05-01

The Ge1- x Sn x layers were grown by using rapid thermal chemical-vapor deposition (RTCVD) on boron-doped p-type Si (100) substrates with Sn compositions up to x = 0.83%. In order to obtain effect of the Sn composition on the structural and the optical characteristics, we utilized highresolution X-ray diffraction (HR-XRD), etch pit density (EPD), atomic force microscopy (AFM), Raman spectroscopy, and photocurrent (PC) spectra. The Sn compositions in the Ge1- x Sn x layers were found to be of x = 0.00%, 0.51%, 0.65%, and 0.83%. The root-mean-square (RMS) of the surface roughness of the Ge1- x Sn x layer increased from 2.02 nm to 3.40 nm as the Sn composition was increased from 0.51% to 0.83%, and EPD was on the order of 108 cm-2. The Raman spectra consist of only one strong peak near 300 cm-1, which is assigned to the Ge-Ge LO peaks and the Raman peaks shift to the wave number with increasing Sn composition. Photocurrent spectra show near energy band gap peaks and their peak energies decrease with increasing Sn composition due to band-gap bowing in the Ge1- x Sn x layer. An increase in the band gap bowing parameter was observed with increasing Sn composition.

X-ray topography using the forward transmitted beam under multiple-beam diffraction conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsusaka, Y., E-mail: tsusaka@sci.u-hyogo.ac.jp; Takano, H.; Takeda, S.

2016-02-15

X-ray topographs are taken for a sapphire wafer with the [0001] surface normal, as an example, by forward transmitted synchrotron x-ray beams combined with two-dimensional electronic arrays in the x-ray detector having a spatial resolution of 1 μm. They exhibit no shape deformation and no position shift of the dislocation lines on the topographs. Since the topography is performed under multiple-beam diffraction conditions, the topographic images of a single diffraction (two-wave approximation condition) or plural diffractions (six-wave approximation condition) can be recorded without large specimen position changes. As usual Lang topographs, it is possible to determine the Burgers vector ofmore » each dislocation line. Because of high parallelism of the incoming x-rays and linear sensitivity of the electronic arrays to the incident x-rays, the present technique can be used to visualize individual dislocations in single crystals of the dislocation density as high as 1 × 10{sup 5} cm{sup −2}.« less

Investigation of the commensurate magnetic structure in the heavy-fermion compound CePt 2 In 7 using magnetic resonant x-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gauthier, Nicolas; Wermeille, Didier; Casati, Nicola

In this paper, we investigated the magnetic structure of the heavy-fermion compound CePt 2In 7 below T N = 5.34 (2) K using magnetic resonant x-ray diffraction at ambient pressure. The magnetic order is characterized by a commensurate propagation vector k 1/2 = (1/2, 1/2, 1/2) with spins lying in the basal plane. Our measurements did not reveal the presence of an incommensurate order propagating along the high-symmetry directions in reciprocal space but cannot exclude other incommensurate modulations or weak scattering intensities. The observed commensurate order can be described equivalently by either a single-k structure or by a multi-k structure.more » Furthermore we explain how a commensurate-only ordering may explain the broad distribution of internal fields observed in nuclear quadrupolar resonance experiments [Sakai et al., Phys. Rev. B 83, 140408 (2011)] that was previously attributed to an incommensurate order. We also report powder x-ray diffraction showing that the crystallographic structure of CePt 2In 7 changes monotonically with pressure up to P = 7.3 GPa at room temperature. The determined bulk modulus B 0 = 81.1 (3) GPa is similar to those of the Ce-115 family. Broad diffraction peaks confirm the presence of pronounced strain in polycrystalline samples of CePt 2In 7. Lastly, we discuss how strain effects can lead to different electronic and magnetic properties between polycrystalline and single crystal samples.« less

Investigation of the commensurate magnetic structure in the heavy-fermion compound CePt 2 In 7 using magnetic resonant x-ray diffraction

DOE PAGES

Gauthier, Nicolas; Wermeille, Didier; Casati, Nicola; ...

2017-08-10

In this paper, we investigated the magnetic structure of the heavy-fermion compound CePt 2In 7 below T N = 5.34 (2) K using magnetic resonant x-ray diffraction at ambient pressure. The magnetic order is characterized by a commensurate propagation vector k 1/2 = (1/2, 1/2, 1/2) with spins lying in the basal plane. Our measurements did not reveal the presence of an incommensurate order propagating along the high-symmetry directions in reciprocal space but cannot exclude other incommensurate modulations or weak scattering intensities. The observed commensurate order can be described equivalently by either a single-k structure or by a multi-k structure.more » Furthermore we explain how a commensurate-only ordering may explain the broad distribution of internal fields observed in nuclear quadrupolar resonance experiments [Sakai et al., Phys. Rev. B 83, 140408 (2011)] that was previously attributed to an incommensurate order. We also report powder x-ray diffraction showing that the crystallographic structure of CePt 2In 7 changes monotonically with pressure up to P = 7.3 GPa at room temperature. The determined bulk modulus B 0 = 81.1 (3) GPa is similar to those of the Ce-115 family. Broad diffraction peaks confirm the presence of pronounced strain in polycrystalline samples of CePt 2In 7. Lastly, we discuss how strain effects can lead to different electronic and magnetic properties between polycrystalline and single crystal samples.« less

X-Ray Diffraction and Electron Spectroscopy of Epitaxial Molecular C sub 60 Films

DTIC Science & Technology

1991-02-28

This document has been approved for public release and sale ; its distribution is unlimited 91 2 25 092 UNMCASSI A% ’FMWG REPORT DOCUMENTATION PAGE to...heights of the elastic peaks have been normalized to each other. 12 𔃽.8 20,04 A for C60 (from Ref, 1) ~CLf) IT", V- V- 00 TI- ( itun Ajej~;qjy) Allsuejul

Structures having enhanced biaxial texture

DOEpatents

Goyal, Amit; Budai, John D.; Kroeger, Donald M.; Norton, David P.; Specht, Eliot D.; Christen, David K.

1999-01-01

A biaxially textured alloy article includes a rolled and annealed biaxially textured base metal substrate characterized by an x-ray diffraction phi scan peak of no more than 20.degree. FWHM; and a biaxially textured layer of an alloy or another material on a surface thereof. The article further includes at least one of an electromagnetic device or an electro-optical device epitaxially joined to the alloy.

Multiple defocused coherent diffraction imaging: method for simultaneously reconstructing objects and probe using X-ray free-electron lasers.

PubMed

Hirose, Makoto; Shimomura, Kei; Suzuki, Akihiro; Burdet, Nicolas; Takahashi, Yukio

2016-05-30

The sample size must be less than the diffraction-limited focal spot size of the incident beam in single-shot coherent X-ray diffraction imaging (CXDI) based on a diffract-before-destruction scheme using X-ray free electron lasers (XFELs). This is currently a major limitation preventing its wider applications. We here propose multiple defocused CXDI, in which isolated objects are sequentially illuminated with a divergent beam larger than the objects and the coherent diffraction pattern of each object is recorded. This method can simultaneously reconstruct both objects and a probe from the coherent X-ray diffraction patterns without any a priori knowledge. We performed a computer simulation of the prposed method and then successfully demonstrated it in a proof-of-principle experiment at SPring-8. The prposed method allows us to not only observe broad samples but also characterize focused XFEL beams.

Angular rheology study of colloidal nanocrystals using Coherent X-ray Diffraction

NASA Astrophysics Data System (ADS)

Liang, Mengning; Harder, Ross; Robinson, Ian

2007-03-01

A new method using coherent x-ray diffraction provides a way to investigate the rotational motion of a colloidal suspension of crystals in real time. Coherent x-ray diffraction uses the long coherence lengths of synchrotron sources to illuminate a nanoscale particle coherently over its spatial dimensions. The penetration of high energy x-rays into various media allows for in-situ measurements making it ideal for suspensions. This technique has been used to image the structure of nanocrystals for some time but also has the capability of providing information about the orientation and dynamics of crystals. The particles are imaged in a specific diffraction condition allowing us to determine their orientation and observe how they rotate in real time with exceptional resolution. Such sensitivity allows for the study of rotational Brownian motion of nanocrystals in various suspensions and conditions. We present a study of the angular rheology of alumina and TiO2 colloidal nanocrystals in media using coherent x-ray diffraction.

Characterization of polycrystalline materials using synchrotron X-ray imaging and diffraction techniques

NASA Astrophysics Data System (ADS)

Ludwig, W.; King, A.; Herbig, M.; Reischig, P.; Marrow, J.; Babout, L.; Lauridsen, E. M.; Proudhon, H.; Buffière, J. Y.

2010-12-01

The combination of synchrotron radiation x-ray imaging and diffraction techniques offers new possibilities for in-situ observation of deformation and damage mechanisms in the bulk of polycrystalline materials. Minute changes in electron density (i.e., cracks, porosities) can be detected using propagation based phase contrast imaging, a 3-D imaging mode exploiting the coherence properties of third generation synchrotron beams. Furthermore, for some classes of polycrystalline materials, one may use a 3-D variant of x-ray diffraction imaging, termed x-ray diffraction contrast tomography. X-ray diffraction contrast tomography provides access to the 3-D shape, orientation, and elastic strain state of the individual grains from polycrystalline sample volumes containing up to thousand grains. Combining both imaging modalities, one obtains a comprehensive description of the materials microstructure at the micrometer length scale. Repeated observation during (interrupted) mechanical tests provide unprecedented insight into crystallographic and grain microstructure related aspects of polycrystalline deformation and degradation mechanisms.

Quantitative analysis of thoria phase in Th-U alloys using diffraction studies

NASA Astrophysics Data System (ADS)

Thakur, Shital; Krishna, P. S. R.; Shinde, A. B.; Kumar, Raj; Roy, S. B.

2017-05-01

In the present study the quantitative phase analysis of Th-U alloys in bulk form namely Th-52 wt% U and Th-3wt%U has been performed over the data obtained from both X ray diffraction and neutron diffraction technique using Rietveld method of FULLPROF software. Quantifying thoria (ThO2) phase present in bulk of the sample is limited due to surface oxidation and low penetration of x rays in high Z material. Neutron diffraction study probing bulk of the samples has been presented in comparison with x-ray diffraction study.

Selenium single-wavelength anomalous diffraction de novo phasing using an X-ray-free electron laser

DOE PAGES

Hunter, Mark S.; Yoon, Chun Hong; DeMirci, Hasan; ...

2016-11-04

Structural information about biological macromolecules near the atomic scale provides important insight into the functions of these molecules. To date, X-ray crystallography has been the predominant method used for macromolecular structure determination. However, challenges exist when solving structures with X-rays, including the phase problem and radiation damage. X-ray-free electron lasers (X-ray FELs) have enabled collection of diffraction information before the onset of radiation damage, yet the majority of structures solved at X-ray FELs have been phased using external information via molecular replacement. De novo phasing at X-ray FELs has proven challenging due in part to per-pulse variations in intensity andmore » wavelength. Here we report the solution of a selenobiotinyl-streptavidin structure using phases obtained by the anomalous diffraction of selenium measured at a single wavelength (Se-SAD) at the Linac Coherent Light Source. Finally, our results demonstrate Se-SAD, routinely employed at synchrotrons for novel structure determination, is now possible at X-ray FELs.« less

Macromolecular structures probed by combining single-shot free-electron laser diffraction with synchrotron coherent X-ray imaging.

PubMed

Gallagher-Jones, Marcus; Bessho, Yoshitaka; Kim, Sunam; Park, Jaehyun; Kim, Sangsoo; Nam, Daewoong; Kim, Chan; Kim, Yoonhee; Noh, Do Young; Miyashita, Osamu; Tama, Florence; Joti, Yasumasa; Kameshima, Takashi; Hatsui, Takaki; Tono, Kensuke; Kohmura, Yoshiki; Yabashi, Makina; Hasnain, S Samar; Ishikawa, Tetsuya; Song, Changyong

2014-05-02

Nanostructures formed from biological macromolecular complexes utilizing the self-assembly properties of smaller building blocks such as DNA and RNA hold promise for many applications, including sensing and drug delivery. New tools are required for their structural characterization. Intense, femtosecond X-ray pulses from X-ray free-electron lasers enable single-shot imaging allowing for instantaneous views of nanostructures at ambient temperatures. When combined judiciously with synchrotron X-rays of a complimentary nature, suitable for observing steady-state features, it is possible to perform ab initio structural investigation. Here we demonstrate a successful combination of femtosecond X-ray single-shot diffraction with an X-ray free-electron laser and coherent diffraction imaging with synchrotron X-rays to provide an insight into the nanostructure formation of a biological macromolecular complex: RNA interference microsponges. This newly introduced multimodal analysis with coherent X-rays can be applied to unveil nano-scale structural motifs from functional nanomaterials or biological nanocomplexes, without requiring a priori knowledge.

Magnetism of Ho 1-xTb xAl₂ alloys: Critical dependence of a first-order transition on Tb concentration

DOE PAGES

Khan, Mahmud; Mudryk, Ya.; Gschneidner, K. A.; ...

2011-12-27

HoAl₂ exhibits a first-order spin reorientation transition at 20 K, which is manifested as a sharp peak in the heat capacity. When Ho is partially replaced by only 5% of Tb, the sharp heat-capacity peak in Ho 1-xTb xAl₂ (x = 0.05) disappears, and then reappears again for x ≥ 0.07. For x = 0.05, the anomaly corresponding to the spin reorientation transition is barely seen in the heat capacity, but as x exceeds 0.07 the weak anomaly transforms to a sharp peak. The spin reorientation transition temperature increases to 29 K for x = 0.05, and as x increasesmore » further the transition shifts to lower temperature and returns to ~20 K for x = 0.25. The transition is no longer observed when x exceeds 0.60. Temperature-dependent x-ray powder-diffraction data confirm the first-order nature of the spin reorientation transition for the alloy with x = 0.40, and indicate that the compound retains the room-temperature cubic structure within the sensitivity of the technique. Experimental observations are discussed considering the easy magnetization directions of HoAl₂ and TbAl₂.« less

New Phases of YBaCuGeO Superconductors Identified from X-ray Diffraction and Infra-red Absorption Measurements

NASA Astrophysics Data System (ADS)

Abo-Arais, Ahmed; Dawoud, Mohamad Ahmad Taher

2005-01-01

X-ray powder diffraction patterns and infra-red absorption spectra have been evaluated and analysed for the Y1 Ba2 Cu3 O7-d - Gex compound samples prepared by the solid state reaction with x values ranging from 0.0 to 1.13. All samples show bulk superconductivity above liquid nitrogen temperature using the levitation test (Meissner effect). Samples with Ge content up to x = 0.2 have offset Tc between 83K and 92K while the sample with x = 1.13 shows semiconducting behavior above 100K. As a result of the solid state interaction between YBCO and Ge, new phases are observed and determined, mainly three phases are concluded from X-ray powder diffraction analysis: (i) Ba2GeO4 (ii) Y2BaCuO5 (iii) BaCO3. The unit cell parameters a, b and c of the orthorhombic superconducting phase are calculated for all the prepared samples. The anisotropy factor is evaluated and related to the new structural phases in YBCO-Ge composite system. The I-R absorption spectra for the samples with orthorhombic symmetry have been determined. The phonon modes between ~ 400 cm-1 and 630 cm-1 are attributed to the Cu - O octahedron and pyramid vibrations for the CuO2 -planes and CuO-chains, while the peaks in the range from ~ 700 cm-1 to ~ 860 cm-1 may be due to defects such as the new phase Ba2GeO4 and the green phase Y2BaCuO5. The obtained results are discussed according to the superconductor - semi-conductor composite model and with the phonon-mediated charge transfer between CuO2 -planes and CuO- chains through apex oxygen (BaO).

The enhancement in optical and magnetic properties of Na-doped LaFeO3

NASA Astrophysics Data System (ADS)

Devi, E.; Kalaiselvi, B. J.

2018-04-01

La1-xNaxFeO3(x=0.00 and 0.05) were synthesized by sol-gel auto-combustion method. No evidence of impurity phase and the peak (121) slightly shift towards lower angle is confirmed by X-ray diffraction analysis (XRD). The UV-visible spectra show strong absorption peak centered at approximately 231 nm and the calculated optical band gap are found to be 2.73eV, 2.36eV for x = 0.00 and 0.05, respectively. The M-H loop of pure sample is anti-ferromagnetic, whereas those of the Na doped sample shows enhanced ferromagnetic behavior. The remnant magnetization (Mr), saturation magnetization (Ms) and coercive field (Hc) of Na-doped sample are enhanced to 1.06emu/g, 5.39emu/g and 182.84kOe, respectively.

Thermoluminescence (TL) properties and x-ray diffraction (XRD) analysis of high purity CaSO{sub 4}:Dy TL material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamarudin, Nadira; Abdullah, Wan Saffiey Wan; Dollah, Mohd Taufik

2014-09-03

This paper presents the characterization and TL properties of dysprosium (Dy) doped calcium sulfate (CaSO{sub 4}) TL material produced by co-precipitation technique with 0.5mol% concentration of dopant. The morphology of the produced TL material was studied using scanning electron microscope (SEM) and the micrograph shows that rectangular parallelepiped shaped crystal with the average of 150 μm in length were produced. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectra show that the TL material produced is high purity anhydrite CaSO{sub 4} with average crystallite size of 74 nm with orthorhombic crystal system. Themore » TL behavior of produced CaSO{sub 4}:Dy was studied using a TLD reader after exposure to gamma ray by Co{sup 60} source with the doses of 1,5 and 10 Gy. The glow curve shows linear response with glow peak around 230°C which is desired development in the field of radiation dosimetry.« less

Perovskite-Type Oxides. I. Structural, Magnetic, and Morphological Properties of LaMn 1- xCu xO 3 and LaCo 1- xCu xO 3 Solid Solutions with Large Surface Area

NASA Astrophysics Data System (ADS)

Porta, Piero; De Rossi, Sergio; Faticanti, Marco; Minelli, Giuliano; Pettiti, Ida; Lisi, Luciana; Turco, Maria

1999-09-01

Perovskite-type compounds of general formula LaMn1-xCuxO3 and LaCo1-xCuxO3 (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by calcining the citrate gel precursors at 823, 923, and 1073 K. The decomposition of the precursors was followed by thermal analysis and the oxides were investigated by means of elemental analysis (atomic absorption and redox titration), X-ray powder diffraction, BET surface area, X-ray absorption (EXAFS and XANES), electron microscopy (SEM and TEM), and magnetic susceptibility. LaMn1-xCuxO3 samples are perovskite-like single phases up to x=0.6. At x=0.8 CuO and La2CuO4 phases are present in addition to perovskite. For x=1.0 the material is formed by CuO and La2CuO4. Mn(IV) was found by redox titration in all Mn-based perovskite samples, its fraction increasing with the increase in copper content. EXAFS and XANES analyses confirmed the presence of Mn(IV). Cation vacancies in equal amounts in the 12-coordinated A and octahedral B sites are suggested in the samples with x=0.0 and x=0.2, while for x=0.6 anionic vacancies are present. Materials with sufficiently high surface area (22-36 m2 g-1 for samples fired at 923 K and 14-22 m2 g-1 for those fired at 1073 K) were obtained. Crystallite sizes in the ranges 390-500 and 590-940 Å for samples calcined at 923 and 1073 K, respectively, were determined from the FWHM of the (102) X-ray diffraction peak. TEM patterns of LaMnO3 showed almost regular hexagonal prismatic crystals with sizes of the same order of magnitude (800 Å) of those drawn from X-ray diffraction, while no evidence of defect clustering was drawn out from TEM and electron diffraction images. For the sample with x=0.6, TEM and electron diffraction patterns revealed perturbation of the structure. Magnetic susceptibility studies show a ferromagnetic behavior that decreases with increase in x. LaCo1-xCuxO3 samples are perovskite-like single phases up to x=0.2. For x=0.4 a small amount of La2CuO4, in addition to perovskite, is detected. For x≥0.6 massive formation of La2CuO4 and CuO is observed. Only trivalent cobalt is found by redox titration. Magnetic susceptibility studies have shown that trivalent cobalt is present in all samples as a mixture of paramagnetic Co3+ and diamagnetic CoIII ions, the Co3+ fraction being, at least up to x=0.4, equal to ≈0.34. Antiferromagnetic behavior, which increases with increase in x, is observed in all LaCo1-xCuxO3 samples. LaCoO3 is a stoichiometric perovskite. The substitution of cobalt by Cu2+ leads to a positive charge defectivity which is compensated by oxygen vacancies. EXAFS and XANES analyses confirmed the presence of trivalent cobalt. Materials with fairly high surface area (in the ranges 19-27 and 13-21 m2 g-1 for samples calcined at 923 and 1073 K, respectively) were obtained. Crystallite sizes of ≈400 and ≈1000 Å for samples calcined at 923 and 1073 K, respectively, were determined from the FWHM of the (102) X-ray diffraction peak. Materials with not very clear morphology and crystals with definite structure are distinguishable by SEM for samples calcined at 1073 and at 1273 K, respectively. TEM patterns, for samples calcined at 1073 K, evidence almost regular hexagonal prismatic crystals connected to form "linked structures" and some "spotty crystals," suggesting short-range ordered local defects. For copper-containing samples, calcined at 1273 K, a higher degree of defectivity (probably associated with the interaction of anion vacancies) and the occurrence of "planar faults" are shown by TEM.

Structure of nanocrystalline calcium silicate hydrates: insights from X-ray diffraction, synchrotron X-ray absorption and nuclear magnetic resonance.

PubMed

Grangeon, Sylvain; Claret, Francis; Roosz, Cédric; Sato, Tsutomu; Gaboreau, Stéphane; Linard, Yannick

2016-06-01

The structure of nanocrystalline calcium silicate hydrates (C-S-H) having Ca/Si ratios ranging between 0.57 ± 0.05 and 1.47 ± 0.04 was studied using an electron probe micro-analyser, powder X-ray diffraction, 29 Si magic angle spinning NMR, and Fourier-transform infrared and synchrotron X-ray absorption spectroscopies. All samples can be described as nanocrystalline and defective tobermorite. At low Ca/Si ratio, the Si chains are defect free and the Si Q 3 and Q 2 environments account, respectively, for up to 40.2 ± 1.5% and 55.6 ± 3.0% of the total Si, with part of the Q 3 Si being attributable to remnants of the synthesis reactant. As the Ca/Si ratio increases up to 0.87 ± 0.02, the Si Q 3 environment decreases down to 0 and is preferentially replaced by the Q 2 environment, which reaches 87.9 ± 2.0%. At higher ratios, Q 2 decreases down to 32.0 ± 7.6% for Ca/Si = 1.38 ± 0.03 and is replaced by the Q 1 environment, which peaks at 68.1 ± 3.8%. The combination of X-ray diffraction and NMR allowed capturing the depolymerization of Si chains as well as a two-step variation in the layer-to-layer distance. This latter first increases from ∼11.3 Å (for samples having a Ca/Si ratio <∼0.6) up to 12.25 Å at Ca/Si = 0.87 ± 0.02, probably as a result of a weaker layer-to-layer connectivity, and then decreases down to 11 Å when the Ca/Si ratio reaches 1.38 ± 0.03. The decrease in layer-to-layer distance results from the incorporation of interlayer Ca that may form a Ca(OH) 2 -like structure, nanocrystalline and intermixed with C-S-H layers, at high Ca/Si ratios.

Magnetic and dielectric properties of Ca-substituted BiFeO3 nanoferrites by the sol-gel method.

PubMed

Lin, Jinpei; Guo, Zeping; Li, Mei; Lin, Qing; Huang, Kangling; He, Yun

2018-01-01

A multiferroic material can simultaneously show two or more basic magnetic properties, including ferromagnetism, antiferromagnetism, and ferroelectricity. BiFeO 3 is a multiferroic material with a rhombohedral distorted perovskite structure. Doping can reduce the volatility of Bi and greatly improve the magnetoelectric properties of BiFeO 3 . To investigate the influence of the doping content we used the following analytical methods: X-ray powder diffraction (XRD), scanning electron microscopy (SEM), microwave network analysis (PNA-N5244A), and the Superconducting Quantum Interference Device (Quantum Design MPMS) test. With the increase of Ca 2+ concentration in the solution, the grain size of Bi 1- x Ca x FeO 3 becomes smaller, showing the role of Ca 2+ ions as the dopant for fine grains. The calcination temperatures are the major causes for the saturated magnetization. The residual magnetization ( M r ) and the coercive force ( H c ) decrease linearly with the increase of x value, and due to the effect of Ca 2+ substitution at Bi 3+ sites, which causes the valence change of Fe and/or the oxygen vacancies. The XRD result indicates that the diffraction peak emerges with the increase of Ca 2+ and the main diffraction peak achieves a high angle. The best calcining temperature is 600 °C, and the morphology is very dependent on the calcining temperature.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang X. R.; Siddons D.; Macrander, A.T.

Realization of x-ray Fabry-Perot (FP) resonance in back-Bragg-reflection crystal cavities has been proposed and explored for many years, but to date no satisfactory performance has been achieved. Here we show that single-cavity crystal resonators intrinsically have limited finesse and efficiency. To break this limit, we demonstrate that monolithic multicavity resonators with equal-width cavities and specific plate thickness ratios can generate ultrahigh-resolution FP resonance with high efficiency, steep peak tails, and ultrahigh contrast simultaneously. The resonance mechanism is similar to that of sequentially cascaded single-cavity resonators. The ultranarrow-bandwidth FP resonance is anticipated to have various applications, including modern ultrahigh-resolution or precisionmore » x-ray monochromatization, spectroscopy, coherence purification, coherent diffraction, phase contrast imaging, etc.« less

SYNCHROTRON RADIATION, FREE ELECTRON LASER, APPLICATION OF NUCLEAR TECHNOLOGY, ETC.: A new cell for X-ray absorption spectroscopy study under high pressure

NASA Astrophysics Data System (ADS)

Zheng, Li-Rong; Che, Rong-Zheng; Liu, Jing; Du, Yong-Hua; Zhou, Ying-Li; Hu, Tian-Dou

2009-08-01

X-ray absorption fine structure (XAFS) spectroscopy is a powerful technique for the investigation of the local environment around selected atoms in condensed matter. XAFS under pressure is an important method for the synchrotron source. We design a cell for a high pressure XAFS experiment. Sintered boron carbide is used as the anvils of this high pressure cell in order to obtain a full XAFS spectrum free from diffraction peaks. In addition, a hydraulic pump was adopted to make in-suit pressure modulation. High quality XAFS spectra of ZrH2 under high pressure (up to 13 GPa) were obtained by this cell.

X-ray diffraction and X-ray standing-wave study of the lead stearate film structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blagov, A. E.; Dyakova, Yu. A.; Kovalchuk, M. V.

2016-05-15

A new approach to the study of the structural quality of crystals is proposed. It is based on the use of X-ray standing-wave method without measuring secondary processes and considers the multiwave interaction of diffraction reflections corresponding to different harmonics of the same crystallographic reflection. A theory of multiwave X-ray diffraction is developed to calculate the rocking curves in the X-ray diffraction scheme under consideration for a long-period quasi-one-dimensional crystal. This phase-sensitive method is used to study the structure of a multilayer lead stearate film on a silicon substrate. Some specific structural features are revealed for the surface layer ofmore » the thin film, which are most likely due to the tilt of the upper layer molecules with respect to the external normal to the film surface.« less

Molybdenum cell for x-ray diffraction measurements of fluid alkali metals at high temperatures and high pressures

NASA Astrophysics Data System (ADS)

Matsuda, Kazuhiro; Tamura, Kozaburo; Katoh, Masahiro; Inui, Masanori

2004-03-01

We have developed a sample cell for x-ray diffraction measurements of fluid alkali metals at high temperatures and high pressures. All parts of the cell are made of molybdenum which is resistant to the chemical corrosion of alkali metals. Single crystalline molybdenum disks electrolytically thinned down to 40 μm were used as the walls of the cell through which x rays pass. The crystal orientation of the disks was controlled in order to reduce the background from the cell. All parts of the cell were assembled and brazed together using a high-temperature Ru-Mo alloy. Energy dispersive x-ray diffraction measurements have been successfully carried out for fluid rubidium up to 1973 K and 16.2 MPa. The obtained S(Q) demonstrates the applicability of the molybdenum cell to x-ray diffraction measurements of fluid alkali metals at high temperatures and high pressures.

High-resolution ab initio three-dimensional x-ray diffraction microscopy

DOE PAGES

Chapman, Henry N.; Barty, Anton; Marchesini, Stefano; ...

2006-01-01

Coherent x-ray diffraction microscopy is a method of imaging nonperiodic isolated objects at resolutions limited, in principle, by only the wavelength and largest scattering angles recorded. We demonstrate x-ray diffraction imaging with high resolution in all three dimensions, as determined by a quantitative analysis of the reconstructed volume images. These images are retrieved from the three-dimensional diffraction data using no a priori knowledge about the shape or composition of the object, which has never before been demonstrated on a nonperiodic object. We also construct two-dimensional images of thick objects with greatly increased depth of focus (without loss of transverse spatialmore » resolution). These methods can be used to image biological and materials science samples at high resolution with x-ray undulator radiation and establishes the techniques to be used in atomic-resolution ultrafast imaging at x-ray free-electron laser sources.« less

Enhancing resolution in coherent x-ray diffraction imaging.

PubMed

Noh, Do Young; Kim, Chan; Kim, Yoonhee; Song, Changyong

2016-12-14

Achieving a resolution near 1 nm is a critical issue in coherent x-ray diffraction imaging (CDI) for applications in materials and biology. Albeit with various advantages of CDI based on synchrotrons and newly developed x-ray free electron lasers, its applications would be limited without improving resolution well below 10 nm. Here, we review the issues and efforts in improving CDI resolution including various methods for resolution determination. Enhancing diffraction signal at large diffraction angles, with the aid of interference between neighboring strong scatterers or templates, is reviewed and discussed in terms of increasing signal-to-noise ratio. In addition, we discuss errors in image reconstruction algorithms-caused by the discreteness of the Fourier transformations involved-which degrade the spatial resolution, and suggest ways to correct them. We expect this review to be useful for applications of CDI in imaging weakly scattering soft matters using coherent x-ray sources including x-ray free electron lasers.

Structural properties and electrochemistry of α-LiFeO2

NASA Astrophysics Data System (ADS)

Abdel-Ghany, A. E.; Mauger, A.; Groult, H.; Zaghib, K.; Julien, C. M.

2012-01-01

In this work, we study the physico-chemistry and electrochemistry of lithium ferrite synthesized by solid-state reaction. Characterization included X-ray diffraction (XRD), scanning electronic microscopy (SEM), Raman scattering (RS), Fourier transform infrared spectroscopy (FTIR), and SQUID magnetometry. XRD peaks gradually sharpen with increasing firing temperature; all the diffraction peaks can be indexed to the cubic α-LiFeO2 phase (Fm3m space group) with the refined cell parameter a = 4.155 Å. RS and FTIR spectra show the vibrational modes due to covalent Fe-O bonds and the Li-cage mode at low-frequency. The electrochemical properties of Li/LiFeO2 are revisited along with the post-mortem analysis of the positive electrode material using XRD and Raman experiments.

A portable X-ray diffraction apparatus for in situ analyses of masters' paintings

NASA Astrophysics Data System (ADS)

Eveno, Myriam; Duran, Adrian; Castaing, Jacques

2010-09-01

It is rare that the analyses of materials in paintings can be carried out by taking micro-samples. Valuable works of art are best studied in situ by non-invasive techniques. For that purpose, a portable X-ray diffraction and fluorescence apparatus has been designed and constructed at the C2RMF. This apparatus has been used for paintings of Rembrandt, Leonardo da Vinci, Van Gogh, Mantegna, etc. Results are given to illustrate the performance of X-ray diffraction, especially when X-ray fluorescence does not bring sufficient information to conclude.

X-ray fractography on fatigue fractured surface of austenitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yajima, Zenjiro; Tokuyama, Hideki; Kibayashi, Yasuo

1995-12-31

X-ray diffraction observation of the material internal structure beneath fracture surfaces provide fracture analysis with useful information to investigate the conditions and mechanisms of fracture. X-ray fractography is a generic name given to this technique. In the present study, X-ray fractography was applied to fatigue fracture surfaces of austenitic stainless steel (AISI 304) which consisted of solution treatment. The fatigue tests were carried out on compact tension (CT) specimens. The plastic strain on the fracture surface was estimated from measuring the line broadening of X-ray diffraction profiles. The line broadening of X-ray diffraction profiles was measured on and beneath fatiguemore » fracture surfaces. The depth of the plastic zone left on fracture surfaces was evaluated from the line broadening. The results are discussed on the basis of fracture mechanics.« less

Diffraction and Imaging Study of Imperfections of Protein Crystals with Coherent X-rays

NASA Technical Reports Server (NTRS)

Hu, Z. W.; Thomas, B. R.; Chernov, A. A.; Chu, Y. S.; Lai, B.

2004-01-01

High angular-resolution x-ray diffraction and phase contrast x-ray imaging were combined to study defects and perfection of protein crystals. Imperfections including line defects, inclusions and other microdefects were observed in the diffraction images of a uniformly grown lysozyme crystal. The observed line defects carry distinct dislocation features running approximately along the <110> growth front and have been found to originate mostly in a central growth area and occasionally in outer growth regions. Slow dehydration led to the broadening of a fairly symmetric 4 4 0 rocking curve by a factor of approximately 2.6, which was primarily attributed to the dehydration-induced microscopic effects that are clearly shown in diffraction images. X-ray imaging and diffraction characterization of the quality of apoferritin crystals will also be discussed in the presentation.

A New Hard X-ray Wiggler for DORIS III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tischer, M.; Gumprecht, L.; Pflueger, J.

2007-01-19

A 4 m long hard X-ray wiggler has been built and installed in the DORIS III storage ring at DESY. The device replaces an old wiggler especially designed for angiography studies. Future use of this beamline at the HARWI straight section has been dedicated to hard X-ray scattering and diffraction experiments for material science and geological investigations. The required energy range is from 30 keV to about 200 keV with emphasis on the {approx}100 keV spectral range. The magnet configuration corresponds to a hybrid structure with additional side magnets to achieve a 2 T peak field for the specified periodmore » length of 110 mm. The wiggler position in the storage ring has been moved 8 m upstream into the next cell which allowed for reduction of the minimum magnetic wiggler gap to 14 mm.« less

History and Solution of the Phase Problem in theTheory of Structure Determination of Crystals from X-ray Diffraction Experiments

ScienceCinema

Wolf, Emil [University of Rochester, Rochester, New York, United States

2017-12-09

Since the pioneering work of Max von Laue on interference and diffraction of x-rays, carried out almost 100 years ago, numerous attempts have been made to determine structures of crystalline media from x-ray diffraction experiments. The usefulness of all of them has been limited by the inability of measuring phases of the diffracted beams. In this talk, the most important research carried out in this field will be reviewed and a recently obtained solution of the phase problem will be presented.

Photoluminescence and energy transfer process in Gd{sub 2}O{sub 3}:Eu{sup 3+}, Tb{sup 3+}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selvalakshmi, T.; Bose, A. Chandra, E-mail: acbose@nitt.edu

2016-05-23

Variation in photoluminescence (PL) properties of Eu{sup 3+} and Tb{sup 3+} as a function of co-dopant (Tb{sup 3+}) concentration are studied for Gd{sub 2-x-y}O{sub 3}: Eu{sup 3+}{sub x} Tb{sup 3+}{sub y} (x = 0.02, y = 0.01, 0.03, 0.05). The crystal structure analysis is carried out by X-ray Diffraction (XRD). Absence of addition peaks corresponding europium or terbium phase confirms the phase purity. Diffuse reflectance spectroscopy (DRS) reveals the absorption peaks corresponding to host matrix, Eu{sup 3+} and Tb{sup 3+}. The bandgap calculated from Kubelka – Munk function is also reported. PL spectra are recorded at the excitation wavelength ofmore » 307 nm and the emission peak corresponding to Eu{sup 3+} confirms the energy transfer from Tb{sup 3+} to Eu{sup 3+}. The agglomeration of particles acts as quenching centres for energy transfer at higher concentrations.« less

Energetics and timing of the hard and soft X-ray emissions in white light flares

NASA Technical Reports Server (NTRS)

Neidig, Donald F.; Kane, Sharad R.

1993-01-01

By comparing the light curves in optical, hard X-ray, and soft X-ray wavelengths for eight well-observed flares, we confirm previous results indicating that the white light flare (WLF) is associated with the flare impulsive phase. The WLF emission peaks within seconds after the associated hard X-ray peak, and nearly two minutes before the 1-8 A soft X-ray peak. It is further shown that the peak power in nonthermal electrons above 50 keV is typically an order of magnitude larger, and the power in 1-8 A soft X-rays radiated over 2pi sr, at the time of the WLF peak, is an order of magnitude smaller than the peak WLF power.

XRayView: a teaching aid for X-ray crystallography.

PubMed

Phillips, G N

1995-10-01

A software package, XRayView, has been developed that uses interactive computer graphics to introduce basic concepts of x-ray diffraction by crystals, including the reciprocal lattice, the Ewald sphere construction, Laue cones, the wavelength dependence of the reciprocal lattice, primitive and centered lattices and systematic extinctions, rotation photography. Laue photography, space group determination and Laue group symmetry, and the alignment of crystals by examination of reciprocal space. XRayView is designed with "user-friendliness" in mind, using pull-down menus to control the program. Many of the experiences of using real x-ray diffraction equipment to examine crystalline diffraction can be simulated. Exercises are available on-line to guide the users through many typical x-ray diffraction experiments.

Synthesis and characterization of spinel type high-power cathode materials Li MxMn2-x O4 (M=Ni, Co, Cr)

NASA Astrophysics Data System (ADS)

Yoon, Y. K.; Park, C. W.; Ahn, H. Y.; Kim, D. H.; Lee, Y. S.; Kim, J.

2007-05-01

The transition metal-doped spinel cathode materials, LiM0.5Mn1.5O4 (M=Ni. Co, Cr) were prepared by solid-state reaction. The structure and morphology of the samples were investigated by X-ray diffraction, Rietveld refinement and scanning electron microscopy (SEM). The diffraction peaks of all the samples corresponded to a single phase of cubic spinel structure with a space group Fd3m. Field-emission SEM shows octahedron like shapes and the primary particles size was between 500 nm and 2 μm. Oxidation states of Ni, Co and Cr were found to be 2+, 2+ and 3+ as revealed by X-ray photoelectron spectroscopy. During discharging, LiNi0.5Mn1.5O4 and LiCo0.5Mn1.5O4 sample shows more than 130 mAh/g between 3.5 and 5.2 V at a current density of 0.65 mA/cm2 and well developed plateau around 5 V, respectively.

Application of MEMS-based x-ray optics as tuneable nanosecond choppers

NASA Astrophysics Data System (ADS)

Chen, Pice; Walko, Donald A.; Jung, Il Woong; Li, Zhilong; Gao, Ya; Shenoy, Gopal K.; Lopez, Daniel; Wang, Jin

2017-08-01

Time-resolved synchrotron x-ray measurements often rely on using a mechanical chopper to isolate a set of x-ray pulses. We have started the development of micro electromechanical systems (MEMS)-based x-ray optics, as an alternate method to manipulate x-ray beams. In the application of x-ray pulse isolation, we recently achieved a pulse-picking time window of half a nanosecond, which is more than 100 times faster than mechanical choppers can achieve. The MEMS device consists of a comb-drive silicon micromirror, designed for efficiently diffracting an x-ray beam during oscillation. The MEMS devices were operated in Bragg geometry and their oscillation was synchronized to x-ray pulses, with a frequency matching subharmonics of the cycling frequency of x-ray pulses. The microscale structure of the silicon mirror in terms of the curvature and the quality of crystallinity ensures a narrow angular spread of the Bragg reflection. With the discussion of factors determining the diffractive time window, this report showed our approaches to narrow down the time window to half a nanosecond. The short diffractive time window will allow us to select single x-ray pulse out of a train of pulses from synchrotron radiation facilities.

Fabrication of high-resolution x-ray diffractive optics at King's College London

NASA Astrophysics Data System (ADS)

Charalambous, Pambos S.; Anastasi, Peter A. F.; Burge, Ronald E.; Popova, Katia

1995-09-01

The fabrication of high resolution x-ray diffractive optics, and Fresnel zone plates (ZPs) in particular, is a very demanding multifaceted technological task. The commissioning of more (and brighter) synchrotron radiation sources, has increased the number of x-ray imaging beam lines world wide. The availability of cheaper and more effective laboratory x-ray sources, has further increased the number of laboratories involved in x-ray imaging. The result is an ever increasing demand for x-ray optics with a very wide range of specifications, reflecting the particular type of x-ray imaging performed at different laboratories. We have been involved in all aspects of high resolution nanofabrication for a number of years, and we have explored many different methods of lithography, which, although unorthodox, open up possibilities, and increase our flexibility for the fabrication of different diffractive optical elements, as well as other types of nanostructures. The availability of brighter x-ray sources, means that the diffraction efficiency of the ZPs is becoming of secondary importance, a trend which will continue in the future. Resolution, however, is important and will always remain so. Resolution is directly related to the accuracy af pattern generation, as well as the ability to draw fine lines. This is the area towards which we have directed most of our efforts so far.

Study of the Decomposition and Phase Transition of Uranium Nitride under UHV Conditions via TDS, XRD, SEM, and XPS.

PubMed

Wang, Xiaofang; Long, Zhong; Bin, Ren; Yang, Ruilong; Pan, Qifa; Li, Fangfang; Luo, Lizhu; Hu, Yin; Liu, Kezhao

2016-11-07

Uranium nitrides are among the most promising fuels for Generation IV nuclear reactors, but until now, very little has been known about their thermal stability properties under nonequilibrium conditions. In this work, thermal decomposition of nitrogen-rich uranium nitride (denoted as UN 2-x ) under ultrahigh-vacuum (UHV) conditions was investigated by thermal desorption spectroscopy (TDS). It has been shown that the nitrogen TDS spectrum consists of two peaks at about 723 and 1038 K. The X-ray diffraction, scanning electron microscopy, and X-ray photoelectron microscopy results indicate that UN 2-x (UN 2 phase) decomposed into the α-U 2 N 3 phase in the first step and the α-U 2 N 3 phase decomposed into the UN phase in the second step.

Phase Compositions of Self Reinforcement Al2O3/CaAl12O19 Composite using X-ray Diffraction Data and Rietveld Technique

NASA Astrophysics Data System (ADS)

Asmi, D.; Low, I. M.; O'Connor, B.

2008-03-01

The analysis of x-ray diffraction (XRD) patterns by the Rietveld technique was tested to the quantitatively phase compositions of self reinforcement Al2O3/CaAl12O19 composite. Room-temperature XRD patterns revealed that α-Al2O3 was the only phase presence in the CA0 sample, whereas the α-Al2O3 and CaAl12O19 phases were found for CA5, CA15, CA30, and CA50 samples. The peak intensity of CA6 in the self reinforcement Al2O3/CaAl12O19 composites increased in proportion with increase in CaAl12O19 content in contrast to α-Al2O3. The diffraction patterns for CA100 sample shows minor traces of α-Al2O3 even in relatively low peak intensity. It is suggesting that the in-situ reaction sintering of raw materials were not react completely to form 100 wt% CaAl12O19 at temperature 1650 °C. Quantitative phase compositions of self reinforcement Al2O3/CaAl12O19 composites by Rietveld analysis with XRD data has been well demonstrated. The results showed that the GOF values are relatively low and the fluctuation in the difference plots shows a reasonable fit between the observed and the calculated plot.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, Maninder; McCloy, John S.; Kukkadapu, Ravi

Two sizes of iron/iron-oxide (Fe/Fe-oxide) nanoclusters (NCs) of 10 nm and 35 nm diameters were prepared using a cluster deposition technique. Both these NCs displayed XRD peaks due to body-centered cubic (bcc) Fe0 and magnetite-like phase. Mossbauer spectroscopy (MS) measurements: a) confirmed the core-shell nature of the NCs, b) the Fe-oxide shell to be nanocrystalline and partially oxidized, and c) the Fe-oxide spins are significantly canted. In addition to the bcc Fe and magnetite-like phases, a phase similar to tetragonal σ-Fe-Cr (8% Cr) was CLEARLY evident in the larger NC, based on X-ray diffraction. Origin of the tetragonallike phase inmore » the larger NC was not clear but could be due to significant distortion of the Fe0 core lattice planes; subtle peaks due to this phase were also apparent in the smaller NC. Unambiguous evidence for the presence of such a phase, however, was not clear from MS, X-ray photoelectron spectroscopy, vibrating sample magnetometry, X-ray magnetic circular dichroism, nor transmission electron microscopy. To our knowledge, this is the first report of tetragonallike phase in the Fe/Fe-oxide core-shell systems.« less

Two-photon x-ray diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stohr, J.

The interference pattern of a circular photon source has long been used to define the optical diffraction limit. Here we show the breakdown of conventional x-ray diffraction theory for the fundamental case of a “source”, consisting of a back-illuminated thin film in a circular aperture. When the conventional spontaneous x-ray scattering by atoms in the film is replaced at high incident intensity by stimulated resonant scattering, the film becomes the source of cloned photon twins and the diffraction pattern becomes self-focused beyond the diffraction limit. Furthermore, the case of cloned photon pairs is compared to and distinguished from entangled photonmore » pairs or biphotons.« less

Two-photon x-ray diffraction

DOE PAGES

Stohr, J.

2017-01-11

The interference pattern of a circular photon source has long been used to define the optical diffraction limit. Here we show the breakdown of conventional x-ray diffraction theory for the fundamental case of a “source”, consisting of a back-illuminated thin film in a circular aperture. When the conventional spontaneous x-ray scattering by atoms in the film is replaced at high incident intensity by stimulated resonant scattering, the film becomes the source of cloned photon twins and the diffraction pattern becomes self-focused beyond the diffraction limit. Furthermore, the case of cloned photon pairs is compared to and distinguished from entangled photonmore » pairs or biphotons.« less

Local structural variation with oxygen fugacity in Fe 2SiO 4+x fayalitic iron silicate melts

DOE PAGES

Alderman, O.L.G.; Lazareva, L.; Wilding, M. C.; ...

2017-01-07

Here, the structure of molten Fe 2SiO 4+x has been studied using both high-energy X-ray diffraction and Fe K-edge X-ray absorption near-edge structure (XANES) spectroscopy, combined with aerodynamic levitation and laser beam heating. A wide range of Fe 3+ contents were accessed by varying the levitation and atmospheric gas composition. Diffraction measurements were made in the temperature ( T) and oxygen partial pressure ranges 1624(21) < T < 2183(94) K (uncertainties in parentheses) and –5.6(3) < ΔFMQ < +2.8(5) log units (relative to the Fayalite-Magnetite-Quartz buffer). Iron K-edge XANES measurements covered the ranges 1557(33) < T < 1994(36) K andmore » –2.1(3) < ΔFMQ < +4.4(3) log units. Fe 3+ contents, x = Fe 3+/ΣFe, estimated directly from the pre-edge peaks of the XANES spectra varied between 0.15(1) and 0.40(2). While these agree in some cases with semi-empirical models, notable discrepancies are discussed in the context of the redox kinetics and the limitations in both the models and in the calibrations used to derive oxidation state from XANES spectra. XANES pre-edge peak areas imply average Fe–O coordination numbers, n FeO, close to 5 for all Fe 3+/ΣFe. Diffraction measurements yielded values of 4.4(2) < n FeO < 4.7(1). There is limited evidence for a linear trend n FeO(x) = 4.46(3) + 0.4(1)x. Asymmetric Fe–O bond length distributions peak at around 1.96 Å and have a shoulder arising from longer interatomic distances. Mean r FeO lie close to 2.06 Å, consistent with n FeO close to 5. These observations suggest that Fe 2+ is less efficient at stabilizing tetrahedral Fe 3+ compared to large monovalent alkali cations. Comparison of in-situ XANES estimates of Fe 3+/ΣFe in the melts to those of the quenched solids obtained from XANES as well as Mössbauer spectroscopy indicate rapid oxidation during cooling, enabled by stirring of the melt by the levitation gas flow. As such, the oxidation state of hot komatiitic and other highly fluid melts may not be retained, even during rapid cooling, as it is for cooler basaltic and more silicic magmas.« less

Local structural variation with oxygen fugacity in Fe2SiO4+x fayalitic iron silicate melts

NASA Astrophysics Data System (ADS)

Alderman, O. L. G.; Lazareva, L.; Wilding, M. C.; Benmore, C. J.; Heald, S. M.; Johnson, C. E.; Johnson, J. A.; Hah, H.-Y.; Sendelbach, S.; Tamalonis, A.; Skinner, L. B.; Parise, J. B.; Weber, J. K. R.

2017-04-01

The structure of molten Fe2SiO4+x has been studied using both high-energy X-ray diffraction and Fe K-edge X-ray absorption near-edge structure (XANES) spectroscopy, combined with aerodynamic levitation and laser beam heating. A wide range of Fe3+ contents were accessed by varying the levitation and atmospheric gas composition. Diffraction measurements were made in the temperature (T) and oxygen partial pressure ranges 1624(21) < T < 2183(94) K (uncertainties in parentheses) and -5.6(3) < ΔFMQ < +2.8(5) log units (relative to the Fayalite-Magnetite-Quartz buffer). Iron K-edge XANES measurements covered the ranges 1557(33) < T < 1994(36) K and -2.1(3) < ΔFMQ < +4.4(3) log units. Fe3+ contents, x = Fe3+/ΣFe, estimated directly from the pre-edge peaks of the XANES spectra varied between 0.15(1) and 0.40(2). While these agree in some cases with semi-empirical models, notable discrepancies are discussed in the context of the redox kinetics and the limitations in both the models and in the calibrations used to derive oxidation state from XANES spectra. XANES pre-edge peak areas imply average Fe-O coordination numbers, nFeO, close to 5 for all Fe3+/ΣFe. Diffraction measurements yielded values of 4.4(2) < nFeO < 4.7(1). There is limited evidence for a linear trend nFeO(x) = 4.46(3) + 0.4(1)x. Asymmetric Fe-O bond length distributions peak at around 1.96 Å and have a shoulder arising from longer interatomic distances. Mean rFeO lie close to 2.06 Å, consistent with nFeO close to 5. These observations suggest that Fe2+ is less efficient at stabilizing tetrahedral Fe3+ compared to large monovalent alkali cations. Comparison of in-situ XANES estimates of Fe3+/ΣFe in the melts to those of the quenched solids obtained from XANES as well as Mössbauer spectroscopy indicate rapid oxidation during cooling, enabled by stirring of the melt by the levitation gas flow. As such, the oxidation state of hot komatiitic and other highly fluid melts may not be retained, even during rapid cooling, as it is for cooler basaltic and more silicic magmas.

Characterization of X80 and X100 Microalloyed Pipeline Steel Using Quantitative X-ray Diffraction

NASA Astrophysics Data System (ADS)

Wiskel, J. B.; Li, X.; Ivey, D. G.; Henein, H.

2018-06-01

Quantitative X-ray diffraction characterization of four (4) X80 and three (3) X100 microalloyed steels was undertaken. The effect of through-thickness position, processing parameters, and composition on the measured crystallite size, microstrain, and J index (relative magnitude of crystallographic texture) was determined. Microstructure analysis using optical microscopy, scanning electron microscopy, transmission electron microscopy, and electron-backscattered diffraction was also undertaken. The measured value of microstrain increased with increasing alloy content and decreasing cooling interrupt temperature. Microstructural features corresponding to crystallite size in the X80 steels were both above and below the detection limit for quantitative X-ray diffraction. The X100 steels consistently exhibited microstructure features below the crystallite size detection limit. The yield stress of each steel increased with increasing microstrain. The increase in microstrain from X80 to X100 is also associated with a change in microstructure from predominantly polygonal ferrite to bainitic ferrite.

A comparison investigation of optical, structural and luminescence properties of CdOxTe1-x and CdTexSe1-x nanoparticles prepared by a simple one pot method

NASA Astrophysics Data System (ADS)

Kiprotich, Sharon; Onani, Martin O.; Dejene, Francis B.

2018-04-01

We present L-cysteine capped CdOXTe1-X and CdTeXSe1-X nanoparticles (NPs) prepared in one pot. The as-prepared CdOXTe1-X NPs were found to have a hexagonal crystal structure of CdTe with a cubic phase of CdO. There was, however, change in phase to cubic type when 2 mM of Se was introduced into the CdTe at 60 min of reaction time. The average crystallite sizes obtained from X-ray diffraction analysis for CdOXTe1-X and CdTeXSe1-X NPs were in the range of 10-36 nm. The diffraction peaks shifted to higher diffraction angle with longer growth time. Scanning electron microscope images display change in shape and size as reaction progress. Photoluminescence (PL) emission was observed to shift from 510-566 nm and 620-653 nm for CdOXTe1-X and CdTeXSe1-X NPs respectively followed by variation in the peak intensities. The emission spectra displayed a good symmetry and a narrow full width at half maximum ranging from 41 to 100 nm in both cases. The absorbance analysis of the as-prepared NPs displayed well-resolved absorption bands. The optical band gaps of the as-prepared NPs were found to decrease with increase in reaction time. Reaction parameters such as pH, reaction time, reaction temperature and the molar concentration could have major effects on the optical properties of the as-prepared nanoparticles hence their need to control them.

Diffractive-refractive optics: (+,-,-,+) X-ray crystal monochromator with harmonics separation.

PubMed

Hrdý, Jaromír; Mikulík, Petr; Oberta, Peter

2011-03-01

A new kind of two channel-cut crystals X-ray monochromator in dispersive (+,-,-,+) position which spatially separates harmonics is proposed. The diffracting surfaces are oriented so that the diffraction is inclined. Owing to refraction the diffracted beam is sagittally deviated. The deviation depends on wavelength and is much higher for the first harmonics than for higher harmonics. This leads to spatial harmonics separation. The idea is supported by ray-tracing simulation.

High-pressure synthesis of predicted oxynitride perovskite: Yttrium Silicon Oxynitride (YSiO2N)

NASA Astrophysics Data System (ADS)

Ahart, Muhtar; Somayazulu, M.; Vadapoo, Rajasekarakumar; Cohen, R. E.

We synthesized the previously predicted polar oxynitride perovskite in a diamond anvil cell with laser heating. YSiO2N was predicted to have the polar P4mm structure with an effective spontaneous polarization of 130 μC/cm2. A mixture of Yttrium nitride (YN) and amorphous Silicon dioxide (SiO2) were loaded into a diamond anvil cell and laser heated at or above 1200 C at 12 GPa. The run products were investigated by x-ray diffraction, Raman spectroscopy, and second harmonic generation, for their phase and structural properties. The x-ray diffraction pattern (a = 3.235 Å, c = 4.485 Å) shows the phase formation of YSiO2N and matches with the diffraction pattern derived from the first-principle predicted lattice parameters. However, minor unknown peaks are on the diffraction pattern indicating of the co-existence of other unknown phases. Further study of Raman spectroscopy observes the theoretically predicted modes, and second harmonic generation shows strong non-linear optical signal, which confirms the polar properties of YSiO2N. This work is supported by ONR Grants N00014-12-1-1038 and N00014-14-1-0561, by the ERC Advanced Grant ToMCaT.

MUDMASTER: A Program for Calculating Crystalline Size Distributions and Strain from the Shapes of X-Ray Diffraction Peaks

USGS Publications Warehouse

Eberl, D.D.; Drits, V.A.; Środoń, Jan; Nüesch, R.

1996-01-01

Particle size may strongly influence the physical and chemical properties of a substance (e.g. its rheology, surface area, cation exchange capacity, solubility, etc.), and its measurement in rocks may yield geological information about ancient environments (sediment provenance, degree of metamorphism, degree of weathering, current directions, distance to shore, etc.). Therefore mineralogists, geologists, chemists, soil scientists, and others who deal with clay-size material would like to have a convenient method for measuring particle size distributions. Nano-size crystals generally are too fine to be measured by light microscopy. Laser scattering methods give only average particle sizes; therefore particle size can not be measured in a particular crystallographic direction. Also, the particles measured by laser techniques may be composed of several different minerals, and may be agglomerations of individual crystals. Measurement by electron and atomic force microscopy is tedious, expensive, and time consuming. It is difficult to measure more than a few hundred particles per sample by these methods. This many measurements, often taking several days of intensive effort, may yield an accurate mean size for a sample, but may be too few to determine an accurate distribution of sizes. Measurement of size distributions by X-ray diffraction (XRD) solves these shortcomings. An X-ray scan of a sample occurs automatically, taking a few minutes to a few hours. The resulting XRD peaks average diffraction effects from billions of individual nano-size crystals. The size that is measured by XRD may be related to the size of the individual crystals of the mineral in the sample, rather than to the size of particles formed from the agglomeration of these crystals. Therefore one can determine the size of a particular mineral in a mixture of minerals, and the sizes in a particular crystallographic direction of that mineral.

A single-solenoid pulsed-magnet system for single-crystal scattering studies

NASA Astrophysics Data System (ADS)

Islam, Zahirul; Capatina, Dana; Ruff, Jacob P. C.; Das, Ritesh K.; Trakhtenberg, Emil; Nojiri, Hiroyuki; Narumi, Yasuo; Welp, Ulrich; Canfield, Paul C.

2012-03-01

We present a pulsed-magnet system that enables x-ray single-crystal diffraction in addition to powder and spectroscopic studies with the magnetic field applied on or close to the scattering plane. The apparatus consists of a single large-bore solenoid, cooled by liquid nitrogen. A second independent closed-cycle cryostat is used for cooling samples near liquid helium temperatures. Pulsed magnetic fields close to ˜30 T with a zero-to-peak-field rise time of ˜2.9 ms are generated by discharging a 40 kJ capacitor bank into the magnet coil. The unique characteristic of this instrument is the preservation of maximum scattering angle (˜23.6°) on the entrance and exit sides of the magnet bore by virtue of a novel double-funnel insert. This instrument will facilitate x-ray diffraction and spectroscopic studies that are impractical, if not impossible, to perform using split-pair and narrow-opening solenoid magnets. Furthermore, it offers a practical solution for preserving optical access in future higher-field pulsed magnets.

Cadmium sulfide rod-bundle structures decorated with nanoparticles from an inorganic/organic composite

NASA Astrophysics Data System (ADS)

Pan, Jun; Xi, Baojuan; Li, Jingfa; Yan, Yan; Li, Qianwen; Qian, Yitai

2011-08-01

We report a new morphology of wurzite cadmium sulfide with nanoparticles decorated on rod-bundle structures, which were synthesized via calcinations of an inorganic/organic composite at 400 °C in air. The composite was hydrothermally synthesized at 180 °C using thioglycolic acid (TGA) and cadmium acetate as starting materials. The structure, composition, and morphology of the prepared material were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope, FT-IR spectrometry, photoluminescence spectrometry, and UV-visible spectrometry. Results indicated that the composite could be defined as CdS 0.65/Cd-TGA0.35. X-ray diffraction revealed that the annealed product is CdS with wurtizite phase. The diameter of the rod is about 150-400 nm and the length from the top to the bottom of the decorated nanoparticle is about 100 nm. The composite showed high intensity of photoluminescence with similar peak position, compared to that of wurtzite CdS, because of the structure defects.

Preparation, Physical-Chemical Characterization, and Cytocompatibility of Polymeric Calcium Phosphate Cements

PubMed Central

Khashaba, Rania M.; Moussa, Mervet; Koch, Christopher; Jurgensen, Arthur R.; Missimer, David M.; Rutherford, Ronny L.; Chutkan, Norman B.; Borke, James L.

2011-01-01

Aim. Physicochemical mechanical and in vitro biological properties of novel formulations of polymeric calcium phosphate cements (CPCs) were investigated. Methods. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light activated polyalkenoic acid, or polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs. Setting time, compressive and diametral strength of CPCs was compared with zinc polycarboxylate cement (control). Specimens were characterized using X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. In vitro cytotoxicity of CPCs and control was assessed. Results. X-ray diffraction analysis showed hydroxyapatite, monetite, and brushite. Acid-base reaction was confirmed by the appearance of stretching peaks in IR spectra of set cements. SEM revealed rod-like crystals and platy crystals. Setting time of cements was 5–12 min. Type III showed significantly higher strength values compared to control. Type III yielded high biocompatibility. Conclusions. Type III CPCs show promise for dental applications. PMID:21941551

Effect of radiation induced crosslinking and degradation of ETFE films

NASA Astrophysics Data System (ADS)

Zen, H. A.; Ribeiro, G.; Geraldes, A. N.; Souza, C. P.; Parra, D. F.; Lugão, A. B.

2013-03-01

In this study the ETFE film with 125 μm of thickness was placed inside a nylon bag and filled with either acetylene, nitrogen or oxygen. Following the procedure, the samples were irradiated at 5, 10 and 20 kGy. The physical and chemical properties of the modified and pristine films were evaluated by rheological and thermal analyses (TG and DSC), X-ray diffraction (XRD) and infrared spectroscopy (IR-ATR). In rheological analysis the storage modulus (G') indicates opposite profiles when the atmospheres (acetylene and oxygen) are evaluated according to the absorbed dose. For the samples submitted to radiation under oxygen atmosphere it is possible to observe the degradation process with the low levels of the storage modulus. The changes in the degree of crystallinity were verified in all modified samples when compared to the pristine polymer and this behavior was confirmed by DSC analysis. A decrease in the intensity of crystalline peak by X-ray diffraction was observed.

Illite polytype quantification using Wildfire© calculated x-ray diffraction patterns

USGS Publications Warehouse

Grathoff, Georg H.; Moore, D.M.

1996-01-01

Illite polytype quantification allows the differentiation of diagenetic and detrital illite components. In Paleozoic shales from the Illinois Basin, we observe 3 polytypes: 1Md, 1M and 2M1. 1Md and 1M are of diagenetic origin and 2M1 is of detrital origin. In this paper, we compare experimental X-ray diffraction (XRD) traces with traces calculated using WILDFIRE© and quantify mixtures of all 3 polytypes, adjusting the effects of preferred orientation and overlapping peaks. The broad intensity (“illite hump”) around the illite 003, which is very common in illite from shales, is caused by the presence of 1Md illite and mixing of illite polytypes and is not an artifact of sample preparation or other impurities in the sample. Illite polytype quantification provides a tool to extrapolate the K/Ar age and chemistry of the detrital and diagenetic end-members by analysis of different size fractions containing different proportions of diagenetic and detrital illite polytypes.

Time-resolved x-ray diffraction and electrical resistance measurements of structural phase transitions in zirconium

DOE PAGES

Velisavljevic, N.; Sinogeikin, S.; Saavedra, R.; ...

2014-05-07

Here, we have designed a portable pressure controller module to tune compression rates and maximum pressures attainable in a standard gas-membrane diamond anvil cell (DAC). During preliminary experiments, performed on zirconium (Zr) metal sample, pressure jumps of up to 80 GPa were systematically obtained in less than 0.2s (resulting in compression rate of few GPa/s up to more than 400 GPa/s). In-situ x-ray diffraction and electrical resistance measurements were performed simultaneously during this rapid pressure increase to provide the first time resolved data on α → ω → β structural evolution in Zr at high pressures. Direct control of compressionmore » rates and peak pressures, which can be held for prolonged time, allows for investigation of structural evolution and kinetics of structural phase transitions of materials under previously unexplored compression rate-pressure conditions that bridge traditional static and shock/dynamic experimental platforms.« less

Low temperature dielectric relaxation in ordinary perovskite ferroelectrics: enlightenment from high-energy x-ray diffraction

DOE PAGES

Ochoa, D. A.; Levit, R.; Fancher, C. M.; ...

2017-04-05

We report that ordinary ferroelectrics exhibit a second order phase transition that is characterized by a sharp peak in the dielectric permittivity at a frequency-independent temperature. Furthermore, these materials show a low temperature dielectric relaxation that appears to be a common behavior of perovskite systems. Tetragonal lead zirconate titanate is used here as a model system in order to explore the origin of such an anomaly, since there is no consensus about the physical phenomenon involved in it. Crystallographic and domain structure studies are performed from temperature dependent synchrotron x-ray diffraction measurement. Results indicate that the dielectric relaxation cannot bemore » associated with crystallographic or domain configuration changes. The relaxation process is then parameterized by using the Vogel–Fulcher–Tammann phenomenological equation. Finally, results allow us to hypothesize that the observed phenomenon is due to changes in the dynamic behavior of the ferroelectric domains related to the fluctuation of the local polarization.« less

Characterization of food additive-potato starch complexes by FTIR and X-ray diffraction.

PubMed

Dankar, Iman; Haddarah, Amira; Omar, Fawaz E L; Pujolà, Montserrat; Sepulcre, Francesc

2018-09-15

Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques were used to study the effect of four food additives, agar, alginate, lecithin and glycerol, at three different concentrations, 0.5, 1 and 1.5%, on the molecular structure of potato puree prepared from commercial potato powder. Vibrational spectra revealed that the amylose-amylopectin skeleton present in the raw potato starch was missing in the potato powder but could be fully recovered upon water addition when the potato puree was prepared. FTIR peaks corresponding to water were clearly present in the potato powder, indicating the important structural role of water molecules in the recovery of the initial molecular conformation. None of the studied puree samples presented a crystalline structure or strong internal order. A comparison of the FTIR and XRD results revealed that the additives exerted some effects, mainly on the long-range order of the starch structure via interacting with and changing -OH and hydrogen bond interactions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Green Synthesis of Magnetite (Fe3O4) Nanoparticles Using Seaweed ( Kappaphycus alvarezii) Extract

NASA Astrophysics Data System (ADS)

Yew, Yen Pin; Shameli, Kamyar; Miyake, Mikio; Kuwano, Noriyuki; Bt Ahmad Khairudin, Nurul Bahiyah; Bt Mohamad, Shaza Eva; Lee, Kar Xin

2016-06-01

In this study, a simple, rapid, and eco-friendly green method was introduced to synthesize magnetite nanoparticles (Fe3O4-NPs) successfully. Seaweed Kappaphycus alvarezii ( K. alvarezii) was employed as a green reducing and stabilizing agents. The synthesized Fe3O4-NPs were characterized with X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) techniques. The X-ray diffraction planes at (220), (311), (400), (422), (511), (440), and (533) were corresponding to the standard Fe3O4 patterns, which showed the high purity and crystallinity of Fe3O4-NPs had been synthesized. Based on FT-IR analysis, two characteristic absorption peaks were observed at 556 and 423 cm-1, which proved the existence of Fe3O4 in the prepared nanoparticles. TEM image displayed the synthesized Fe3O4-NPs were mostly in spherical shape with an average size of 14.7 nm.

Green Synthesis of Magnetite (Fe3O4) Nanoparticles Using Seaweed (Kappaphycus alvarezii) Extract.

PubMed

Yew, Yen Pin; Shameli, Kamyar; Miyake, Mikio; Kuwano, Noriyuki; Bt Ahmad Khairudin, Nurul Bahiyah; Bt Mohamad, Shaza Eva; Lee, Kar Xin

2016-12-01

In this study, a simple, rapid, and eco-friendly green method was introduced to synthesize magnetite nanoparticles (Fe3O4-NPs) successfully. Seaweed Kappaphycus alvarezii (K. alvarezii) was employed as a green reducing and stabilizing agents. The synthesized Fe3O4-NPs were characterized with X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) techniques. The X-ray diffraction planes at (220), (311), (400), (422), (511), (440), and (533) were corresponding to the standard Fe3O4 patterns, which showed the high purity and crystallinity of Fe3O4-NPs had been synthesized. Based on FT-IR analysis, two characteristic absorption peaks were observed at 556 and 423 cm(-1), which proved the existence of Fe3O4 in the prepared nanoparticles. TEM image displayed the synthesized Fe3O4-NPs were mostly in spherical shape with an average size of 14.7 nm.

Unit cell parameters of wurtzite InP nanowires determined by x-ray diffraction.

PubMed

Kriegner, D; Wintersberger, E; Kawaguchi, K; Wallentin, J; Borgström, M T; Stangl, J

2011-10-21

High resolution x-ray diffraction is used to study the structural properties of the wurtzite polytype of InP nanowires. Wurtzite InP nanowires are grown by metal-organic vapor phase epitaxy using S-doping. From the evaluation of the Bragg peak position we determine the lattice parameters of the wurtzite InP nanowires. The unit cell dimensions are found to differ from the ones expected from geometric conversion of the cubic bulk InP lattice constant. The atomic distances along the c direction are increased whereas the atomic spacing in the a direction is reduced in comparison to the corresponding distances in the zinc-blende phase. Using core/shell nanowires with a thin core and thick nominally intrinsic shells we are able to determine the lattice parameters of wurtzite InP with a negligible influence of the S-doping due to the much larger volume in the shell. The determined material properties will enable the ab initio calculation of electronic and optical properties of wurtzite InP nanowires.

Elaboration of m-cresol polyamide12/ polyaniline composite films for antistatic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mezdour, D.; Tabellout, M.; Bardeau, J.-F

2013-12-16

The present work deals with the preparation of transparent antistatic films from an extreme dilution of an intrinsically conducting polymer (ICP) with not coloured polymers. Our approach is based on the chemical polymerization of a very thin layer of Polyaniline (PANI) around particles of an insulating polymer (PA12). Films were obtained by dissolving the synthesized core-shell particles in m-Cresol. The electric property and structure relationships were investigated by using dielectric relaxation spectroscopy, X-ray diffraction and micro-Raman spectroscopy. Composite films exhibited a well established dc conductivity over all the frequency range for 10 wt. % of PANI concentration related to themore » conductive properties of the PANI clusters. X-ray diffraction data show broader and lower intensity of PA12 peaks when increasing PANI content, probably due to the additional doping effect of m- cresol. The doping of PA12/PANI films with Dodecyl benzene sulfonic acid (DBSA) was unequivocally verified by Raman spectroscopy.« less

Room Temperature Elastic Moduli and Vickers Hardness of Hot-Pressed LLZO Cubic Garnet

DTIC Science & Technology

2012-01-01

polishing compounds, Leco, St. Joseph, MI). X - ray diffraction and scanning electron microscopy (SEM) The microstructure of the hot-pressed specimens...was examined on uncoated fracture surfaces by SEM with an accelerating voltage of 1 and 3 kV. Phase purity was evaluated from X - ray diffraction data...the micro- structure appeared to be homogenous for the two hot- pressed LLZO specimens included in this study (Fig. 1). X - ray diffraction confirmed that

Thermoelectric properties and thermal stability of Bi-doped PbTe single crystal

NASA Astrophysics Data System (ADS)

Chen, Zhong; Li, Decong; Deng, Shuping; Tang, Yu; Sun, Luqi; Liu, Wenting; Shen, Lanxian; Yang, Peizhi; Deng, Shukang

2018-06-01

In this study, n-type Bi-doped single-crystal PbTe thermoelectric materials were prepared by melting and slow cooling method according to the stoichiometric ratio of Pb:Bi:Te = 1-x:x:1 (x = 0, 0.1, 0.15, 0.2, 0.25). The X-ray diffraction patterns of Pb1-xBixTe samples show that all main diffraction peaks are well matched with the PbTe matrix, which has a face-centered cubic structure with the space group Fm 3 bar m . Electron probe microanalysis reveals that Pb content decreases gradually, and Te content remains invariant basically with the increase of Bi content, indicating that Bi atoms are more likely to replace Pb atoms. Thermal analysis shows that the prepared samples possess relatively high thermal stability. Simultaneously, transmission electron microscopy and selected area electron diffraction pattern indicate that the prepared samples have typical single-crystal structures with good mechanical properties. Moreover, the electrical conductivity of the prepared samples improved significantly compared with that of the pure sample, and the maximum ZT value of 0.84 was obtained at 600 K by the sample with x = 0.2.

Aesthetic value improvement of the ruby stone using heat treatment and its synergetic surface study

NASA Astrophysics Data System (ADS)

Sahoo, Rakesh K.; Mohapatra, Birendra K.; Singh, Saroj K.; Mishra, Barada K.

2015-02-01

The surface behavior of the natural ruby stones before and after heat treatment with metal oxide additives like: zinc oxide (ZnO) and lead oxide (PbO) have been studied. The surface appearance of the ruby stones processed with the metal oxides changed whereas the bulk densities of the stones remained within the range of 3.9-4.0 g/cm3. The cracks healing and pores filling by the metal oxides on the surface of the ruby have been examined using scanning electron microscopy. The chemical compositions based on the XPS survey scans are in good agreement with the expected composition. The phase and crystallinity of the ruby stones original and heat-treated were obtained from their X-ray diffraction patterns. The change in peak separation between R1 and R2 - peaks in photoluminescence spectra and the contrary binding energy shift of the Al 2p peaks in the X-ray photoelectron spectra have been explicated. Moreover, in this work we describe the change in surface chemical and physical characteristics of the ruby stone before and after heat treatment.

X-ray diffraction investigation of amorphous calcium phosphate and hydroxyapatite under ultra-high hydrostatic pressure

NASA Astrophysics Data System (ADS)

Lam, Elisa; Gu, Qinfen; Swedlund, Peter J.; Marchesseau, Sylvie; Hemar, Yacine

2015-11-01

The changes in the crystal structures of synthetically prepared amorphous calcium phosphate (ACP) and hydroxyapatite (HAP) in water (1:1 mass ratio) were studied by synchrotron X-ray diffraction (XRD) under ultra-high hydrostatic pressures as high as 2.34 GPa for ACP and 4 GPa for HAP. At ambient pressure, the XRD patterns of the ACP and HAP samples in capillary tubes and their environmental scanning electron micrographs indicated amorphous and crystalline characteristics for ACP and HAP, respectively. At pressures greater than 0.25 GPa, an additional broad peak was observed in the XRD pattern of the ACP phase, indicating a partial phase transition from an amorphous phase to a new high-pressure amorphous phase. The peak areas and positions of the ACP phase, as obtained through fitting of the experimental data, indicated that the ACP exhibited increased pseudo-crystalline behavior at pressures greater than 0.96 GPa. Conversely, no structural changes were observed for the HAP phase up to the highest applied pressure of 4 GPa. For HAP, a unit-cell reduction during compression was evidenced by a reduction in both refined lattice parameters a and c. Both ACP and HAP reverted to their original structures when the pressure was fully released to ambient pressure.

Crystal structure and density of helium to 232 kbar

NASA Technical Reports Server (NTRS)

Mao, H. K.; Wu, Y.; Jephcoat, A. P.; Hemley, R. J.; Bell, P. M.; Bassett, W. A.

1988-01-01

The properties of helium and hydrogen at high pressure are topics of great interest to the understanding of planetary interiors. These materials constitute 95 percent of the entire solar system. A technique was presented for the measurement of X-ray diffraction from single-crystals of low-Z condenses gases in a diamond-anvil cell at high pressure. The first such single-crystal X-ray diffraction measurements on solid hydrogen to 26.5 GPa were presented. The application of this technique to the problem of the crystal structure, equation of state, and phase diagram of solid helium is reported. Crucial for X-ray diffraction studies of these materials is the use of a synchrotron radiation source which provides high brillance, narrow collimation of the incident and diffracted X-ray beams to reduce the background noise, and energy-dispersive diffraction techniques with polychromatic (white) radiation, which provides high detection efficiency.

Structural investigation of porcine stomach mucin by X-ray fiber diffraction and homology modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veluraja, K., E-mail: veluraja@msuniv.ac.in; Vennila, K.N.; Umamakeshvari, K.

Research highlights: {yields} Techniques to get oriented mucin fibre. {yields} X-ray fibre diffraction pattern for mucin. {yields} Molecular modeling of mucin based on X-ray fibre diffraction pattern. -- Abstract: The basic understanding of the three dimensional structure of mucin is essential to understand its physiological function. Technology has been developed to achieve orientated porcine stomach mucin molecules. X-ray fiber diffraction of partially orientated porcine stomach mucin molecules show d-spacing signals at 2.99, 4.06, 4.22, 4.7, 5.37 and 6.5 A. The high intense d-spacing signal at 4.22 A is attributed to the antiparallel {beta}-sheet structure identified in the fraction of themore » homology modeled mucin molecule (amino acid residues 800-980) using Nidogen-Laminin complex structure as a template. The X-ray fiber diffraction signal at 6.5 A reveals partial organization of oligosaccharides in porcine stomach mucin. This partial structure of mucin will be helpful in establishing a three dimensional structure for the whole mucin molecule.« less

A nearly on-axis spectroscopic system for simultaneously measuring UV-visible absorption and X-ray diffraction in the SPring-8 structural genomics beamline.

PubMed

Sakaguchi, Miyuki; Kimura, Tetsunari; Nishida, Takuma; Tosha, Takehiko; Sugimoto, Hiroshi; Yamaguchi, Yoshihiro; Yanagisawa, Sachiko; Ueno, Go; Murakami, Hironori; Ago, Hideo; Yamamoto, Masaki; Ogura, Takashi; Shiro, Yoshitsugu; Kubo, Minoru

2016-01-01

UV-visible absorption spectroscopy is useful for probing the electronic and structural changes of protein active sites, and thus the on-line combination of X-ray diffraction and spectroscopic analysis is increasingly being applied. Herein, a novel absorption spectrometer was developed at SPring-8 BL26B2 with a nearly on-axis geometry between the X-ray and optical axes. A small prism mirror was placed near the X-ray beamstop to pass the light only 2° off the X-ray beam, enabling spectroscopic analysis of the X-ray-exposed volume of a crystal during X-ray diffraction data collection. The spectrometer was applied to NO reductase, a heme enzyme that catalyzes NO reduction to N2O. Radiation damage to the heme was monitored in real time during X-ray irradiation by evaluating the absorption spectral changes. Moreover, NO binding to the heme was probed via caged NO photolysis with UV light, demonstrating the extended capability of the spectrometer for intermediate analysis.

Investigating the Effects of Low Temperature Annealing of Amorphous Corrosion Resistant Alloys.

DTIC Science & Technology

1980-11-01

Ray Diffraction.................................................... 6 Differential Scanning Calorimetry....................................... 9...17 LIST OF FIGURES Figure 1. X- Ray Diffraction Results From Fe32Ni 36Cr 4P 2 B Annealed for One Hour at...Various Temperatures (Cr Ka Radiation) ................................. 7 Figure 2. X- Ray Diffraction Results From FeU2NiaeCr14SieB Annealed for One

Evidence from x-ray and neutron powder diffraction patterns that the so-called icosahedral and decagonal quasicrystals of MnAl(6) and other alloys are twinned cubic crystals.

PubMed

Pauling, L

1987-06-01

It is shown that the x-ray powder diffraction patterns of rapidly quenched MnAl(6) and Mg(32)(Al,Zn)(49) and the neutron powder diffraction pattern of MnAl(6) are compatible with the proposed 820-atom primitive cubic structure [Pauling, L. (1987) Phys. Rev. Lett. 58, 365-368]. The values found for the edge of the unit cube are 23.365 A (x-ray) and 23.416 A (neutron) for MnAl(6) and 24.313 A (x-ray) for Mg(32)(Al,Zn)(49).

Evidence from x-ray and neutron powder diffraction patterns that the so-called icosahedral and decagonal quasicrystals of MnAl6 and other alloys are twinned cubic crystals

PubMed Central

Pauling, Linus

1987-01-01

It is shown that the x-ray powder diffraction patterns of rapidly quenched MnAl6 and Mg32(Al,Zn)49 and the neutron powder diffraction pattern of MnAl6 are compatible with the proposed 820-atom primitive cubic structure [Pauling, L. (1987) Phys. Rev. Lett. 58, 365-368]. The values found for the edge of the unit cube are 23.365 Å (x-ray) and 23.416 Å (neutron) for MnAl6 and 24.313 Å (x-ray) for Mg32(Al,Zn)49. PMID:16593841

High-energy X-ray diffraction using the Pixium 4700 flat-panel detector.

PubMed

Daniels, J E; Drakopoulos, M

2009-07-01

The Pixium 4700 detector represents a significant step forward in detector technology for high-energy X-ray diffraction. The detector design is based on digital flat-panel technology, combining an amorphous Si panel with a CsI scintillator. The detector has a useful pixel array of 1910 x 2480 pixels with a pixel size of 154 microm x 154 microm, and thus it covers an effective area of 294 mm x 379 mm. Designed for medical imaging, the detector has good efficiency at high X-ray energies. Furthermore, it is capable of acquiring sequences of images at 7.5 frames per second in full image mode, and up to 60 frames per second in binned region of interest modes. Here, the basic properties of this detector applied to high-energy X-ray diffraction are presented. Quantitative comparisons with a widespread high-energy detector, the MAR345 image plate scanner, are shown. Other properties of the Pixium 4700 detector, including a narrow point-spread function and distortion-free image, allows for the acquisition of high-quality diffraction data at high X-ray energies. In addition, high frame rates and shutterless operation open new experimental possibilities. Also provided are the necessary data for the correction of images collected using the Pixium 4700 for diffraction purposes.

Crystallization and preliminary X-ray diffraction analysis of a chitin-binding domain of hyperthermophilic chitinase from Pyrococcus furiosus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, Tsutomu; Ishikawa, Kazuhiko; Hagihara, Yoshihisa

The expression, purification and preliminary X-ray diffraction studies of a chitin-binding domain of the chitinase from P. furiosus are reported. The crystallization and preliminary X-ray diffraction analysis of the chitin-binding domain of chitinase from a hyperthermophilic archaeon, Pyrococcus furiosus, are reported. The recombinant protein was prepared using an Escherichia coli overexpression system and was crystallized by the hanging-drop vapour-diffusion method. An X-ray diffraction data set was collected to 1.70 Å resolution. The crystal belonged to space group P4{sub 3}2{sub 1}2 or P4{sub 1}2{sub 1}2. The unit-cell parameters were determined to be a = b = 48.8, c = 85.0 Å.

Long-Wavelength X-Ray Diffraction and Its Applications in Macromolecular Crystallography.

PubMed

Weiss, Manfred S

2017-01-01

For many years, diffraction experiments in macromolecular crystallography at X-ray wavelengths longer than that of Cu-K α (1.54 Å) have been largely underappreciated. Effects caused by increased X-ray absorption result in the fact that these experiments are more difficult than the standard diffraction experiments at short wavelengths. However, due to the also increased anomalous scattering of many biologically relevant atoms, important additional structural information can be obtained. This information, in turn, can be used for phase determination, for substructure identification, in molecular replacement approaches, as well as in structure refinement. This chapter reviews the possibilities and the difficulties associated with such experiments, and it provides a short description of two macromolecular crystallography synchrotron beam lines dedicated to long-wavelength X-ray diffraction experiments.

Data processing software suite SITENNO for coherent X-ray diffraction imaging using the X-ray free-electron laser SACLA.

PubMed

Sekiguchi, Yuki; Oroguchi, Tomotaka; Takayama, Yuki; Nakasako, Masayoshi

2014-05-01

Coherent X-ray diffraction imaging is a promising technique for visualizing the structures of non-crystalline particles with dimensions of micrometers to sub-micrometers. Recently, X-ray free-electron laser sources have enabled efficient experiments in the `diffraction before destruction' scheme. Diffraction experiments have been conducted at SPring-8 Angstrom Compact free-electron LAser (SACLA) using the custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors. In the experiments, ten thousands of single-shot diffraction patterns can be collected within several hours. Then, diffraction patterns with significant levels of intensity suitable for structural analysis must be found, direct-beam positions in diffraction patterns determined, diffraction patterns from the two CCD detectors merged, and phase-retrieval calculations for structural analyses performed. A software suite named SITENNO has been developed to semi-automatically apply the four-step processing to a huge number of diffraction data. Here, details of the algorithm used in the suite are described and the performance for approximately 9000 diffraction patterns collected from cuboid-shaped copper oxide particles reported. Using the SITENNO suite, it is possible to conduct experiments with data processing immediately after the data collection, and to characterize the size distribution and internal structures of the non-crystalline particles.

Data processing software suite SITENNO for coherent X-ray diffraction imaging using the X-ray free-electron laser SACLA

PubMed Central

Sekiguchi, Yuki; Oroguchi, Tomotaka; Takayama, Yuki; Nakasako, Masayoshi

2014-01-01

Coherent X-ray diffraction imaging is a promising technique for visualizing the structures of non-crystalline particles with dimensions of micrometers to sub-micrometers. Recently, X-ray free-electron laser sources have enabled efficient experiments in the ‘diffraction before destruction’ scheme. Diffraction experiments have been conducted at SPring-8 Angstrom Compact free-electron LAser (SACLA) using the custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors. In the experiments, ten thousands of single-shot diffraction patterns can be collected within several hours. Then, diffraction patterns with significant levels of intensity suitable for structural analysis must be found, direct-beam positions in diffraction patterns determined, diffraction patterns from the two CCD detectors merged, and phase-retrieval calculations for structural analyses performed. A software suite named SITENNO has been developed to semi-automatically apply the four-step processing to a huge number of diffraction data. Here, details of the algorithm used in the suite are described and the performance for approximately 9000 diffraction patterns collected from cuboid-shaped copper oxide particles reported. Using the SITENNO suite, it is possible to conduct experiments with data processing immediately after the data collection, and to characterize the size distribution and internal structures of the non-crystalline particles. PMID:24763651

Spectroscopic imaging, diffraction, and holography with x-ray photoemission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-02-01

X-ray probes are capable of determining the spatial structure of an atom in a specific chemical state, over length scales from about a micron all the way down to atomic resolution. Examples of these probes include photoemission microscopy, energy-dependent photoemission diffraction, photoelectron holography, and X-ray absorption microspectroscopy. Although the method of image formation, chemical-state sensitivity, and length scales can be very different, these X-ray techniques share a common goal of combining a capability for structure determination with chemical-state specificity. This workshop will address recent advances in holographic, diffraction, and direct imaging techniques using X-ray photoemission on both theoretical and experimentalmore » fronts. A particular emphasis will be on novel structure determinations with atomic resolution using photoelectrons.« less

An instrument for in situ coherent x-ray studies of metal-organic vapor phase epitaxy of III-nitrides.

PubMed

Ju, Guangxu; Highland, Matthew J; Yanguas-Gil, Angel; Thompson, Carol; Eastman, Jeffrey A; Zhou, Hua; Brennan, Sean M; Stephenson, G Brian; Fuoss, Paul H

2017-03-01

We describe an instrument that exploits the ongoing revolution in synchrotron sources, optics, and detectors to enable in situ studies of metal-organic vapor phase epitaxy (MOVPE) growth of III-nitride materials using coherent x-ray methods. The system includes high-resolution positioning of the sample and detector including full rotations, an x-ray transparent chamber wall for incident and diffracted beam access over a wide angular range, and minimal thermal sample motion, giving the sub-micron positional stability and reproducibility needed for coherent x-ray studies. The instrument enables surface x-ray photon correlation spectroscopy, microbeam diffraction, and coherent diffraction imaging of atomic-scale surface and film structure and dynamics during growth, to provide fundamental understanding of MOVPE processes.

An instrument for in situ coherent x-ray studies of metal-organic vapor phase epitaxy of III-nitrides

NASA Astrophysics Data System (ADS)

Ju, Guangxu; Highland, Matthew J.; Yanguas-Gil, Angel; Thompson, Carol; Eastman, Jeffrey A.; Zhou, Hua; Brennan, Sean M.; Stephenson, G. Brian; Fuoss, Paul H.

2017-03-01

We describe an instrument that exploits the ongoing revolution in synchrotron sources, optics, and detectors to enable in situ studies of metal-organic vapor phase epitaxy (MOVPE) growth of III-nitride materials using coherent x-ray methods. The system includes high-resolution positioning of the sample and detector including full rotations, an x-ray transparent chamber wall for incident and diffracted beam access over a wide angular range, and minimal thermal sample motion, giving the sub-micron positional stability and reproducibility needed for coherent x-ray studies. The instrument enables surface x-ray photon correlation spectroscopy, microbeam diffraction, and coherent diffraction imaging of atomic-scale surface and film structure and dynamics during growth, to provide fundamental understanding of MOVPE processes.

Investigating the Effect of Pyridine Vapor Treatment on Perovskite Solar Cells - Oral Presentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ong, Alison J.

2015-08-25

Perovskite photovoltaics have recently come to prominence as a viable alternative to crystalline silicon based solar cells. In an effort to create consistent and high-quality films, we studied the effect of various annealing conditions as well as the effect of pyridine vapor treatment on mixed halide methylammonium lead perovskite films. Of six conditions tested, we found that annealing at 100 degree Celsius for 90 minutes followed by 120 degree Celsius for 15 minutes resulted in the purest perovskite. Perovskite films made using that condition were treated with pyridine for various amounts of time, and the effects on perovskite microstructure weremore » studied using x-ray diffraction, UV-Vis spectroscopy, and time-resolved photoluminescence lifetime analysis (TRPL). A previous study found that pyridine vapor caused perovskite films to have higher photoluminescence intensity and become more homogenous. In this study we found that the effects of pyridine are more complex: while films appeared to become more homogenous, a decrease in bulkphotoluminescence lifetime was observed. In addition, the perovskite bandgap appeared to decrease with increased pyridine treatment time. Finally, X-ray diffraction showed that pyridine vapor treatment increased the perovskite (110) peak intensity but also often gave rise to new unidentified peaks, suggesting the formation of a foreign species. It was observed that the intensity of this unknown species had an inverse correlation with the increase in perovskite peak intensity, and also seemed to be correlated with the decrease in TRPL lifetime.« less

Investigating the Effect of Pyridine Vapor Treatment on Perovskite Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ong, Alison

2015-08-20

Perovskite photovoltaics have recently come to prominence as a viable alternative to crystalline silicon based solar cells. In an effort to create consistent and high-quality films, we studied the effect of various annealing conditions as well as the effect of pyridine vapor treatment on mixed halide methylammonium lead perovskite films. Of six conditions tested, we found that annealing at 100°C for 90 minutes followed by 120°C for 15 minutes resulted in the purest perovskite. Perovskite films made using that condition were treated with pyridine for various amounts of time, and the effects on perovskite microstructure were studied using x-ray diffraction,more » UV-Vis spectroscopy, and time-resolved photoluminescence lifetime analysis (TRPL). A previous study found that pyridine vapor caused perovskite films to have higher photoluminescence intensity and become more homogenous. In this study we found that the effects of pyridine are more complex: while films appeared to become more homogenous, a decrease in bulk photoluminescence lifetime was observed. In addition, the perovskite bandgap appeared to decrease with increased pyridine treatment time. Finally, X-ray diffraction showed that pyridine vapor treatment increased the perovskite (110) peak intensity but also often gave rise to new unidentified peaks, suggesting the formation of a foreign species. It was observed that the intensity of this unknown species had an inverse correlation with the increase in perovskite peak intensity, and also seemed to be correlated with the decrease in TRPL lifetime.« less

Combined X-ray and neutron fibre diffraction studies of biological and synthetic polymers

NASA Astrophysics Data System (ADS)

Parrot, I. M.; Urban, V.; Gardner, K. H.; Forsyth, V. T.

2005-08-01

The fibrous state is a natural one for polymer molecules which tend to assume regular helical conformations rather than the globular structures characteristic of many proteins. Fibre diffraction therefore has broad application to the study of a wide range of biological and synthetic polymers. The purpose of this paper is to illustrate the general scope of the method and in particular to demonstrate the impact of a combined approach involving both X-ray and neutron diffraction methods. While the flux of modern X-ray synchrotron radiation sources allows high quality datasets to be recorded with good resolution within a very short space of time, neutron studies can provide unique information through the ability to locate hydrogen or deuterium atoms that are often difficult or impossible to locate using X-ray methods. Furthermore, neutron fibre diffraction methods can, through the ability to selectively label specific parts of a structure, be used to highlight novel aspects of polymer structure that can not be studied using X-rays. Two examples are given. The first describes X-ray and neutron diffraction studies of conformational transitions in DNA. The second describes structural studies of the synthetic high-performance polymer poly(p-phenylene terephthalamide) (PPTA), known commercially as Kevlar® or Twaron®.

Conceptual Design for Time-Resolved X-ray Diffraction in a Single Laser-Driven Compression Experiment

NASA Astrophysics Data System (ADS)

Benedetti, Laura Robin; Eggert, J. H.; Kilkenny, J. D.; Bradley, D. K.; Bell, P. M.; Palmer, N. E.; Rygg, J. R.; Boehly, T. R.; Collins, G. W.; Sorce, C.

2017-06-01

Since X-ray diffraction is the most definitive method for identifying crystalline phases of a material, it is an important technique for probing high-energy-density materials during laser-driven compression experiments. We are developing a design for collecting several x-ray diffraction datasets during a single laser-driven experiment, with a goal of achieving temporal resolution better than 1ns. The design combines x-ray streak cameras, for a continuous temporal record of diffraction, with fast x-ray imagers, to collect several diffraction patterns with sufficient solid angle range and resolution to identify crystalline texture. Preliminary experiments will be conducted at the Omega laser and then implemented at the National Ignition Facility. We will describe the status of the conceptual design, highlighting tradeoffs in the design process. We will also discuss the technical issues that must be addressed in order to develop a successful experimental platform. These include: Facility-specific geometric constraints such as unconverted laser light and target alignment; EMP issues when electronic diagnostics are close to the target; X-ray source requirements; and detector capabilities. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, LLNL-ABS-725146.

Deformation Behavior of Cementite in Deformed High Carbon Steel Observed by X-ray Diffraction with Synchrotron Radiation

NASA Astrophysics Data System (ADS)

Taniyama, Akira; Takayama, Toru; Arai, Masahiro; Hamada, Takanari

2017-10-01

The deformation behavior of cementite in drawn pearlitic steel and spheroidal cementite steel, which have hypereutectoid composition, was investigated by X-ray diffraction using synchrotron radiation. A detailed analysis of diffraction peak profiles reveals that the deformation behavior strongly depends on the shape of cementite in steel. The unit cell volume of the cementite in the drawn pearlitic steel compressively and elastically deforms by 1.5 to 2 pct of the initial volume at the early stage of drawing, whereas that in the drawn spheroidal cementite steel is compressed by 1 pct of the initial volume even at a large true strain. The cementite in the drawn pearlitic steel fragments into small pieces with increasing the true strain, and these pieces change to amorphous cementite. The dislocation densities of the cementite in the drawn pearlitic steel and in the drawn spheroidal cementite steel are estimated to be 1013/m2 before drawing and 1014/m2 after drawing. Although the large strain is induced in the cementite by drawing, the maximum strain energy in the cementite is too small to contribute to the dissolution of the cementite.

Phase transformation in δ-Pu alloys at low temperature: An in situ microstructural characterization using X-ray diffraction

NASA Astrophysics Data System (ADS)

Ravat, B.; Platteau, C.; Texier, G.; Oudot, B.; Delaunay, F.

2009-09-01

In order to investigate the martensitic transformation, an isothermal hold at -130 °C for 48 h was performed on a highly homogenized PuGa alloy. The modifications of the microstructure were characterized in situ thanks to a specific tool. This device was developed at the CEA-Valduc to analyze the crystalline structure of plutonium alloys as a function of temperature and more especially at low temperature using X-ray diffraction. The analysis of the recorded diffraction patterns highlighted that the martensitic transformation for this alloy is the result of a direct δ → α' + δ phase transformation. Moreover, a significant Bragg's peaks broadening corresponding to the δ-phase was observed. A microstructural analysis was made to characterize anisotropic microstrain resulting from the stress induced by the unit cell volume difference between the δ and α' phases. The amount of α'-phase evolved was analyzed within the framework of the Avrami theory in order to characterize the nucleation process. The results suggested that the growth mechanism corresponded to a general mechanism where the nucleation sites were in the δ-grain edges and the α'-phase had a plate-like morphology.

IDATEN and G-SITENNO: GUI-assisted software for coherent X-ray diffraction imaging experiments and data analyses at SACLA.

PubMed

Sekiguchi, Yuki; Yamamoto, Masaki; Oroguchi, Tomotaka; Takayama, Yuki; Suzuki, Shigeyuki; Nakasako, Masayoshi

2014-11-01

Using our custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors, cryogenic coherent X-ray diffraction imaging experiments have been undertaken at the SPring-8 Angstrom Compact free electron LAser (SACLA) facility. To efficiently perform experiments and data processing, two software suites with user-friendly graphical user interfaces have been developed. The first is a program suite named IDATEN, which was developed to easily conduct four procedures during experiments: aligning KOTOBUKI-1, loading a flash-cooled sample into the cryogenic goniometer stage inside the vacuum chamber of KOTOBUKI-1, adjusting the sample position with respect to the X-ray beam using a pair of telescopes, and collecting diffraction data by raster scanning the sample with X-ray pulses. Named G-SITENNO, the other suite is an automated version of the original SITENNO suite, which was designed for processing diffraction data. These user-friendly software suites are now indispensable for collecting a large number of diffraction patterns and for processing the diffraction patterns immediately after collecting data within a limited beam time.

Dynamical diffraction imaging (topography) with X-ray synchrotron radiation

NASA Technical Reports Server (NTRS)

Kuriyama, M.; Steiner, B. W.; Dobbyn, R. C.

1989-01-01

By contrast to electron microscopy, which yields information on the location of features in small regions of materials, X-ray diffraction imaging can portray minute deviations from perfect crystalline order over larger areas. Synchrotron radiation-based X-ray optics technology uses a highly parallel incident beam to eliminate ambiguities in the interpretation of image details; scattering phenomena previously unobserved are now readily detected. Synchrotron diffraction imaging renders high-resolution, real-time, in situ observations of materials under pertinent environmental conditions possible.

Development of Thin Films as Potential Structural Cathodes to Enable Multifunctional Energy-Storage Structural Composite Batteries for the U.S. Army’s Future Force

DTIC Science & Technology

2011-09-01

glancing angle X - ray diffraction (GAXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and electrochemical...Emission SEM FWHM full width at half maximum GAXRD glancing angle X - ray diffraction H3COCH2CH2OH 2-methoxyethanol LiMn2O4 lithium manganese oxide...were characterized by scanning electron microscopy (SEM), X - ray diffraction (XRD), and atomic force microscopy (AFM). In addition,

Simultaneous X-ray fluorescence and scanning X-ray diffraction microscopy at the Australian Synchrotron XFM beamline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, Michael W. M.; Phillips, Nicholas W.; van Riessen, Grant A.

2016-08-11

Owing to its extreme sensitivity, quantitative mapping of elemental distributionsviaX-ray fluorescence microscopy (XFM) has become a key microanalytical technique. The recent realisation of scanning X-ray diffraction microscopy (SXDM) meanwhile provides an avenue for quantitative super-resolved ultra-structural visualization. The similarity of their experimental geometries indicates excellent prospects for simultaneous acquisition. Here, in both step- and fly-scanning modes, robust, simultaneous XFM-SXDM is demonstrated.

Macroscopic X-ray Powder Diffraction Scanning: Possibilities for Quantitative and Depth-Selective Parchment Analysis.

PubMed

Vanmeert, Frederik; De Nolf, Wout; Dik, Joris; Janssens, Koen

2018-06-05

At or below the surface of painted works of art, valuable information is present that provides insights into an object's past, such as the artist's technique and the creative process that was followed or its conservation history but also on its current state of preservation. Various noninvasive techniques have been developed over the past 2 decades that can probe this information either locally (via point analysis) or on a macroscopic scale (e.g., full-field imaging and raster scanning). Recently macroscopic X-ray powder diffraction (MA-XRPD) mapping using laboratory X-ray sources was developed. This method can visualize highly specific chemical distributions at the macroscale (dm 2 ). In this work we demonstrate the synergy between the quantitative aspects of powder diffraction and the noninvasive scanning capability of MA-XRPD highlighting the potential of the method to reveal new types of information. Quantitative data derived from a 15th/16th century illuminated sheet of parchment revealed three lead white pigments with different hydrocerussite-cerussite compositions in specific pictorial elements, while quantification analysis of impurities in the blue azurite pigment revealed two distinct azurite types: one rich in barite and one in quartz. Furthermore, on the same artifact, the depth-selective possibilities of the method that stem from an exploitation of the shift of the measured diffraction peaks with respect to reference data are highlighted. The influence of different experimental parameters on the depth-selective analysis results is briefly discussed. Promising stratigraphic information could be obtained, even though the analysis is hampered by not completely understood variations in the unit cell dimensions of the crystalline pigment phases.

A 2D Metal-Organic Framework with a Flexible Cyclohexane-1,2,5,6-tetracarboxylic Acid Ligand: Synthesis, Characterization and Photoluminescent Property

PubMed Central

Wang, Rongming; Zhang, Jian; Li, Lijuan

2009-01-01

A novel metal-organic framework, [Zn2(OH)(Hcht)(4,4′-bpy)]n·4nH2O (1) (H4cht = cyclohexane-1,2,4,5-tetracarboxylic acid and 4,4′-bpy = 4,4′-bipyridine), was synthesized by the hydrothermal reaction of Zn(NO3)2.6H2O, 4,4′-bipyridine, and cyclohexane-1,2,4,5-tetracarboxylic acid in the presence of sodium carbonate. The complex was obtained by controlling the ratio of the starting materials and a reaction temperature at 120°C and was characterized by IR, X-ray powder diffraction, thermogravimetric analysis, fluorescent spectrum, and single crystal X-ray diffraction. Single-crystal X-ray investigation reveals that the structure features a two-dimensional framework with novel coordination mode of Hcht ligand and all Hcht ligands exclusively convert to a sole conformation in the complex. IR spectrum reveals the characteristic absorption peaks of asymmetric stretching vibrations that result from the protonated and deprotonated carboxyl groups,. Thermogravimetric analysis shows four clear courses of weight loss, which corresponds to the decomposition of different ligands. Fluorescent spectrum displays that complex 1 is a potential blue-luminescent material. PMID:20383315

The first X-ray diffraction measurements on Mars.

PubMed

Bish, David; Blake, David; Vaniman, David; Sarrazin, Philippe; Bristow, Thomas; Achilles, Cherie; Dera, Przemyslaw; Chipera, Steve; Crisp, Joy; Downs, R T; Farmer, Jack; Gailhanou, Marc; Ming, Doug; Morookian, John Michael; Morris, Richard; Morrison, Shaunna; Rampe, Elizabeth; Treiman, Allan; Yen, Albert

2014-11-01

The Mars Science Laboratory landed in Gale crater on Mars in August 2012, and the Curiosity rover then began field studies on its drive toward Mount Sharp, a central peak made of ancient sediments. CheMin is one of ten instruments on or inside the rover, all designed to provide detailed information on the rocks, soils and atmosphere in this region. CheMin is a miniaturized X-ray diffraction/X-ray fluorescence (XRD/XRF) instrument that uses transmission geometry with an energy-discriminating CCD detector. CheMin uses onboard standards for XRD and XRF calibration, and beryl:quartz mixtures constitute the primary XRD standards. Four samples have been analysed by CheMin, namely a soil sample, two samples drilled from mudstones and a sample drilled from a sandstone. Rietveld and full-pattern analysis of the XRD data reveal a complex mineralogy, with contributions from parent igneous rocks, amorphous components and several minerals relating to aqueous alteration. In particular, the mudstone samples all contain one or more phyllosilicates consistent with alteration in liquid water. In addition to quantitative mineralogy, Rietveld refinements also provide unit-cell parameters for the major phases, which can be used to infer the chemical compositions of individual minerals and, by difference, the composition of the amorphous component.

Investigation of high-energy ion-irradiated MA957 using synchrotron radiation under in-situ tension

DOE PAGES

Mo, Kun; Yun, Di; Miao, Yinbin; ...

2016-01-02

In this paper, an MA957 oxide dispersion-strengthened (ODS) alloy was irradiated with high-energy ions in the Argonne Tandem Linac Accelerator System. Fe ions at an energy of 84 MeV bombarded MA957 tensile specimens, creating a damage region similar to 7.5 μm in depth; the peak damage (similar to 40 dpa) was estimated to be at similar to 7 μm from the surface. Following the irradiation, in-situ high-energy X-ray diffraction measurements were performed at the Advanced Photon Source in order to study the dynamic deformation behavior of the specimens after ion irradiation damage. In-situ X-ray measurements taken during tensile testing ofmore » the ion-irradiated MA957 revealed a difference in loading behavior between the irradiated and un-irradiated regions of the specimen. At equivalent applied stresses, lower lattice strains were found in the radiation-damaged region than those in the un-irradiated region. This might be associated with a higher level of Type II stresses as a result of radiation hardening. The study has demonstrated the feasibility of combining high-energy ion radiation and high-energy synchrotron X-ray diffraction to study materials' radiation damage in a dynamic manner.« less

Growth and luminescent properties of Yb:YAG and Ca co-doped Yb:YAG ultrafast scintillation crystals

NASA Astrophysics Data System (ADS)

Zhu, Maodong; Qi, Hongji; Pan, Mingyan; Hou, Qing; Jiang, Benxue; Jin, Yaxue; Han, Hetong; Song, Zhaohui; Zhang, Hui

2018-05-01

In this work, Yb-doped Y3Al5O12 [yttrium aluminum garnet (YAG)] crystals and Ca co-doped Yb:YAG crystals were grown by the Czochralski (CZ) method. The chemical formulas of the two crystals are (Yb0.1Y0.9)3Al5O12 and (Ca0.001Yb0.1Y0.899)3Al5O12, respectively. The structural, optical and luminescent properties of the Yb:YAG and Ca, Yb:YAG crystals were investigated by X-ray rocking curve, X-ray diffraction, Raman spectra, UV-Visble-NIR absorption spectra and X-ray fluorescence. X-ray fluorescence spectrum with two emission peaks at 330 nm and 490 nm were observed in the two kinds of crystals, which would increase slightly after the annealing. Comparing to the Yb:YAG crystal, Ca co-doped Yb:YAG crystal behaved the better luminescent intensity without changing the crystal structure and vibrational modes. This indicates that by doping Ca2+ in Yb:YAG crystal may be an appropriate way to enhance the luminescent property of the scintillation crystal.

Experimental and theoretical investigation of the rocking curves measured for Mo K α X-ray characteristic lines in the double-crystal nondispersive scheme

NASA Astrophysics Data System (ADS)

Marchenkov, N. V.; Chukhovskii, F. N.; Blagov, A. E.

2015-03-01

The rocking curves (RCs) for Mo K α1 h Mo K α2 characteristic X-ray lines have been experimentally and theoretically studied in the nondispersive scheme of an X-ray double-crystal TPC-K diffractometer. The results of measurements and theoretical calculations of double-crystal RCs for characteristic X-rays from tubes with a molybdenum anode and different widths of slits show that a decrease in the slit width leads to an increase in the relative contribution of the Mo K α2-line RC in comparison with the intensity of the tails of the Mo K α1-line RC. It is shown that the second peak of the Mo K α2 line becomes increasingly pronounced in the tail of the Mo K α1-line RC with a decrease in the slit width. Two plane-parallel Si plates (input faces {110}, diffraction vector h <220>) were used as a monochromator crystal and a sample. The results of measuring double-crystal RCs are in good agreement with theoretical calculations.

An Excel Spreadsheet for a One-Dimensional Fourier Map in X-ray Crystallography

ERIC Educational Resources Information Center

Clegg, William

2004-01-01

The teaching of crystal structure determination with single-crystal X-ray diffraction at undergraduate level faces numerous challenges. Single-crystal X-ray diffraction is used in a vast range of chemical research projects and forms the basis for a high proportion of structural results that are presented to high-school, undergraduate, and graduate…

Laser-induced Multi-energy Processing in Diamond Growth

DTIC Science & Technology

2012-05-01

microscopy (SEM) and energy dispersive X - ray (EDX) measurements, Drs. Yi Liu and Shah Valloppilly from Nebraska Center for Materials and Nanoscience...NCMN) at UNL for help on X - Ray diffraction (XRD) measurements, and Professor Steve W. Martin and Dr. Young Sik Kim from the Department of Material...spectroscopy and X - ray diffraction ................... 62 4.4 Conclusions

Two-dimensional time-resolved X-ray diffraction study of liquid/solid fraction and solid particle size in Fe-C binary system with an electrostatic levitator furnace

NASA Astrophysics Data System (ADS)

Yonemura, M.; Okada, J.; Watanabe, Y.; Ishikawa, T.; Nanao, S.; Shobu, T.; Toyokawa, H.

2013-03-01

Liquid state provides functions such as matter transport or a reaction field and plays an important role in manufacturing processes such as refining, forging or welding. However, experimental procedures are significantly difficult for an observation of solidification process of iron and iron-based alloys in order to identify rapid transformations subjected to fast temperature evolution. Therefore, in order to study the solidification in iron and iron-based alloys, we considered a combination of high energy X-ray diffraction measurements and an electrostatic levitation method (ESL). In order to analyze the liquid/solid fraction, the solidification of melted spherical specimens was measured at a time resolution of 0.1 seconds during rapid cooling using the two-dimensional time-resolved X-ray diffraction. Furthermore, the observation of particle sizes and phase identification was performed on a trial basis using X-ray small angle scattering with X-ray diffraction.

Imaging single cells in a beam of live cyanobacteria with an X-ray laser.

PubMed

van der Schot, Gijs; Svenda, Martin; Maia, Filipe R N C; Hantke, Max; DePonte, Daniel P; Seibert, M Marvin; Aquila, Andrew; Schulz, Joachim; Kirian, Richard; Liang, Mengning; Stellato, Francesco; Iwan, Bianca; Andreasson, Jakob; Timneanu, Nicusor; Westphal, Daniel; Almeida, F Nunes; Odic, Dusko; Hasse, Dirk; Carlsson, Gunilla H; Larsson, Daniel S D; Barty, Anton; Martin, Andrew V; Schorb, Sebastian; Bostedt, Christoph; Bozek, John D; Rolles, Daniel; Rudenko, Artem; Epp, Sascha; Foucar, Lutz; Rudek, Benedikt; Hartmann, Robert; Kimmel, Nils; Holl, Peter; Englert, Lars; Duane Loh, Ne-Te; Chapman, Henry N; Andersson, Inger; Hajdu, Janos; Ekeberg, Tomas

2015-02-11

There exists a conspicuous gap of knowledge about the organization of life at mesoscopic levels. Ultra-fast coherent diffractive imaging with X-ray free-electron lasers can probe structures at the relevant length scales and may reach sub-nanometer resolution on micron-sized living cells. Here we show that we can introduce a beam of aerosolised cyanobacteria into the focus of the Linac Coherent Light Source and record diffraction patterns from individual living cells at very low noise levels and at high hit ratios. We obtain two-dimensional projection images directly from the diffraction patterns, and present the results as synthetic X-ray Nomarski images calculated from the complex-valued reconstructions. We further demonstrate that it is possible to record diffraction data to nanometer resolution on live cells with X-ray lasers. Extension to sub-nanometer resolution is within reach, although improvements in pulse parameters and X-ray area detectors will be necessary to unlock this potential.

Surface Relaxation in Protein Crystals

NASA Technical Reports Server (NTRS)

Boutet, S.; Robinson, I. K.; Hu, Z. W.; Thomas, B. R.; Chernov, A. A.

2002-01-01

Surface X-ray diffraction measurements were performed on (111) growth faces of crystals of the Cellular iron-storage protein horse spleen ferritin. Crystal Trunkation Rods (CTR) were measured. A fit of the measured profile of the CTR revealed a surface roughness of 48 +/- 4.5 A and a top layer spacing contraction of 3.9 +/- 1.5%. In addition to the peak from the CTR, the rocking curves of the crystals displayed unexpected extra peaks. Multiple-scattering is demonstrated to account for them. Future applications of the method could allow the exploration of hydration effects on the growth of protein crystals.

Intermediate- and short-range order in phosphorus-selenium glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bytchkov, Aleksei; Hennet, Louis; Price, David L.

2011-04-01

State-of-the-art neutron and x-ray diffraction measurements have been performed to provide a definitive picture of the intermediate- and short-range structures of P{sub x}Se{sub 1-x} glasses spanning two glass regions, x 0.025-0.54 and 0.64-0.84. Liquid P{sub 4}Se{sub 3} and amorphous red P and Se were also measured. Detailed information was obtained about the development with increasing phosphorous concentration of intermediate-range order on the length scale {approx}6 A ring , based on the behavior of the first sharp diffraction peak. Attention is also paid to the feature in the structure factor at 7.5 A ring {sup -1}, identified in earlier numerical simulations,more » provides further evidence of the existence of molecular units. The real-space transforms yield a reliable statistical picture of the changing short-range order as x increases, using the information about types and concentrations of local structural units provided by previous NMR measurements to interpret the trends observed.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brummer, Gordie, E-mail: gbrummer@bu.edu; Photonics Center, Boston University, Boston, Massachusetts 02215; Nothern, Denis

Distributed Bragg reflectors (DBRs) with peak reflectivity at approximately 280 nm, based on compositionally graded Al{sub x}Ga{sub 1−x}N alloys, were grown on 6H-SiC substrates by plasma-assisted molecular beam epitaxy. DBRs with square, sinusoidal, triangular, and sawtooth composition profiles were designed with the transfer matrix method. The crystal structure of these DBRs was studied with high-resolution x-ray diffraction of the (1{sup ¯}015) reciprocal lattice point. The periodicity of the DBR profiles was confirmed with cross-sectional Z-contrast scanning transmission electron microscopy. The peak reflectance of these DBRs with 15.5 periods varies from 77% to 56% with corresponding full width at half maximum ofmore » 17–14 nm. Coupled mode analysis was used to explain the dependence of the reflectivity characteristics on the profile of the graded composition.« less

Development of ultrashort x-ray/gamma-ray sources using ultrahigh power lasers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kim, Hyung Taek; Nakajima, Kazuhisa; Hojbota, Calin; Jeon, Jong Ho; Rhee, Yong-Joo; Lee, Kyung Hwan; Lee, Seong Ku; Sung, Jae Hee; Lee, Hwang Woon; Pathak, Vishwa B.; Pae, Ki Hong; Sebban, Stéphane; Tissandier, Fabien; Gautier, Julien; Ta Phuoc, Kim; Malka, Victor; Nam, Chang Hee

2017-05-01

Short-pulse x-ray/gamma-ray sources have become indispensable light sources for investigating material science, bio technology, and photo-nuclear physics. In past decades, rapid advancement of high intensity laser technology led extensive progresses in the field of radiation sources based on laser-plasma interactions - x-ray lasers, betatron radiation and Compton gamma-rays. Ever since the installation of a 100-TW laser in 2006, we have pursued the development of ultrashort x-ray/gamma-ray radiations, such as x-ray lasers, relativistic high-order harmonics, betatron radiation and all-optical Compton gamma-rays. With the construction of two PW Ti:Sapphire laser beamlines having peak powers of 1.0 PW and 1.5 PW in 2010 and 2012, respectively [1], we have investigated the generation of multi-GeV electron beams [2] and MeV betatron radiations. We plan to carry out the Compton backscattering to generate MeV gamma-rays from the interaction of a GeV electron beam and a PW laser beam. Here, we present the recent progress in the development of ultrashort x-ray/gamma-ray radiation sources based on laser plasma interactions and the plan for developing Compton gamma-ray sources driven by the PW lasers. In addition, we will present the applications of laser-plasma x-ray lasers to x-ray holography and coherent diffraction imaging. [references] 1. J. H. Sung, S. K. Lee, T. J. Yu, T. M. Jeong, and J. Lee, Opt. Lett. 35, 3021 (2010). 2. H. T. Kim, K. H. Pae, H. J. Cha, I J. Kim, T. J. Yu, J. H. Sung, S. K. Lee, T. M. Jeong, J. Lee, Phys. Rev. Lett. 111, 165002 (2013).

Heteroepitaxial growth of Ba1 - xSrxTiO3/YBa2Cu3O7 - x by plasma-enhanced metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Chern, C. S.; Liang, S.; Shi, Z. Q.; Yoon, S.; Safari, A.; Lu, P.; Kear, B. H.; Goodreau, B. H.; Marks, T. J.; Hou, S. Y.

1994-06-01

Epitaxial Ba1-xSrxTiO3(BST)/YBa2Cu3O7-x heterostructures with superior electrical and dielectric properties have been fabricated by plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD). Data of x-ray diffraction and high resolution transmission electron microscopy showed that <100> oriented Ba1-xSrxTiO3 layers were epitaxially deposited on epitaxial (001) YBa2Cu3O7-x layers. The leakage current density through the Ba1-xSrxTiO3 films was about 10-7 A/cm2 at 2 V (about 2×105 V/cm) operation. Moreover, the results of capacitance-temperature measurements showed that the PE-MOCVD Ba1-xSrxTiO3 films had Curie temperatures of about 30 °C and a peak dielectric constant of 600 at zero bias voltage. The Rutherford backscattering spectrometry and x-ray diffraction results showed that the BST film composition was controlled between Ba0.75Sr0.25TiO3 and Ba0.8Sr0.2TiO3. The structural and electrical properties of the Ba1-xSrxTiO3/YBa2Cu3O7-x heterostructure indicated that conductive oxide materials with close lattice to Ba1-xSrxTiO3 can be good candidates for the bottom electrode.

Crystal structure prediction supported by incomplete experimental data

NASA Astrophysics Data System (ADS)

Tsujimoto, Naoto; Adachi, Daiki; Akashi, Ryosuke; Todo, Synge; Tsuneyuki, Shinji

2018-05-01

We propose an efficient theoretical scheme for structure prediction on the basis of the idea of combining methods, which optimize theoretical calculation and experimental data simultaneously. In this scheme, we formulate a cost function based on a weighted sum of interatomic potential energies and a penalty function which is defined with partial experimental data totally insufficient for conventional structure analysis. In particular, we define the cost function using "crystallinity" formulated with only peak positions within the small range of the x-ray-diffraction pattern. We apply this method to well-known polymorphs of SiO2 and C with up to 108 atoms in the simulation cell and show that it reproduces the correct structures efficiently with very limited information of diffraction peaks. This scheme opens a new avenue for determining and predicting structures that are difficult to determine by conventional methods.

Impedance spectroscopic and dielectric properties of nanosized Y2/3Cu3Ti4O12 ceramic

NASA Astrophysics Data System (ADS)

Sharma, Sunita; Yadav, Shiv Sundar; Singh, M. M.; Mandal, K. D.

2014-11-01

Yttrium Copper Titanate (Y2/3Cu3Ti4O12) nanoceramic is structurally analogous to CaCu3Ti4O12 (CCTO). X-ray diffraction (XRD) of Y2/3Cu3Ti4O12 (YCTO) shows the presence of all normal peaks of CCTO. SEM micrograph exhibits the presence of bimodal grains of size ranging from 1-2 μm. Bright field TEM image clearly displays nanocrystalline particle which is supported by presence of a few clear rings in the corresponding selected area electron diffraction (SAED) pattern. It exhibits a high value of dielectric constant (ɛ‧ = 8434) at room temperature and 100 Hz frequency with characteristic relaxation peaks. Impedance and modulus studies revealed the presence of temperature-dependent Maxwell-Wagner type of relaxation in the ceramic.

THz-pump and X-ray-probe sources based on an electron linac

NASA Astrophysics Data System (ADS)

Setiniyaz, Sadiq; Park, Seong Hee; Kim, Hyun Woo; Vinokurov, Nikolay A.; Jang, Kyu-Ha; Lee, Kitae; Baek, In Hyung; Jeong, Young Uk

2017-11-01

We describe a compact THz-pump and X-ray-probe beamline, based on an electron linac, for ultrafast time-resolved diffraction applications. Two high-energy electron (γ > 50) bunches, 5 ns apart, impinge upon a single-foil or multifoil radiator and generate THz radiation and X-rays simultaneously. The THz pulse from the first bunch is synchronized to the X-ray beam of the second bunch by using an adjustable optical delay of a THz pulse. The peak power of THz radiation from the multifoil radiator is estimated to be 0.14 GW for a 200 pC well-optimized electron bunch. GEANT4 simulations show that a carbon foil with a thickness of 0.5-1.0 mm has the highest yield of 10-20 keV hard X-rays for a 25 MeV beam, which is approximately 103 photons/(keV pC-electrons) within a few degrees of the polar angle. A carbon multifoil radiator with 35 foils (25 μm thick each) can generate close to 103 hard X-rays/(keV pC-electrons) within a 2° acceptance angle. With 200 pC charge and a 100 Hz repetition rate, we can generate 107 X-rays per 1 keV energy bin per second or 105 X-rays per 1 keV energy bin per pulse. The longitudinal time profile of an X-ray pulse ranges from 400 to 600 fs depending on the acceptance angle. The broadening of the time duration of an X-ray pulse is observed owing to its diverging effect. A double-crystal monochromator will be used to select and transport the desired X-rays to the sample. The heating of the radiators by an electron beam is negligible because of the low beam current.

Luminescent properties under X-ray excitation of Ba(1-x)PbxWO4 disordered solid solution

NASA Astrophysics Data System (ADS)

Bakiz, B.; Hallaoui, A.; Taoufyq, A.; Benlhachemi, A.; Guinneton, F.; Villain, S.; Ezahri, M.; Valmalette, J.-C.; Arab, M.; Gavarri, J.-R.

2018-02-01

A series of polycrystalline barium-lead tungstate Ba1-xPbxWO4 with 0 ≤ x ≤ 1 was synthesized using a classical solid-state method with thermal treatment at 1000 °C. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Raman (FT-Raman) spectroscopy. X-ray diffraction profile analyses were performed using Rietveld method. These materials crystallized in the scheelite tetragonal structure and behaved as quasi ideal solid solution. Raman spectroscopy confirmed the formation of the solid solution. Structural distortions were evidenced in X-ray diffraction profiles and in vibration Raman spectra. The scanning electron microscopy experiments showed large and rounded irregular grains. Luminescence experiments were performed under X-ray excitation. The luminescence emission profiles have been interpreted in terms of four Gaussian components, with a major contribution of blue emission. The integrated intensity of luminescence reached a maximum value in the composition range x = 0.3-0.6, in relation with distortions of crystal lattice.

Structural investigations in helium charged titanium films using grazing incidence XRD and EXAFS spectroscopy

NASA Astrophysics Data System (ADS)

Wan, Chubin; Zhou, Xiaosong; Wang, Yuting; Li, Shina; Ju, Xin; Peng, Shuming

2014-01-01

The crystal structure and local atomic arrangements surrounding Ti atoms were determined for He-charged hexagonal close-packed (hcp) Ti films and measured at glancing angles by synchrotron radiation X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy, respectively. The charged specimens were prepared by direct current magnetron sputtering with a He/Ar mixture. He atoms with a relatively medium concentration (He/Ti atomic ratio as high as 17 at.%) were incorporated evenly in the deposited films. XRD results showed the changes in the peak intensities in Ti films with different He contents. EXAFS Fourier Transform analysis indicated that the average Ti-Ti distance decreased significantly, and proved the existence of phase transition.

Ultrasound-assisted microwave preparation of Ag-doped CdS nanoparticles.

PubMed

Ma, Jun; Tai, Guo'an; Guo, Wanlin

2010-03-01

Ag-doped CdS nanoparticles were synthesized by an ultrasound-assisted microwave synthesis method. The X-ray diffraction patterns reveal a structural evolution from cubic to hexagonal with increasing molar ratios of Ag(+)/Cd(2+) from 0% to 5%. It shows that the Ag-doped hexagonal CdS nanoparticles are polycrystal. The X-ray photoelectron spectroscopy of the CdS nanoparticles doping with 5% Ag(+) shows that the doped Ag in CdS is metallic. Simultaneously, the characteristic Raman peaks of the CdS nanoparticles enhance with increasing Ag(+) concentrations. The photocatalytic activity of different Ag-doped samples show a reasonable change due to different ratios of Ag which doped into CdS. Copyright 2009 Elsevier B.V. All rights reserved.

Crystalline multiwall carbon nanotubes and their application as a field emission electron source.

PubMed

Liu, Peng; Zhou, Duanliang; Zhang, Chunhai; Wei, Haoming; Yang, Xinhe; Wu, Yang; Li, Qingwei; Liu, Changhong; Du, Bingchu; Liu, Liang; Jiang, Kaili; Fan, Shoushan

2018-05-18

Using super-aligned carbon nanotube (CNT) film, we have fabricated van der Waals crystalline multiwall CNTs (MWCNT) by adopting high pressure and high temperature processing. The CNTs keep parallel to each other and are distributed uniformly. X-ray diffraction characterization shows peaks at the small angle range, which can be assigned to the spacing of the MWCNT crystals. The mechanical, electrical and thermal properties are all greatly improved compared with the original CNT film. The field emission properties of van der Waals crystalline MWCNTs are tested and they show a better surface morphology stability for the large emission current. We have further fabricated a field emission x-ray tube and demonstrated a precise resolution imaging ability.

Femtosecond response of polyatomic molecules to ultra-intense hard X-rays.

PubMed

Rudenko, A; Inhester, L; Hanasaki, K; Li, X; Robatjazi, S J; Erk, B; Boll, R; Toyota, K; Hao, Y; Vendrell, O; Bomme, C; Savelyev, E; Rudek, B; Foucar, L; Southworth, S H; Lehmann, C S; Kraessig, B; Marchenko, T; Simon, M; Ueda, K; Ferguson, K R; Bucher, M; Gorkhover, T; Carron, S; Alonso-Mori, R; Koglin, J E; Correa, J; Williams, G J; Boutet, S; Young, L; Bostedt, C; Son, S-K; Santra, R; Rolles, D

2017-06-01

X-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10 20 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecular system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects-an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure-the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 10 20 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.

Femtosecond response of polyatomic molecules to ultra-intense hard X-rays

DOE PAGES

Rudenko, A.; Inhester, L.; Hanasaki, K.; ...

2017-05-31

We report x-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10 20 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecularmore » system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects—an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure—the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 10 20 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Fnally, our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.« less

Femtosecond response of polyatomic molecules to ultra-intense hard X-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudenko, A.; Inhester, L.; Hanasaki, K.

We report x-ray free-electron lasers enable the investigation of the structure and dynamics of diverse systems, including atoms, molecules, nanocrystals and single bioparticles, under extreme conditions. Many imaging applications that target biological systems and complex materials use hard X-ray pulses with extremely high peak intensities (exceeding 10 20 watts per square centimetre). However, fundamental investigations have focused mainly on the individual response of atoms and small molecules using soft X-rays with much lower intensities. Studies with intense X-ray pulses have shown that irradiated atoms reach a very high degree of ionization, owing to multiphoton absorption, which in a heteronuclear molecularmore » system occurs predominantly locally on a heavy atom (provided that the absorption cross-section of the heavy atom is considerably larger than those of its neighbours) and is followed by efficient redistribution of the induced charge. In serial femtosecond crystallography of biological objects—an application of X-ray free-electron lasers that greatly enhances our ability to determine protein structure—the ionization of heavy atoms increases the local radiation damage that is seen in the diffraction patterns of these objects and has been suggested as a way of phasing the diffraction data. On the basis of experiments using either soft or less-intense hard X-rays, it is thought that the induced charge and associated radiation damage of atoms in polyatomic molecules can be inferred from the charge that is induced in an isolated atom under otherwise comparable irradiation conditions. Here we show that the femtosecond response of small polyatomic molecules that contain one heavy atom to ultra-intense (with intensities approaching 10 20 watts per square centimetre), hard (with photon energies of 8.3 kiloelectronvolts) X-ray pulses is qualitatively different: our experimental and modelling results establish that, under these conditions, the ionization of a molecule is considerably enhanced compared to that of an individual heavy atom with the same absorption cross-section. This enhancement is driven by ultrafast charge transfer within the molecule, which refills the core holes that are created in the heavy atom, providing further targets for inner-shell ionization and resulting in the emission of more than 50 electrons during the X-ray pulse. Fnally, our results demonstrate that efficient modelling of X-ray-driven processes in complex systems at ultrahigh intensities is feasible.« less

Synthesis of Mn doped ZnS nanocrystals: Crystallographic and morphological study

NASA Astrophysics Data System (ADS)

Shaikh, Azharuddin Z.; Shirsath, Narendra B.; Sonawane, Prabhakar S.

2018-05-01

The influence of doping concentration on the physical properties of ZnS nanocrystals synthesized using coprecipitation method at room temperature is reported in this paper. In particular, we have studied the structural properties of Zn1-xMnxS where (x=0.01, 0.03, 0.05) by X-ray diffraction. X-ray peak broadening analysis used to calculate the crystalline sizes, lattice parameters, number of unit cell per particle and volume of unit cell. Crystalline ZnS with a cubic structure is confirmed by XRD results. The grain size of pure and Mn doped samples were found in the range of 7nm to 9nm. All the physical parameters of cubic ZnS nanocrystals were calculated are similar with standard values. The scanning electron microscope (SEM) which revealed that the synthesized nanocrystals are well-crystalline and possessing cubic phase.

X-ray Diffraction, Big and Small

NASA Image and Video Library

2012-10-30

A conventional X-ray diffraction instrument left is the size of a large refrigerator, in contrast to the compact size of the Chemistry and Mineralogy CheMin instrument on NASA Curiosity rover top right.

Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source

PubMed Central

Munke, Anna; Andreasson, Jakob; Aquila, Andrew; Awel, Salah; Ayyer, Kartik; Barty, Anton; Bean, Richard J.; Berntsen, Peter; Bielecki, Johan; Boutet, Sébastien; Bucher, Maximilian; Chapman, Henry N.; Daurer, Benedikt J.; DeMirci, Hasan; Elser, Veit; Fromme, Petra; Hajdu, Janos; Hantke, Max F.; Higashiura, Akifumi; Hogue, Brenda G.; Hosseinizadeh, Ahmad; Kim, Yoonhee; Kirian, Richard A.; Reddy, Hemanth K.N.; Lan, Ti-Yen; Larsson, Daniel S.D.; Liu, Haiguang; Loh, N. Duane; Maia, Filipe R.N.C.; Mancuso, Adrian P.; Mühlig, Kerstin; Nakagawa, Atsushi; Nam, Daewoong; Nelson, Garrett; Nettelblad, Carl; Okamoto, Kenta; Ourmazd, Abbas; Rose, Max; van der Schot, Gijs; Schwander, Peter; Seibert, M. Marvin; Sellberg, Jonas A.; Sierra, Raymond G.; Song, Changyong; Svenda, Martin; Timneanu, Nicusor; Vartanyants, Ivan A.; Westphal, Daniel; Wiedorn, Max O.; Williams, Garth J.; Xavier, Paulraj Lourdu; Yoon, Chun Hong; Zook, James

2016-01-01

Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here. PMID:27478984

Signal-to-noise and radiation exposure considerations in conventional and diffraction x-ray microscopy

DOE PAGES

Huang, Xiaojing; Miao, Huijie; Steinbrener, Jan; ...

2009-01-01

Using a signal-to-noise ratio estimation based on correlations between multiple simulated images, we compare the dose efficiency of two soft x-ray imaging systems: incoherent brightfield imaging using zone plate optics in a transmission x-ray microscope (TXM), and x-ray diffraction microscopy (XDM) where an image is reconstructed from the far-field coherent diffraction pattern. In XDM one must computationally phase weak diffraction signals; in TXM one suffers signal losses due to the finite numerical aperture and efficiency of the optics. In simulations with objects representing isolated cells such as yeast, we find that XDM has the potential for delivering equivalent resolution imagesmore » using fewer photons. As a result, this can be an important advantage for studying radiation-sensitive biological and soft matter specimens.« less

Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source

DOE PAGES

Munke, Anna; Andreasson, Jakob; Aquila, Andrew; ...

2016-08-01

Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded. Here, the diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB)more » as a resource for algorithm development, the contents of which are described here.« less

Influence of neutron irradiation on the microstructure of nuclear graphite: An X-ray diffraction study

NASA Astrophysics Data System (ADS)

Zhou, Z.; Bouwman, W. G.; Schut, H.; van Staveren, T. O.; Heijna, M. C. R.; Pappas, C.

2017-04-01

Neutron irradiation effects on the microstructure of nuclear graphite have been investigated by X-ray diffraction on virgin and low doses (∼ 1.3 and ∼ 2.2 dpa), high temperature (750° C) irradiated samples. The diffraction patterns were interpreted using a model, which takes into account the turbostratic disorder. Besides the lattice constants, the model introduces two distinct coherent lengths in the c-axis and the basal plane, that characterise the volumes from which X-rays are scattered coherently. The methodology used in this work allows to quantify the effect of irradiation damage on the microstructure of nuclear graphite seen by X-ray diffraction. The results show that the changes of the deduced structural parameters are in agreement with previous observations from electron microscopy, but not directly related to macroscopic changes.