Science.gov

Sample records for resolved powder diffraction

  1. In-situ time resolved synchrotron powder diffraction studies of synthesis and chemical reactions

    SciTech Connect

    Norby, P.

    1995-09-01

    Equipment for time and temperature dependent powder diffraction has been developed, especially in order to be able to study hydrothermal syntheses of zeolites. The system is very versatile and has so far been used to study e.g. hydrothermal syntheses of zeolites and aluminophosphates, syntheses of layered phosphates, formation of Sorel cements, dehydration and phase transformations of zeolites, solid state synthesis of lanthanum manganites, ion exchange of zeolites using molten salt, and oxidation/reduction of lanthanum manganites at high temperatures. The sample is contained in quartz capillaries and is heated using a stream of hot air. External pressure can be applied allowing hydrothermal syntheses at temperatures up to 200 C to be performed. Controlled atmosphere is obtained by flowing gas or a mixture of gases through the capillary.

  2. Time-resolved in situ powder X-ray diffraction reveals the mechanisms of molten salt synthesis.

    PubMed

    Moorhouse, Saul J; Wu, Yue; Buckley, Hannah C; O'Hare, Dermot

    2016-11-24

    We report the first use of high-energy monochromatic in situ X-ray powder diffraction to gain unprecedented insights into the chemical processes occurring during high temperature, lab-scale metal oxide syntheses. During the flux synthesis of the n = 4 Aurivillius phase, Bi5Ti3Fe0.5Cr0.5O15 at 950 °C in molten Na2SO4 we observe the progression of numerous metastable phases. Using sequential multiphase Rietveld refinement of the time-dependent in situ XRD data, we are able to obtain mechanistic understanding of this reaction under a range of conditions.

  3. Devitrification of Mechanically Alloyed Zr-Ti-Nb-Cu-Ni-Al Glassy Powders Studied by Time-Resolved X-ray Diffraction

    SciTech Connect

    Scudino, S.; Sordelet, D.J.; Eckert, J.

    2009-04-13

    The crystallization of mechanically alloyed Zr{sub 67}Ti{sub 6.14}Nb{sub 1.92}Cu{sub 10.67}Ni{sub 8.52}Al{sub 5.75} glassy powder is investigated by time-resolved X-ray diffraction. The powder displays a multi-step crystallization behavior characterized by the formation of a metastable nanoscale quasicrystalline phase during the first stage of the crystallization process. At higher temperatures, coinciding with the second crystallization event, the amorphous-to-quasicrystalline transformation is followed by the precipitation of the tetragonal Zr{sub 2}Cu phase (space group I4/mmm) and the tetragonal Zr{sub 2}Ni phase (space group I4/mcm). The transformations are gradual and the quasicrystals and the subsequent phases coexist over a temperature interval of about 25K.

  4. The crystal structure of lueshite at 298 K resolved by high-resolution time-of-flight neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Mitchell, Roger H.; Kennedy, Brendan J.; Knight, Kevin S.

    2017-06-01

    Refinement of time-of-flight high-resolution neutron powder diffraction data for lueshite (Na, Ca)(Nb, Ta, Ti)O3, the natural analogue of synthetic NaNbO3, demonstrates that lueshite at room temperature (298 K) adopts an orthorhombic structure with a 2a p × 2a p × 4a p superlattice described by space group Pmmn [#59: a = 7.8032(4) Å; b = 7.8193(4) Å; c = 15.6156(9) Å]. This structure is analogous to that of phase S of synthetic NaNbO3 observed at 753-783 K (480-510 °C). In common with synthetic NaNbO3, lueshite exhibits a series of phase transitions with decreasing temperature from a cubic (Pm\\bar{3}m ) aristotype through tetragonal (P4/mbm) and orthorhombic (Cmcm) structures. However, the further sequence of phase transitions differs in that for lueshite the series terminates with the room temperature S (Pmmn) phase, and the R (Pmmn or Pnma) and P (Pbcm) phases of NaNbO3 are not observed. The appearance of the S phase in lueshite at a lower temperature, relative to that of NaNbO3, is attributable to the effects of solid solution of Ti, Ta and Ca in lueshite.

  5. High Resolution Powder Diffraction and Structure Determination

    SciTech Connect

    Cox, D. E.

    1999-04-23

    It is clear that high-resolution synchrotrons X-ray powder diffraction is a very powerful and convenient tool for material characterization and structure determination. Most investigations to date have been carried out under ambient conditions and have focused on structure solution and refinement. The application of high-resolution techniques to increasingly complex structures will certainly represent an important part of future studies, and it has been seen how ab initio solution of structures with perhaps 100 atoms in the asymmetric unit is within the realms of possibility. However, the ease with which temperature-dependence measurements can be made combined with improvements in the technology of position-sensitive detectors will undoubtedly stimulate precise in situ structural studies of phase transitions and related phenomena. One challenge in this area will be to develop high-resolution techniques for ultra-high pressure investigations in diamond anvil cells. This will require highly focused beams and very precise collimation in front of the cell down to dimensions of 50 {micro}m or less. Anomalous scattering offers many interesting possibilities as well. As a means of enhancing scattering contrast it has applications not only to the determination of cation distribution in mixed systems such as the superconducting oxides discussed in Section 9.5.3, but also to the location of specific cations in partially occupied sites, such as the extra-framework positions in zeolites, for example. Another possible application is to provide phasing information for ab initio structure solution. Finally, the precise determination of f as a function of energy through an absorption edge can provide useful information about cation oxidation states, particularly in conjunction with XANES data. In contrast to many experiments at a synchrotron facility, powder diffraction is a relatively simple and user-friendly technique, and most of the procedures and software for data analysis

  6. Determination of cellulose crystallinity from powder diffraction diagrams: Powder Diffraction Diagrams

    SciTech Connect

    Lindner, Benjamin; Petridis, Loukas; Langan, Paul; Smith, Jeremy C.

    2014-10-01

    Commonly one-dimensional (1D) (spherically averaged) powder diffraction diagrams are used to determine the degree of cellulose crystallinity in biomass samples. Here, it is shown using molecular modeling how disorder in cellulose fibrils can lead to considerable uncertainty in conclusions drawn concerning crystallinity based on 1D powder diffraction data alone. For example, cellulose microfibrils that contain both crystalline and noncrystalline segments can lead to powder diffraction diagrams lacking identifiable peaks, while microfibrils without any crystalline segments can lead to such peaks. Moreover, this leads to false positives, that is, assigning disordered cellulose as crystalline, and false negatives, that is, categorizing fibrils with crystalline segments as amorphous. Finally, the reliable determination of the fraction of crystallinity in any given biomass sample will require a more sophisticated approach combining detailed experiment and simulation.

  7. Ampicillin Trihydrate from Synchrotron Powder Diffraction Data

    SciTech Connect

    Burley,J.; van de Streek, J.; Stephens, P.

    2006-01-01

    The crystal structure of ampicillin trihydrate {l_brace}systematic name: 6-[D(-)-{alpha}-aminophenylacetamido]penicillanic acid trihydrate{r_brace}, C{sub 16}H{sub 19}N{sub 3}O{sub 4}S{center_dot}3H{sub 2}O, a broad-spectrum {beta}-lactam antibiotic of the aminopenicillin type, has been determined from synchrotron X-ray powder diffraction data. The three water molecules form an infinite hydrogen-bonded chain through the crystal structure, with hydrogen bonds to the NH{sub 3}{sup +}, COO{sup -}, C{double_bond}O and NH groups of the ampicillin molecules.

  8. Macromolecular Powder Diffraction: Ready for genuine biological problems.

    PubMed

    Karavassili, Fotini; Margiolaki, Irene

    2016-01-01

    Knowledge of 3D structures of biological molecules plays a major role in both understanding important processes of life and developing pharmaceuticals. Among several methods available for structure determination, macromolecular X-ray powder diffraction (XRPD) has transformed over the past decade from an impossible dream to a respectable method. XRPD can be employed in biosciences for various purposes such as observing phase transitions, characterizing bulk pharmaceuticals, determining structures via the molecular replacement method, detecting ligands in protein-ligand complexes, as well as combining micro-sized single crystal crystallographic data and powder diffraction data. Studies using synchrotron and laboratory sources in some standard configuration setups are reported in this review, including their respective advantages and disadvantages. Methods presented here provide an alternative, complementary set of tools to resolve structural problems. A variety of already existing software packages for powder diffraction data processing and analysis, some of which have been adapted to large unit cell studies, are briefly described. This review aims to provide necessary elements of theory and current methods, along with practical explanations, available software packages and highlighted case studies.

  9. XRAYL: a program for producing idealized powder diffraction line profiles from overlapped powder patterns

    SciTech Connect

    Hubbard, C.R.; Morosin, B.; Stewart, J.M.

    1996-09-01

    The X-ray diffraction patterns of samples of polycrystalline materials are used to identify and characterize phases. Very often the total (or composite) profile consists of a series of overlapping profiles. In many applications it is necessary to separate the component profiles from the total profile. (In this document the terms {ital profile, line}, and {ital peak} are used interchangeably to represent these features of X-ray or neutron diffraction patterns.) A computer program, XRAYL, first developed in the 1980s and subsequently enlarged and improved, allows the fitting of analytical functions to powder diffraction lines. The fitting process produces parameters of chosen profile functions, diffraction line by diffraction line. The resulting function parameters may then be used to generate ``idealized`` powder diffraction lines as counts at steps in 2{Omega}. The generated lines are effectively free of statistical noise and contributions from overlapping lines. Each separated line extends to background on both sides of the generated profile. XRAYL may, therefore, be used in X-ray powder diffraction profile analysis as a preprocessor program that is, separating peaks and feeding the ``resolved`` data to subsequent analysis programs. This self- contained document includes: (1) a description of the fitting functions coded into XRAYL, (2) an outline of the least-squares algorithm used in fitting the profile function, (3) the file formats and contents utilized by the computer code, (4) the user options and their presentation requirements for execution of the program, (5) an example of input and output for a test case, and (6) source code listings on a diskette.

  10. X-ray diffraction investigation of ultrafine boron nitride powders

    SciTech Connect

    Gurov, S.V.; Chukalin, V.I.; Rezchikova, T.V.; Torbov, V.J.; Troitskii, V.N.

    1986-01-01

    This paper presents an x-ray diffraction analysis of ultrafine boron nitride powders of different mean particle sizes. Diffraction spectra of the ultrafine boron nitride powders were obtained using a DRON-1 apparatus. The experimental facts are indicative of a turbostratic character of deformation of the hexagonal lattice of ultrafinely divided boron nitride.

  11. Pulsed Neutron Powder Diffraction for Materials Science

    NASA Astrophysics Data System (ADS)

    Kamiyama, T.

    2008-03-01

    The accelerator-based neutron diffraction began in the end of 60's at Tohoku University which was succeeded by the four spallation neutron facilities with proton accelerators at the High Energy Accelerator Research Organization (Japan), Argonne National Laboratory and Los Alamos Laboratory (USA), and Rutherford Appleton Laboratory (UK). Since then, the next generation source has been pursued for 20 years, and 1MW-class spallation neutron sources will be appeared in about three years at the three parts of the world: Japan, UK and USA. The joint proton accelerator project (J-PARC), a collaborative project between KEK and JAEA, is one of them. The aim of the talk is to describe about J-PARC and the neutron diffractometers being installed at the materials and life science facility of J-PARC. The materials and life science facility of J-PARC has 23 neutron beam ports and will start delivering the first neutron beam of 25 Hz from 2008 May. Until now, more than 20 proposals have been reviewed by the review committee, and accepted proposal groups have started to get fund. Those proposals include five polycrystalline diffractometers: a super high resolution powder diffractometer (SHRPD), a 0.2%-resolution powder diffractometer of Ibaraki prefecture (IPD), an engineering diffractometers (Takumi), a high intensity S(Q) diffractometer (VSD), and a high-pressure dedicated diffractometer. SHRPD, Takumi and IPD are being designed and constructed by the joint team of KEK, JAEA and Ibaraki University, whose member are originally from the KEK powder group. These three instruments are expected to start in 2008. VSD is a super high intensity diffractometer with the highest resolution of Δd/d = 0.3%. VSD can measure rapid time-dependent phenomena of crystalline materials as well as glass, liquid and amorphous materials. The pair distribution function will be routinely obtained by the Fourier transiformation of S(Q) data. Q range of VSD will be as wide as 0.01 Å-1

  12. Pulsed Neutron Powder Diffraction for Materials Science

    SciTech Connect

    Kamiyama, T.

    2008-03-17

    The accelerator-based neutron diffraction began in the end of 60's at Tohoku University which was succeeded by the four spallation neutron facilities with proton accelerators at the High Energy Accelerator Research Organization (Japan), Argonne National Laboratory and Los Alamos Laboratory (USA), and Rutherford Appleton Laboratory (UK). Since then, the next generation source has been pursued for 20 years, and 1MW-class spallation neutron sources will be appeared in about three years at the three parts of the world: Japan, UK and USA. The joint proton accelerator project (J-PARC), a collaborative project between KEK and JAEA, is one of them. The aim of the talk is to describe about J-PARC and the neutron diffractometers being installed at the materials and life science facility of J-PARC. The materials and life science facility of J-PARC has 23 neutron beam ports and will start delivering the first neutron beam of 25 Hz from 2008 May. Until now, more than 20 proposals have been reviewed by the review committee, and accepted proposal groups have started to get fund. Those proposals include five polycrystalline diffractometers: a super high resolution powder diffractometer (SHRPD), a 0.2%-resolution powder diffractometer of Ibaraki prefecture (IPD), an engineering diffractometers (Takumi), a high intensity S(Q) diffractometer (VSD), and a high-pressure dedicated diffractometer. SHRPD, Takumi and IPD are being designed and constructed by the joint team of KEK, JAEA and Ibaraki University, whose member are originally from the KEK powder group. These three instruments are expected to start in 2008. VSD is a super high intensity diffractometer with the highest resolution of {delta}d/d = 0.3%. VSD can measure rapid time-dependent phenomena of crystalline materials as well as glass, liquid and amorphous materials. The pair distribution function will be routinely obtained by the Fourier transiformation of S(Q) data. Q range of VSD will be as wide as 0.01 A{sup -1}

  13. The Powder Diffraction File: Past, Present, and Future.

    PubMed

    Smith, Deane K; Jenkins, Ron

    1996-01-01

    The Powder Diffraction file has been the primary reference for Powder Diffraction Data for more than half a century. The file is a collection of about 65 000 reduced powder patterns stored as sets of d/I data along with the appropriate crystallographic, physical and experimental information. This paper reviews the development and growth of the PDF and discusses the role of the ICDD in the maintenance and dissemination of the file.

  14. The Powder Diffraction File: Past, Present, and Future

    PubMed Central

    Smith, Deane K.; Jenkins, Ron

    1996-01-01

    The Powder Diffraction file has been the primary reference for Powder Diffraction Data for more than half a century. The file is a collection of about 65 000 reduced powder patterns stored as sets of d/I data along with the appropriate crystallographic, physical and experimental information. This paper reviews the development and growth of the PDF and discusses the role of the ICDD in the maintenance and dissemination of the file. PMID:27805163

  15. Quality experimental and calculated powder x-ray diffraction

    SciTech Connect

    Sullenger, D.B.; Cantrell, J.S.; Beiter, T.A.; Tomlin, D.W.

    1996-08-01

    For several years, we have submitted quality powder XRD patterns to the International Centre for Diffraction Data for inclusion as reference standards in their Powder Diffraction File. The procedure followed is described; examples used are {beta}-UH{sub 3}, {alpha}- BaT{sub 2}, alpha-lithium disilicate ({alpha}-Li{sub 2}Si{sub 2}O{sub 5}), and 2,2`,4,4`,6,6`hexanitroazobenzene-III (HNAB-III).

  16. Single Hit Energy-resolved Laue Diffraction

    NASA Astrophysics Data System (ADS)

    Patel, Shamim; Suggit, Matthew; Stubley, Paul; Hawreliak, James; Ciricosta, Orlando; Comley, Andrew; Collins, Gilbert; Eggert, Jon; Foster, John; Wark, Justin; Higginbotham, Andrew

    2015-06-01

    In-situ white light Laue diffraction is a technique to interrogate the structure of materials undergoing dynamic compression up to megabar pressures. We present an extension to the existing Laue diffraction platform in which CCD cameras are used in single photon mode enabling a measurement of the energy of a subset of diffraction peaks. Careful choice of which diffraction peaks are observed allows for a measurement of the longitudinal and transverse strains. This allows for the measurement of absolute volume of the unit cell in addition to its aspect ratio. We present results for silicon, where only longitudinal elastic strain has been observed. VISAR measurements show the presence of a two wave structure and measurements made from the diffraction patterns on the CCD show that material downstream of the second wave does not contribute to the observed diffraction peaks, suggesting that this material may be highly disordered, or has undergone large scale rotation.

  17. Total-scattering pair-distribution function of organic material from powder electron diffraction data

    DOE PAGES

    Gorelik, Tatiana E.; Billinge, Simon J. L.; Schmidt, Martin U.; ...

    2015-04-01

    This paper shows for the first time that pair-distribution function analyses can be carried out on organic and organo-metallic compounds from powder electron diffraction data. Different experimental setups are demonstrated, including selected area electron diffraction (SAED) and nanodiffraction in transmission electron microscopy (TEM) or nanodiffraction in scanning transmission electron microscopy (STEM) modes. The methods were demonstrated on organo-metallic complexes (chlorinated and unchlorinated copper-phthalocyanine) and on purely organic compounds (quinacridone). The PDF curves from powder electron diffraction data, called ePDF, are in good agreement with PDF curves determined from X-ray powder data demonstrating that the problems of obtaining kinematical scattering datamore » and avoiding beam-damage of the sample are possible to resolve.« less

  18. Total-scattering pair-distribution function of organic material from powder electron diffraction data

    SciTech Connect

    Gorelik, Tatiana E.; Billinge, Simon J. L.; Schmidt, Martin U.; Kolb, Ute

    2015-04-01

    This paper shows for the first time that pair-distribution function analyses can be carried out on organic and organo-metallic compounds from powder electron diffraction data. Different experimental setups are demonstrated, including selected area electron diffraction (SAED) and nanodiffraction in transmission electron microscopy (TEM) or nanodiffraction in scanning transmission electron microscopy (STEM) modes. The methods were demonstrated on organo-metallic complexes (chlorinated and unchlorinated copper-phthalocyanine) and on purely organic compounds (quinacridone). The PDF curves from powder electron diffraction data, called ePDF, are in good agreement with PDF curves determined from X-ray powder data demonstrating that the problems of obtaining kinematical scattering data and avoiding beam-damage of the sample are possible to resolve.

  19. Idealized powder diffraction patterns for cellulose polymorphs

    USDA-ARS?s Scientific Manuscript database

    Cellulose samples are routinely analyzed by X-ray diffraction to determine their crystal type (polymorph) and crystallinity. However, the connection is seldom made between those efforts and the crystal structures of cellulose that have been determined with synchrotron X-radiation and neutron diffrac...

  20. Single Hit Energy-resolved Laue Diffraction

    SciTech Connect

    Patel, Shamim; Suggit, Matthew J.; Stubley, Paul G.; Ciricosta, Orlando; Wark, Justin S.; Higginbotham, Andrew; Hawreliak, James A.; Collins, Gilbert W.; Eggert, Jon H.; Comley, Andrew J.; Foster, John M.

    2015-05-15

    In situ white light Laue diffraction has been successfully used to interrogate the structure of single crystal materials undergoing rapid (nanosecond) dynamic compression up to megabar pressures. However, information on strain state accessible via this technique is limited, reducing its applicability for a range of applications. We present an extension to the existing Laue diffraction platform in which we record the photon energy of a subset of diffraction peaks. This allows for a measurement of the longitudinal and transverse strains in situ during compression. Consequently, we demonstrate measurement of volumetric compression of the unit cell, in addition to the limited aspect ratio information accessible in conventional white light Laue. We present preliminary results for silicon, where only an elastic strain is observed. VISAR measurements show the presence of a two wave structure and measurements show that material downstream of the second wave does not contribute to the observed diffraction peaks, supporting the idea that this material may be highly disordered, or has undergone large scale rotation.

  1. Single Hit Energy-resolved Laue Diffraction.

    PubMed

    Patel, Shamim; Suggit, Matthew J; Stubley, Paul G; Hawreliak, James A; Ciricosta, Orlando; Comley, Andrew J; Collins, Gilbert W; Eggert, Jon H; Foster, John M; Wark, Justin S; Higginbotham, Andrew

    2015-05-01

    In situ white light Laue diffraction has been successfully used to interrogate the structure of single crystal materials undergoing rapid (nanosecond) dynamic compression up to megabar pressures. However, information on strain state accessible via this technique is limited, reducing its applicability for a range of applications. We present an extension to the existing Laue diffraction platform in which we record the photon energy of a subset of diffraction peaks. This allows for a measurement of the longitudinal and transverse strains in situ during compression. Consequently, we demonstrate measurement of volumetric compression of the unit cell, in addition to the limited aspect ratio information accessible in conventional white light Laue. We present preliminary results for silicon, where only an elastic strain is observed. VISAR measurements show the presence of a two wave structure and measurements show that material downstream of the second wave does not contribute to the observed diffraction peaks, supporting the idea that this material may be highly disordered, or has undergone large scale rotation.

  2. Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams

    SciTech Connect

    Hastings, J.B.; Rudakov, F.M.; Dowell, D.H.; Schmerge, J.F.; Cardoza, J.D.; Castro, J.M.; Gierman, S.M.; Loos, H.; Weber, P.M.; /Brown U.

    2006-10-24

    An rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. We observed single-shot diffraction patterns from a 160 nm Al foil using the 5.4 MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100 fs are possible.

  3. Time resolved fluorescence of cow and goat milk powder

    NASA Astrophysics Data System (ADS)

    Brandao, Mariana P.; de Carvalho dos Anjos, Virgílio; Bell., Maria José V.

    2017-01-01

    Milk powder is an international dairy commodity. Goat and cow milk powders are significant sources of nutrients and the investigation of the authenticity and classification of milk powder is particularly important. The use of time-resolved fluorescence techniques to distinguish chemical composition and structure modifications could assist develop a portable and non-destructive methodology to perform milk powder classification and determine composition. This study goal is to differentiate milk powder samples from cows and goats using fluorescence lifetimes. The samples were excited at 315 nm and the fluorescence intensity decay registered at 468 nm. We observed fluorescence lifetimes of 1.5 ± 0.3, 6.4 ± 0.4 and 18.7 ± 2.5 ns for goat milk powder; and 1.7 ± 0.3, 6.9 ± 0.2 and 29.9 ± 1.6 ns for cow's milk powder. We discriminate goat and cow powder milk by analysis of variance using Fisher's method. In addition, we employed quadratic discriminant analysis to differentiate the milk samples with accuracy of 100%. Our results suggest that time-resolved fluorescence can provide a new method to the analysis of powder milk and its composition.

  4. High-speed detector for time-resolved diffraction studies

    PubMed Central

    Singh, Bipin; Miller, Stuart R.; Bhandari, Harish B.; Graceffa, Rita; Irving, Thomas C.; Nagarkar, Vivek V.

    2013-01-01

    There are a growing number of high brightness synchrotron sources that require high-frame-rate detectors to provide the time-scales required for performing time-resolved diffraction experiments. We report on the development of a very high frame rate CMOS X-ray detector for time-resolved muscle diffraction and time-resolved solution scattering experiments. The detector is based on a low-afterglow scintillator, provides a megapixel resolution with frame rates of up to 120,000 frames per second, an effective pixel size of 64 µm, and can be adapted for various X-ray energies. The paper describes the detector design and initial results of time-resolved diffraction experiments on a synchrotron beamline. PMID:24489595

  5. Powder diffraction studies using anomalous dispersion

    SciTech Connect

    Cox, D.E. ); Wilkinson, A.P. . Dept. of Materials)

    1993-01-01

    With the increasing availability and accessibility of high resolution powder diffractometers at many synchrotron radiation sources throughout the world, there is rapidly-growing interest in the exploitation of anomalous dispersion techniques for structural studies of polycrystalline materials. In conjunction with the Rietveld profile method for structure refinement, such studies are especially useful for the determination of the site distributions of two or more atoms which are near neighbors in the periodic table, or atoms which are distributed among partially occupied sites. Additionally, it is possible to (1) determine the mean-square displacements associated with different kinds of atoms distributed over a single set of sites, (2) distinguish between different oxidation states and coordination geometries of a particular atom in a compound and (3) to determine f' for a wide range of atomic species as a function of energy in the vicinity of an absorption edge. Experimental methods for making anomalous dispersion measurements are described in some detail, including data collection strategies, data analysis and correlation problems, possible systematic errors, and the accuracy of the results. Recent work in the field is reviewed, including cation site-distribution studies (e.g. doped high [Tc] superconductors, ternary alloys, FeCo[sub 2](PO[sub 4])[sub 3], FeNi[sub 2]BO[sub 5]), oxidation-state contrast (e.g. YBa[sub 2]Cu[sub 3]O[sub 6+x], Eu[sub 3]O[sub 4], GaCl[sub 2], Fe[sub 2]PO[sub 5]), and the effect of coordination geometry (e.g. Y[sub 3]Ga[sub 5]O[sub l2]).

  6. Powder diffraction studies using anomalous dispersion

    SciTech Connect

    Cox, D.E.; Wilkinson, A.P.

    1993-05-01

    With the increasing availability and accessibility of high resolution powder diffractometers at many synchrotron radiation sources throughout the world, there is rapidly-growing interest in the exploitation of anomalous dispersion techniques for structural studies of polycrystalline materials. In conjunction with the Rietveld profile method for structure refinement, such studies are especially useful for the determination of the site distributions of two or more atoms which are near neighbors in the periodic table, or atoms which are distributed among partially occupied sites. Additionally, it is possible to (1) determine the mean-square displacements associated with different kinds of atoms distributed over a single set of sites, (2) distinguish between different oxidation states and coordination geometries of a particular atom in a compound and (3) to determine f` for a wide range of atomic species as a function of energy in the vicinity of an absorption edge. Experimental methods for making anomalous dispersion measurements are described in some detail, including data collection strategies, data analysis and correlation problems, possible systematic errors, and the accuracy of the results. Recent work in the field is reviewed, including cation site-distribution studies (e.g. doped high {Tc} superconductors, ternary alloys, FeCo{sub 2}(PO{sub 4}){sub 3}, FeNi{sub 2}BO{sub 5}), oxidation-state contrast (e.g. YBa{sub 2}Cu{sub 3}O{sub 6+x}, Eu{sub 3}O{sub 4}, GaCl{sub 2}, Fe{sub 2}PO{sub 5}), and the effect of coordination geometry (e.g. Y{sub 3}Ga{sub 5}O{sub l2}).

  7. Powder Diffraction Simulated by a Polycrystalline Film of Spherical Colloids

    ERIC Educational Resources Information Center

    Campbell, Dean J.; Xia, Younan

    2006-01-01

    This article describes a simple way to demonstrate powder diffraction in a classroom setting using a dry film of spherical colloids on a glass substrate. Use of transparent, elastomeric poly(dimethylsiloxane) as a supporting substrate for the spheres rather than glass enables demonstration of the reciprocal lattice effect. (Contains 4 figures and…

  8. Powder Diffraction Simulated by a Polycrystalline Film of Spherical Colloids

    ERIC Educational Resources Information Center

    Campbell, Dean J.; Xia, Younan

    2006-01-01

    This article describes a simple way to demonstrate powder diffraction in a classroom setting using a dry film of spherical colloids on a glass substrate. Use of transparent, elastomeric poly(dimethylsiloxane) as a supporting substrate for the spheres rather than glass enables demonstration of the reciprocal lattice effect. (Contains 4 figures and…

  9. Frequency analysis for modulation-enhanced powder diffraction.

    PubMed

    Chernyshov, Dmitry; Dyadkin, Vadim; van Beek, Wouter; Urakawa, Atsushi

    2016-07-01

    Periodic modulation of external conditions on a crystalline sample with a consequent analysis of periodic diffraction response has been recently proposed as a tool to enhance experimental sensitivity for minor structural changes. Here the intensity distributions for both a linear and nonlinear structural response induced by a symmetric and periodic stimulus are analysed. The analysis is further extended for powder diffraction when an external perturbation changes not only the intensity of Bragg lines but also their positions. The derived results should serve as a basis for a quantitative modelling of modulation-enhanced diffraction data measured in real conditions.

  10. Angle-resolved diffraction grating biosensor based on porous silicon

    NASA Astrophysics Data System (ADS)

    Lv, Changwu; Jia, Zhenhong; Liu, Yajun; Mo, Jiaqing; Li, Peng; Lv, Xiaoyi

    2016-03-01

    In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.

  11. Angle-resolved diffraction grating biosensor based on porous silicon

    SciTech Connect

    Lv, Changwu; Li, Peng; Jia, Zhenhong Liu, Yajun; Mo, Jiaqing; Lv, Xiaoyi

    2016-03-07

    In this study, an optical biosensor based on a porous silicon composite structure was fabricated using a simple method. This structure consists of a thin, porous silicon surface diffraction grating and a one-dimensional porous silicon photonic crystal. An angle-resolved diffraction efficiency spectrum was obtained by measuring the diffraction efficiency at a range of incident angles. The angle-resolved diffraction efficiency of the 2nd and 3rd orders was studied experimentally and theoretically. The device was sensitive to the change of refractive index in the presence of a biomolecule indicated by the shift of the diffraction efficiency spectrum. The sensitivity of this sensor was investigated through use of an 8 base pair antifreeze protein DNA hybridization. The shifts of the angle-resolved diffraction efficiency spectrum showed a relationship with the change of the refractive index, and the detection limit of the biosensor reached 41.7 nM. This optical device is highly sensitive, inexpensive, and simple to fabricate. Using shifts in diffraction efficiency spectrum to detect biological molecules has not yet been explored, so this study establishes a foundation for future work.

  12. The MYTHEN detector for X-ray powder diffraction experiments at the Swiss Light Source

    PubMed Central

    Bergamaschi, Anna; Cervellino, Antonio; Dinapoli, Roberto; Gozzo, Fabia; Henrich, Beat; Johnson, Ian; Kraft, Philipp; Mozzanica, Aldo; Schmitt, Bernd; Shi, Xintian

    2010-01-01

    The MYTHEN single-photon-counting silicon microstrip detector has been developed at the Swiss Light Source for time-resolved powder diffraction experiments. An upgraded version of the detector has been installed at the SLS powder diffraction station allowing the acquisition of diffraction patterns over 120° in 2θ in fractions of seconds. Thanks to the outstanding performance of the detector and to the calibration procedures developed, the quality of the data obtained is now comparable with that of traditional high-resolution point detectors in terms of FWHM resolution and peak profile shape, with the additional advantage of fast and simultaneous acquisition of the full diffraction pattern. MYTHEN is therefore optimal for time-resolved or dose-critical measurements. The characteristics of the MYTHEN detector together with the calibration procedures implemented for the optimization of the data are described in detail. The refinements of two known standard powders are discussed together with a remarkable application of MYTHEN to organic compounds in relation to the problem of radiation damage. PMID:20724787

  13. Application of a hybrid pixel detector to powder diffraction.

    PubMed

    Basolo, S; Bérar, J F; Boudet, N; Breugnon, P; Caillot, B; Clemens, J C; Delpierre, P; Dinkespiler, B; Hustache, S; Koudobine, I; Meessen, Ch; Menouni, M; Mouget, C; Palancher, H; Pangaud, P; Potheau, R; Vigeolas, E

    2007-01-01

    Results obtained using a hybrid pixel photon-counting detector in powder diffraction experiments are presented. The detector works at room temperature and its dynamic response ranges from 0.01 photons pixel(-1) s(-1) up to 10(6) photons pixel(-1) s(-1). The pixel sizes are 0.33 mm x 0.33 mm for a total area of 68 mm x 68 mm. On recording high-resolution diffraction patterns of powders, a reduction of the experimental time by more than a factor of 20 is obtained without loss of data quality. The example of an X-zeolite shows that such detectors can be used for very demanding anomalous experiments. In situ experiments of quenching liquid oxides show that frames of 0.01 s can be achieved for studying such processes.

  14. Fractal analysis of powder X-ray diffraction patterns

    NASA Astrophysics Data System (ADS)

    Ortiz-Cruz, A.; Santolalla, C.; Moreno, E.; de los Reyes-Heredia, J. A.; Alvarez-Ramirez, J.

    2012-02-01

    X-ray diffraction (XRD) patterns with broad background are commonly found in the characterization of materials with a certain degree of amorphicity, so the sharp intensity peaks associated with material phases are not well defined. This work used rescaled range (denoted by R/S) analysis, a method intended for fractal analysis of noisy signals, to characterize XRD patterns with broad background. It is found that XRD patterns with broad background are not random at all, but contain information on regularities expressed as autocorrelations of the intensity signal. Sol-gel alumina fired at different temperatures was used as an example to illustrate the applicability of the method. It is shown that fractal R/S analysis is able to locate angular regions that can be associated to ideal International Centre for Diffraction Data Powder Diffraction File (ICDD PDF) lines of diverse alumina phases.

  15. A compact electron gun for time-resolved electron diffraction

    SciTech Connect

    Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A.

    2015-01-15

    A novel compact time-resolved electron diffractometer has been built with the primary goal of studying the ultrafast molecular dynamics of photoexcited gas-phase molecules. Here, we discuss the design of the electron gun, which is triggered by a Ti:Sapphire laser, before detailing a series of calibration experiments relating to the electron-beam properties. As a further test of the apparatus, initial diffraction patterns have been collected for thin, polycrystalline platinum samples, which have been shown to match theoretical patterns. The data collected demonstrate the focusing effects of the magnetic lens on the electron beam, and how this relates to the spatial resolution of the diffraction pattern.

  16. Powder diffraction from solids in the terapascal regime

    NASA Astrophysics Data System (ADS)

    Rygg, J. R.; Eggert, J. H.; Lazicki, A. E.; Coppari, F.; Hawreliak, J. A.; Hicks, D. G.; Smith, R. F.; Sorce, C. M.; Uphaus, T. M.; Yaakobi, B.; Collins, G. W.

    2012-11-01

    A method of obtaining powder diffraction data on dynamically compressed solids has been implemented at the Jupiter and OMEGA laser facilities. Thin powdered samples are sandwiched between diamond plates and ramp compressed in the solid phase using a gradual increase in the drive-laser intensity. The pressure history in the sample is determined by back-propagation of the measured diamond free-surface velocity. A pulse of x rays is produced at the time of peak pressure by laser illumination of a thin Cu or Fe foil and collimated at the sample plane by a pinhole cut in a Ta substrate. The diffracted signal is recorded on x-ray sensitive material, with a typical d-spacing uncertainty of ˜0.01 Å. This diagnostic has been used up to 0.9 TPa (9 Mbar) to verify the solidity, measure the density, constrain the crystal structure, and evaluate the strain-induced texturing of a variety of compressed samples spanning atomic numbers from 6 (carbon) to 82 (lead). Further refinement of the technique will soon enable diffraction measurements in solid samples at pressures exceeding 1 TPa.

  17. The High Resolution Powder Diffraction Beam Line at ESRF

    PubMed Central

    Fitch, A. N.

    2004-01-01

    The optical design and performance of the high-resolution powder diffraction beam line BM16 at ESRF are discussed and illustrated. Some recent studies carried out on BM16 are described, including crystal structure solution and refinement, anomalous scattering, in situ measurements, residual strain in engineering components, investigation of microstructure, and grazing-incidence diffraction from surface layers. The beam line is built on a bending magnet, and operates in the energy range from 5 keV to 40 keV. After the move to an undulator source in 2002, it will benefit from an extented energy range up to 60 keV and increased flux and resolution. It is anticipated that enhancements to the data quality will be achieved, leading to the solution of larger crystal structures, and improvements in the accuracy of refined structures. The systematic exploitation of anisotropic thermal expansion will help reduce the effects of peak overlap in the analysis of powder diffraction data. PMID:27366602

  18. Developments in Forumlation Analyses by Powder Diffraction Analysis

    SciTech Connect

    Hubbard, Camden R; Fawcett, T. G.; Faber, J.; Needham, F.; Kabekkodu, S.; Kaduk, J.

    2006-01-01

    Diffraction analyses have been used for decades to analyze solid state formulations in both powder and tablet form. The ability to perform a nondestructive analysis is often combined with the capability of Search/Match algorithms to successively identify phases and reanalyze the residual pattern until multiple phases have been identified. One of the strengths of the diffraction technique has been to routinely identify multi-component materials from a single analysis, without pretreatment to physically or chemically separate out the components, thus minimizing the possibility that the specimen has been altered by the preparation method. However this method depends on having a database that can correctly analyze each successive phase in the multi-component analysis. Developments in X-ray analysis hardware and software have combined to dramatically improve the throughput, speed and accuracy of formulation analyses. In this paper, we will focus on a complimentary development, the growth and application of a comprehensive database based on the Powder Diffraction File{trademark} (PDF(reg. sign)). The PDF(reg. sign) is an edited and standardized combination of several crystallographic databases with {approx} 497,000 published entries. The comprehensive nature of this database, combined with phase identification and digital pattern simulations, was used to identify complex formulations with crystalline and non-crystalline ingredients. We will show how these parallel developments enhance the ability to correctly identify complex formularies.

  19. Powder diffraction from solids in the terapascal regime

    SciTech Connect

    Rygg, J. R.; Eggert, J. H.; Lazicki, A. E.; Coppari, F.; Hawreliak, J. A.; Hicks, D. G.; Smith, R. F.; Uphaus, T. M.; Collins, G. W.; Sorce, C. M.; Yaakobi, B.

    2012-11-15

    A method of obtaining powder diffraction data on dynamically compressed solids has been implemented at the Jupiter and OMEGA laser facilities. Thin powdered samples are sandwiched between diamond plates and ramp compressed in the solid phase using a gradual increase in the drive-laser intensity. The pressure history in the sample is determined by back-propagation of the measured diamond free-surface velocity. A pulse of x rays is produced at the time of peak pressure by laser illumination of a thin Cu or Fe foil and collimated at the sample plane by a pinhole cut in a Ta substrate. The diffracted signal is recorded on x-ray sensitive material, with a typical d-spacing uncertainty of {approx}0.01 A. This diagnostic has been used up to 0.9 TPa (9 Mbar) to verify the solidity, measure the density, constrain the crystal structure, and evaluate the strain-induced texturing of a variety of compressed samples spanning atomic numbers from 6 (carbon) to 82 (lead). Further refinement of the technique will soon enable diffraction measurements in solid samples at pressures exceeding 1 TPa.

  20. New synchrotron powder diffraction facility for long-duration experiments

    PubMed Central

    Murray, Claire A.; Potter, Jonathan; Day, Sarah J.; Baker, Annabelle R.; Thompson, Stephen P.; Kelly, Jon; Morris, Christopher G.; Tang, Chiu C.

    2017-01-01

    A new synchrotron X-ray powder diffraction instrument has been built and commissioned for long-duration experiments on beamline I11 at Diamond Light Source. The concept is unique, with design features to house multiple experiments running in parallel, in particular with specific stages for sample environments to study slow kinetic systems or processes. The instrument benefits from a high-brightness X-ray beam and a large area detector. Diffraction data from the commissioning work have shown that the objectives and criteria are met. Supported by two case studies, the results from months of measurements have demonstrated the viability of this large-scale instrument, which is the world’s first dedicated facility for long-term studies (weeks to years) using synchrotron radiation. PMID:28190992

  1. New synchrotron powder diffraction facility for long-duration experiments.

    PubMed

    Murray, Claire A; Potter, Jonathan; Day, Sarah J; Baker, Annabelle R; Thompson, Stephen P; Kelly, Jon; Morris, Christopher G; Yang, Sihai; Tang, Chiu C

    2017-02-01

    A new synchrotron X-ray powder diffraction instrument has been built and commissioned for long-duration experiments on beamline I11 at Diamond Light Source. The concept is unique, with design features to house multiple experiments running in parallel, in particular with specific stages for sample environments to study slow kinetic systems or processes. The instrument benefits from a high-brightness X-ray beam and a large area detector. Diffraction data from the commissioning work have shown that the objectives and criteria are met. Supported by two case studies, the results from months of measurements have demonstrated the viability of this large-scale instrument, which is the world's first dedicated facility for long-term studies (weeks to years) using synchrotron radiation.

  2. Powder X-ray diffraction can differentiate between enantiomeric variants of calcium lactate pentahydrate crystal in cheese.

    PubMed

    Tansman, G F; Kindstedt, P S; Hughes, J M

    2014-12-01

    Powder X-ray diffraction has been used for decades to identify crystals of calcium lactate pentahydrate in Cheddar cheese. According to this method, diffraction patterns are generated from a powdered sample of the crystals and compared with reference cards within a database that contains the diffraction patterns of known crystals. During a preliminary study of crystals harvested from various Cheddar cheese samples, we observed 2 slightly different but distinct diffraction patterns that suggested that calcium lactate pentahydrate may be present in 2 different crystalline forms. We hypothesized that the 2 diffraction patterns corresponded to 2 enantiomeric forms of calcium lactate pentahydrate (L- and DL-) that are believed to occur in Cheddar cheese, based on previous studies involving enzymatic analyses of the lactate enantiomers in crystals obtained from Cheddar cheeses. However, the powder X-ray diffraction database currently contains only one reference diffraction card under the title “calcium lactate pentahydrate.” To resolve this apparent gap in the powder X-ray diffraction database, we generated diffraction patterns from reagent-grade calcium l-lactate pentahydrate and laboratory-synthesized calcium dl-lactate pentahydrate. From the resulting diffraction patterns we determined that the existing reference diffraction card corresponds to calcium dl-lactate pentahydrate and that the other form of calcium lactate pentahydrate observed in cheese crystals corresponds to calcium l-lactate pentahydrate. Therefore, this report presents detailed data from the 2 diffraction patterns, which may be used to prepare 2 reference diffraction cards that differentiate calcium l-lactate pentahydrate from calcium dl-lactate pentahydrate. Furthermore, we collected crystals from the exteriors and interiors of Cheddar cheeses to demonstrate the ability of powder X-ray diffraction to differentiate between the 2 forms of calcium lactate pentahydrate crystals in Cheddar cheeses

  3. Powder diffraction from solids in the terapascal regime

    NASA Astrophysics Data System (ADS)

    Rygg, J.

    2013-06-01

    A method of obtaining powder diffraction data on dynamically-compressed solids has been implemented at the Jupiter and OMEGA laser facilities. Thin powdered samples are sandwiched between diamond plates, and ramp compressed in the solid phase using a gradual increase in the drive-laser intensity. The pressure history in the sample is determined by back-propagation of the measured diamond free-surface velocity. A pulse of x-rays is produced at the time of peak pressure by laser illumination of a thin Cu or Fe foil, and collimated at the sample plane by a pinhole cut in a Ta substrate. The diffracted signal is recorded on x-ray sensitive material, with a typical d-spacing uncertainty of approximately 0.01 Å. This diagnostic has been used up to 1.2 TPa (12 Mbar) to verify the solidity, measure the density, constrain the crystal structure, and evaluate the strain-induced texturing of a variety of compressed samples spanning atomic numbers from 6 (carbon) to 82 (lead).

  4. Synchrotron and laboratory studies utilizing a new powder diffraction technique

    SciTech Connect

    Knapp, G.S.; Beno, M.A.; Jennings, G.; Engbretson, M.; Ramanathan, M.

    1992-10-01

    We have developed a new type of powder diffractometer that is much more efficient than existing methods. The diffractometer has the potential of both high count rates and very high resolution when used at a synchrotron source. The laboratory based instrument has an order of magnitude improvement in count rate over existing methods. The method uses a focusing diffracted beam monochromator in combination with a multichannel detector. The incident x-rays fall on a flat plate or capillary sample and are intercepted by a bent focusing monochromator which has the focus of the bend at the sample surface. The powder diffraction lines emerging from the bent crystal monochromator are detected by a linear or 2-dimensional detector. This allows us to eliminate the background from fluorescence or other scattering and to take data over a range of 3[degrees] to 4[degrees] instead of one angle at a time thereby providing a large improvement over conventional diffractometers. Results are presented for fluorapatite Fe[sub 2]O[sub 3], and a high-TC superconductor.

  5. Synchrotron and laboratory studies utilizing a new powder diffraction technique

    SciTech Connect

    Knapp, G.S.; Beno, M.A.; Jennings, G.; Engbretson, M.; Ramanathan, M.

    1992-10-01

    We have developed a new type of powder diffractometer that is much more efficient than existing methods. The diffractometer has the potential of both high count rates and very high resolution when used at a synchrotron source. The laboratory based instrument has an order of magnitude improvement in count rate over existing methods. The method uses a focusing diffracted beam monochromator in combination with a multichannel detector. The incident x-rays fall on a flat plate or capillary sample and are intercepted by a bent focusing monochromator which has the focus of the bend at the sample surface. The powder diffraction lines emerging from the bent crystal monochromator are detected by a linear or 2-dimensional detector. This allows us to eliminate the background from fluorescence or other scattering and to take data over a range of 3{degrees} to 4{degrees} instead of one angle at a time thereby providing a large improvement over conventional diffractometers. Results are presented for fluorapatite Fe{sub 2}O{sub 3}, and a high-TC superconductor.

  6. 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.

  7. Examination of reactor grade graphite using neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    DiJulio, D. D.; Hawari, A. I.

    2009-07-01

    Graphite is of principal interest in Generation IV nuclear reactor concepts. In particular, graphite will be the moderator for the Very High Temperature Reactor. In support of experimental and computational investigations that aim at understanding the behavior of reactor grade graphite under operating conditions, neutron powder diffraction experiments have been performed at the North Carolina State University PULSTAR reactor. The collected diffraction patterns exhibit intense broadening of several of the reflections, characteristic of turbostratic stacking. In order to quantify this disorder structurally, a model combined with a Rietveld-like refinement approach was implemented, which includes several refinable parameters that aim at describing this type of structure. Stacking parameters representing the probabilities of a random and registered shift between stacking packages were defined. The results indicate that the studied reactor grade graphite specimens contain a small fraction of layer disorder. The inferred interlayer spacing for the specimens is slightly larger than the theoretical value for graphite of 0.335 nm and the lattice constant is slightly less than 0.246 nm. The developed methodology is found to be successful in fitting the neutron diffraction patterns of reactor grade graphite.

  8. Femtosecond time-resolved MeV electron diffraction

    DOE PAGES

    Zhu, Pengfei; Zhu, Y.; Hidaka, Y.; ...

    2015-06-02

    We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS2 are obtained utilizing a 5 fC (~3 × 104 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirms that electron beam has a normalized emittance of ~50 nm rad. The transverse and longitudinal coherence length is ~11 and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~100 fs (rms). The temporal resolution is demonstrated by observing themore » evolution of Bragg and superlattice peaks of 1T-TaS2 following an 800 nm optical pump and was found to be 130 fs. Lastly, our results demonstrate the advantages of MeV electrons, including large elastic differential scattering cross-section and access to high-order reflections, and the feasibility of ultimately realizing below 10 fs time-resolved electron diffraction.« less

  9. Femtosecond time-resolved MeV electron diffraction

    SciTech Connect

    Zhu, Pengfei; Zhu, Y.; Hidaka, Y.; Wu, L.; Cao, J.; Berger, H.; Geck, J.; Kraus, R.; Pjerov, S.; Shen, Y.; Tobey, R. I.; Hill, J. P.; Wang, X. J.

    2015-06-02

    We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS2 are obtained utilizing a 5 fC (~3 × 104 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirms that electron beam has a normalized emittance of ~50 nm rad. The transverse and longitudinal coherence length is ~11 and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~100 fs (rms). The temporal resolution is demonstrated by observing the evolution of Bragg and superlattice peaks of 1T-TaS2 following an 800 nm optical pump and was found to be 130 fs. Lastly, our results demonstrate the advantages of MeV electrons, including large elastic differential scattering cross-section and access to high-order reflections, and the feasibility of ultimately realizing below 10 fs time-resolved electron diffraction.

  10. In situ studies of zeolite syntheses using powder diffraction methods: Crystallization of ``instant zeolite A`` powder and CoAPO-5

    SciTech Connect

    Norby, P.; Christensen, A.N.; Hanson, J.C.

    1994-02-01

    A series of hydrothermal zeolite synthesis were performed on a powder diffractometer using synchrotron radiation and a position sensitive detector. Direct observation of the induction period (nucleation stage), crystallization and transformation of zeolite 4A (Na-LTA) was possible due to the intense X-ray beam which allows fast data collection. High pressure experiments were performed, allowing observation of hydrothermal synthesis of a cobalt substituted AlPO{sub 4}-zeolite, CoAPO-5, up to 165{degrees}C. The temperature dependence of crystallization rates of CoAPO-5 was studied. This is to our knowledge the first time resolved powder diffraction studies of zeolite syntheses using angle dispersive synchrotron powder diffraction.

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

    SciTech Connect

    Sinsheimer, John; Bouet, Nathalie; Ghose, Sanjit; Dooryhee, Eric; Conley, Ray

    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 and in situ and operando diffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, over a continuous range of diffraction angles, and work for X-ray energies of tens to hundreds of kiloelectronvolts. In addition, 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.

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

    SciTech Connect

    Sinsheimer, John; Bouet, Nathalie; Ghose, Sanjit; Dooryhee, Eric; Conley, Ray

    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 and in situ and operando diffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, over a continuous range of diffraction angles, and work for X-ray energies of tens to hundreds of kiloelectronvolts. In addition, 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.

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

    DOE PAGES

    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 and in situ and operando diffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, overmore » a continuous range of diffraction angles, and work for X-ray energies of tens to hundreds of kiloelectronvolts. In addition, 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

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

    SciTech Connect

    Sinsheimer, John J.; Bouet, Nathalie; ghose, Sanjit; Dooryhee, Eric Yves Emmanuel; Conley, Ray

    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 and in situ and operando diffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, over a continuous range of 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.

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

    PubMed

    Sinsheimer, John; Bouet, Nathalie; Ghose, Sanjit; Dooryhee, Eric; Conley, Ray

    2016-11-01

    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 and in situ and operando diffraction measurements. For example, the slits can measure a majority of any diffraction cone for any polycrystalline material, over a continuous range of 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.

  16. Synchrotron Powder X-ray Diffraction Study of the Structure and Dehydration Behavior of Sepiolite

    NASA Astrophysics Data System (ADS)

    Post, J. E.; Bish, D. L.; Heaney, P. J.

    2006-05-01

    Sepiolite is a hydrous Mg-silicate clay mineral with fibrous morphology that typically occurs as fine-grained, poorly crystalline masses. It occurs in a wide variety of geological environments and has been mined for centuries because of its many uses, e.g. in the pharmaceutical, fertilizer, and pesticide industries. Its versatile functionality derives from the large surface area and microporosity that are characteristic of the material. In recent years, sepiolite has received considerable attention with regard to the adsorption of organics, for use as a support for catalysts, as a molecular sieve, and as an inorganic membrane for ultrafiltration. Because of its fine-grained and poorly crystalline nature, it has not been possible to study sepiolite's crystal structure using single-crystal X-ray diffraction methods, and consequently many details of the structure are still not well known. In this study, Rietveld refinements using synchrotron powder X-ray diffraction data were used to investigate the crystal structure and dehydration behavior of sepiolite from Durango, Mexico. The room- temperature (RT) sepiolite structure in air compares well with previous models but reveals an additional zeolitic water site. The RT structure under vacuum retained only ~1/8 of the zeolitic water and the volume decreased 1.3%. Real-time, temperature-resolved synchrotron powder X-ray diffraction data and Rietveld refinements were used to investigate the behavior of the sepiolite structure from 300 to 925 K. Rietveld refinements revealed that most of the zeolitic water is lost by ~390 K, accompanied by a decrease in the a and c unit-cell parameters. Above ~600 K the sepiolite structure folds as one-half of the crystallographically bound water is lost. Rietveld refinements of the "anhydrous" sepiolite structure reveal that, in general, unit-cell parameters a, b, â and volume steadily decrease with increasing temperature; there is an obvious change in slope at ~820 K suggesting a phase

  17. Powder neutron diffraction studies of a carbonate fluorapatite

    SciTech Connect

    Leventouri, Th.; Chakoumakos, B. C.; Moghaddam, H. Y.; Perdikatsis, V.

    2000-02-01

    Atomic positional disorder of a single-phase natural carbonate fluorapatite (francolite) is revealed from analysis of the atomic displacement parameters (ADPs) refined from neutron powder diffraction data as a function of temperature and carbonate content. The ADPs of the francolite show a strong disturbance at the P, O3, and F sites. When it is heat treated to partially or completely remove the carbonate, the ADPs as well as the other structural parameters resemble those of a fluorapatite (Harding pegmatite) that was measured under the same conditions. The various structural changes are consistent with a substitution mechanism whereby the planar carbonate group replaces a phosphate group and lies on the mirror plane of the apatite structure. (c) 2000 Materials Research Society.

  18. Powder X-ray diffraction laboratory, Reston, Virginia

    USGS Publications Warehouse

    Piatak, Nadine M.; Dulong, Frank T.; Jackson, John C.; Folger, Helen W.

    2014-01-01

    The powder x-ray diffraction (XRD) laboratory is managed jointly by the Eastern Mineral and Environmental Resources and Eastern Energy Resources Science Centers. Laboratory scientists collaborate on a wide variety of research problems involving other U.S. Geological Survey (USGS) science centers and government agencies, universities, and industry. Capabilities include identification and quantification of crystalline and amorphous phases, and crystallographic and atomic structure analysis for a wide variety of sample media. Customized laboratory procedures and analyses commonly are used to characterize non-routine samples including, but not limited to, organic and inorganic components in petroleum source rocks, ore and mine waste, clay minerals, and glassy phases. Procedures can be adapted to meet a variety of research objectives.

  19. Parts per Million Powder X-ray Diffraction

    DOE PAGES

    Newman, Justin A.; Schmitt, Paul D.; Toth, Scott J.; ...

    2015-10-14

    Here in this paper we demonstrate the use of second harmonic generation (SHG) microscopy-guided synchrotron powder X-ray diffraction (PXRD) for the detection of trace crystalline active pharmaceutical ingredients in a common polymer blend. The combined instrument is capable of detecting 100 ppm crystalline ritonavir in an amorphous hydroxypropyl methylcellulose matrix with a high signal-to-noise ratio (>5000). The high spatial resolution afforded by SHG microscopy allows for the use of a minibeam collimator to reduce the total volume of material probed by synchrotron PXRD. The reduction in probed volume results in reduced background from amorphous material. The ability to detect lowmore » crystalline loading has the potential to improve measurements in the formulation pipeline for pharmaceutical solid dispersions, for which even trace quantities of crystalline active ingredients can negatively impact the stability and bioavailability of the final drug product.« less

  20. Parts per Million Powder X-ray Diffraction

    SciTech Connect

    Newman, Justin A.; Schmitt, Paul D.; Toth, Scott J.; Deng, Fengyuan; Zhang, Shijie; Simpson, Garth J.

    2015-10-14

    Here in this paper we demonstrate the use of second harmonic generation (SHG) microscopy-guided synchrotron powder X-ray diffraction (PXRD) for the detection of trace crystalline active pharmaceutical ingredients in a common polymer blend. The combined instrument is capable of detecting 100 ppm crystalline ritonavir in an amorphous hydroxypropyl methylcellulose matrix with a high signal-to-noise ratio (>5000). The high spatial resolution afforded by SHG microscopy allows for the use of a minibeam collimator to reduce the total volume of material probed by synchrotron PXRD. The reduction in probed volume results in reduced background from amorphous material. The ability to detect low crystalline loading has the potential to improve measurements in the formulation pipeline for pharmaceutical solid dispersions, for which even trace quantities of crystalline active ingredients can negatively impact the stability and bioavailability of the final drug product.

  1. Acemetacin cocrystal structures by powder X-ray diffraction

    PubMed Central

    Bolla, Geetha

    2017-01-01

    Cocrystals of acemetacin drug (ACM) with nicotinamide (NAM), p-aminobenzoic acid (PABA), valerolactam (VLM) and 2-pyridone (2HP) were prepared by melt crystallization and their X-ray crystal structures determined by high-resolution powder X-ray diffraction. The powerful technique of structure determination from powder data (SDPD) provided details of molecular packing and hydrogen bonding in pharmaceutical cocrystals of acemetacin. ACM–NAM occurs in anhydrate and hydrate forms, whereas the other structures crystallized in a single crystalline form. The carboxylic acid group of ACM forms theacid–amide dimer three-point synthon R 3 2(9)R 2 2(8)R 3 2(9) with three different syn amides (VLM, 2HP and caprolactam). The conformations of the ACM molecule observed in the crystal structures differ mainly in the mutual orientation of chlorobenzene fragment and the neighboring methyl group, being anti (type I) or syn (type II). ACM hydrate, ACM—NAM, ACM–NAM-hydrate and the piperazine salt of ACM exhibit the type I conformation, whereas ACM polymorphs and other cocrystals adopt the ACM type II conformation. Hydrogen-bond interactions in all the crystal structures were quantified by calculating their molecular electrostatic potential (MEP) surfaces. Hirshfeld surface analysis of the cocrystal surfaces shows that about 50% of the contribution is due to a combination of strong and weak O⋯H, N⋯H, Cl⋯H and C⋯H interactions. The physicochemical properties of these cocrystals are under study. PMID:28512568

  2. Spatially resolved contrast measurement of diffractive micromirror arrays

    NASA Astrophysics Data System (ADS)

    Sicker, Cornelius; Heber, Jörg; Berndt, Dirk; Rückerl, Florian; Tinevez, Jean-Yves; Shorte, Spencer; Wagner, Michael; Schenk, Harald

    2015-02-01

    Diffractive micromirror arrays (MMA) are a special class of optical MEMS, serving as spatial light modulators (SLM) that control the phase of reflected light. Since the surface profile is the determining factor for an accurate phase modulation, high-precision topographic characterization techniques are essential to reach highest optical performance. While optical profiling techniques such as white-light interferometry are still considered to be most suitable to this task, the practical limits of interferometric techniques start to become apparent with the current state of optical MEMS technology. Light scatter from structured surfaces carries information about their topography, making scatter techniques a promising alternative. Therefore, a spatially resolved scatter measurement technique, which takes advantage of the MMA's diffractive principle, has been implemented experimentally. Spectral measurements show very high contrast ratios (up to 10 000 in selected samples), which are consistent with calculations from micromirror roughness parameters obtained by white-light interferometry, and demonstrate a high sensitivity to changes in the surface topography. The technique thus seems promising for the fast and highly sensitive characterization of diffractive MMAs.

  3. High throughput screening of ligand binding to macromolecules using high resolution powder diffraction

    DOEpatents

    Von Dreele, Robert B.; D'Amico, Kevin

    2006-10-31

    A process is provided for the high throughput screening of binding of ligands to macromolecules using high resolution powder diffraction data including producing a first sample slurry of a selected polycrystalline macromolecule material and a solvent, producing a second sample slurry of a selected polycrystalline macromolecule material, one or more ligands and the solvent, obtaining a high resolution powder diffraction pattern on each of said first sample slurry and the second sample slurry, and, comparing the high resolution powder diffraction pattern of the first sample slurry and the high resolution powder diffraction pattern of the second sample slurry whereby a difference in the high resolution powder diffraction patterns of the first sample slurry and the second sample slurry provides a positive indication for the formation of a complex between the selected polycrystalline macromolecule material and at least one of the one or more ligands.

  4. Zoledronic acid: monoclinic and triclinic polymorphs from powder diffraction data.

    PubMed

    Chernyshev, Vladimir V; Shkavrov, Sergey V; Paseshnichenko, Ksenia A; Puryaeva, Tamara P; Velikodny, Yurii A

    2013-03-01

    The crystal structures of the monoclinic and triclinic polymorphs of zoledronic acid, C5H10N2O7P2, have been established from laboratory powder X-ray diffraction data. The molecules in both polymorphs are described as zwitterions, namely 1-(2-hydroxy-2-phosphonato-2-phosphonoethyl)-1H-imidazol-3-ium. Strong intermolecular hydrogen bonds (with donor-acceptor distances of 2.60 Å or less) link the molecules into layers, parallel to the (100) plane in the monoclinic polymorph and to the (1-10) plane in the triclinic polymorph. The phosphonic acid groups form the inner side of each layer, while the imidazolium groups lie to the outside of the layer, protruding in opposite directions. In both polymorphs, layers related by translation along [100] interact through weak hydrogen bonds (with donor-acceptor distances greater than 2.70 Å), forming three-dimensional layered structures. In the monoclinic polymorph, there are hydrogen-bonded centrosymmetric dimers linked by four strong O-H...O hydrogen bonds, which are not present in the triclinic polymorph.

  5. Patterson-function direct methods for structure determination of organic compounds from powder diffraction data. XVI.

    PubMed

    Rius, Jordi

    2011-01-01

    A new type of direct methods (DM) called Patterson-function DM are presented that directly explore the Patterson instead of the modulus function. Since they work with the experimental intensities, they are particularly well suited for handling powder diffraction data. These methods are based on the maximization of the sum function S(P) ∝ ∑H(I(H)-)G(-H)(Φ) in terms of the Φ phases of the structure factors. The quantity accessible from the experiment is I(H), the equidistributed multiplet intensity of reflection H, and is the average intensity taken over all non-systematically absent reflections. G(-H)(Φ) is the calculated structure-factor amplitude of the squared structure that includes the positivity and the atomicity of the density function in its definition. The S(P) sum function can be optimized with the Patterson-function tangent formula (TF) using a variant of the S-FFT algorithm [Rius et al. (2007), Acta Cryst. A63, 131-134]. It is important that overlapped reflections also participate in the phase refinement, so that not only the resolved reflections but the whole pattern contribute decisively to the refinement. The increase in effective data resolution minimizes Fourier series termination effects and improves the accuracy of G(Φ). The Patterson-function TF has been applied to synchrotron powder data of various organic compounds. In all cases the molecules were easily identified in the respective Fourier maps. By way of illustration the method is applied to synchrotron powder data of a dimer formed by 30 symmetry-independent non-H atoms. Since single-crystal data may be regarded as overlap-free powder data, it is clear that Patterson-function DM can cope with powder and single-crystal data.

  6. Femtosecond electron diffraction: heralding the era of atomically resolved dynamics

    NASA Astrophysics Data System (ADS)

    Sciaini, Germán; Miller, R. J. Dwayne

    2011-09-01

    One of the great dream experiments in Science is to directly observe atomic motions as they occur. Femtosecond electron diffraction provided the first 'light' of sufficient intensity to achieve this goal by attaining atomic resolution to structural changes on the relevant timescales. This review covers the technical progress that made this new level of acuity possible and gives a survey of the new insights gained from an atomic level perspective of structural dynamics. Atomic level views of the simplest possible structural transition, melting, are discussed for a number of systems in which both thermal and purely electronically driven atomic displacements can be correlated with the degree of directional bonding. Optical manipulation of charge distributions and effects on interatomic forces/bonding can be directly observed through the ensuing atomic motions. New phenomena involving strongly correlated electron-lattice systems are also discussed in which optically induced changes in the potential energy landscape lead to ballistic structural changes. Concepts such as the structural order parameters are now directly observable at the atomic level of inspection to give a remarkable view of the extraordinary degree of cooperativity involved in strongly correlated electron-lattice systems. These recent examples, in combination with time-resolved real space imaging now possible with electron probes, are truly defining an emerging field that holds great promise to make a significant impact in how we understand structural dynamics. This article is dedicated to the memory of Professor David John Hugh Cockayne, a world leader in electron microscopy, who sadly passed away in December.

  7. X-Ray Diffraction Powder Patterns and Thin Section Observations from the Sierra Madera Impact Structure

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

    X-Ray powder diffraction analysis and thin section observations of carbonate and siliciclastic samples from the Sierra Madera impact structure indicate moderate shock pressures (8 to 30 GPa) were generated during the formation of this crater.

  8. Differential evolution: crystal structure determination of a triclinic polymorph of adipamide from powder diffraction data.

    PubMed

    Seaton, Colin C; Tremayne, Maryjane

    2002-04-21

    The crystal structure of a previously unknown triclinic polymorph of adipamide has been solved from laboratory X-ray powder diffraction data using a new direct space global optimisation method based on differential evolution.

  9. Taking It to Extremes - Powder Diffraction Under Non-Ambient Conditions

    NASA Astrophysics Data System (ADS)

    Millar, David I. A.; Pulham, Colin R.

    Structural studies of materials under elevated pressures provide a fascinating insight into the physical and chemical behaviour of matter under the wide range of conditions experienced throughout the Universe. Both x-ray and neutron powder diffraction techniques play a crucial role in structural studies and are therefore at the forefront of high-pressure research. These notes provide a short introduction to the principles and experimental practice of high-pressure powder diffraction techniques.

  10. Monitoring model drug microencapsulation in PLGA scaffolds using X-ray powder diffraction.

    PubMed

    Aina, Adeyinka; Gupta, Manish; Boukari, Yamina; Morris, Andrew; Billa, Nashiru; Doughty, Stephen

    2016-03-01

    The microencapsulation of three model drugs; metronidazole, paracetamol and sulphapyridine into Poly (dl-Lactide-Co-Glycolide) (PLGA) scaffolds were probed using X-ray Powder Diffraction (XRPD). Changes in the diffraction patterns of the PLGA scaffolds after encapsulation was suggestive of a chemical interaction between the pure drugs and the scaffolds and not a physical intermixture.

  11. Monitoring model drug microencapsulation in PLGA scaffolds using X-ray powder diffraction

    PubMed Central

    Aina, Adeyinka; Gupta, Manish; Boukari, Yamina; Morris, Andrew; Billa, Nashiru; Doughty, Stephen

    2015-01-01

    The microencapsulation of three model drugs; metronidazole, paracetamol and sulphapyridine into Poly (dl-Lactide-Co-Glycolide) (PLGA) scaffolds were probed using X-ray Powder Diffraction (XRPD). Changes in the diffraction patterns of the PLGA scaffolds after encapsulation was suggestive of a chemical interaction between the pure drugs and the scaffolds and not a physical intermixture. PMID:27013917

  12. A time-resolved diffraction study of the Ta--C solid combustion system

    SciTech Connect

    Larson, E.M.; Wong, J.; Holt, J.B.; Waide, P.A.; Nutt, G.; Rupp, B.; Terminello, L.J. )

    1993-07-01

    The formation of TaC and Ta[sub 2]C by combustion synthesis from their elemental constituents has been studied by time-resolved x-ray diffraction (TRXRD) using synchrotron radiation. The reactions have been followed with a time resolution down to 50 ms. Since the adiabatic temperatures for both reactions are well below any liquidus temperature in the Ta--C phase diagram, no melting occurs and these combustion reactions occur purely in the solid state. The phase transformations associated with these reactions are followed by monitoring the disappearance of reactant and appearance of product powder diffraction peaks in real time as the reaction front propagates through the combusting specimen. In the synthesis of TaC, the results show the formation of the subcarbide (Ta[sub 2]C) phase as an intermediate. In the synthesis of Ta[sub 2]C, the reaction proceeds directly to the product with no discernable intermediate Ta--C phase within a 50 ms time frame. The chemical dynamics associated with the combustion synthesis of TaC may be described by an initial phase transformation to hexagonal Ta[sub 2]C arising from carbon diffusion into the Ta metal lattice. As more carbon is available this intermediate subcarbide phase, which has one-half of its octahedral interstices occupied by the carbon, further transforms to the cubic TaC final product, in which all octahedral sites are now occupied. The time-resolved data indicate that the rate of formation of Ta[sub 2]C is a factor of two faster than that of TaC.

  13. Expected values and variances of Bragg peak intensities measured in a nanocrystalline powder diffraction experiment

    DOE PAGES

    Öztürk, Hande; Noyan, I. Cevdet

    2017-08-24

    A rigorous study of sampling and intensity statistics applicable for a powder diffraction experiment as a function of crystallite size is presented. Our analysis yields approximate equations for the expected value, variance and standard deviations for both the number of diffracting grains and the corresponding diffracted intensity for a given Bragg peak. The classical formalism published in 1948 by Alexander, Klug & Kummer [J. Appl. Phys.(1948),19, 742–753] appears as a special case, limited to large crystallite sizes, here. It is observed that both the Lorentz probability expression and the statistics equations used in the classical formalism are inapplicable for nanocrystallinemore » powder samples.« less

  14. Bayesian probability theory applied to the space group problem in powder diffraction

    NASA Astrophysics Data System (ADS)

    Markvardsen, A. J.

    2004-11-01

    Crystal structure determination from powder diffraction data has become a viable option for molecules with less than 50 non-hydrogen atoms in the asymmetric unit and this includes the majority of compounds of pharmaceutical interest. The solution of crystal structures, including space group determination, is more challenging from powder diffraction data than from single crystal diffraction data. Here, it will be demonstrated how a Bayesian probability analysis of this problem has helped to provide a new algorithm for the determination of the space group symmetry of a crystal from powder diffraction data. Specifically, the relative probabilities of different extinction symbols are accessed within a particular crystal system. Examples will be presented to illustrate this approach.

  15. New Powder Diffraction File (PDF-4) in relational database format: advantages and data-mining capabilities.

    PubMed

    Kabekkodu, Soorya N; Faber, John; Fawcett, Tim

    2002-06-01

    The International Centre for Diffraction Data (ICDD) is responding to the changing needs in powder diffraction and materials analysis by developing the Powder Diffraction File (PDF) in a very flexible relational database (RDB) format. The PDF now contains 136,895 powder diffraction patterns. In this paper, an attempt is made to give an overview of the PDF-4, search/match methods and the advantages of having the PDF-4 in RDB format. Some case studies have been carried out to search for crystallization trends, properties, frequencies of space groups and prototype structures. These studies give a good understanding of the basic structural aspects of classes of compounds present in the database. The present paper also reports data-mining techniques and demonstrates the power of a relational database over the traditional (flat-file) database structures.

  16. Femtosecond powder diffraction with a laser-driven hard X-ray source.

    PubMed

    Zamponi, F; Ansari, Z; Woerner, M; Elsaesser, T

    2010-01-18

    X-ray powder diffraction with a femtosecond time resolution is introduced to map ultrafast structural dynamics of polycrystalline condensed matter. Our pump-probe approach is based on photoexcitation of a powder sample with a femtosecond optical pulse and probing changes of its structure by diffracting a hard X-ray pulse generated in a laser-driven plasma source. We discuss the key aspects of this scheme including an analysis of detection sensitivity and angular resolution. Applying this technique to the prototype molecular material ammonium sulfate, up to 20 powder diffraction rings are recorded simultaneously with a time resolution of 100 fs. We describe how to derive transient charge density maps of the material from the extensive set of diffraction data in a quantitative way.

  17. Synchrotron x-ray powder diffraction studies in pulsed magnetic fields

    NASA Astrophysics Data System (ADS)

    Frings, P.; Vanacken, J.; Detlefs, C.; Duc, F.; Lorenzo, J. E.; Nardone, M.; Billette, J.; Zitouni, A.; Bras, W.; Rikken, G. L. J. A.

    2006-06-01

    X-ray powder diffraction experiments under pulsed magnetic fields were carried out at the DUBBLE beamline (BM26B) at the ESRF. A mobile generator delivered 110kJ to the magnet coil, which was sufficient to generate peak fields of 30T. A liquid He flow cryostat allowed us to vary the sample temperature accurately between 8 and 300K. Powder diffraction patterns of several samples were recorded using 21keV monochromatic x-rays and an on-line image plate detector. Here we present the first results on the suppression of the Jahn-Teller structural distortion in TbVO4 by magnetic field. These data clearly demonstrate the feasibility of x-ray powder diffraction experiments under pulsed magnetic fields with relatively inexpensive instrumentation.

  18. Powder x ray diffraction patterns of energetic materials for use as reference standards

    NASA Astrophysics Data System (ADS)

    Sullenger, D. B.; Cantrell, J. S.; Beiter, T. A.

    1993-03-01

    This report lists eighteen quality powder x-ray diffraction patterns produced at Mound for various explosives of recent and current interest. In each case the best possible experimental pattern, obtained from the substance in question via automated diffractometric step-scans, was compared with the corresponding pattern, calculated from the lattice and atomic positional parameters of the crystal structure, if known, and a reconciliation sought between the two was sought. In order to make these patterns more useful to various types of practitioners, previously published patterns for these substances have been included, together with a brief description of their crystallographies, some Chemical Abstracts reference information about them, and an evaluation of their quality via accepted powder diffraction criteria. Most of these patterns have been accepted by the International Center for Diffraction Data for inclusion in their Powder Data File; the others will be submitted in due course.

  19. Correlating cycling history with structural evolution in commercial 26650 batteries using in operando neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Goonetilleke, Damian; Pramudita, James C.; Hagan, Mackenzie; Al Bahri, Othman K.; Pang, Wei Kong; Peterson, Vanessa K.; Groot, Jens; Berg, Helena; Sharma, Neeraj

    2017-03-01

    Ex situ and time-resolved in operando neutron powder diffraction (NPD) has been used to study the structural evolution of the graphite negative electrode and LiFePO4 positive electrode within ANR26650M1A commercial batteries from A123 Systems, in what to our knowledge is the first reported NPD study investigating a 26650-type battery. Batteries with different and accurately-known electrochemical and storage histories were studied, enabling the tell-tale signs of battery degradation to be elucidated using NPD. The ex-situ NPD data revealed that the intensity of the graphite/lithiated graphite (LixC6 or LiyC) reflections was affected by battery history, with lower lithiated graphite (LiC12) reflection intensities typically corresponding to more abused batteries. This indicates that the lithiation of graphite is less progressed in more abused batteries, and hence these batteries have lower capacities. In operando NPD allows the rate of structural evolution in the battery electrode materials to be correlated to the applied current. Interestingly, the electrodes exhibit different responses to the applied current that depend on the battery cycling history, with this particularly evident for the negative electrode. Therefore, this work illustrates how NPD can be used to correlate a battery history with electrode structure.

  20. 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.

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

    PubMed

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

    2015-10-05

    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.

  2. Beamline I11 at Diamond: a new instrument for high resolution powder diffraction.

    PubMed

    Thompson, S P; Parker, J E; Potter, J; Hill, T P; Birt, A; Cobb, T M; Yuan, F; Tang, C C

    2009-07-01

    The performance characteristics of a new synchrotron x-ray powder diffraction beamline (I11) at the Diamond Light Source are presented. Using an in-vacuum undulator for photon production and deploying simple x-ray optics centered around a double-crystal monochromator and a pair of harmonic rejection mirrors, a high brightness and low bandpass x-ray beam is delivered at the sample. To provide fast data collection, 45 Si(111) analyzing crystals and detectors are installed onto a large and high precision diffractometer. High resolution powder diffraction data from standard reference materials of Si, alpha-quartz, and LaB6 are used to characterize instrumental performance.

  3. Understanding the instrumental profile of synchrotron radiation X-ray powder diffraction beamlines.

    PubMed

    Rebuffi, Luca; Sánchez Del Río, Manuel; Busetto, Edoardo; Scardi, Paolo

    2017-05-01

    A Monte Carlo algorithm has been developed to calculate the instrumental profile function of a powder diffraction synchrotron beamline. Realistic models of all optical elements are implemented in a ray-tracing software. The proposed approach and the emerging paradigm have been investigated and verified for several existing X-ray powder diffraction beamlines. The results, which can be extended to further facilities, show a new and general way of assessing the contribution of instrumental broadening to synchrotron radiation data, based on ab initio simulations.

  4. Implementation of Lamarckian concepts in a Genetic Algorithm for structure solution from powder diffraction data

    NASA Astrophysics Data System (ADS)

    Turner, Giles W.; Tedesco, Emilio; Harris, Kenneth D. M.; Johnston, Roy L.; Kariuki, Benson M.

    2000-04-01

    Previous implementations of Genetic Algorithms in direct-space strategies for structure solution from powder diffraction data have employed the operations of mating, mutation and natural selection, with the fitness of each structure based on comparison between calculated and experimental powder diffraction patterns (we define fitness as a function of weighted-profile R-factor Rwp). We report an extension to this method, in which each structure generated in the Genetic Algorithm is subjected to local minimization of Rwp with respect to structural variables. This approach represents an implementation of Lamarckian concepts of evolution, and is found to give significant improvements in efficiency and reliability.

  5. A method for automated determination of the crystal structures from X-ray powder diffraction data

    SciTech Connect

    Hofmann, D. W. M. Kuleshova, L. N.

    2006-05-15

    An algorithm is proposed for determining the crystal structure of compounds. In the framework of this algorithm, X-ray powder diffraction patterns are compared using a new similarity index. Unlike the indices traditionally employed in X-ray powder diffraction analysis, the new similarity index can be applied even in the case of overlapping peaks and large differences in unit cell parameters. The capabilities of the proposed procedure are demonstrated by solving the crystal structures of a number of organic pigments (PY111, PR181, Me-PR170)

  6. Synchrotron X-ray Powder Diffraction Studies in Pulsed Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Detlefs, C.; Frings, P.; Vanacken, J.; Duc, F.; Lorenzo, J. E.; Nardone, M.; Billette, J.; Zitouni, A.; Bras, W.; Rikken, G. L. J. A.

    2007-01-01

    X-ray powder diffraction experiments under pulsed magnetic fields were carried out at the DUBBLE beamline (BM26B) at the ESRF. A mobile generator delivered 110kJ to the magnet coil, which was sufficient to generate peak fields of 30T. A liquid He flow cryostat allowed us to vary the sample temperature accurately between 8K and 300K.

  7. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    SciTech Connect

    Lawson, A.C.; Smith, K.

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs.

  8. Application of singular value decomposition analysis to time-dependent powder diffraction data of an in-situ photodimerization reaction

    PubMed Central

    Mabied, Ahmed F.; Nozawa, Shunsuke; Hoshino, Manabu; Tomita, Ayana; Sato, Tokushi; Adachi, Shin-ichi

    2014-01-01

    Singular value decomposition (SVD) analysis has important applications for time-dependent crystallographic data, extracting significant information. Herein, a successful application of SVD analysis of time-resolved powder diffraction data over the course of an in-situ photodimerization reaction of anthracene derivatives is introduced. SVD revealed significant results in the case of 9-methylanthracene and 1-chloroanthracene. The results support the formation of the 9-methylanthracene stable dimer phase and suggest the existence of an excimer state. PMID:24763645

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

    SciTech Connect

    Tanaka, Masahiko Katsuya, Yoshio Sakata, Osami

    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 absorption 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.

  10. Three-dimensional electron diffraction as a complementary technique to powder X-ray diffraction for phase identification and structure solution of powders

    PubMed Central

    Yun, Yifeng; Zou, Xiaodong; Hovmöller, Sven; Wan, Wei

    2015-01-01

    Phase identification and structure determination are important and widely used techniques in chemistry, physics and materials science. Recently, two methods for automated three-dimensional electron diffraction (ED) data collection, namely automated diffraction tomography (ADT) and rotation electron diffraction (RED), have been developed. Compared with X-ray diffraction (XRD) and two-dimensional zonal ED, three-dimensional ED methods have many advantages in identifying phases and determining unknown structures. Almost complete three-dimensional ED data can be collected using the ADT and RED methods. Since each ED pattern is usually measured off the zone axes by three-dimensional ED methods, dynamic effects are much reduced compared with zonal ED patterns. Data collection is easy and fast, and can start at any arbitrary orientation of the crystal, which facilitates automation. Three-dimensional ED is a powerful technique for structure identification and structure solution from individual nano- or micron-sized particles, while powder X-ray diffraction (PXRD) provides information from all phases present in a sample. ED suffers from dynamic scattering, while PXRD data are kinematic. Three-dimensional ED methods and PXRD are complementary and their combinations are promising for studying multiphase samples and complicated crystal structures. Here, two three-dimensional ED methods, ADT and RED, are described. Examples are given of combinations of three-dimensional ED methods and PXRD for phase identification and structure determination over a large number of different materials, from Ni–Se–O–Cl crystals, zeolites, germanates, metal–organic frameworks and organic compounds to intermetallics with modulated structures. It is shown that three-dimensional ED is now as feasible as X-ray diffraction for phase identification and structure solution, but still needs further development in order to be as accurate as X-ray diffraction. It is expected that three-dimensional ED

  11. Three-dimensional electron diffraction as a complementary technique to powder X-ray diffraction for phase identification and structure solution of powders.

    PubMed

    Yun, Yifeng; Zou, Xiaodong; Hovmöller, Sven; Wan, Wei

    2015-03-01

    Phase identification and structure determination are important and widely used techniques in chemistry, physics and materials science. Recently, two methods for automated three-dimensional electron diffraction (ED) data collection, namely automated diffraction tomography (ADT) and rotation electron diffraction (RED), have been developed. Compared with X-ray diffraction (XRD) and two-dimensional zonal ED, three-dimensional ED methods have many advantages in identifying phases and determining unknown structures. Almost complete three-dimensional ED data can be collected using the ADT and RED methods. Since each ED pattern is usually measured off the zone axes by three-dimensional ED methods, dynamic effects are much reduced compared with zonal ED patterns. Data collection is easy and fast, and can start at any arbitrary orientation of the crystal, which facilitates automation. Three-dimensional ED is a powerful technique for structure identification and structure solution from individual nano- or micron-sized particles, while powder X-ray diffraction (PXRD) provides information from all phases present in a sample. ED suffers from dynamic scattering, while PXRD data are kinematic. Three-dimensional ED methods and PXRD are complementary and their combinations are promising for studying multiphase samples and complicated crystal structures. Here, two three-dimensional ED methods, ADT and RED, are described. Examples are given of combinations of three-dimensional ED methods and PXRD for phase identification and structure determination over a large number of different materials, from Ni-Se-O-Cl crystals, zeolites, germanates, metal-organic frameworks and organic compounds to intermetallics with modulated structures. It is shown that three-dimensional ED is now as feasible as X-ray diffraction for phase identification and structure solution, but still needs further development in order to be as accurate as X-ray diffraction. It is expected that three-dimensional ED methods

  12. Synergy between transmission electron microscopy and powder diffraction: application to modulated structures.

    PubMed

    Batuk, Dmitry; Batuk, Maria; Abakumov, Artem M; Hadermann, Joke

    2015-04-01

    The crystal structure solution of modulated compounds is often very challenging, even using the well established methodology of single-crystal X-ray crystallography. This task becomes even more difficult for materials that cannot be prepared in a single-crystal form, so that only polycrystalline powders are available. This paper illustrates that the combined application of transmission electron microscopy (TEM) and powder diffraction is a possible solution to the problem. Using examples of anion-deficient perovskites modulated by periodic crystallographic shear planes, it is demonstrated what kind of local structural information can be obtained using various TEM techniques and how this information can be implemented in the crystal structure refinement against the powder diffraction data. The following TEM methods are discussed: electron diffraction (selected area electron diffraction, precession electron diffraction), imaging (conventional high-resolution TEM imaging, high-angle annular dark-field and annular bright-field scanning transmission electron microscopy) and state-of-the-art spectroscopic techniques (atomic resolution mapping using energy-dispersive X-ray analysis and electron energy loss spectroscopy).

  13. The impact of powder diffraction on the structural characterization of organic crystalline materials.

    PubMed

    Tremayne, Maryjane

    2004-12-15

    The bulk properties of organic crystalline materials depend on their molecular and crystal structures but, as many of these materials cannot be prepared in a suitable form for conventional single-crystal diffraction studies, structural characterization and rationalization of these properties must be obtained from powder diffraction data. The recent development of direct-space structure solution methods has enabled the study of a wide range of organic materials using powder diffraction data, many of structural complexity only made tractable by these advances in methodology. These direct-space methods are based on a number of global optimization techniques including Monte Carlo, simulated annealing, genetic algorithm and differential evolution approaches. In this article, the implementation and relative efficiency and reliability of these methods are discussed, and their impact on the structural study of organic materials is illustrated by examples of polymorphic systems, pharmaceutical, pigment and polypeptide structures and compounds used in the study of intermolecular networks.

  14. Ab initio phasing of X-ray powder diffraction patterns by charge flipping.

    PubMed

    Wu, Jinsong; Leinenweber, Kurt; Spence, John C H; O'Keeffe, Michael

    2006-08-01

    Determining crystal structures from powder X-ray diffraction data remains a challenging problem in materials science. By embedding a Le-Bail-like procedure within the recently discovered charge-flipping phasing algorithm, an extremely simple, fast and effective ab initio method has been developed to determine phases directly from indexed powder diffraction patterns. The algorithm solves the degeneracy problem by applying spherical averaging for overlapping Bragg reflections, while solving the phase problem by using the Oszlányi-Süto charge-flipping algorithm. The processes of peak decomposition and phasing are integrated within the same iteration, and a dynamic support is used. The Fienup hybrid input-output algorithm is also incorporated to minimize stagnation. The ability of the algorithm to find structure-factor phases rapidly is found to assist with the fundamental problem of degeneracy (overlapping reflections) which is intrinsic to powder diffraction data. Space-group and chemical-composition information are not needed as inputs, and can be determined from the result. The method is illustrated using several experimental powder patterns of indifferent quality.

  15. Unmixing 40Ar/39Ar Muscovite Ages Using Powder X-ray Diffraction

    NASA Astrophysics Data System (ADS)

    McAleer, R. J.; Kunk, M. J.; Valley, P. M.; Walsh, G. J.; Bish, D. L.; Wintsch, R. P.

    2014-12-01

    Whole rock powder X-ray diffraction (XRD) experiments from eight samples collected across a retrograde ductile shear zone in the Devonian Littleton Formation near Claremont, NH, exhibit broad and asymmetric to bimodal muscovite 00l reflections. These composite 00l reflections exhibit a systematic change in shape with increasing retrograde strain. Microtextural relationships, electron microprobe quantitative analyses, and element mapping indicate that the change in peak shape reflects progressive dissolution of metastable Na-rich muscovite and the precipitation of stable Na-poor muscovite. 40Ar/39Ar step heating experiments on muscovite concentrates from these samples show a decrease in total gas age from 274 to 258 Ma as the highest strain zone is approached, and steps within individual spectra range in age by ~20 m.y. The correlation between age and 00l peak shape suggests that the argon isotopic system also tracks the dissolution-precipitation process. Furthermore, the variation in age during step heating indicates that these populations exhibit different in-vacuo degassing behavior. Comparison of whole rock and muscovite concentrate XRD patterns from the same samples shows that the mineral separation process can fractionate these muscovite populations. With this knowledge, four muscovite concentrates were prepared from a single hand sample, analyzed by XRD, and dated. Combining modal estimates from XRD experiments with total gas ages, the four splits narrowly define a mixing line that resolves end-member ages of 250 and 300 Ma for the neocrystallized and earlier high grade populations of muscovite, respectively. These ages are consistent with age data from all other samples. The results show that, in some settings, powder XRD provides a powerful and time effective method to both identify the existence of and establish the proportions of multiple compositional populations of muscovite prior to 40Ar/39Ar analysis. This approach will be especially useful in

  16. X-ray powder diffraction patterns for certain beta-lactam, tetracycline and macrolide antibiotic drugs.

    PubMed

    Thangadurai, S; Abraham, J T; Srivastava, A K; Moorthy, M Nataraja; Shukla, S K; Anjaneyulu, Y

    2005-07-01

    X-ray powder diffraction (XRD) data for eight beta-lactam viz., ampicillin sodium, ampicillin trihydrate, penicillin G procaine, benzathine penicillin, benzyl penicillin sodium, cefalexin, cefotaxime sodium and ceftriaxone sodium; three tetracyclines viz., doxycycline hydrochloride, oxytetracycline dihydrate and tetracycline hydrochloride; and two macrolide viz., azithromycin and erythromycin estolate antibiotic drugs were obtained using a powder diffractometer. The drugs were scanned from Bragg angles (2theta) of 10 degrees to 70 degrees. The obtained data were tabulated in terms of the lattice spacing (A) and relative line intensities (I/I(I)). This new information may be useful for identifying these drugs from confiscated materials, which has been frequently encountered in forensic laboratories.

  17. MnO spin-wave dispersion curves from neutron powder diffraction

    SciTech Connect

    Goodwin, Andrew L.; Dove, Martin T.; Tucker, Matthew G.; Keen, David A.

    2007-02-15

    We describe a model-independent approach for the extraction of spin-wave dispersion curves from powder neutron total scattering data. Our approach is based on a statistical analysis of real-space spin configurations to calculate spin-dynamical quantities. The RMCPROFILE implementation of the reverse Monte Carlo refinement process is used to generate a large ensemble of supercell spin configurations from MnO powder diffraction data collected at 100 K. Our analysis of these configurations gives spin-wave dispersion curves for MnO that agree well with those determined independently using neutron triple-axis spectroscopic techniques.

  18. Structural investigation of Lisinopril by powder X-ray diffraction and solid-state NMR

    NASA Astrophysics Data System (ADS)

    Filip, Xenia; Tripon, Carmen; Borodi, Gheorghe; Oprean, Luminiţa; Filip, Claudiu

    2009-08-01

    Structural studies on polycrystalline Lisinopril (N-N-[(s)-1-carboxy-3-phenylpropyl]-L-lysil-L-proline) are performed by combined powder X-Ray diffraction and 13C solid-state nuclear magnetic resonance (NMR). The crystal structure of this drug, used primarily for the treatment of hypertension, has not yet been determined due to the impossibility of synthesizing single crystals of sufficient quality. It is shown here that valuable insights into the crystal and molecular structure of Lisinopril can be obtained on polycrystalline powder based on the complementary character of the information provided by the two techniques.

  19. 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 SrTiO3 thin-film sample.

  20. Powder diffraction by fixed incident angle reflection using a curved position-sensitive detector

    SciTech Connect

    Haggerty, Ryan P.; Sarin, Pankaj; Bérar, Jean-Francois; Apostolov, Zlatomir D.; Kriven, Waltraud M.

    2010-05-25

    As curved position-sensitive detectors improve in angular resolution, the effects that fixed incident angle reflection have on X-ray diffraction peaks become more apparent. In this study the effects of sample transparency, incident beam height, detector resolution and sample displacement on the intensity, location, width and shape of powder diffraction peaks were examined. The functions describing each of these phenomena are presented and were successfully used to quantitatively model the diffraction peaks collected in this geometry. Three distinct regimes of diffraction peak resolution were identified from the phenomena that limit the peak variance. Pertinent criteria based on experimental parameters have been outlined to classify fixed incident angle reflection experiments into each regime. Guidelines for improvement of experimental resolution and for conducting analysis of data acquired using fixed incident angle reflection geometry and curved position-sensitive detectors are also provided.

  1. A new approach for structure analysis of two-dimensional membrane protein crystals using X-ray powder diffraction data

    PubMed Central

    Dilanian, R A; Darmanin, C; Varghese, J N; Wilkins, S W; Oka, T; Yagi, N; Quiney, H M; Nugent, K A

    2011-01-01

    The application of powder diffraction methods to problems in structural biology is generally regarded as intractable because of the large number of unresolved, overlapping X-ray reflections. Here, we use information about unit cell lattice parameters, space group transformations, and chemical composition as a priori information in a bootstrap process that resolves the ambiguities associated with overlapping reflections. The measured ratios of reflections that can be resolved experimentally are used to refine the position, the shape, and the orientation of low-resolution molecular structures within the unit cell, in leading to the resolution of the overlapping reflections. The molecular model is then made progressively more sophisticated as additional diffraction information is included in the analysis. We apply our method to the recovery of the structure of the bacteriorhodopsin molecule (bR) to a resolution of 7 Å using experimental data obtained from two-dimensional purple membrane crystals. The approach can be used to determine the structure factors directly or to provide reliable low-resolution phase information that can be refined further by the conventional methods of protein crystallography. PMID:21154412

  2. Effect of microfibril twisting on theoretical powder diffraction patterns of cellulose Iβ

    PubMed

    Hadden, Jodi A; French, Alfred D; Woods, Robert J

    2014-04-01

    Previous studies of calculated diffraction patterns for cellulose crystallites suggest that distortions that arise once models have been subjected to MD simulation are the result of both microfibril twisting and changes in unit cell dimensions induced by the empirical force field; to date, it has not been possible to separate the individual contributions of these effects. To provide a better understanding of how twisting manifests in diffraction data, the present study demonstrates a method for generating twisted and linear cellulose structures that can be compared without the bias of dimensional changes, allowing assessment of the impact of twisting alone. Analysis of unit cell dimensions, microfibril volume, hydrogen bond patterns, glycosidic torsion angles, and hydroxymethyl group orientations confirmed that the twisted and linear structures collected with this method were internally consistent, and theoretical powder diffraction patterns for the two were shown to be effectively indistinguishable. These results indicate that differences between calculated patterns for the crystal coordinates and twisted structures from MD simulation can result entirely from changes in unit cell dimensions, and not from microfibril twisting alone. Although powder diffraction patterns for models in the 81-chain size regime were shown to be unaffected by twisting, suggesting that a modest degree of twist is not inconsistent with experimental data, it may be that other diffraction techniques are capable of detecting this structural difference. Until such time as definitive experimental evidence comes to light, the results of this study suggest that both twisted and linear microfibrils may represent an appropriate model for cellulose Iβ.

  3. Pulsed neutron powder diffraction at high pressure by a capacity-increased sapphire anvil cell

    NASA Astrophysics Data System (ADS)

    Okuchi, Takuo; Yoshida, Masashi; Ohno, Yoshiki; Tomioka, Naotaka; Purevjav, Narangoo; Osakabe, Toyotaka; Harjo, Stefanus; Abe, Jun; Aizawa, Kazuya; Sasaki, Shigeo

    2013-12-01

    A new design of opposed anvil cell for time-of-flight neutron powder diffraction was prepared for use at advanced pulsed sources. A couple of single-crystal sapphire sphere anvils and a gasket of fully hardened Ti-Zr null alloy were combined to compress 35 mm3 of sample volume to 1 GPa and 11 mm3 to 2 GPa of pressures, respectively. A very high-quality powder diffraction pattern was obtained at Japan Proton Accelerator Research Complex for a controversial high pressure phase of methane hydrate. The counting statistics, resolution, absolute accuracy and d-value range of the pattern were all improved to be best suitable for precise structure refinement. The sample is optically accessible to be measured by Raman and fluorescence spectroscopy during and after compression. The current cell will be an alternative choice to study hydrogenous materials of complex structures that are stable at the described pressure regime.

  4. Real-time powder diffraction studies of energy materials under non-equilibrium conditions

    PubMed Central

    Peterson, Vanessa K.; Auckett, Josie E.; Pang, Wei-Kong

    2017-01-01

    Energy materials form the central part of energy devices. An essential part of their function is the ability to reversibly host charge or energy carriers, and analysis of their phase composition and structure in real time under non-equilibrium conditions is mandatory for a full understanding of their atomic-scale functional mechanism. Real-time powder diffraction is increasingly being applied for this purpose, forming a critical step in the strategic chemical engineering of materials with improved behaviour. This topical review gives examples of real-time analysis using powder diffraction of rechargeable battery electrodes and porous sorbent materials used for the separation and storage of energy-relevant gases to demonstrate advances in the insights which can be gained into their atomic-scale function.

  5. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    SciTech Connect

    Cui, J.; Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J.; Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D.; Marinescu, M.; Huang, Q. Z.; Wu, H.; Vuong, N. V.; Liu, J. P.

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μB at 50 K and 300 K, respectively.

  6. Implementation and use of Robust Refinement in Powder Diffraction in the Presence of Impurities

    SciTech Connect

    Stone, K.; Lapidus, S; Stephens, P

    2009-01-01

    A modification to the usual least-squares analysis is implemented for the robust refinement of structural parameters from powder diffraction data in the presence of unmodeled impurities. This is accomplished in the program TOPAS-Academic by an iterative reweighting of the data as the model is refined. The method is tested and characterized using mixtures of known materials, acetaminophen and ibuprofen. The technique is also used to refine two previously unknown structures.

  7. Application of Laser Plasma X-rays to Time-resolved Debye-Sherrer Diffraction

    SciTech Connect

    Kanegae, Y.; Kinoshita, K.; Hosokai, T.; Ohkubo, T.; Yoshii, K.; Ueda, T.; Watanabe, T.; Zhidkov, A.; Uesaka, M.

    2003-08-26

    We have studied Laser Plasma X-ray(LPX) in order to apply to time-resolved protein crystallography. We consider that our works will contribute for application of X-ray pulse and breed short pulse handling techniques. LPX pulse duration is femto{approx}pico-second. So, we expect that the laser plasma X-ray system has the potential to satisfy the requirement of time-scale to resolve the early period of protein's structural change. We need about more than 1012photns/shot X-ray to get a diffraction image of organics. We have reinforced our LPX system to get a diffraction image. Now, we try laser pre-pulse effect by experiments and calculations. As the first step of our aim, we will obtain the Debey-Sherrer diffraction image of a biological sample.

  8. Chemical analyses and x-ray diffraction patterns of powders and films of chloroaluminum phthalocyanine

    NASA Astrophysics Data System (ADS)

    Cote, Roland; Denes, G.; Gastonguay, Louis; Dodelet, Jean-Pol

    1992-12-01

    Fine powders and sublimed films (15 micrometers thick) of pure chloroaluminum phthalocyanine (ClAlPc) undergo both, chemical reaction and structural modification, when immersed in aqueous solutions containing anions (I3-/I- or Br- at various acid pH values). The x-ray diffraction diagrams of powder and films of untreated ClAlPc exhibit a strong characteristic peak corresponding to a d-spacing of 3.29 angstrom. A 48 h. immersion of ClAlPc (powder or film) resulted in the appearance of a new peak at 3.45 angstrom in the diffraction diagram. The peak intensity at d equals 3.45 angstrom is only 11% (powder) or 47% (film) of the main peak intensity at d equals 3.29 angstrom. It clearly shows that the crystal structure of ClAlPc has only been partially modified in both cases. However, the modification is more complete for the film than for the powder. Chemical analyses by neutron activation were performed on fine powders of ClAlPc before and after immersion. For instance ClAlPc absorbs 7.6% by weight of iodine after 24 h of immersion in I3-/I- (0.005 M/0.4 M) redox electrolyte at pH 1.0. The decrease in the chlorine content of untreated ClAlPc from 6.1% to 3.7% after immersion could be explained in terms of an hydrolysis reaction of some ClAlPc. These results lead us to a model where by the surface of the ClAlPc crystallites would be hydrolyzed to HOAlPc and heavily doped with anions taken up from the aqueous solution. These transformations improve the photoactivity of the material.

  9. An X-ray diffraction analysis of crystallised whey and whey-permeate powders.

    PubMed

    Nijdam, Justin; Ibach, Alexander; Eichhorn, Klaus; Kind, Matthias

    2007-11-26

    Amorphous whey, whey-permeate and lactose powders have been crystallised at various air temperatures and humidities, and these crystallised powders have been examined using X-ray diffraction. The most stable lactose crystal under normal storage conditions, alpha-lactose monohydrate, forms preferentially in whey and whey-permeate powders at 50 degrees C, provided sufficient moisture is available, whereas anhydrous beta-lactose and mixed anhydrous lactose crystals, which are unstable under normal storage conditions, form preferentially at 90 degrees C. Thus, faster crystallisation at higher temperatures is offset by the formation of lactose-crystal forms that are less stable under normal storage conditions. Very little alpha-lactose monohydrate crystallised in the pure lactose powders over the range of temperatures and humidities tested, because the crystallisation of alpha- and beta-lactose is considerably more rapid than the mutarotation of beta- to alpha-lactose in the amorphous phase and the hydration of alpha-lactose during crystallisation. Protein and salts hinder the crystallisation process, which provides more time for mutarotation and crystal hydration in the whey and whey-permeate powders.

  10. On the origin of sharp peaks in the X-ray diffraction patterns of xanthan powders.

    PubMed

    Lad, M; Todd, T; Morris, G A; MacNaughtan, W; Sworn, G; Foster, T J

    2013-08-15

    A series of xanthans containing different levels of the charged group pyruvate has been examined. The X-ray diffraction patterns of the powders of these materials had different levels of a sharp pattern superimposed on an amorphous background. As the moisture content increased so the intensity of the sharp pattern increased up to a level between 20% and 40% moisture content where the sharp pattern disappeared. X-ray diffraction pattern identification software and an inorganic X-ray diffraction database showed the origin of the sharp peaks to be due to sodium sulphate polymorphs. The behaviour of the xanthans was thought to be due to the differences in charge on the molecule; however, the increase in the crystalline component observed with increased amounts of water was unexpected. The possibility of the drying of samples was considered but the interplay between ions, the charged polymer and the water present was considered necessary to more closely describe the results.

  11. Time-resolved coherent X-ray diffraction imaging of surface acoustic waves.

    PubMed

    Nicolas, Jan-David; Reusch, Tobias; Osterhoff, Markus; Sprung, Michael; Schülein, Florian J R; Krenner, Hubert J; Wixforth, Achim; Salditt, Tim

    2014-10-01

    Time-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50 ps (pulse length).

  12. Time-resolved coherent X-ray diffraction imaging of surface acoustic waves

    PubMed Central

    Nicolas, Jan-David; Reusch, Tobias; Osterhoff, Markus; Sprung, Michael; Schülein, Florian J. R.; Krenner, Hubert J.; Wixforth, Achim; Salditt, Tim

    2014-01-01

    Time-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50 ps (pulse length). PMID:25294979

  13. Time-resolved studies of impact-initiated combustion in aluminum powder compacts

    NASA Astrophysics Data System (ADS)

    Breidenich, Jennifer; Dixon, Sean; Aydelotte, Brady; Thadhani, Naresh

    2011-06-01

    The mechanisms of combustion reaction occurring under impact loading of aluminum powder compacts are studied using UV/Vis spectroscopy to gain time-resolved chemical information. Impact experiments performed on aluminum powder compacts reveal light emission due to reaction at velocities greater than 400m/s in air, while no reaction is observed in a vacuum (50mTorr). Light emission and reaction occurrence is also sensitive to the density of the Al powder compacts. Upon combustion, wavelengths indicative of the well-known reaction Al +O2 --> AlO + O , a sharp doublet at 398 nm and multiple broad peaks between 420 and 500 nm, are observed. Microsecond time-resolved chemical information is gained through analysis of these wavelengths using a spectrometer coupled with an electron multiplier CCD camera. The impact initiated reaction is also monitored by high speed imaging of transient deformation profiles which are compared to those predicted using numerical simulations employing ANSYS-AUTODYN-3D computer code. The insight obtained from the combination of these analyses of impact-initiated combustion reaction in aluminum powder compacts will be presented. Funded by DTRA, Grant No. HDTRA1-10-1-0038

  14. Assessment of the Stoichiometry of Multicomponent Crystals Using Only X-ray Powder Diffraction Data.

    PubMed

    Maguire, Courtney K; Brunskill, Andrew P J

    2015-06-01

    Knowledge of the unit cell volume of a crystalline form and the expected space filling requirements of an API molecule can be used to determine if a crystalline material is likely to be multicomponent, such as a solvate, hydrate, salt, or a co-crystal. The unit cell information can be readily accessed from powder diffraction data alone utilizing powder indexing methodology. If the unit cell has additional space not likely attributable to the API entity, then there is either a void or another component within the crystal lattice. This "leftover" space can be used to determine the likely stoichiometry of the additional component. A simple approach for calculating the expected required volume for a given molecule within a crystal using an atom based additive approach will be discussed. Coupling this estimation with the actual unit cell volumes and space group information obtained from powder indexing allows for the rapid evaluation of the likely stoichiometry of multicomponent crystals using diffraction data alone. This approach is particularly useful for the early assessment of new phases during salt, co-crystal, and polymorph screening, and also for the characterization of stable and unstable solvates.

  15. Fast X-ray powder diffraction on I11 at Diamond.

    PubMed

    Thompson, Stephen P; Parker, Julia E; Marchal, Julien; Potter, Jonathan; Birt, Adrian; Yuan, Fajin; Fearn, Richard D; Lennie, Alistair R; Street, Steven R; Tang, Chiu C

    2011-07-01

    The commissioning and performance characterization of a position-sensitive detector designed for fast X-ray powder diffraction experiments on beamline I11 at Diamond Light Source are described. The detecting elements comprise 18 detector-readout modules of MYTHEN-II silicon strip technology tiled to provide 90° coverage in 2θ. The modules are located in a rigid housing custom designed at Diamond with control of the device fully integrated into the beamline data acquisition environment. The detector is mounted on the I11 three-circle powder diffractometer to provide an intrinsic resolution of Δ2θ approximately equal to 0.004°. The results of commissioning and performance measurements using reference samples (Si and AgI) are presented, along with new results from scientific experiments selected to demonstrate the suitability of this facility for powder diffraction experiments where conventional angle scanning is too slow to capture rapid structural changes. The real-time dehydrogenation of MgH(2), a potential hydrogen storage compound, is investigated along with ultrafast high-throughput measurements to determine the crystallite quality of different samples of the metastable carbonate phase vaterite (CaCO(3)) precipitated and stabilized in the presence of amino acid molecules in a biomimetic synthesis process.

  16. Powder X-ray diffraction detection on a paper-based platform.

    PubMed

    Ouyang, Liangfei; Liu, Qian; Xu, Chaoping; Liu, Changgui; Liang, Heng

    2017-03-01

    We developed paper-based powder X-ray diffraction (PP-XRD) to implement phase identification and/or crystal structure determination on paper-based platforms. These aims are not possible with other paper-based detectors, such as Raman spectroscopy and mass spectrometry. PP-XRD overcomes these limitations. Here we reported the simple and low-cost in situ PP-XRD protocol for phase identifications of inorganic and organic materials. We demonstrated that sample amounts of lead nitrate on paper substrate can be reduced into 1/30 of conventional ones by using the standard glass substrate at the same signal-to-noise ratio (S/N) of the X-ray diffraction (XRD) pattern. The paper-based method was comparable in sample quantity and intensity with zero background holder method, even though single crystal Si(100) substrate as zero background holder was used for the specimen preparation of CTAB (C19H42BrN). More importantly, paper substrates helped reduce preferred orientation that was generally present in routine powder XRD. Also, combined with paper chromatography, overlap peaks were eliminated in the XRD detection patterns of lead nitrate and cobalt nitrate hexahydrate. This new PP-XRD protocol may accelerate the process to identify phase or determine the molecular structures of new materials using trace sample directly. It also includes a hyphenated technique of powder XRD with a simple paper-based microfluidic separation of chemical solutions.

  17. Neutron and X-ray powder diffraction study of skutterudite thermoelectrics

    SciTech Connect

    Wang, H.; Kirkham, M. J.; Watkins, T. R.; Payzant, E. A.; Salvador, J. R.; Thompson, A. J.; Sharp, J.; Brown, D.; Miller, D.

    2016-02-17

    N- and p-type filled-skutterudite materials prepared for thermoelectric power generation modules were analyzed by neutron diffraction at the POWGEN beam line of the Spallation Neutron Source (SNS) and X-ray diffraction (XRD). The skutterudite powders were processed by melt spinning, followed by ball milling and annealing. The n-type material consists of Ba–Yb–Co–Sb and the p-type material consists of Di–Fe–Ni–Sb or Di–Fe–Co–Sb (Di = didymium, an alloy of Pr and Nd). Powders for prototype module fabrication from General Motors and Marlow Industries were analyzed in this study. XRD and neutron diffraction studies confirm that both the n- and p-type materials have cubic symmetry. Structural Rietveld refinements determined the lattice parameters and atomic parameters of the framework and filler atoms. The cage filling fraction was found to depend linearly on the lattice parameter, which in turn depends on the average framework atom size. Ultimately, this knowledge may allow the filling fraction of these skutterudite materials to be purposefully adjusted, thereby tuning the thermoelectric properties.

  18. Neutron and X-ray powder diffraction study of skutterudite thermoelectrics

    DOE PAGES

    Wang, H.; Kirkham, M. J.; Watkins, T. R.; ...

    2016-02-17

    N- and p-type filled-skutterudite materials prepared for thermoelectric power generation modules were analyzed by neutron diffraction at the POWGEN beam line of the Spallation Neutron Source (SNS) and X-ray diffraction (XRD). The skutterudite powders were processed by melt spinning, followed by ball milling and annealing. The n-type material consists of Ba–Yb–Co–Sb and the p-type material consists of Di–Fe–Ni–Sb or Di–Fe–Co–Sb (Di = didymium, an alloy of Pr and Nd). Powders for prototype module fabrication from General Motors and Marlow Industries were analyzed in this study. XRD and neutron diffraction studies confirm that both the n- and p-type materials have cubicmore » symmetry. Structural Rietveld refinements determined the lattice parameters and atomic parameters of the framework and filler atoms. The cage filling fraction was found to depend linearly on the lattice parameter, which in turn depends on the average framework atom size. Ultimately, this knowledge may allow the filling fraction of these skutterudite materials to be purposefully adjusted, thereby tuning the thermoelectric properties.« less

  19. A Mössbauer and X-ray powder diffraction study of some ferrous hematinics.

    PubMed

    Coe, E M; Bowen, L H; Bereman, R D

    1995-06-01

    Iron deficiency anemia is a relatively common illness that can arise from a number of different causes. Three ferrous salts are usually used in its treatment: ferrous fumarate, gluconate, and sulfate. They are administered orally and are relatively well tolerated. These hematinics have been studied by Mössbauer spectroscopy and X-ray powder diffraction, and can easily be distinguished by both techniques. It was found that the two ferrous sulfates studied (Eckerd and SmithKline Beckman Co.) most closely resemble the monohydrate by comparison of the X-ray powder pattern with those of the JCPDS. Both the ferrous fumarate (Femiron) and gluconate (Spring Valley) had approximately 10% ferric iron present. To the authors' knowledge, this is the first reported Mössbauer spectrum for ferrous fumarate.

  20. Development of MnBi permanent magnet: neutron diffraction of MnBi powder

    SciTech Connect

    Cui, Jun; Choi, Jung-Pyung; Li, Guosheng; Polikarpov, Evgueni; Darsell, Jens T.; Kramer, Matthew J.; Zarkevich, Nikolai; Wang, L. L.; Johnson, D. D.; Marinescu, Melania; Huang, Qingzhen; Wu, Hui; Vuong, Nguyen V.; Liu, J.Ping

    2014-03-05

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained power. The result shows that the purity of the obtained powder is about 91wt.% at 300K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μB at 50 K and 300 K respectively.

  1. Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals

    SciTech Connect

    Haugh, M. J. Jacoby, K. D.; Wu, M.; Loisel, G. P.

    2014-11-15

    This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

  2. Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals.

    PubMed

    Haugh, M J; Wu, M; Jacoby, K D; Loisel, G P

    2014-11-01

    This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

  3. Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystalsa)

    NASA Astrophysics Data System (ADS)

    Haugh, M. J.; Wu, M.; Jacoby, K. D.; Loisel, G. P.

    2014-11-01

    This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

  4. Recombination of photodissociated iodine: A time-resolved x-ray-diffraction study

    SciTech Connect

    Wulff, M.; Bratos, S.; Plech, A.; Vuilleumier, R.; Mirloup, F.; Lorenc, M.; Kong, Q.; Ihee, H.

    2006-01-21

    A time-resolved x-ray-diffraction experiment is presented that aims to study the recombination of laser-dissociated iodine molecules dissolved in CCl{sub 4}. This process is monitored over an extended time interval from pico- to microseconds. The variations of atom-atom distances are probed with a milliangstrom resolution. A recent theory of time-resolved x-ray diffraction is used to analyze the experimental data; it employs the correlation function approach of statistical mechanics. The most striking outcome of this study is the experimental determination of time-dependent I-I atom-atom distribution functions. The structure of the CCl{sub 4} solvent changes simultaneously; the solvent thus appears as a reaction partner rather than an inert medium hosting it. Thermal expansion of the system is nonuniform in time, an effect due to the presence of the acoustic horizon. One concludes that a time-resolved x-ray diffraction permits real-time visualization of solvent and solute motions during a chemical reaction.

  5. Measuring the X-ray Resolving Power of Bent Potassium Acid Phthalate Diffraction Crystals

    SciTech Connect

    Haugh, M. J.; Wu, M.; Jacoby, K. D.; Loisel, G. P.

    2014-11-01

    This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories (SNL) in Albuquerque, NM. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a dual goniometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.

  6. Ultrafast Dynamics of a Charge Density Wave via Time-Resolved Resonant Diffraction

    NASA Astrophysics Data System (ADS)

    Moore, R. G.

    2012-02-01

    Understanding the emergence of collective behavior in correlated electron systems remains at the forefront of modern condensed matter physics. The key to such an understanding is unraveling the contributions from the coupling degrees of freedom in exotic many body states. Density waves, both of charge and spin, have been studied for decades and a wealth of information and insight has been gained. However, there are still open questions that need to be solved for a complete description of the phenomena as there are several existing density wave systems that exhibit prototypical behavior while violating traditional theory. Ultrafast dynamics of such a system, TbTe3, has been investigated via time-resolved resonant diffraction at the SXR endstation at LCLS. Oscillations of the amplitude mode and coherent phonons have been observed previously in time resolved photoemission and reflectivity measurement but, here we reveal a direct observation of the lattice response via resonant diffraction. Watching dynamics of the two dimensional Te plane density wave diffraction peak at a resonant energy of a bystander Tb atom reveals new insights into the coupling responsible for the formation of the state. Results and comparison with previous time resolved measurements will be discussed.

  7. Neutron powder diffraction studies as a function of temperature of structure II hydrate formed from propane

    USGS Publications Warehouse

    Rawn, C.J.; Rondinone, A.J.; Chakoumakos, B.C.; Circone, S.; Stern, L.A.; Kirby, S.H.; Ishii, Y.

    2003-01-01

    Neutron powder diffraction data confirm that hydrate samples synthesized with propane crystallize as structure type II hydrate. The structure has been modeled using rigid-body constraints to describe C3H8 molecules located in the eight larger polyhedral cavities of a deuterated host lattice. Data were collected at 12, 40, 100, 130, 160, 190, 220, and 250 K and used to calculate the thermal expansivity from the temperature dependence of the lattice parameters. The data collected allowed for full structural refinement of atomic coordinates and the atomic-displacement parameters.

  8. TSX-PLUS MULTI-TASKING UPGRADE FOR THE NICOLET L-11 POWDER DIFFRACTION SYSTEM.

    USGS Publications Warehouse

    Fitzpatrick, J.; Queen, David L.

    1985-01-01

    In August of 1982, a single-user, dual-translator, automated powder diffraction system was purchased by the Denver Research Institute for use on project work in the Chemical and Materials Sciences Division. Within a short period of time, the system had already become saturated with users. Scheduling conflicts arose. In view of these problems, an answer was sought in the form of hardware and software changes which would allow many users access to the system simultaneously. A low-cost, minimum impact solution was eventually found. The elements of the solution are reported.

  9. A GUINIER CAMERA FOR SR POWDER DIFFRACTION: HIGH RESOLUTION AND HIGH THROUGHPUT.

    SciTech Connect

    SIDDONS,D.P.; HULBERT, S.L.; STEPHENS, P.W.

    2006-05-28

    The paper describe a new powder diffraction instrument for synchrotron radiation sources which combines the high throughput of a position-sensitive detector system with the high resolution normally only provided by a crystal analyzer. It uses the Guinier geometry which is traditionally used with an x-ray tube source. This geometry adapts well to the synchrotron source, provided proper beam conditioning is applied. The high brightness of the SR source allows a high resolution to be achieved. When combined with a photon-counting silicon microstrip detector array, the system becomes a powerful instrument for radiation-sensitive samples or time-dependent phase transition studies.

  10. On the reliability of powder diffraction Line Profile Analysis of plastically deformed nanocrystalline systems

    PubMed Central

    Rebuffi, Luca; Troian, Andrea; Ciancio, Regina; Carlino, Elvio; Amimi, Amine; Leonardi, Alberto; Scardi, Paolo

    2016-01-01

    An iron-molybdenum alloy powder was extensively deformed by high energy milling, so to refine the bcc iron domain size to nanometer scale (~10 nm) and introduce a strong inhomogeneous strain. Both features contribute to comparable degree to the diffraction peak profile broadening, so that size and strain contributions can be easily separated by exploiting their different dependence on the diffraction angle. To assess the reliability of Line Profile Analysis, results were compared with evidence from other techniques, including scanning and transmission electron microscopy and X-ray small angle scattering. Results confirm the extent of the size broadening effect, whereas molecular dynamics simulations provide insight into the origin of the local atomic, inhomogeneous strain, pointing out the role of dislocations, domain boundaries and interactions among crystalline domains. PMID:26860471

  11. Studies of clays and clay minerals using x-ray powder diffraction and the Rietveld method

    SciTech Connect

    Bish, D.L.

    1993-09-01

    The Rietveld method was originally developed (Rietveld, 1967, 1969) to refine crystal structures using neutron powder diffraction data. Since then, the method has been increasingly used with X-ray powder diffraction data, and today it is safe to say that this is the most common application of the method. The method has been applied to numerous natural and synthetic materials, most of which do not usually form crystals large enough for study with single-crystal techniques. It is the ability to study the structures of materials for which sufficiently large single crystals do not exist that makes the method so powerful and popular. It would thus appear that the method is ideal for studying clays and clay minerals. In many cases this is true, but the assumptions implicit in the method and the disordered nature of many clay minerals can limit titsapplicability. This chapter will describe the Rietveld method, emphasizing the assumptions important for the study of disordered materials, and it will outline the potential applications of the method to these minerals. These applications include, in addition to the refinement of crystal structures, quantitative analysis of multicomponent mixtures, analysis of peak broadening, partial structure solution, and refinement of unit-cell parameters.

  12. Crystallography of Powdered Samples at High Pressure: Practical Aspects of Diffraction Data Collection and Analysis.

    NASA Astrophysics Data System (ADS)

    Crichton, W. A.

    2006-12-01

    In this presentation we will give an overview of some typical techniques used to collect, and to analyse, angle- dispersive x-ray diffraction data from powdered samples under high-pressure (and temperature) conditions. The presentation will have a practical basis, using data collected from samples at high-pressure and temperature conditions using large-volume presses and diamond-anvil cells that have been either resistively or laser-heated. We will show how these experiments have been optimised to obtain a variety of different experimental results (phase identification and phase diagram mapping, EoS measurement, structure solution, etc). We will demonstrate different analysis procedures, explain their methodology and, as often as possible, present these analyses with software that is freely available. Demonstration of the techniques will take the audience though basic elements of diffraction data collection and methods of phase identification to indexing and unit-cell refinement, though some common structure solution methods and Rietveld refinement strategies. We will also discuss methods for collecting better data and maximising the information that can be gleaned from powdered samples (of minerals, ceramics, element, glasses, liquids and other materials) at high pressure.

  13. Synchrotron X-ray Powder Diffraction and Absorption Spectroscopy in Pulsed Magnetic Fields with Milliseconds Duration

    NASA Astrophysics Data System (ADS)

    Vanacken, J.; Detlefs, C.; Mathon, O.; Frings, P.; Duc, F.; Lorenzo, J. E.; Nardone, M.; Billette, J.; Zitouni, A.; Dominguez, M.-C.; Herczeg, J.; Bras, W.; Moshchalkov, V. V.; Rikken, G.

    2007-03-01

    X-ray Powder Diffraction and X-ray Absorption Spectroscopy experiments (WAS) and X-ray magnetic circular dichroism (XMCD) experiments were carried out at the ESRF DUBBLE beam line (BM26) and at the energy dispersive beam line (ID24), respectively. A mobile pulse generator, developed at the LNCMP, delivered 110kJ to the load coil, which was sufficient to generate peak fields of 30T with a rise time of about 5 ms. A liquid He flow cryostat allowed us to vary the sample temperature accurately between 4.2K and 300K. Powder diffraction patterns of TbVO4 were recorded in a broad temperature range using 21 keV monochromatic X-rays and using an on-line image plate detector. We observed the suppression of the Jahn-Teller structural distortion in TbVO4 due to the high magnetic pulsed field. XAS spectra could be measured and finite XMCD signals, directly proportional to the magnetic moment on the Gd absorber atom, were measured in thin Gd foils. Thanks to its element and orbital selectivity, XMCD proofs to be very useful in probing the magnetic properties and due to the strong brilliance of the synchrotron beam, the signals can be measured even in the ms range.

  14. Optimizations in angular dispersive neutron powder diffraction using divergent beam geometries

    NASA Astrophysics Data System (ADS)

    Buchsteiner, Alexandra; Stüßer, Norbert

    2009-01-01

    Angular dispersive neutron powder diffractometers are usually built using beam divergencies defined by Soller type collimators. To account for the needs of resolution for crystal structure refinement a good in-pile collimation α1, a high take-off angle above 90∘ at the monochromator and a good collimation α3 in front of the detector bank are chosen whereas the value of α2 for the collimation between monochromator and sample is less crucial. During the last years new strategies were developed at our institute using wide divergent beam geometries defined by fan collimators or slit-type diaphragms which correlate ray direction and wavelength within the beam. Here we present the performance of a newly developed fan collimator, which enables one to adjust the opening of the collimator channels on both sides independently. This fan collimator is positioned in front of the monochromator at the instrument E6 at the Helmholtz Centre Berlin (formerly Hahn-Meitner-Institut Berlin). It will be shown that control of the beam divergency allows optimization of the resolution in a large angular diffraction range. Hence the resolution and intensity can be adapted to the needs of powder diffraction. Monte Carlo simulations using McStas are used to check and prove the optimal setting of the instrument. We obtain a very good agreement between experimental and simulated data and demonstrate the superior outcome of the new instrument configuration with respect to Soller type instruments.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Intramolecular electron diffraction in vibrationally resolved K-shell photoionization of methane

    NASA Astrophysics Data System (ADS)

    Plésiat, Etienne; Argenti, Luca; Kukk, Edwin; Miron, Catalin; Ueda, Kiyoshi; Decleva, Piero; Martín, Fernando

    2012-02-01

    Current techniques based on x-ray or electron diffraction are successfully employed for structure determination in condensed matter but are sometimes limited when applied to low density media such as the gas phase. Here we show that vibrationally resolved photoelectron spectroscopy based on x rays generated by third generation synchrotron light sources can be used to infer the structure of isolated molecules in a simple and efficient way. In particular, we show that vibrational ratios obtained from inner shell C 1s photoelectron spectroscopy of isolated methane molecules exhibit pronounced oscillations that are the fingerprints of electron diffraction by the surrounding atomic centers, thus providing the necessary information for the determination of the molecular geometry.

  17. Time Resolved X-Ray Diffraction of Reactive Solids Under Dynamic Loadings

    NASA Astrophysics Data System (ADS)

    Yoo, Choong-Shik

    2015-06-01

    We present novel time-resolved (TR) x-ray diffraction and TR Raman spectroscopy capable of probing structural and chemical evolutions of solids undergoing chemical and phase transformations. These methods are applicable to a wide range of dynamic experiments to study both single event phenomena of solids under thermal, electric or mechanical impact conditions and non-single event phenomena under dynamic-diamond anvil cell (d-DAC) and high frequency pulse (or ramp) laser-heated DAC. In this talk, relevant technology developments are described with several examples of our recent studies on reactive metals and dense molecular systems, which are synergistic to many proposed activities to develop dynamic synchrotron x-ray diffraction capabilities centered at advanced third and fourth generation light sources.

  18. Electro-optic sampling for time resolving relativistic ultrafast electron diffraction

    SciTech Connect

    Scoby, C. M.; Musumeci, P.; Moody, J.; Gutierrez, M.; Tran, T.

    2009-01-22

    The Pegasus laboratory at UCLA features a state-of-the-art electron photoinjector capable of producing ultrashort (<100 fs) high-brightness electron bunches at energies of 3.75 MeV. These beams recently have been used to produce static diffraction patterns from scattering off thin metal foils, and it is foreseen to take advantage of the ultrashort nature of these bunches in future pump-probe time-resolved diffraction studies. In this paper, single shot 2-d electro-optic sampling is presented as a potential technique for time of arrival stamping of electron bunches used for diffraction. Effects of relatively low bunch charge (a few 10's of pC) and modestly relativistic beams are discussed and background compensation techniques to obtain high signal-to-noise ratio are explored. From these preliminary tests, electro-optic sampling is suitable to be a reliable nondestructive time stamping method for relativistic ultrafast electron diffraction at the Pegasus lab.

  19. Developments in time-resolved high pressure x-ray diffraction using rapid compression and decompression

    SciTech Connect

    Smith, Jesse S.; Sinogeikin, Stanislav V.; Lin, Chuanlong; Rod, Eric; Bai, Ligang; Shen, Guoyin

    2015-07-15

    Complementary advances in high pressure research apparatus and techniques make it possible to carry out time-resolved high pressure research using what would customarily be considered static high pressure apparatus. This work specifically explores time-resolved high pressure x-ray diffraction with rapid compression and/or decompression of a sample in a diamond anvil cell. Key aspects of the synchrotron beamline and ancillary equipment are presented, including source considerations, rapid (de)compression apparatus, high frequency imaging detectors, and software suitable for processing large volumes of data. A number of examples are presented, including fast equation of state measurements, compression rate dependent synthesis of metastable states in silicon and germanium, and ultrahigh compression rates using a piezoelectric driven diamond anvil cell.

  20. Atomic motion of resonantly vibrating quartz crystal visualized by time-resolved X-ray diffraction

    SciTech Connect

    Aoyagi, Shinobu; Osawa, Hitoshi; Sugimoto, Kunihisa; Fujiwara, Akihiko

    2015-11-16

    Transient atomic displacements during a resonant thickness-shear vibration of AT-cut α-quartz are revealed by time-resolved X-ray diffraction under an alternating electric field. The lattice strain resonantly amplified by the alternating electric field is ∼10{sup 4} times larger than that induced by a static electric field. The resonantly amplified lattice strain is achieved by fast displacements of oxygen anions and collateral resilient deformation of Si−O−Si angles bridging rigid SiO{sub 4} tetrahedra, which efficiently transduce electric energy into elastic energy.

  1. Time-resolved X-ray diffraction of Ti in dynamic-DAC

    NASA Astrophysics Data System (ADS)

    Tomasino, Dane; Yoo, Choong-Shik

    2017-01-01

    Understanding the dynamic response of solids under extreme conditions of pressure, temperature and strain rate is a fundamental scientific quest and a basic research need in materials science. Specifically, obtaining an atomistic description of structural and chemical changes of solids under rapid heating and/or compression over a large temporal, spatial and energy range is challenging but critical to understanding material stability or metastable structure, chemical mechanism, transition dynamic, and mechanical deformation. In this paper, we present time-resolved synchrotron x-ray diffraction probing the structural evolution of Ti across the α-ω phase transition in dynamic-diamond anvil cell.

  2. X-ray diffraction in temporally and spatially resolved biomolecular science.

    PubMed

    Helliwell, John R; Brink, Alice; Kaenket, Surasak; Starkey, Victoria Laurina; Tanley, Simon W M

    2015-01-01

    Time-resolved Laue protein crystallography at the European Synchrotron Radiation Facility (ESRF) opened up the field of sub-nanosecond protein crystal structure analyses. There are a limited number of such time-resolved studies in the literature. Why is this? The X-ray laser now gives us femtosecond (fs) duration pulses, typically 10 fs up to ∼50 fs. Their use is attractive for the fastest time-resolved protein crystallography studies. It has been proposed that single molecules could even be studied with the advantage of being able to measure X-ray diffraction from a 'crystal lattice free' single molecule, with or without temporal resolved structural changes. This is altogether very challenging R&D. So as to assist this effort we have undertaken studies of metal clusters that bind to proteins, both 'fresh' and after repeated X-ray irradiation to assess their X-ray-photo-dynamics, namely Ta6Br12, K2PtI6 and K2PtBr6 bound to a test protein, hen egg white lysozyme. These metal complexes have the major advantage of being very recognisable shapes (pseudo spherical or octahedral) and thereby offer a start to (probably very difficult) single molecule electron density map interpretations, both static and dynamic. A further approach is to investigate the X-ray laser beam diffraction strength of a well scattering nano-cluster; an example from nature being the iron containing ferritin. Electron crystallography and single particle electron microscopy imaging offers alternatives to X-ray structural studies; our structural studies of crustacyanin, a 320 kDa protein carotenoid complex, can be extended either by electron based techniques or with the X-ray laser representing a fascinating range of options. General outlook remarks concerning X-ray, electron and neutron macromolecular crystallography as well as 'NMR crystallography' conclude the article.

  3. Compact low power infrared tube furnace for in situ X-ray powder diffraction.

    PubMed

    Doran, A; Schlicker, L; Beavers, C M; Bhat, S; Bekheet, M F; Gurlo, A

    2017-01-01

    We describe the development and implementation of a compact, low power, infrared heated tube furnace for in situ powder X-ray diffraction experiments. Our silicon carbide (SiC) based furnace design exhibits outstanding thermal performance in terms of accuracy control and temperature ramping rates while simultaneously being easy to use, robust to abuse and, due to its small size and low power, producing minimal impact on surrounding equipment. Temperatures in air in excess of 1100 °C can be controlled at an accuracy of better than 1%, with temperature ramping rates up to 100 °C/s. The complete "add-in" device, minus power supply, fits in a cylindrical volume approximately 15 cm long and 6 cm in diameter and resides as close as 1 cm from other sensitive components of our experimental synchrotron endstation without adverse effects.

  4. Kinetics of Methane Hydrate Decomposition Studied via in Situ Low Temperature X-ray Powder Diffraction

    SciTech Connect

    Everett, Susan M; Rawn, Claudia J; Keffer, David J.; Mull, Derek L; Payzant, E Andrew; Phelps, Tommy Joe

    2013-01-01

    Gas hydrates are known to have a slowed decomposition rate at ambient pressure and temperatures below the melting point of ice termed self-preservation or anomalous preservation. As hydrate exothermically decomposes, gas is released and water of the clathrate cages transforms into ice. Two regions of slowed decomposition for methane hydrate, 180 200 K and 230 260 K, were observed, and the kinetics were studied by in situ low temperature x-ray powder diffraction. The kinetic constants for ice formation from methane hydrate were determined by the Avrami model within each region and activation energies, Ea, were determined by the Arrhenius plot. Ea determined from the data for 180 200 K was 42 kJ/mol and for 230 260 K was 22 kJ/mol. The higher Ea in the colder temperature range was attributed to a difference in the microstructure of ice between the two regions.

  5. Compact low power infrared tube furnace for in situ X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Doran, A.; Schlicker, L.; Beavers, C. M.; Bhat, S.; Bekheet, M. F.; Gurlo, A.

    2017-01-01

    We describe the development and implementation of a compact, low power, infrared heated tube furnace for in situ powder X-ray diffraction experiments. Our silicon carbide (SiC) based furnace design exhibits outstanding thermal performance in terms of accuracy control and temperature ramping rates while simultaneously being easy to use, robust to abuse and, due to its small size and low power, producing minimal impact on surrounding equipment. Temperatures in air in excess of 1100 °C can be controlled at an accuracy of better than 1%, with temperature ramping rates up to 100 °C/s. The complete "add-in" device, minus power supply, fits in a cylindrical volume approximately 15 cm long and 6 cm in diameter and resides as close as 1 cm from other sensitive components of our experimental synchrotron endstation without adverse effects.

  6. X-ray powder diffraction data for ErH(2-x)Dx

    SciTech Connect

    Browning, Jim

    2008-01-01

    We report X-ray powder diffraction data for ErH2-xD x formed by hydrogen (i.e. protium)-deuterium loading of Er metal. Lattice parameters for the varying hydrogen-deuterium compositions followed Vergard's law behavior. The cubic lattice parameter at room temperature for ErH2-xD x obeys a linear relationship according to the formula a = 5.1287 -1.1120 10-4 x; where a = the lattice parameter of the fluorite-type structure and x = the mole percent of deuterium. Microstrain measurements suggest a possible ordering of hydrogen and deuterium in the composition ErH1D1.

  7. Clarithromycin form I determined by synchrotron X-ray powder diffraction.

    PubMed

    Noguchi, Shuji; Miura, Keiko; Fujiki, Sadahiro; Iwao, Yasunori; Itai, Shigeru

    2012-02-01

    The structure of the metastable form I polymorph of the macrolide antibiotic clarithromycin, C(38)H(69)NO(13), was determined by a powder diffraction method using synchrotron radiation. The space group of form I is P2(1)2(1)2. The initial model was determined by a molecular replacement method using the structure of clarithromycin form 0 as a search model, and the final structure was obtained through Rietveld refinements. In the form I crystal structure, the clarithromycin molecules are aligned parallel along the a axis in a head-to-tail manner with intermolecular hydrogen bonds between the hydroxy O atoms. The dimethylamine groups of the clarithromycin molecule interdigitate between neighbouring head-to-tail clarithromycin alignments. The novel crystal packing found in form I provides a mechanism that describes the transformation of form 0 to form I.

  8. Crystal structure of trirubidium citrate from laboratory X-ray powder diffraction data and DFT comparison.

    PubMed

    Rammohan, Alagappa; Kaduk, James A

    2017-02-01

    The crystal structure of trirubidium citrate, 3Rb(+)·C6H5O7(3-), has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The two independent Rb(+) cations are seven- and eight-coordinate, with bond-valence sums of 0.99 and 0.92 valence units. The coordination polyhedra share edges and corners to form a three-dimensional framework. The only hydrogen bond is an intra-molecular one between the hy-droxy group and the central carboxyl-ate, with graph set S(5). The hydro-phobic methyl-ene groups lie in pockets in the framework.

  9. Crystal structure of trirubidium citrate from laboratory X-ray powder diffraction data and DFT comparison

    PubMed Central

    Kaduk, James A.

    2017-01-01

    The crystal structure of trirubidium citrate, 3Rb+·C6H5O7 3−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The two independent Rb+ cations are seven- and eight-coordinate, with bond-valence sums of 0.99 and 0.92 valence units. The coordination polyhedra share edges and corners to form a three-dimensional framework. The only hydrogen bond is an intra­molecular one between the hy­droxy group and the central carboxyl­ate, with graph set S(5). The hydro­phobic methyl­ene groups lie in pockets in the framework. PMID:28217353

  10. Thermal properties of CaMo O4 : Lattice dynamics and synchrotron powder diffraction studies

    NASA Astrophysics Data System (ADS)

    Senyshyn, A.; Kraus, H.; Mikhailik, V. B.; Vasylechko, L.; Knapp, M.

    2006-01-01

    The structure of calcium molybdate was studied by means of synchrotron based high-resolution powder diffraction methods in the temperature range 12-300K . The scheelite structure type was confirmed for CaMoO4 in the temperature region investigated and no structural anomalies were observed. Thermal expansion coefficients extracted from the thermal dependencies of the cell sizes are found to be in good agreement with the predictions from our lattice dynamics calculations that form the background for microscopic interpretation of the experimental data. From the analyses of experimental results and the calculated thermal expansion coefficients, elastic constants, phonon density of states, heat capacities, entropy, and Grüneisen parameters it is concluded that a quasiharmonic lattice dynamics approach provides a good description of these properties for CaMoO4 at temperatures below 800K .

  11. A 30 T pulsed magnet with conical bore for synchrotron powder diffraction.

    PubMed

    Billette, J; Duc, F; Frings, P; Nardone, M; Zitouni, A; Detlefs, C; Roth, T; Crichton, W; Lorenzo, J E; Rikken, G L J A

    2012-04-01

    We report on the design, construction, and operation of a horizontal field, 30 T magnet system with a conical bore optimized for synchrotron x-ray powder diffraction. The magnet offers ±31° optical access downstream of the sample, which allows to measure a sufficiently large number of Debye rings for an accurate crystal structure analysis. Combined with a 290 kJ generator, magnetic field pulses of 60 ms length were generated in the magnet, with a rise time of 4.1 ms and a repetition rate of 6 pulses/h at 30 T. The coil is mounted inside a liquid nitrogen bath. A liquid helium flow cryostat reaches into the coil and allows sample temperature between 5 and 250 K. The setup was used on the European Synchrotron Radiation Facility beamlines ID20 and ID06.

  12. A 30 T pulsed magnet with conical bore for synchrotron powder diffraction

    NASA Astrophysics Data System (ADS)

    Billette, J.; Duc, F.; Frings, P.; Nardone, M.; Zitouni, A.; Detlefs, C.; Roth, T.; Crichton, W.; Lorenzo, J. E.; Rikken, G. L. J. A.

    2012-04-01

    We report on the design, construction, and operation of a horizontal field, 30 T magnet system with a conical bore optimized for synchrotron x-ray powder diffraction. The magnet offers ±31° optical access downstream of the sample, which allows to measure a sufficiently large number of Debye rings for an accurate crystal structure analysis. Combined with a 290 kJ generator, magnetic field pulses of 60 ms length were generated in the magnet, with a rise time of 4.1 ms and a repetition rate of 6 pulses/h at 30 T. The coil is mounted inside a liquid nitrogen bath. A liquid helium flow cryostat reaches into the coil and allows sample temperature between 5 and 250 K. The setup was used on the European Synchrotron Radiation Facility beamlines ID20 and ID06.

  13. On the numerical corrections of time-of-flight neutron powder diffraction data.

    SciTech Connect

    Avdeev, M.; Jorgensen, J.; Short, S.; Von Dreele, R.

    2007-08-01

    Time-of-flight neutron powder diffraction data for NIST Standard Reference Materials have been used to study the adequacy of the peak profile model obtained from a convolution of back-to-back exponentials with a pseudo-Voigt function that is widely used in Rietveld refinement. It is shown that, while the empirical models for d-spacing (wavelength) dependence of Gaussian and Lorentzian components of the pseudo-Voigt function and rise exponent are satisfactory, the behavior of the decay exponent and peak positions demonstrate significant deviations, which can be corrected by numerical methods. The practical side of this process as implemented in GSAS and FULLPROF and the effect of the corrections on the Rietveld analysis results are discussed.

  14. Is the Separable Propagator Perturbation Approach Accurate in Calculating Angle Resolved Photoelectron Diffraction Spectra?

    NASA Astrophysics Data System (ADS)

    Ng, C. N.; Chu, T. P.; Wu, Huasheng; Tong, S. Y.; Huang, Hong

    1997-03-01

    We compare multiple scattering results of angle-resolved photoelectron diffraction spectra between the exact slab method and the separable propagator perturbation method. In the slab method,footnote C.H. Li, A.R. Lubinsky and S.Y. Tong, Phys. Rev. B17, 3128 (1978). the source wave and multiple scattering within the strong scattering atomic layers are expanded in spherical waves while interlayer scattering is expressed in plane waves. The transformation between spherical waves and plane waves is done exactly. The plane waves are then matched across the solid-vacuum interface to a single outgoing plane wave in the detector's direction. The separable propagator perturbation approach uses two approximations: (i) A separable representation of the Green's function propagator and (ii) A perturbation expansion of multiple scattering terms. Results of c(2x2) S-Ni(001) show that this approximate method fails to converge due to the very slow convergence of the separable representation for scattering angles less than 90^circ. However, this method is accurate in the backscattering regime and may be applied to XAFS calculations.(J.J. Rehr and R.C. Albers, Phys. Rev. B41, 8139 (1990).) The use of this method for angle-resolved photoelectron diffraction spectra is substantially less reliable.

  15. Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading.

    PubMed

    Lambert, P K; Hustedt, C J; Vecchio, K S; Huskins, E L; Casem, D T; Gruner, S M; Tate, M W; Philipp, H T; Woll, A R; Purohit, P; Weiss, J T; Kannan, V; Ramesh, K T; Kenesei, P; Okasinski, J S; Almer, J; Zhao, M; Ananiadis, A G; Hufnagel, T C

    2014-09-01

    We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ~10(3)-10(4) s(-1) in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10-20 keV) and is well suited to weakly absorbing materials such as magnesium alloys. The second technique is useful for more strongly absorbing materials, and uses high-energy x-rays (86 keV) and a fast shutter synchronized with the Kolsky bar to produce short (~40 μs) pulses timed with the arrival of the strain pulse at the specimen, recording the diffraction pattern on a large-format amorphous silicon detector. For both techniques we present sample data demonstrating the ability of these techniques to characterize elastic strains and polycrystalline texture as a function of time during high-rate deformation.

  16. A novel setup for time-resolved X-ray diffraction on gas gun experiments

    NASA Astrophysics Data System (ADS)

    Zucchini, Frédéric; Chauvin, Camille; Loyen, Arnaud; Combes, Philippe; Petit, Jacques; Bland, Simon

    2017-01-01

    Polymorphic phase transitions in metals have been investigated for a long time under dynamic loadings through usual dynamic compression diagnostics such as velocity and temperature measurements. Such measurements were valuable for revealing the key role of kinetic effects in most phase transition mechanisms. However, the information extracted was mostly macroscopic. Obtaining direct insight about the crystallographic structure under dynamic loadings is critical for understanding mechanisms governing shock-induced structural changes. For example, in order to evidence a mixture phase or to determine the time scale of a transition, structural information may be extremely valuable. Over the last 20 years a significant number of X-ray diffraction experiments were carried under dynamic loading, either using laboratory X-ray sources or synchrotron radiation. We are developing a novel experimental setup based on a compact High Pulsed Power generator capable of producing intense X radiation through an X-pinch X-ray source. This source is specifically designed for time-resolved X-ray diffraction in Bragg geometry on gas gun experiments. Promising preliminary diffraction data obtained under static conditions are presented.

  17. Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading

    PubMed Central

    Lambert, P. K.; Hustedt, C. J.; Vecchio, K. S.; Huskins, E. L.; Casem, D. T.; Gruner, S. M.; Tate, M. W.; Philipp, H. T.; Woll, A. R.; Purohit, P.; Weiss, J. T.; Kannan, V.; Ramesh, K. T.; Kenesei, P.; Okasinski, J. S.; Almer, J.; Zhao, M.; Ananiadis, A. G.; Hufnagel, T. C.

    2014-01-01

    We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ∼103–104 s−1 in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10–20 keV) and is well suited to weakly absorbing materials such as magnesium alloys. The second technique is useful for more strongly absorbing materials, and uses high-energy x-rays (86 keV) and a fast shutter synchronized with the Kolsky bar to produce short (∼40 μs) pulses timed with the arrival of the strain pulse at the specimen, recording the diffraction pattern on a large-format amorphous silicon detector. For both techniques we present sample data demonstrating the ability of these techniques to characterize elastic strains and polycrystalline texture as a function of time during high-rate deformation. PMID:25273733

  18. Thermal transport in thin films measured by time-resolved, grazing incidence x-ray diffraction.

    SciTech Connect

    Walko, D. A.; Sheu, Y.-M.; Trigo, M.; Reis, D. A.

    2011-01-01

    We use depth- and time-resolved x-ray diffraction to study thermal transport across single crystal Bi films grown on sapphire in order to determine the thermal conductivity of the film and the Kapitza conductance of the interface. Ultrafast Ti:sapphire laser pulses were used to heat the films; x-ray diffraction then measured the film's lattice expansion. Use of grazing incidence diffraction geometry provided depth sensitivity, as the x-ray angle of incidence was varied near the critical angle. The shift of the film's Bragg peak position with time was used to determine the film temperature averaged over an x-ray penetration depth that could be selected by choice of the angle of incidence. For films that were thick compared to the laser penetration depth, we observed a large temperature gradient at early times. In this case, measurements with the incident angle near or well above the critical angle were more sensitive to the film conductivity or Kapitza conductance, respectively. For thinner films, however, cooling was dominated by the Kapitza conductance at all accessible time scales.

  19. Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading

    SciTech Connect

    Lambert, P. K.; Hustedt, C. J.; Zhao, M.; Ananiadis, A. G.; Hufnagel, T. C.; Vecchio, K. S.; Huskins, E. L.; Casem, D. T.; Gruner, S. M.; Tate, M. W.; Philipp, H. T.; Purohit, P.; Weiss, J. T.; Woll, A. R.; Kannan, V.; Ramesh, K. T.; Kenesei, P.; Okasinski, J. S.; Almer, J.

    2014-09-15

    We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ∼10{sup 3}–10{sup 4} s{sup −1} in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10–20 keV) and is well suited to weakly absorbing materials such as magnesium alloys. The second technique is useful for more strongly absorbing materials, and uses high-energy x-rays (86 keV) and a fast shutter synchronized with the Kolsky bar to produce short (∼40 μs) pulses timed with the arrival of the strain pulse at the specimen, recording the diffraction pattern on a large-format amorphous silicon detector. For both techniques we present sample data demonstrating the ability of these techniques to characterize elastic strains and polycrystalline texture as a function of time during high-rate deformation.

  20. Powder diffraction in Bragg–Brentano geometry with straight linear detectors

    PubMed Central

    Kriegner, Dominik; Matěj, Zdeněk; Kužel, Radomír; Holý, Václav

    2015-01-01

    A common way of speeding up powder diffraction measurements is the use of one- or two-dimensional detectors. This usually goes hand in hand with worse resolution and asymmetric peak profiles. In this work the influence of a straight linear detector on the resolution function in the Bragg–Brentano focusing geometry is discussed. Because of the straight nature of most modern detectors geometrical defocusing occurs, which heavily influences the line shape of diffraction lines at low angles. An easy approach to limit the resolution-degrading effects is presented. The presented algorithm selects an adaptive range of channels of the linear detector at low angles, resulting in increased resolution. At higher angles the whole linear detector is used and the data collection remains fast. Using this algorithm a well behaved resolution function is obtained in the full angular range, whereas using the full linear detector the resolution function varies within one pattern, which hinders line-shape and Rietveld analysis. PMID:25844084

  1. High-pressure powder x-ray diffraction study of EuVO{sub 4}

    SciTech Connect

    Garg, Alka B.; Errandonea, D.

    2015-03-15

    The high-pressure structural behavior of europium orthovanadate has been studied using in-situ, synchrotron based, high-pressure x-ray powder diffraction technique. Angle-dispersive x-ray diffraction measurements were carried out at room temperature up to 34.7 GPa using a diamond-anvil cell, extending the pressure range reported in previous experiments. We confirmed the occurrence of zircon–scheelite phase transition at 6.8 GPa and the coexistence of low- and high-pressure phases up to 10.1 GPa. In addition, clear evidence of a scheelite–fregusonite transition is found at 23.4 GPa. The fergusonite structure remains stable up to 34.7 GPa, the highest pressure reached in the present measurements. A partial decomposition of EuVO{sub 4} was also observed from 8.1 to 12.8 GPa; however, this fact did not preclude the identification of the different crystal structures of EuVO{sub 4}. The crystal structures of the different phases have been Rietveld refined and their equations of state (EOS) have been determined. The results are compared with the previous experimental data and theoretical calculations. - Graphical abstract: The high-pressure structural sequence of EuVO{sub 4}. - Highlights: • EuVO{sub 4} is studied under pressure up to 35 GPa using synchrotron XRD. • The zircón–scheelite–fergusonite structural sequence is observed. • Crystal structures are refined and equations of state determined.

  2. Performance calculations of the X-ray powder diffraction beamline at NSLS-II.

    PubMed

    Shi, Xianbo; Ghose, Sanjit; Dooryhee, Eric

    2013-03-01

    The X-ray Powder Diffraction (XPD) beamline at the National Synchrotron Light Source II is a multi-purpose high-energy X-ray diffraction beamline with high throughput and high resolution. The beamline uses a sagittally bent double-Laue crystal monochromator to provide X-rays over a large energy range (30-70 keV). In this paper the optical design and the calculated performance of the XPD beamline are presented. The damping wiggler source is simulated by the SRW code and a filter system is designed to optimize the photon flux as well as to reduce the heat load on the first optics. The final beamline performance under two operation modes is simulated using the SHADOW program. For the first time a multi-lamellar model is introduced and implemented in the ray tracing of the bent Laue crystal monochromator. The optimization and the optical properties of the vertical focusing mirror are also discussed. Finally, the instrumental resolution function of the XPD beamline is described in an analytical method.

  3. In Situ Powder Diffraction Studies of Electrode Materials in Rechargeable Batteries.

    PubMed

    Sharma, Neeraj; Pang, Wei Kong; Guo, Zaiping; Peterson, Vanessa K

    2015-09-07

    The ability to directly track the charge carrier in a battery as it inserts/extracts from an electrode during charge/discharge provides unparalleled insight for researchers into the working mechanism of the device. This crystallographic-electrochemical information can be used to design new materials or modify electrochemical conditions to improve battery performance characteristics, such as lifetime. Critical to collecting operando data used to obtain such information in situ while a battery functions are X-ray and neutron diffractometers with sufficient spatial and temporal resolution to capture complex and subtle structural changes. The number of operando battery experiments has dramatically increased in recent years, particularly those involving neutron powder diffraction. Herein, the importance of structure-property relationships to understanding battery function, why in situ experimentation is critical to this, and the types of experiments and electrochemical cells required to obtain such information are described. For each battery type, selected research that showcases the power of in situ and operando diffraction experiments to understand battery function is highlighted and future opportunities for such experiments are discussed. The intention is to encourage researchers to use in situ and operando techniques and to provide a concise overview of this area of research.

  4. Elasticity and Anelasticity of Materials from Time-Resolved X-ray Diffraction

    NASA Astrophysics Data System (ADS)

    Sinogeikin, S. V.; Smith, J.; Lin, C.; Bai, L.; Rod, E.; Shen, G.

    2014-12-01

    Recent advances in synchrotron sources, x-ray optics, area detectors, and sample environment control have enabled many time-resolved experimental techniques for studying materials at extreme pressure and temperature conditions. The High Pressure Collaborative Access Team (HPCAT) at the Advanced Photon Source has made a sustained effort to develop and assemble a powerful collection of high-pressure apparatus for time-resolved research, and considerable time has been invested in developing techniques for collecting high-quality time-resolved x-ray scattering data. In this talk we will outline recently developed capabilities at HPCAT for studying elasticity and anelasticity of minerals using fast compression and cyclic compression-decompression. A few recent studies will be highlighted. For example, with fast x-ray area detectors having millisecond time resolution, accurate thermal equations of state of materials at temperatures up to 1000K and megabar pressures can be collected in a matter of seconds using membrane-driven diamond anvil cells (DAC), yielding unprecedented time and pressure resolution of true isotherms. Short duration of the experiments eliminates temperature variation during the experiments and in general allows volume measurements at higher pressures and temperatures. Alternatively, high-frequency (kilohertz range) radial diffraction measurements in a panoramic DAC combined with fast, precise cyclic loading/unloading by piezo drive could provide the short time scale necessary for studying rheology of minerals from the elastic response and lattice relaxation as a function of pressure, temperature and strain rate. Finally, we consider some possible future applications for time-resolved high-pressure, high-temperature research of mantle minerals.

  5. Using Variable Temperature Powder X-Ray Diffraction to Determine the Thermal Expansion Coefficient of Solid MgO

    ERIC Educational Resources Information Center

    Corsepius, Nicholas C.; DeVore, Thomas C.; Reisner, Barbara A.; Warnaar, Deborah L.

    2007-01-01

    A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase)and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a…

  6. An Inquiry-Based Project Focused on the X-Ray Powder Diffraction Analysis of Common Household Solids

    ERIC Educational Resources Information Center

    Hulien, Molly L.; Lekse, Jonathan W.; Rosmus, Kimberly A.; Devlin, Kasey P.; Glenn, Jennifer R.; Wisneski, Stephen D.; Wildfong, Peter; Lake, Charles H.; MacNeil, Joseph H.; Aitken, Jennifer A.

    2015-01-01

    While X-ray powder diffraction (XRPD) is a fundamental analytical technique used by solid-state laboratories across a breadth of disciplines, it is still underrepresented in most undergraduate curricula. In this work, we incorporate XRPD analysis into an inquiry-based project that requires students to identify the crystalline component(s) of…

  7. An Inquiry-Based Project Focused on the X-Ray Powder Diffraction Analysis of Common Household Solids

    ERIC Educational Resources Information Center

    Hulien, Molly L.; Lekse, Jonathan W.; Rosmus, Kimberly A.; Devlin, Kasey P.; Glenn, Jennifer R.; Wisneski, Stephen D.; Wildfong, Peter; Lake, Charles H.; MacNeil, Joseph H.; Aitken, Jennifer A.

    2015-01-01

    While X-ray powder diffraction (XRPD) is a fundamental analytical technique used by solid-state laboratories across a breadth of disciplines, it is still underrepresented in most undergraduate curricula. In this work, we incorporate XRPD analysis into an inquiry-based project that requires students to identify the crystalline component(s) of…

  8. Using Variable Temperature Powder X-Ray Diffraction to Determine the Thermal Expansion Coefficient of Solid MgO

    ERIC Educational Resources Information Center

    Corsepius, Nicholas C.; DeVore, Thomas C.; Reisner, Barbara A.; Warnaar, Deborah L.

    2007-01-01

    A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase)and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a…

  9. Identification of Polymorphic Forms of Active Pharmaceutical Ingredient in Low-Concentration Dry Powder Formulations by Synchrotron X-Ray Powder Diffraction.

    PubMed

    Egusa, Kenji; Okazaki, Fumiaki; Schiewe, Joerg; Werthmann, Ulrike; Wolkenhauer, Markus

    2017-09-13

    The identification of different (pseudo) polymorphs of an active pharmaceutical ingredient in dry powder formulations is of importance during development and entire product lifecycle, e.g., quality control. Whereas determination of polymorphic differences of pure substances is rather easy, in dry powder formulations, it is generally difficult and the difficulties increase particularly, if the substance of interest is present only in low concentrations in the formulation. Such a formulation is Spiriva(®) inhalation powder (Boehringer Ingelheim), which contains only 0.4 w/w% of the active pharmaceutical ingredient tiotropium bromide monohydrate in a matrix of α-lactose monohydrate as excipient. In this study, identification of 0.4 w/w% tiotropium bromide in the dry powder formulation was examined by X-ray powder diffraction (XRPD) using a synchrotron radiation source and the results were compared with the conventional laboratory XRPD measurements. The detection limit of tiotropium bromide by the laboratory XRPD was around 2-5 w/w%, and hence, detection of 0.4 w/w% tiotropium bromide was impossible. The synchrotron XRPD was capable to detect significantly lower level of tiotropium bromide by at least an order of magnitude. Four different polymorphic forms of tiotropium bromide present at 0.4 w/w% concentration in lactose powder blends were unambiguously identified by the synchrotron XRPD method.

  10. Time-, frequency-, and wavevector-resolved x-ray diffraction from single molecules

    PubMed Central

    Bennett, Kochise; Biggs, Jason D.; Zhang, Yu; Dorfman, Konstantin E.; Mukamel, Shaul

    2014-01-01

    Using a quantum electrodynamic framework, we calculate the off-resonant scattering of a broadband X-ray pulse from a sample initially prepared in an arbitrary superposition of electronic states. The signal consists of single-particle (incoherent) and two-particle (coherent) contributions that carry different particle form factors that involve different material transitions. Single-molecule experiments involving incoherent scattering are more influenced by inelastic processes compared to bulk measurements. The conditions under which the technique directly measures charge densities (and can be considered as diffraction) as opposed to correlation functions of the charge-density are specified. The results are illustrated with time- and wavevector-resolved signals from a single amino acid molecule (cysteine) following an impulsive excitation by a stimulated X-ray Raman process resonant with the sulfur K-edge. Our theory and simulations can guide future experimental studies on the structures of nano-particles and proteins. PMID:24880284

  11. High-performance X-ray detectors for the new powder diffraction beamline I11 at Diamond.

    PubMed

    Tartoni, Nicola; Thompson, Stephen P; Tang, Chiu C; Willis, Brian L; Derbyshire, Gareth E; Wright, Anthony G; Jaye, Stephen C; Homer, J Michael; Pizzey, John D; Bell, Anthony M T

    2008-01-01

    The design and performance characterization of a new light-weight and compact X-ray scintillation detector is presented. The detectors are intended for use on the new I11 powder diffraction beamline at the third-generation Diamond synchrotron facility where X-ray beams of high photon brightness are generated by insertion devices. The performance characteristics of these detection units were measured first using a radioactive source (efficiency of detection and background count rate) and then synchrotron X-rays (peak stability, light yield linearity and response consistency). Here, the results obtained from these tests are reported, and the suitability of the design for the Diamond powder beamline is demonstrated by presenting diffraction data obtained from a silicon powder standard using a prototype multicrystal analyser stage.

  12. In situ neutron diffraction studies of single crystals and powders during microwave irradiation.

    PubMed

    Harrison, Andrew; Ibberson, Richard; Robb, Graeme; Whittaker, Gavin; Wilson, Chick; Youngson, Douglas

    2003-01-01

    Microwave dielectric heating has become an important method in chemical synthesis and materials processing over the past 15 years, and in the case of the reactions in solutions, there is a well-developed understanding of heating mechanisms and their influence on reaction rate. In the solid-state however, there is much less clarity, despite the advantages to be gained from better insight into the way in which such electromagnetic radiation may couple directly to charge carriers, accelerating reactions in good conductors. The related issue of the influence of microwave irradiation on biological systems, in particular, proteins, and the way in which this may pose hazards to health is similarly poorly understood despite the obvious relevance this may have to the current debate on the influence of electromagnetic radiation, in particular, microwave transmission, on human health. One reason for the paucity of fundamental insight in both fields is because most work has been performed with microwave equipment whose design is derived from that of a domestic oven, and which is not ideal for in situ studies of microwave driven processes. We have been developing new methods of irradiating a variety of solid samples while measuring structural parameters through a range of diffraction techniques, and describe apparatus that will enable X-ray or neutron scattering measurements to be performed on powders or single crystals under microwave irradiation with controlled power level. We also describe preliminary studies of a single crystal of the molecular solid aspirin, and a powder of the microwave-susceptible ionic material BaTiO3, during microwave irradiation.

  13. Powder neutron diffraction of α-UB 2C (α-UB 2C-type)

    NASA Astrophysics Data System (ADS)

    Rogl, Peter; Fischer, Peter

    1991-02-01

    The crystal structure of α-UB 2C (low temperature modification below T = 1675(25)°C) was determined from powder X-ray data (RT) and powder neutron diffraction data (at 29 K) employing the Rietveld-Young-Wiles profile analysis method. α-UB 2C crystallizes in the orthorhombic space group Pmma with a = 0.60338(3), b = 0.35177(2), c = 0.41067(2) nm, V = 0.0872 nm 3, Z = 2. The residuals of the neutron refinement were R1 = 0.032 and RF = 0.043. The crystal structure of α-UB 2C is a new structure type where planar nonregular 6 3-U-metal layers alternate with planar nonmetal layers of the type (B 6C 2) 3. Boron atoms are in a typical triangular prismatic metal surrounding with a tetrakaidekahedral coordination B[U 6B 2C 1], whereas carbon atoms occupy the center points of rectangular bipyramids C[U 4B 2]. The crystal structure of α-UB 2C derives from the high temperature modification β-UB 2C (ThB 2C-type, R overline3m ), which reveals a similar stacking of slightly puckered metal layers 6 3, alternating with planar layers B 6 · (B 6C 3) 2. The phase transition from β-UB 2C to α-UB 2C is thus essentially generated by carbon diffusion within the limit∞2 B 6 · (B 6C 3) 2 layers to form limit∞2 (B 6C 2) 3 layers.

  14. X-ray diffraction and time-resolved fluorescence analyses of Aequorea green fluorescent protein crystals.

    PubMed

    Perozzo, M A; Ward, K B; Thompson, R B; Ward, W W

    1988-06-05

    The energy transfer protein, green fluorescent protein, from the hydromedusan jellyfish Aequorea victoria has been crystallized in two morphologies suitable for x-ray diffraction analysis. Hexagonal plates have been obtained in the P6122 or P6522 space group with a = b = 77.5, c = 370 A, and no more than three molecules per asymmetric unit. Monoclinic parallel-epipeds have been obtained in the C2 space group with a = 93.3, b = 66.5, c = 45.5 A, beta = 108 degrees, and one molecule per asymmetric unit. The monoclinic form is better suited for use in a structure determination, and a data set was collected from the native crystal. Time-resolved fluorescence measurements of large single crystals are possible due to the unique, covalently bound chromophore present in this molecule. Fluorescence emission spectra of Aequorea green fluorescent protein in solution and from either the hexagonal or monoclinic single crystal show similar profiles suggesting that the conformations of protein in solution and in the crystal are similar. Multifrequency phase fluorimetric data obtained from a single crystal were best fit by a single fluorescence lifetime very close to that exhibited by the protein in solution. The complementary structural data obtained from fluorescence spectroscopy and x-ray diffraction crystallography will aid in the elucidation of this novel protein's structure-function relationship.

  15. Coherent convergent-beam time-resolved X-ray diffraction.

    PubMed

    Spence, John C H; Zatsepin, Nadia A; Li, Chufeng

    2014-07-17

    The use of coherent X-ray lasers for structural biology allows the use of nanometre diameter X-ray beams with large beam divergence. Their application to the structure analysis of protein nanocrystals and single particles raises new challenges and opportunities. We discuss the form of these coherent convergent-beam (CCB) hard X-ray diffraction patterns and their potential use for time-resolved crystallography, normally achieved by Laue (polychromatic) diffraction, for which the monochromatic laser radiation of a free-electron X-ray laser is unsuitable. We discuss the possibility of obtaining single-shot, angle-integrated rocking curves from CCB patterns, and the dependence of the resulting patterns on the focused beam coordinate when the beam diameter is larger or smaller than a nanocrystal, or smaller than one unit cell. We show how structure factor phase information is provided at overlapping interfering orders and how a common phase origin between different shots may be obtained. Their use in refinement of the phase-sensitive intensity between overlapping orders is suggested. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  16. Time-Resolved Soft X-ray Diffraction Reveals Transient Structural Distortions of Ternary Liquid Crystals

    PubMed Central

    Quevedo, Wilson; Peth, Christian; Busse, Gerhard; Scholz, Mirko; Mann, Klaus; Techert, Simone

    2009-01-01

    Home-based soft X-ray time-resolved scattering experiments with nanosecond time resolution (10 ns) and nanometer spatial resolution were carried out at a table top soft X-ray plasma source (2.2–5.2 nm). The investigated system was the lyotropic liquid crystal C16E7/paraffin/glycerol/formamide/IR 5. Usually, major changes in physical, chemical, and/or optical properties of the sample occur as a result of structural changes and shrinking morphology. Here, these effects occur as a consequence of the energy absorption in the sample upon optical laser excitation in the IR regime. The liquid crystal shows changes in the structural response within few hundred nanoseconds showing a time decay of 182 ns. A decrease of the Bragg peak diffracted intensity of 30% and a coherent macroscopic movement of the Bragg reflection are found as a response to the optical pump. The Bragg reflection movement is established to be isotropic and diffusion controlled (1 μs). Structural processes are analyzed in the Patterson analysis framework of the time-varying diffraction peaks revealing that the inter-lamellar distance increases by 2.7 Å resulting in an elongation of the coherently expanding lamella crystallite. The present studies emphasize the possibility of applying TR-SXRD techniques for studying the mechanical dynamics of nanosystems. PMID:20087463

  17. X-Ray Powder Diffraction as a Tool for the Identification of Impact Deformed Rocks

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    Previous X-ray powder diffraction (XRD) studies indicated shock deformed minerals have broader XRD peaks when compared to 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 and the Mission Canyon Formation of southwest Montana and western Wyoming were used to evaluate the use of X-ray powder diffraction as a tool for distinguishing impact deformed rocks from tectonically deformed rocks. Both sample locations contain rocks subjected to varying degrees of deformation. At Sierra Madera dolostone and limestone samples were collected from the crater rim (lower shock intensity) and the central uplift (higher shock intensity). Carbonate rocks of the Mission Canyon Formation were sampled along a transect across the tectonic front of the Sevier and Laramide orogenies. Peaks in the XRD patterns of shocked calcite in samples from Sierra Madera are generally broader than those of calcite samples from the Mission Canyon Formation whereas peak broadening of shocked dolomite in samples from the outer central uplift of Sierra Madera is similar to those of Mission Canyon Formation samples. Single peak profile patterns of calcite and dolomite samples from both locations are complex and their full width half maxima (FWHM) show no relationship to shock intensity, especially above ~80 ° 2θ. Rietveld refinement of peak shape parameters yields a more precise measure of the 2θ angular dependence of peak FWHM and, therefore, the degree of shock deformation. FWHM values obtained from Rietveld crystal structure refinements increase with shock intensity for all Sierra Madera samples. Additionally, FWHM values of some tectonically deformed Mission Canyon Formation calcites overlap with those of weakly shocked calcite from the crater rim of Sierra Madera. FWHM values of shocked dolomite from the central uplift of Sierra Madera are distinctly higher than tectonically

  18. Combined synchrotron X-ray tomography and X-ray powder diffraction using a fluorescing metal foil.

    PubMed

    Kappen, P; Arhatari, B D; Luu, M B; Balaur, E; Caradoc-Davies, T

    2013-06-01

    This study realizes the concept of simultaneous micro-X-ray computed tomography and X-ray powder diffraction using a synchrotron beamline. A thin zinc metal foil was placed in the primary, monochromatic synchrotron beam to generate a divergent wave to propagate through the samples of interest onto a CCD detector for tomographic imaging, thus removing the need for large beam illumination and high spatial resolution detection. Both low density materials (kapton tubing and a piece of plant) and higher density materials (Egyptian faience) were investigated, and elemental contrast was explored for the example of Cu and Ni meshes. The viability of parallel powder diffraction using the direct beam transmitted through the foil was demonstrated. The outcomes of this study enable further development of the technique towards in situ tomography∕diffraction studies combining micrometer and crystallographic length scales, and towards elemental contrast imaging and reconstruction methods using well defined fluorescence outputs from combinations of known fluorescence targets (elements).

  19. Combined synchrotron X-ray tomography and X-ray powder diffraction using a fluorescing metal foil

    NASA Astrophysics Data System (ADS)

    Kappen, P.; Arhatari, B. D.; Luu, M. B.; Balaur, E.; Caradoc-Davies, T.

    2013-06-01

    This study realizes the concept of simultaneous micro-X-ray computed tomography and X-ray powder diffraction using a synchrotron beamline. A thin zinc metal foil was placed in the primary, monochromatic synchrotron beam to generate a divergent wave to propagate through the samples of interest onto a CCD detector for tomographic imaging, thus removing the need for large beam illumination and high spatial resolution detection. Both low density materials (kapton tubing and a piece of plant) and higher density materials (Egyptian faience) were investigated, and elemental contrast was explored for the example of Cu and Ni meshes. The viability of parallel powder diffraction using the direct beam transmitted through the foil was demonstrated. The outcomes of this study enable further development of the technique towards in situ tomography/diffraction studies combining micrometer and crystallographic length scales, and towards elemental contrast imaging and reconstruction methods using well defined fluorescence outputs from combinations of known fluorescence targets (elements).

  20. Kinetic products in coordination networks: ab initio X-ray powder diffraction analysis.

    PubMed

    Martí-Rujas, Javier; Kawano, Masaki

    2013-02-19

    Porous coordination networks are materials that maintain their crystal structure as molecular "guests" enter and exit their pores. They are of great research interest with applications in areas such as catalysis, gas adsorption, proton conductivity, and drug release. As with zeolite preparation, the kinetic states in coordination network preparation play a crucial role in determining the final products. Controlling the kinetic state during self-assembly of coordination networks is a fundamental aspect of developing further functionalization of this class of materials. However, unlike for zeolites, there are few structural studies reporting the kinetic products made during self-assembly of coordination networks. Synthetic routes that produce the necessary selectivity are complex. The structural knowledge obtained from X-ray crystallography has been crucial for developing rational strategies for design of organic-inorganic hybrid networks. However, despite the explosive progress in the solid-state study of coordination networks during the last 15 years, researchers still do not understand many chemical reaction processes because of the difficulties in growing single crystals suitable for X-ray diffraction: Fast precipitation can lead to kinetic (metastable) products, but in microcrystalline form, unsuitable for single crystal X-ray analysis. X-ray powder diffraction (XRPD) routinely is used to check phase purity, crystallinity, and to monitor the stability of frameworks upon guest removal/inclusion under various conditions, but rarely is used for structure elucidation. Recent advances in structure determination of microcrystalline solids from ab initio XRPD have allowed three-dimensional structure determination when single crystals are not available. Thus, ab initio XRPD structure determination is becoming a powerful method for structure determination of microcrystalline solids, including porous coordination networks. Because of the great interest across scientific

  1. Plant powder teabags: a novel and practical approach to resolve culturability and diversity of rhizobacteria.

    PubMed

    Sarhan, Mohamed S; Mourad, Elhussein F; Hamza, Mervat A; Youssef, Hanan H; Scherwinski, Ann-Christin; El-Tahan, Mahmoud; Fayez, Mohamed; Ruppel, Silke; Hegazi, Nabil A

    2016-08-01

    We have developed teabags packed with dehydrated plant powders, without any supplements, for preparation of plant infusions necessary to develop media for culturing rhizobacteria. These bacteria are efficiently cultivated on such plant teabag culture media, with better progressive in situ recoverability compared to standard chemically synthetic culture media. Combining various plant-based culture media and incubation conditions enabled us to resolve unique denaturing gradient gel electrophoresis (DGGE) bands that were not resolved by tested standard culture media. Based on polymerase chain reaction PCR-DGGE of 16S rDNA fingerprints and sequencing, the plant teabag culture media supported higher diversity and significant increases in the richness of endo-rhizobacteria, namely Gammaproteobacteria (Enterobacteriaceae) and predominantly Alphaproteobacteria (Rhizobiaceae). This culminated in greater retrieval of the rhizobacteria taxa associated with the plant roots. We conclude that the plant teabag culture medium by itself, without any nutritional supplements, is sufficient and efficient for recovering and mirroring the complex and diverse communities of rhizobacteria. Our message to fellow microbial ecologists is: simply dehydrate your plant canopy, teabag it and soak it to prepare your culture media, with no need for any additional supplementary nutrients.

  2. Structure and properties of alkali fullerides and structure solution from powder diffraction

    NASA Astrophysics Data System (ADS)

    Huq, Ashfia

    The close connection between structural and electronic properties of doped fullerene systems has prompted structural studies of these systems to understand their transport characteristics. The existence of a universal curve of superconducting transition temperature vs. lattice parameter among the fcc A3C60 materials is perhaps the most compelling relationship between structure and transport properties in condensed matter physics. In this work we revisit the structure of several alkali doped fullerenes using X-ray and neutron diffraction. Some subtleties of these structures along with their effect on transport properties are discussed. The superconducting A3C60 (where A = K, Rb) systems are generally considered to be BCS type superconductors. However, there is a school of thought arguing that all materials AnC 60 with integer n must be Mott insulators as these binary compounds have rather large Coulomb correlation compared to their band width. We investigated the relationship of the structure of non-stoichiometric Rb3C60 to the superconducting transition temperature and find no evident correlation. We also discuss the structure of Rb 4C60 under pressure to understand the metal insulator phase transition observed in earlier work. We find Rb4C60 undergoes a structural phase transition from a disordered tetragonal phase to an orientationally ordered orthorhombic phase at 10kbar. The nearest neighbor distances in this structure are indeed comparable to the conducting A 3C60. We also offer a detailed structural analysis of the polymer phase of RbC60 and KC60. The art of solving crystal structures from powder diffraction data has developed rapidly over the last decade due to the improvements in computing power and availability of high resolution data from synchrotron sources. In the last chapter, we discuss the application of simulated annealing techniques to solve structures of various organic molecules.

  3. Kinetics of methane hydrate decomposition studied via in situ low temperature X-ray powder diffraction.

    PubMed

    Everett, S Michelle; Rawn, Claudia J; Keffer, David J; Mull, Derek L; Payzant, E Andrew; Phelps, Tommy J

    2013-05-02

    Gas hydrate is known to have a slowed decomposition rate at ambient pressure and temperatures below the melting point of ice. As hydrate exothermically decomposes, gas is released and water of the clathrate cages transforms into ice. Based on results from the decomposition of three nominally similar methane hydrate samples, the kinetics of two regions, 180-200 and 230-260 K, within the overall decomposition range 140-260 K, were studied by in situ low temperature X-ray powder diffraction. The kinetic rate constants, k(a), and the reaction mechanisms, n, for ice formation from methane hydrate were determined by the Avrami model within each region, and activation energies, E(a), were determined by the Arrhenius plot. E(a) determined from the data for 180-200 K was 42 kJ/mol and for 230-260 K was 22 kJ/mol. The higher E(a) in the colder temperature range was attributed to a difference in the microstructure of ice between the two regions.

  4. X-ray Powder Diffraction for Characterization of Raw Materials in Banknotes.

    PubMed

    Marabello, Domenica; Benzi, Paola; Lombardozzi, Antonietta; Strano, Morela

    2017-01-25

    We report about the X-ray powder diffraction characterization of crystalline materials used to produce genuine and counterfeit banknotes, performed with a single-crystal diffractometer that permits fast and nondestructive measurements in different 0.5-mm sized areas; 20-euro denomination genuine banknotes were analyzed, and results were compared with counterfeit banknotes. The analysis shows that the papers used to print real banknotes are composed, as expected, of cotton-based cellulose and titanium dioxide as crystalline additive, but different polymorphs of TiO2 for different emission countries are evidenced. The counterfeit banknotes are composed of cellulose based on wood pulp; moreover, an unexpected significant quantity of TiO2 was found to be mixed with calcite, indicating that the paper employed by forgers is not simply a common low-cost type. The crystalline index and intensity ratios between the peaks attributable to cellulose and fillers can provide additional information to trace back paper suppliers for forensic purposes.

  5. Quantification of febuxostat polymorphs using powder X-ray diffraction technique.

    PubMed

    Qiu, Jing-bo; Li, Gang; Sheng, Yue; Zhu, Mu-rong

    2015-03-25

    Febuxostat is a pharmaceutical compound with more than 20 polymorphs of which form A is most widely used and usually exists in a mixed polymorphic form with form G. In the present study, a quantification method for polymorphic form A and form G of febuxostat (FEB) has been developed using powder X-ray diffraction (PXRD). Prior to development of a quantification method, pure polymorphic form A and form G are characterized. A continuous scan with a scan rate of 3° min(-1) over an angular range of 3-40° 2θ is applied for the construction of the calibration curve using the characteristic peaks of form A at 12.78° 2θ (I/I0100%) and form G at 11.72° 2θ (I/I0100%). The linear regression analysis data for the calibration plots shows good linear relationship with R(2)=0.9985 with respect to peak area in the concentration range 10-60 wt.%. The method is validated for precision, recovery and ruggedness. The limits of detection and quantitation are 1.5% and 4.6%, respectively. The obtained results prove that the method is repeatable, sensitive and accurate. The proposed developed PXRD method can be applied for the quantitative analysis of mixtures of febuxostat polymorphs (forms A and G). Copyright © 2015 Elsevier B.V. All rights reserved.

  6. In-situ early-age hydration study of sulfobelite cements by synchrotron powder diffraction

    SciTech Connect

    Álvarez-Pinazo, G.; Cuesta, A.; García-Maté, M.; Santacruz, I.; Losilla, E.R.; Fauth, F.; Aranda, M.A.G.; De la Torre, A.G.

    2014-02-15

    Eco-friendly belite calcium sulfoaluminate (BCSA) cement hydration behavior is not yet well understood. Here, we report an in-situ synchrotron X-ray powder diffraction study for the first hours of hydration of BCSA cements. Rietveld quantitative phase analysis has been used to establish the degree of reaction (α). The hydration of a mixture of ye'elimite and gypsum revealed that ettringite formation (α ∼ 70% at 50 h) is limited by ye'elimite dissolution. Two laboratory-prepared BCSA cements were also studied: non-active-BCSA and active-BCSA cements, with β- and α′{sub H}-belite as main phases, respectively. Ye'elimite, in the non-active-BCSA system, dissolves at higher pace (α ∼ 25% at 1 h) than in the active-BCSA one (α ∼ 10% at 1 h), with differences in the crystallization of ettringite (α ∼ 30% and α ∼ 5%, respectively). This behavior has strongly affected subsequent belite and ferrite reactivities, yielding stratlingite and other layered phases in non-active-BCSA. The dissolution and crystallization processes are reported and discussed in detail. -- Highlights: •Belite calcium sulfoaluminate cements early hydration mechanism has been determined. •Belite hydration strongly depends on availability of aluminum hydroxide. •Orthorhombic ye’elimite dissolved at a higher pace than cubic one. •Ye’elimite larger reaction degree yields stratlingite formation by belite reaction. •Rietveld method quantified gypsum, anhydrite and bassanite dissolution rates.

  7. Crystal structure of radium sulfate: An X-ray powder diffraction and density functional theory study

    NASA Astrophysics Data System (ADS)

    Matyskin, Artem V.; Ylmen, Rikard; Lagerkvist, Petra; Ramebäck, Henrik; Ekberg, Christian

    2017-09-01

    Radium-barium sulfate (Ra0.76Ba0.24SO4) powder was examined using X-ray Diffraction (XRD) technique and its crystal structure was optimized using Density Functional Theory (DFT). XRD data show that radium and barium sulfate form a solid solution and that Ra0.76Ba0.24SO4 is orthorhombic and isostructural with pure RaSO4, barite (BaSO4), celestite (SrSO4) and anglesite (PbSO4), crystallizing in the space group Pmna (No. 62). The unit cell parameters of the Ra0.76Ba0.24SO4 crystal have been determined using Rietveld refinement and were extrapolated to unit cell parameters of the pure RaSO4 phase using Vegard's law: a=9.129(8), b=5.538(3), c=7.313(5) Å. DFT geometry optimization was used to derive atomic coordinates and interatomic distances in both Ra0.76Ba0.24SO4 and pure RaSO4. The experimental and DFT geometry optimization results obtained in this work are in good agreement with each other, and furthermore with literature data.

  8. Neutron Powder Diffraction Study on the Magnetic Structure of NdPd 5 Al 2

    DOE PAGES

    Metoki, Naoto; Yamauchi, Hiroki; Kitazawa, Hideaki; ...

    2017-02-24

    The magnetic structure of NdPd5Al2 has been studied by neutron powder diffraction. Here, we observed the magnetic reflections with the modulation vector q=(1/2,0,0)q=(1/2,0,0) below the ordering temperature TN. We also found a collinear magnetic structure with a Nd moment of 2.7(3) μB at 0.5 K parallel to the c-axis, where the ferromagnetically ordered a-planes stack with a four-Nd-layer period having a ++-- sequence along the a-direction with the distance between adjacent Nd layers equal to a/2 (magnetic space group Panma). This “stripe”-like modulation is very similar to that in CePd5Al2 with q=(0.235,0.235,0)q=(0.235,0.235,0) with the Ce moment parallel to the c-axis.more » These structures with in-plane modulation are a consequence of the two-dimensional nature of the Fermi surface topology in this family, originating from the unique crystal structure with a very long tetragonal unit cell and a large distance of >7 Å between the rare-earth layers separated by two Pd and one Al layers.« less

  9. Full phase analysis of portland clinker by penetrating synchrotron powder diffraction.

    PubMed

    de la Torre, A G; Cabeza, A; Calvente, A; Bruque, S; Aranda, M A

    2001-01-15

    Fabrication of portland cements commonly depends on X-ray fluorescence (XRF), which measures the elemental compositions. XRF is used to adjust the raw material proportions and to control the process conditions. However, to predict the mechanical strength of the resulting concrete, it is essential to know the phase composition which is, so far, indirectly inferred by the Bogue method. Here, we report a phase analysis of an industrial portland clinker containing six crystalline phases, Ca3SiO5, Ca2SiO4, Ca4Al2Fe2O10, Ca3Al2O6, NaK3(SO4)2, and CaO, by Rietveld refinement of synchrotron X-ray powder diffraction data (lambda = 0.442377 A). Even the minor component, CaO 0.45(2)%, was readily analyzed. We have also carried out a phase study of the same clinker with laboratory X-rays to characterize the changes in the detection limit and errors. Furthermore, by adding a suitable crystalline standard to the same clinker, we have determined the overall amorphous phase content. The procedure established for this state-of-the-art phase analysis shows the high precision that can be achieved by using penetrating X-rays, which is of interest not only in cement chemistry but in other industrially important multiphase systems such as slags, superalloys, or catalysts.

  10. Neutron Powder Diffraction Study on the Magnetic Structure of NdPd5Al2

    NASA Astrophysics Data System (ADS)

    Metoki, Naoto; Yamauchi, Hiroki; Kitazawa, Hideaki; Suzuki, Hiroyuki S.; Hagihala, Masato; Frontzek, Matthias D.; Matsuda, Masaaki; Fernandez-Baca, Jaime A.

    2017-03-01

    The magnetic structure of NdPd5Al2 has been studied by neutron powder diffraction. We observed the magnetic reflections with the modulation vector q = (1/2,0,0) below the ordering temperature TN. We found a collinear magnetic structure with a Nd moment of 2.7(3) μB at 0.5 K parallel to the c-axis, where the ferromagnetically ordered a-planes stack with a four-Nd-layer period having a ++- sequence along the a-direction with the distance between adjacent Nd layers equal to a/2 (magnetic space group Panma). This "stripe"-like modulation is very similar to that in CePd5Al2 with q = (0.235,0.235,0) with the Ce moment parallel to the c-axis. These structures with in-plane modulation are a consequence of the two-dimensional nature of the Fermi surface topology in this family, originating from the unique crystal structure with a very long tetragonal unit cell and a large distance of >7 Å between the rare-earth layers separated by two Pd and one Al layers.

  11. Anomalous thermal expansion in rare-earth gallium perovskites: a comprehensive powder diffraction study

    NASA Astrophysics Data System (ADS)

    Senyshyn, A.; Trots, D. M.; Engel, J. M.; Vasylechko, L.; Ehrenberg, H.; Hansen, T.; Berkowski, M.; Fuess, H.

    2009-04-01

    Crystal structures of rare-earth gallium perovskites LaGaO3, PrGaO3, NdGaO3 and Pr1-xNdxGaO3 (x = 0.25, 0.50, 0.75) solid solutions were investigated in the temperature range 12-300 K by high-resolution powder diffraction using synchrotron or neutron radiation. The previously reported negative thermal expansion in the b direction of the PrGaO3 lattice has been found to be persistent in Pr1-xNdxGaO3 solid solutions and its magnitude has been revealed as proportional to the amount of praseodymium. Evaluation of the obtained temperature evolution of cell dimensions indicated a weak anomalous behaviour of the b lattice parameter in NdGaO3, and its origin is supposed to be the same as in PrGaO3, i.e. a coupling of the crystal electric field levels with phonon excitations of about 23-25 meV energy. The performed bond length analysis revealed an anomalous behaviour of both LnO12 (Ln—rare-earth) and GaO6 coordination polyhedra, which can be a structural manifestation of anomalous thermal expansion in the considered compounds.

  12. X-Ray Powder Diffraction Study of Synthetic Palmierite, K{sub 2}Pb(SO{sub 4}){sub 2}

    SciTech Connect

    TISSOT JR.,RALPH G.; RODRIGUEZ,MARK A.; SIPOLA,DIANA L.; VOIGT,JAMES A.

    2000-12-19

    Palmierite (K{sub 2}Pb(SO{sub 4}){sub 2}) has been prepared via a chemical synthesis method. Intensity differences were observed when X-ray powder data from the newly synthesized compound were compared to the published powder diffraction card (PDF) 29-1015 for Palmierite. Investigation of these differences indicated the possibility of preferred orientation and/or chemical inhomogeneity affecting intensities, particularly those of the basal (00{ell}) reflections. Annealing of the Palmierite was found to reduce the effects of preferred orientation. Electron microprobe analysis confirmed K:Pb:S as 2:1:2 for the annealed Palmierite powder. Subsequent least-squares refinement and Rietveld analysis of the annealed powder showed peak intensities very close to that of a calculated Palmierite pattern (based on single crystal data), yet substantially higher than many of the PDF 29-1015 published intensities. Further investigation of peak intensity variation via calculated patterns suggested that the intensity discrepancies between the annealed sample and those found in PDF 29-1015 were potentially due to chemical variation in the K{sub 2}Pb(SO{sub 4}){sub 2} composition. X-ray powder diffraction and crystal data for Palmierite are reported for the annealed sample. Palmierite is Trigonal/Hexagonal with unit cell parameters a = 5.497(1){angstrom}, c = 20.864(2) {angstrom}, space group R-3m (166), and Z = 3.

  13. Neutron powder diffraction studies of LiIO 3 and (HIO 3, 2LiIO 3)

    NASA Astrophysics Data System (ADS)

    Bouillot, J.; Coquet, E.; Pannetier, J.; Crettez, J.-M.

    1986-02-01

    A study of the kinetics of transition of powdered samples of LiIO 3 has been performed in order to determine the domain of stability of the γ-phase and to refine its structure. For a better undertanding of the transition mechanism which may involve the presence of proton impurities, the decomposition of (HIO 3, 2LiIO 3), while increasing the temperature, has been recorded continuously by means of neutron powder diffraction and the different features appearing in the observed patterns have been analyzed. A tentative interpretation is given.

  14. X-ray powder diffraction and electron diffraction studies of the thortveitite-related L phase, (Zn,Mn)2V2O7.

    PubMed

    Knowles, Kevin M; Vickers, Mary E; Sil, Anjan; Han, Yung Hoe; Jaffrenou, Périne

    2009-04-01

    The phase designated gamma-Zn3(VO4)2 reported as a minor second phase in zinc oxide-based varistor materials doped with vanadium oxide and manganese oxide is shown to be the L phase, (Zn(1-x)Mn(x))2V2O7 (0.188 < x < 0.538), in the pseudo-binary Mn2V2O7-Zn2V2O7 system. Analysis of X-ray powder diffraction patterns and electron diffraction patterns of this phase shows that the previously published a, c and beta values for this thortveitite-related phase are incorrect. Instead, Rietveld refinement of the X-ray powder pattern of the L phase shows that it has a monoclinic C lattice with Z = 6, with a = 10.3791 (1), b = 8.5557 (1), c = 9.3539 (1) A and beta = 98.467 (1) degrees. Although prior convergent-beam electron diffraction work of 'gamma-Zn3(VO4)2' confirmed the C Bravais lattice, the space group was found to be Cm rather than C2/m, the difference perhaps arising from the inability of the X-rays to detect small displacements of oxygen. Attempts to refine the structure in Cm did not produce improved R factors. The relationship between the crystal structure of the L phase and the high-temperature C2/m beta'-Zn2V2O7 thortveitite-type solid solution is discussed.

  15. Aqueous Nucleation and Growth of Titanium Oxides Using Time-Resolved Synchrotron X- ray Diffraction

    NASA Astrophysics Data System (ADS)

    Hummer, D. R.; Heaney, P. J.; Post, J. E.

    2006-05-01

    The inorganic precipitation of oxide minerals in soil environments has profound effects on a variety of geochemical processes. These include the removal of metals from the aqueous phase, the production of coatings that reduce the reactive surface area of pre-existing mineral grains, and the generation of feedstocks for microbial metabolic reactions. Recent observations of transient, metastable phases during the growth of oxide crystallites has raised questions about their role in crystallization mechanisms, and created a need for more detailed structural measurements. To better understand the process of nucleation and growth, we investigated the crystallization of Ti oxides from aqueous 0.5 M TiCl4 solutions using synchrotron X-ray diffraction at temperatures of 100 and 150 °C. Solutions were heated in a 1.0 mm internal diameter quartz glass capillary sealed with epoxy. Powder diffraction patterns of the growing crystallites were collected using image plate technology with a time step of ~ 4 minutes, providing high resolution in situ measurements of structural changes during the crystallization process. The data indicate a co-precipitation of the two crystalline phases anatase and rutile within the first 30 minutes of heating, followed by a gradual phase transition from anatase to rutile during particle coarsening throughout the 10 hour duration of an experiment. The co-existence of anatase and rutile at the onset of crystallization lends additional support to the assertion of nearly identical free energies for anatase and rutile at the nanoscale, believed to be due to the prominence of surface energy effects (Ranade et al., 2001). Whole pattern analyses using the Rietveld refinement method also documented previously unobserved changes in lattice parameters of both phases during growth, on the order of 0.2-0.3 % expansion for each axis. The trends in lattice parameters are observed to be temperature dependent, generally having lower values at higher

  16. Neutron Powder Diffraction Study of CO2 Hydrate as a Function of Pressure

    NASA Astrophysics Data System (ADS)

    Rawn, C. J.; Chakoumakos, B. C.; Garlea, O.; Leeman, J. R.; Alford, J.; Elwood-Madden, M.; Phelps, T. J.

    2009-12-01

    A sample of structure type I gas hydrate was synthesized from pressuring D2O ice with CO2 and was subsequently studied at high pressure by neutron powder diffraction. Once the sample was loaded into a previously cooled TiZr null scattering pressure cell, the sample was pressurized to 0.1 kbar using He gas and was subsequently cooled to 225 K. Data were collected first at 0.1 kbar and then the cell was pressurized to 1 kbar while holding the temperature constant. Subsequent pressures for data collection were obtained by releasing pressure from the cell. The lattice parameters have been refined from the data using the Rietveld method and between 0.1 and 0.7 kbar the unit cell decreased in a linear fashion with a fairly large negative slope, however, between 0.7 and 1 kbar the unit cell changes are negligible and the slope becomes flat. A second sample was studied at ambient pressure and 175 K and initially showed a large amount of solid CO2 and a small amount of ice along with the CO2 hydrate, however, over time the solid CO2 decreased as it sublimed at that temperature. The average lattice parameter from ten data sets collected at this temperature was 11.890(4) Å agreeing well with previously reported lattice parameters. ACKNOWLEDGMENTS This work is sponsored by the Office of Fossil Energy under Field Work Proposal FEAB111 and access to Oak Ridge National Laboratory's High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences. Oak Ridge National Laboratory is managed by UT-Battelle LLC, for the U.S. Department of Energy.

  17. Spatially Resolved Elemental Analysis, Spectroscopy and Diffraction at the GSECARS Sector at the Advanced Photon Source

    SciTech Connect

    Sutton, Stephen R.; Lanzirotti, Antonio; Newville, Matthew; Rivers, Mark L.; Eng, Peter; Lefticariu, Liliana

    2017-01-01

    X-ray microprobes (XRM) coupled with high-brightness synchrotron X-ray facilities are powerful tools for environmental biogeochemistry research. One such instrument, the XRM at the Geo Soil Enviro Center for Advanced Radiation Sources Sector 13 at the Advanced Photon Source (APS; Argonne National Laboratory, Lemont, IL) was recently improved as part of a canted undulator geometry upgrade of the insertion device port, effectively doubling the available undulator beam time and extending the operating energy of the branch supporting the XRM down to the sulfur K edge (2.3 keV). Capabilities include rapid, high-resolution, elemental imaging including fluorescence microtomography, microscale X-ray absorption fine structure spectroscopy including sulfur K edge capability, and microscale X-ray diffraction. These capabilities are advantageous for (i) two-dimensional elemental mapping of relatively large samples at high resolution, with the dwell times typically limited only by the count times needed to obtain usable counting statistics for low concentration elements, (ii) three-dimensional imaging of internal elemental distributions in fragile hydrated specimens, such as biological tissues, avoiding the need for physical slicing, (iii) spatially resolved speciation determinations of contaminants in environmental materials, and (iv) identification of contaminant host phases. In this paper, we describe the XRM instrumentation, techniques, applications demonstrating these capabilities, and prospects for further improvements associated with the proposed upgrade of the APS.

  18. Ultrafast structural dynamics studied by kilohertz time-resolved x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Guo, Xin; Jiang, Zhou-Ya; Chen, Long; Chen, Li-Ming; Xin, Jian-Guo; Peter, M. Rentzepis; Chen, Jie

    2015-10-01

    Ultrashort multi-keV x-ray pulses are generated by electron plasma produced by the irradiation of femtosecond pulses on metals. These sub-picosecond x-ray pulses have extended the field of x-ray spectroscopy into the femtosecond time domain. However, pulse-to-pulse instability and long data acquisition time restrict the application of ultrashort x-ray systems operating at low repetition rates. Here we report on the performance of a femtosecond laser plasma-induced hard x-ray source that operates at 1-kHz repetition rate, and provides a flux of 2.0 × 1010 photons/s of Cu Kα radiation. Using this system for time-resolved x-ray diffraction experiments, we record in real time, the transient processes and structural changes induced by the interaction of 400-nm femtosecond pulse with the surface of a 200-nm thick Au (111) single crystal. Project supported by the National Natural Science Foundation of China (Grant Nos. 61222509 and 11421064) and the W. M. Keck Foundation.

  19. Kinetic Analysis of Cation Exchange in Birnessite using Time-resolved Synchrotron X-ray Diffraction

    SciTech Connect

    C Lopano; P Heaney; J Bandstra; J Post; S Brantley

    2011-12-31

    In this study, we applied time-resolved synchrotron X-ray diffraction (TRXRD) to develop kinetic models that test a proposed two-stage reaction pathway for cation exchange in birnessite. These represent the first rate equations calculated for cation exchange in layered manganates. Our previous work has shown that the substitution of K, Cs, and Ba for interlayer Na in synthetic triclinic birnessite induces measurable changes in unit-cell parameters. New kinetic modeling of this crystallographic data supports our previously postulated two-stage reaction pathway for cation exchange, and we can correlate the kinetic steps with changes in crystal structure. In addition, the initial rates of cation exchange, R ({angstrom}{sup 3} min{sup -1}), were determined from changes in unit-cell volume to follow these rate laws: R = 1.75[K{sup +}{sub (aq)}]{sup 0.56}, R = 41.1[Cs{sup +}{sub (aq)}]{sup 1.10}, R = 1.15[Ba{sup 2+}{sub (aq)}]{sup 0.50}. Thus, the exchange rates for Na in triclinic birnessite decreased in the order: Cs >> K > Ba. These results are likely a function of hydration energy differences of the cations and the preference of the solution phase for the more readily hydrated cation.

  20. PSSP, a Computer Program for the Crystal Structure Solution of Molecular Materials from X-ray Powder Diffraction Data

    SciTech Connect

    Pagola, S.; Stephens, P

    2010-01-01

    This work describes the computer program PSSP (powder structure solution program) for the crystal structure solution of molecular solids from X-ray powder diffraction data. This direct-space structure solution program uses the simulated annealing global optimization algorithm to minimize the difference between integrated intensities calculated from trial models and those extracted in a Le Bail fit of the experimental pattern, using a cost function for dealing with peak overlap through defined intensity correlation coefficients, computationally faster to calculate than R{sub wp}. The methodology outlined is applicable to organic solids composed of moderately complex rigid and flexible molecules, using diffraction data up to relatively low resolution. PSSP performance tests using 11 molecular solids with six to 20 degrees of freedom are analyzed.

  1. Pulsed magnetic field synchrotron X-ray powder diffraction of the Jahn-Teller distortion in TbVO4

    NASA Astrophysics Data System (ADS)

    Vanacken, J.; Frings, P.; Detlefs, C.; Duc, F.; Lorenzo, J. E.; Nardone, M.; Billette, J.; Zitouni, A.; Bras, W.; Rikken, G.

    2006-11-01

    X-ray powder diffraction experiments under pulsed magnetic fields were carried out at the DUBBLE beam line at the ESRF. A mobile generator delivered 110 kJ to the load coil, which was sufficient to generate peak fields of 30 T. A liquid He flow cryostat allowed us to vary the sample temperature accurately between 8 K and 300 K. Powder diffraction patterns of TbVO4 were recorded in a broad temperature range using 21 keV monochromatic X-rays and an on-line image plate detector. We present results on the suppression of the Jahn-Teller structural distortion in TbVO4by to the magnetic field.

  2. Study of polymorphism of Atenolol and Captopril antihypertensives using x-ray powder diffraction and Rietveld refinement

    NASA Astrophysics Data System (ADS)

    Sato, Juliana; Ferreira, Fabio

    2013-03-01

    Characterization of bulk drugs has become increasingly important in the pharmaceutical industry. X-ray powder diffractometry is an effective technique for the identification of crystalline solid-phase drugs. The technique is unique, since it combines specificity with a high degree of accuracy for the characterization of pharmaceuticals in solid state and is an especially useful method to describe the possible polymorphic behavior of drugs substances. In this work X-ray diffraction data have been obtained for two well-known antihypertensive drugs currently being administered in tablet form. They include atenolol and captopril. Atenolol and captopril were purchased from drugstore. The characterizations of the atenolol and captopril samples were carried out by FTIR spectroscopy and X-ray powder diffraction (XRPD). We would like to thank the Brazilian agencies CNPq and FAPESP for their financial support.

  3. Neutron powder diffraction experiments on AMnF 4 (A=K, Rb): nuclear and magnetic structures

    NASA Astrophysics Data System (ADS)

    Morón, M. C.; Palacio, F.; Rodriguez-Carvajal, J.

    1992-06-01

    Neutron powder diffraction experiments show that KMnF 4 is monoclinic, space group P2 1/a, and RbMnF 4 orthorhombic, space group Pmab, between room temperature and 1.5K. The magnetic structure of both compounds is antiferromagnetic with Tc =6.6K for KMnF 4 and T = 3.9K for RbMnF 4.

  4. The use of time-resolved X-ray diffraction and sample techniques for studying the muscle structure during relaxation

    NASA Astrophysics Data System (ADS)

    Vazina, A. A.; Gadzhiev, A. M.; Gerasimov, V. S.; Gorbunova, N. P.; Sergienko, P. M.; Korneev, V. N.; Aulchenko, V. M.; Baru, S. E.

    1995-02-01

    The use of the modern time-resolved X-ray diffraction and sample technique has played an important role in studying muscle structures during contraction at various physiological conditions. We represent time-resolved X-ray data on equatorial diffraction and tension response of the frog sartorius muscle during relaxation. The measurements of the time-course of the intensity change of reflections (1,0), (1,1) and the background under them give a possibility to study the effect of potentiation of contraction by repetitive stimulation in fresh and tired muscles. Model calculations of meridional diffraction patterns for various configurations of cross-bridges in the relaxation phase were carried out.

  5. State-resolved diffraction oscillations imaged for inelastic collisions of NO radicals with He, Ne and Ar.

    PubMed

    von Zastrow, Alexander; Onvlee, Jolijn; Vogels, Sjoerd N; Groenenboom, Gerrit C; van der Avoird, Ad; van de Meerakker, Sebastiaan Y T

    2014-03-01

    Just as light scattering from an object results in diffraction patterns, the quantum mechanical nature of molecules can lead to the diffraction of matter waves during molecular collisions. This behaviour manifests itself as rapid oscillatory structures in measured differential cross-sections, and such observable features are sensitive probes of molecular interaction potentials. However, these structures have proved challenging to resolve experimentally. Here, we use a Stark decelerator to form a beam of state-selected and velocity-controlled NO radicals and measure state-to-state differential cross-sections for inelastic collisions of NO with He, Ne and Ar atoms using velocity map imaging. The monochromatic velocity distribution of the NO beam produced scattering images with unprecedented sharpness and angular resolution, thereby fully resolving quantum diffraction oscillations. We found excellent agreement with quantum close-coupling scattering calculations for these benchmark systems.

  6. Effect of Stacking Faults on the X-Ray Diffraction Profiles of Beta-SiC Powders

    NASA Technical Reports Server (NTRS)

    Pujar, Vijay V.; Cawley, James D.; Levine, Stanley R. (Technical Monitor)

    1995-01-01

    X-ray diffraction patterns or beta-SiC (3C or the cubic polytype or sic) powders often exhibit an additional peak at d = 0.266 nm, high background intensity around the (111) peak, and relative intensities for peaks which differ from those predicted from the crystal structure. Computer simulations were used to show that all these features are due to stacking faults in the powders and not due to the presence of other polytypes in the powders. Such simulations allow diffraction patterns to be generated for different types, frequencies, and spatial distribution or faults. Comparison of the simulation results to the XRD data indicates that the B-SiC particles consist either of heavily faulted clusters distributed irregularly between regions that have only occasional faults or twins, or the powders consist of two types of particles with different populations of faults: those with a high density of faults and those with only twins or occasional faults. Additional information is necessary to determine which description is correct. However, the simulation results can be used to rule out certain fault configurations.

  7. An Implementation of the Fundamental Parameters Approach for Analysis of X-ray Powder Diffraction Line Profiles

    PubMed Central

    Mendenhall, Marcus H.; Mullen, Katharine; Cline, James P.

    2015-01-01

    This work presents an open implementation of the Fundamental Parameters Approach (FPA) models for analysis of X-ray powder diffraction line profiles. The original literature describing these models was examined and code was developed to allow for their use within a Python based least squares refinement algorithm. The NIST interest in the FPA method is specific to its ability to account for the optical aberrations of the powder diffraction experiment allowing for an accurate assessment of lattice parameter values. Lattice parameters are one of the primary certified measurands of NIST Standard Reference Materials (SRMs) for powder diffraction. Lattice parameter values obtained from analysis of data from SRMs 640e and 660c using both the NIST FPA Python code and the proprietary, commercial code Topas, that constitutes the only other actively supported, complete implementation of FPA models within a least-squares data analysis environment, agreed to within 2 fm. This level of agreement demonstrates that both the NIST code and Topas constitute an accurate implementation of published FPA models. PMID:26958448

  8. Direct Observation of Phase Transformations in Austenitic Stainless Steel Welds Using In-situ Spatially Resolved and Time-resolved X-ray Diffraction

    SciTech Connect

    Elmer, J.; Wong, J.; Ressler, T.

    1999-09-23

    Spatially resolved x-ray diffraction (SRXRD) and time resolved x-ray diffraction (TRXRD) were used to investigate real time solid state phase transformations and solidification in AISI type 304 stainless steel gas tungsten arc (GTA) welds. These experiments were conducted at Stanford Synchrotron Radiation Laboratory (SSRL) using a high flux beam line. Spatially resolved observations of {gamma} {leftrightarrow} {delta} solid state phase transformations were performed in the heat affected zone (HAZ) of moving welds and time-resolved observations of the solidification sequence were performed in the fusion zone (FZ) of stationary welds after the arc had been terminated. Results of the moving weld experiments showed that the kinetics of the {gamma}{yields}{delta} phase transformation on heating in the HAZ were sufficiently rapid to transform a narrow region surrounding the liquid weld pool to the {delta} ferrite phase. Results of the stationary weld experiments showed, for the first time, that solidification can occur directly to the {delta} ferrite phase, which persisted as a single phase for 0.5s. Upon solidification to {delta}, the {delta} {yields} {gamma} phase transformation followed and completed in 0.2s as the weld cooled further to room temperature.

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

    PubMed Central

    Tenchov, Boris G.; Yao, Haruhiko; Hatta, Ichiro

    1989-01-01

    The phase transitions in fully hydrated dipalmitoylphosphatidylcholine (DPPC) and DPPC/water/ethanol phases have been studied by lowangle time-resolved x-ray diffraction under conditions similar to those employed in calorimetry (scan rates 0.05-0.5°C/min and uniform temperature throughout the samples). This approach provides more adequate characterization of the equilibrium transition pathways and allows for close correlations between structural and thermodynamic data. No coexistence of the rippled gel (Pβ') and liquid-crystalline (Lα) phases was found in the main transition of DPPC; rather, a loss of correlation in the lamellar structure, observed as broadening of the lamellar reflections, takes place in a narrow temperature range of ∼100 mK at the transition midpoint. Formation of a long-living metastable phase, denoted by Pβ'(mst), differing from the initial Pβ' was observed in cooling direction by both x-ray diffraction and calorimetry. No direct conversion of Pβ'(mst) into Pβ' occurs for over 24 h but only by way of the phase sequence Pβ'(mst) → Lβ' → Pβ'. According to differential scanning calorimetry (DSC), the enthalpy of the Pβ'(mst)-Lα transition is by ∼5% lower than that of the Pβ'-Lα transition. The effects of ethanol (Rowe, E. S. 1983. Biochemistry. 22:3299-3305; Simon, S. A., and T. J. McIntosh. 1984. Biochim. Biophys. Acta 773:169-172) on the mechanism and reversibility of the DPPC main transition were clearly visualized. At ethanol concentrations inducing formation of interdigitated gel phase, the main transition proceeds through a coexistence of the initial and final phases over a finite temperature range. During the subtransition in DPPC recorded at scan rate 0.3°C/min, a smooth monotonic increase of the lamellar spacing from its subgel (Lc) to its gel (Lβ') phase value takes place. The width of the lamellar reflections remains unchanged during this transformation. This provides grounds to propose a

  10. Examination of Short- and Long-Range Atomic Order Nanocrystalline SiC and Diamond by Powder Diffraction Methods

    NASA Technical Reports Server (NTRS)

    Palosz, B.; Grzanka, E.; Stelmakh, S.; Gierlotka, S.; Weber, H.-P.; Proffen, T.; Palosz, W.

    2002-01-01

    The real atomic structure of nanocrystals determines unique, key properties of the materials. Determination of the structure presents a challenge due to inherent limitations of standard powder diffraction techniques when applied to nanocrystals. Alternate methodology of the structural analysis of nanocrystals (several nanometers in size) based on Bragg-like scattering and called the "apparent lattice parameter" (alp) is proposed. Application of the alp methodology to examination of the core-shell model of nanocrystals will be presented. The results of application of the alp method to structural analysis of several nanopowders were complemented by those obtained by determination of the Atomic Pair Distribution Function, PDF. Based on synchrotron and neutron diffraction data measured in a large diffraction vector of up to Q = 25 Angstroms(exp -1), the surface stresses in nanocrystalline diamond and SiC were evaluated.

  11. A Rietveld refinement method for angular- and wavelength-dispersive neutron time-of-flight powder diffraction data

    PubMed Central

    Jacobs, Philipp; Houben, Andreas; Schweika, Werner; Tchougréeff, Andrei L.; Dronskowski, Richard

    2015-01-01

    This paper introduces a two-dimensional extension of the well established Rietveld refinement method for modeling neutron time-of-flight powder diffraction data. The novel approach takes into account the variation of two parameters, diffraction angle 2θ and wavelength λ, to optimally adapt to the varying resolution function in diffraction experiments. By doing so, the refinement against angular- and wavelength-dispersive data gets rid of common data-reduction steps and also avoids the loss of high-resolution information typically introduced by integration. In a case study using a numerically simulated diffraction pattern of Rh0.81Fe3.19N taking into account the layout of the future POWTEX instrument, the profile function as parameterized in 2θ and λ is extracted. As a proof-of-concept, the resulting instrument parameterization is then utilized to perform a typical refinement of the angular- and wavelength-dispersive diffraction pattern of CuNCN, yielding excellent residuals within feasible computational efforts. Another proof-of-concept is carried out by applying the same approach to a real neutron diffraction data set of CuNCN obtained from the POWGEN instrument at the Spallation Neutron Source in Oak Ridge. The paper highlights the general importance of the novel approach for data analysis at neutron time-of-flight diffractometers and its possible inclusion within existing Rietveld software packages. PMID:26664340

  12. A Rietveld refinement method for angular- and wavelength-dispersive neutron time-of-flight powder diffraction data.

    PubMed

    Jacobs, Philipp; Houben, Andreas; Schweika, Werner; Tchougréeff, Andrei L; Dronskowski, Richard

    2015-12-01

    This paper introduces a two-dimensional extension of the well established Rietveld refinement method for modeling neutron time-of-flight powder diffraction data. The novel approach takes into account the variation of two parameters, diffraction angle 2θ and wavelength λ, to optimally adapt to the varying resolution function in diffraction experiments. By doing so, the refinement against angular- and wavelength-dispersive data gets rid of common data-reduction steps and also avoids the loss of high-resolution information typically introduced by integration. In a case study using a numerically simulated diffraction pattern of Rh0.81Fe3.19N taking into account the layout of the future POWTEX instrument, the profile function as parameterized in 2θ and λ is extracted. As a proof-of-concept, the resulting instrument parameterization is then utilized to perform a typical refinement of the angular- and wavelength-dispersive diffraction pattern of CuNCN, yielding excellent residuals within feasible computational efforts. Another proof-of-concept is carried out by applying the same approach to a real neutron diffraction data set of CuNCN obtained from the POWGEN instrument at the Spallation Neutron Source in Oak Ridge. The paper highlights the general importance of the novel approach for data analysis at neutron time-of-flight diffractometers and its possible inclusion within existing Rietveld software packages.

  13. Kinetics of methane-ethane gas replacement in clathrate-hydrates studied by time-resolved neutron diffraction and Raman spectroscopy.

    PubMed

    Murshed, M Mangir; Schmidt, Burkhard C; Kuhs, Werner F

    2010-01-14

    The kinetics of CH(4)-C(2)H(6) replacement in gas hydrates has been studied by in situ neutron diffraction and Raman spectroscopy. Deuterated ethane structure type I (C(2)H(6) sI) hydrates were transformed in a closed volume into methane-ethane mixed structure type II (CH(4)-C(2)H(6) sII) hydrates at 5 MPa and various temperatures in the vicinity of 0 degrees C while followed by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. The role of available surface area of the sI starting material on the formation kinetics of sII hydrates was studied. Ex situ Raman spectroscopic investigations were carried out to crosscheck the gas composition and the distribution of the gas species over the cages as a function of structure type and compared to the in situ neutron results. Raman micromapping on single hydrate grains showed compositional and structural gradients between the surface and core of the transformed hydrates. Moreover, the observed methane-ethane ratio is very far from the one expected for a formation from a constantly equilibrated gas phase. The results also prove that gas replacement in CH(4)-C(2)H(6) hydrates is a regrowth process involving the nucleation of new crystallites commencing at the surface of the parent C(2)H(6) sI hydrate with a progressively shrinking core of unreacted material. The time-resolved neutron diffraction results clearly indicate an increasing diffusion limitation of the exchange process. This diffusion limitation leads to a progressive slowing down of the exchange reaction and is likely to be responsible for the incomplete exchange of the gases.

  14. New routes to synthesizing an ordered perovskite CaCu3Fe2Sb2O12 and its magnetic structure by neutron powder diffraction.

    PubMed

    Larregola, Sebastian A; Zhou, Jianshi; Alonso, Jose A; Pomjakushin, Vladimir; Goodenough, John B

    2014-05-05

    The search for new double-perovskite oxides has grown rapidly in recent years because of their interesting physical properties like ferroelectricity, magnetism, and multiferroics. The synthesis of double perovskites, especially the A-site-ordered perovskites, in most cases needs to be made under high pressure, which is a drawback for applying these materials. Here we have demonstrated synthetic routes at ambient pressure by which we have obtained a high-quality duo-sites-ordered double perovskite, CaCu3Fe2Sb2O12, which has been previously synthesized under high pressure. The availability of a large quantity of the powder sample allows us to determine the crystal and magnetic structures by neutron powder diffraction (NPD) at 300 and 1.3 K. Measurements of the magnetization and heat capacity showed a ferrimagnetic transition at 160 K. A ferrimagnetic structure consisting of the uncompensated antiferromagnetic coupling between neighboring collinear copper and iron spins has been resolved from the low-temperature NPD data.

  15. Structured illumination multimodal 3D-resolved quantitative phase and fluorescence sub-diffraction microscopy

    PubMed Central

    Chowdhury, Shwetadwip; Eldridge, Will J.; Wax, Adam; Izatt, Joseph A.

    2017-01-01

    Sub-diffraction resolution imaging has played a pivotal role in biological research by visualizing key, but previously unresolvable, sub-cellular structures. Unfortunately, applications of far-field sub-diffraction resolution are currently divided between fluorescent and coherent-diffraction regimes, and a multimodal sub-diffraction technique that bridges this gap has not yet been demonstrated. Here we report that structured illumination (SI) allows multimodal sub-diffraction imaging of both coherent quantitative-phase (QP) and fluorescence. Due to SI’s conventionally fluorescent applications, we first demonstrate the principle of SI-enabled three-dimensional (3D) QP sub-diffraction imaging with calibration microspheres. Image analysis confirmed enhanced lateral and axial resolutions over diffraction-limited QP imaging, and established striking parallels between coherent SI and conventional optical diffraction tomography. We next introduce an optical system utilizing SI to achieve 3D sub-diffraction, multimodal QP/fluorescent visualization of A549 biological cells fluorescently tagged for F-actin. Our results suggest that SI has a unique utility in studying biological phenomena with significant molecular, biophysical, and biochemical components. PMID:28663887

  16. In situ X-ray powder diffraction, synthesis, and magnetic properties of InVO{sub 3}

    SciTech Connect

    Lundgren, Rylan J.; Cranswick, Lachlan M.D.; Bieringer, Mario . E-mail: Mario_Bieringer@umanitoba.ca

    2006-12-15

    We report the first synthesis and high-temperature in situ X-ray diffraction study of InVO{sub 3}. Polycrystalline InVO{sub 3} has been prepared via reduction of InVO{sub 4} using a carbon monoxide/carbon dioxide buffer gas. InVO{sub 3} crystallizes in the bixbyite structure in space group Ia-3 (206) with a=9.80636(31) A with In{sup 3+}/V{sup 3+} disorder on the (8b) and (24d) cation sites. In situ powder X-ray diffraction experiments and thermal gravimetric analysis in a CO/CO{sub 2} buffer gas revealed the existence of the metastable phase InVO{sub 3}. Bulk samples with 98.5(2)% purity were prepared using low-temperature reduction methods. The preparative methods limited the crystallinity of this new phase to approximately 225(50) A. Magnetic susceptibility and neutron diffraction experiments suggest a spin-glass ground state for InVO{sub 3}. - Graphical abstract: In situ powder X-ray diffractograms for the reduction of InVO{sub 4} in CO/CO{sub 2}. The three temperature regions show the conversion of InVO{sub 4} to InVO{sub 3} and final decomposition into In{sub 2}O{sub 3} and V{sub 2}O{sub 3}.

  17. Crystal structure analysis of β-tricalcium phosphate Ca 3(PO 4) 2 by neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Yashima, Masatomo; Sakai, Atsushi; Kamiyama, Takashi; Hoshikawa, Akinori

    2003-11-01

    The crystal structure of sintered β-tricalcium phosphate, Ca 3(PO 4) 2, was refined using a high-resolution neutron powder diffraction data and the Rietveld method. This material was confirmed to have a rhombohedral structure (space group R3 c, Z=21). Unit-cell parameters with higher precision ( a= b=10.4352(2) Å, c=37.4029(5) Å, α= β=90°, and γ=120° in the hexagonal setting) and positional parameters for oxygen with equal precision were obtained by the neutron powder diffraction technique, compared with the single-crystal X-ray diffraction data by Dickens et al. (J. Solid State Chem. 10 (1974) 232). The site Ca(4) with atomic coordinates [0.0, 0.0, -0.0851(6)] was confirmed to be very different from the other four Ca sites: The position Ca(4) is three-fold coordinated with oxygen atoms, and has lower occupancy factor of 0.43(4), and a higher isotropic thermal parameter. On the contrary, each of the Ca(1), Ca(2), Ca(3), and Ca(5) is fully occupied by one Ca atom and these positions are coordinated with seven, eight, eight, and six oxygen atoms, respectively. The bond valence sums of Ca(4) and Ca(5) are lower (0.7) and higher (2.7), respectively, than the others (1.8-2.1).

  18. Accurate charge densities from powder X-ray diffraction - a new version of the Aarhus vacuum imaging-plate diffractometer.

    PubMed

    Tolborg, Kasper; Jørgensen, Mads R V; Christensen, Sebastian; Kasai, Hidetaka; Becker, Jacob; Walter, Peter; Dippel, Ann Christin; Als-Nielsen, Jens; Iversen, Bo B

    2017-08-01

    In recent years powder X-ray diffraction has proven to be a valuable alternative to single-crystal X-ray diffraction for determining electron-density distributions in high-symmetry inorganic materials, including subtle deformation in the core electron density. This was made possible by performing diffraction measurements in vacuum using high-energy X-rays at a synchrotron-radiation facility. Here we present a new version of our custom-built in-vacuum powder diffractometer with the sample-to-detector distance increased by a factor of four. In practice this is found to give a reduction in instrumental peak broadening by approximately a factor of three and a large improvement in signal-to-background ratio compared to the previous instrument. Structure factors of silicon at room temperature are extracted using a combined multipole-Rietveld procedure and compared with ab initio calculations and the results from the previous diffractometer. Despite some remaining issues regarding peak asymmetry, the new diffractometer yields structure factors of comparable accuracy to the previous diffractometer at low angles and improved accuracy at high angles. The high quality of the structure factors is further assessed by modelling of core electron deformation with results in good agreement with previous investigations.

  19. A Flow-through Reaction Cell that Couples Time-resolved X-ray Diffraction with Stable Isotope Analysis

    SciTech Connect

    Hanson, J.C.; Wall, A.J.; Heaney, P.J.; Mathur, R.; Post, J.E.; Eng, P.J.

    2011-04-01

    A non-metallic flow-through reaction cell is described, designed for in situ time-resolved X-ray diffraction coupled with stable isotope analysis. The experimental setup allows the correlation of Cu isotope fractionation with changes in crystal structure during copper sulfide dissolution. This flow-through cell can be applied to many classes of fluid-mineral reactions that involve dissolution or ion exchange.

  20. High-throughput powder diffraction measurement system consisting of multiple MYTHEN detectors at beamline BL02B2 of SPring-8

    NASA Astrophysics Data System (ADS)

    Kawaguchi, S.; Takemoto, M.; Osaka, K.; Nishibori, E.; Moriyoshi, C.; Kubota, Y.; Kuroiwa, Y.; Sugimoto, K.

    2017-08-01

    In this study, we developed a user-friendly automatic powder diffraction measurement system for Debye-Scherrer geometry using a capillary sample at beamline BL02B2 of SPring-8. The measurement system consists of six one-dimensional solid-state (MYTHEN) detectors, a compact auto-sampler, wide-range temperature control systems, and a gas handling system. This system enables to do the automatic measurement of temperature dependence of the diffraction patterns for multiple samples. We introduced two measurement modes in the MYTHEN system and developed new attachments for the sample environment such as a gas handling system. The measurement modes and the attachments can offer in situ and/or time-resolved measurements in an extended temperature range between 25 K and 1473 K and various gas atmospheres and pressures. The results of the commissioning and performance measurements using reference materials (NIST CeO2 674b and Si 640c), V2O3 and Ti2O3, and a nanoporous coordination polymer are presented.

  1. High-throughput powder diffraction measurement system consisting of multiple MYTHEN detectors at beamline BL02B2 of SPring-8.

    PubMed

    Kawaguchi, S; Takemoto, M; Osaka, K; Nishibori, E; Moriyoshi, C; Kubota, Y; Kuroiwa, Y; Sugimoto, K

    2017-08-01

    In this study, we developed a user-friendly automatic powder diffraction measurement system for Debye-Scherrer geometry using a capillary sample at beamline BL02B2 of SPring-8. The measurement system consists of six one-dimensional solid-state (MYTHEN) detectors, a compact auto-sampler, wide-range temperature control systems, and a gas handling system. This system enables to do the automatic measurement of temperature dependence of the diffraction patterns for multiple samples. We introduced two measurement modes in the MYTHEN system and developed new attachments for the sample environment such as a gas handling system. The measurement modes and the attachments can offer in situ and/or time-resolved measurements in an extended temperature range between 25 K and 1473 K and various gas atmospheres and pressures. The results of the commissioning and performance measurements using reference materials (NIST CeO2 674b and Si 640c), V2O3 and Ti2O3, and a nanoporous coordination polymer are presented.

  2. Quantitative phase analysis of challenging samples using neutron powder diffraction. Sample #4 from the CPD QPA round robin revisited

    SciTech Connect

    Whitfield, Pamela S.

    2016-04-29

    Here, quantitative phase analysis (QPA) using neutron powder diffraction more often than not involves non-ambient studies where no sample preparation is possible. The larger samples and penetration of neutrons versus X-rays makes neutron diffraction less susceptible to inhomogeneity and large grain sizes, but most well-characterized QPA standard samples do not have these characteristics. Sample #4 from the International Union of Crystallography Commission on Powder Diffraction QPA round robin was one such sample. Data were collected using the POWGEN time-of-flight (TOF) neutron powder diffractometer and analysed together with historical data from the C2 diffractometer at Chalk River. The presence of magnetic reflections from Fe3O4 (magnetite) in the sample was an additional consideration, and given the frequency at which iron-containing and other magnetic compounds are present during in-operando studies their possible impact on the accuracy of QPA is of interest. Additionally, scattering from thermal diffuse scattering in the high-Qregion (<0.6 Å) accessible with TOF data could impact QPA results during least-squares because of the extreme peak overlaps present in this region. Refinement of POWGEN data was largely insensitive to the modification of longer d-spacing reflections by magnetic contributions, but the constant-wavelength data were adversely impacted if the magnetic structure was not included. A robust refinement weighting was found to be effective in reducing quantification errors using the constant-wavelength neutron data both where intensities from magnetic reflections were ignored and included. Results from the TOF data were very sensitive to inadequate modelling of the high-Q (lowd-spacing) background using simple polynomials.

  3. Quantitative phase analysis of challenging samples using neutron powder diffraction. Sample #4 from the CPD QPA round robin revisited

    DOE PAGES

    Whitfield, Pamela S.

    2016-04-29

    Here, quantitative phase analysis (QPA) using neutron powder diffraction more often than not involves non-ambient studies where no sample preparation is possible. The larger samples and penetration of neutrons versus X-rays makes neutron diffraction less susceptible to inhomogeneity and large grain sizes, but most well-characterized QPA standard samples do not have these characteristics. Sample #4 from the International Union of Crystallography Commission on Powder Diffraction QPA round robin was one such sample. Data were collected using the POWGEN time-of-flight (TOF) neutron powder diffractometer and analysed together with historical data from the C2 diffractometer at Chalk River. The presence of magneticmore » reflections from Fe3O4 (magnetite) in the sample was an additional consideration, and given the frequency at which iron-containing and other magnetic compounds are present during in-operando studies their possible impact on the accuracy of QPA is of interest. Additionally, scattering from thermal diffuse scattering in the high-Qregion (<0.6 Å) accessible with TOF data could impact QPA results during least-squares because of the extreme peak overlaps present in this region. Refinement of POWGEN data was largely insensitive to the modification of longer d-spacing reflections by magnetic contributions, but the constant-wavelength data were adversely impacted if the magnetic structure was not included. A robust refinement weighting was found to be effective in reducing quantification errors using the constant-wavelength neutron data both where intensities from magnetic reflections were ignored and included. Results from the TOF data were very sensitive to inadequate modelling of the high-Q (lowd-spacing) background using simple polynomials.« less

  4. Quantitative phase analysis of challenging samples using neutron powder diffraction. Sample #4 from the CPD QPA round robin revisited

    SciTech Connect

    Whitfield, Pamela S.

    2016-04-29

    Here, quantitative phase analysis (QPA) using neutron powder diffraction more often than not involves non-ambient studies where no sample preparation is possible. The larger samples and penetration of neutrons versus X-rays makes neutron diffraction less susceptible to inhomogeneity and large grain sizes, but most well-characterized QPA standard samples do not have these characteristics. Sample #4 from the International Union of Crystallography Commission on Powder Diffraction QPA round robin was one such sample. Data were collected using the POWGEN time-of-flight (TOF) neutron powder diffractometer and analysed together with historical data from the C2 diffractometer at Chalk River. The presence of magnetic reflections from Fe3O4 (magnetite) in the sample was an additional consideration, and given the frequency at which iron-containing and other magnetic compounds are present during in-operando studies their possible impact on the accuracy of QPA is of interest. Additionally, scattering from thermal diffuse scattering in the high-Qregion (<0.6 Å) accessible with TOF data could impact QPA results during least-squares because of the extreme peak overlaps present in this region. Refinement of POWGEN data was largely insensitive to the modification of longer d-spacing reflections by magnetic contributions, but the constant-wavelength data were adversely impacted if the magnetic structure was not included. A robust refinement weighting was found to be effective in reducing quantification errors using the constant-wavelength neutron data both where intensities from magnetic reflections were ignored and included. Results from the TOF data were very sensitive to inadequate modelling of the high-Q (lowd-spacing) background using simple polynomials.

  5. Toward ultrafast time-resolved Debye-Scherrer x-ray diffraction using a laser-plasma source.

    PubMed

    Shymanovich, U; Nicoul, M; Lu, W; Kähle, S; Tarasevitch, A; Sokolowski-Tinten, K; von der Linde, D

    2009-08-01

    An elliptical glass capillary has been used to focus ultrashort Cu K alpha x-ray pulses emitted from a femtosecond laser-produced plasma. Due to its high magnification (7x), the optic transforms the divergent x-ray emission of the plasma into a quasicollimated x-ray beam with a divergence of only 0.18 degrees. As an application we demonstrate the possibility to perform Debye-Scherrer diffraction experiments with the simultaneous detection of several diffraction orders. This will allow one to extend time-resolved x-ray diffraction with femtosecond laser-plasma x-ray sources to a much wider range of materials, which are not easily available as single crystals.

  6. Elasticity of Tantalum to 105 Gpa using a stress and angle-resolved x-ray diffraction

    SciTech Connect

    Cynn, H; Yoo, C S

    1999-08-11

    Determining the mechanical properties such as elastic constants of metals at Mbar pressures has been a difficult task in experiment. Following the development of anisotropic elastic theory by Singh et al. [l], Mao et a1.[2] have recently developed a novel experimental technique to determine the elastic constants of Fe by using the stress and energy-dispersive x-ray diffraction (SEX). In this paper, we present an improved complementary technique, stress and angle-resolved x-ray diffraction (SAX), which we have applied to determine the elastic constants of tantalum to 105 GPa. The extrapolation of the tantalum elastic data shows an excellent agreement with the low-pressure ultrasonic data [3]. We also discuss the improvement of this SAX method over the previous SEX. [elastic constant, anisotropic elastic theory, angle-dispersive synchrotron x-ray diffraction, mechanical properties

  7. Comparison of crystallite shapes in four different varieties of cotton fibers using X-ray powder diffraction data

    NASA Astrophysics Data System (ADS)

    Manju, V. V.; Divakara, S.; Somashekhar, R.

    2017-05-01

    Four different varieties of cotton fibers were obtained from farmers and used after cleaning the fibers physically. X-ray powder diffraction data for these fibers was obtained using imaging plate system (Dip-3200) with dimension 440 × 240 mm2. With the available software, scanning was carried out along the equator to obtain Intensity versus two-theta after correcting for instrumental broadening and Lorentz polarization factors. Using peak-fit program, 12 Bragg reflections were identified and FWHM of these (hkl) reflections, were used to estimate the crystallite size and strain along [hkl] directions. From these data we have suggested a novel method to compute crystallite shape in these cotton fibers.

  8. Diffraction anomalous fine structure analysis on (Bi,Pb){sub 2}PtO{sub 4} powders

    SciTech Connect

    Vacinova, J.; Hodeau, J.L.; Bordet, P.

    1995-12-31

    The Diffraction Anomalous Fine Structure (DAFS) method can provide site selective and chemical selective structural information. The possibilities of DAFS experimental and data analysis procedures are demonstrated for (Bi{sub 1.67},Pb{sub 0.33}) powder samples. Experiments have been performed at both L{sub III} and K Pt edges (11.56.564keV and 78keV), using several data collection set-ups (analyser crystals, 1D-detector, 2D-detector). Based on this example, a comparison between these experimental procedures and analysis is given and discussed.

  9. Crystal structure of anhydrous tripotassium citrate from laboratory X-ray powder diffraction data and DFT comparison

    PubMed Central

    Rammohan, Alagappa; Kaduk, James A.

    2016-01-01

    The crystal structure of anhydrous tripotassium citrate, [K3(C6H5O7)]n, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The three unique potassium cations are 6-, 8-, and 6-coordinate (all irregular). The [KOn] coordination polyhedra share edges and corners to form a three-dimensional framework, with channels running parallel to the c axis. The only hydrogen bond is an intra­molecular one involving the hy­droxy group and the central carboxyl­ate group, with graph-set motif S(5). PMID:27536403

  10. Dynamic crystal rotation resolved by high-speed synchrotron X-ray Laue diffraction

    SciTech Connect

    Huang, J. W.; E, J. C.; Huang, J. Y.; Sun, T.; Fezzaa, K.; Luo, S. N.

    2016-03-30

    Dynamic compression experiments are performed on single-crystal Si under split Hopkinson pressure bar loading, together with simultaneous high-speed (250–350 ns resolution) synchrotron X-ray Laue diffraction and phase-contrast imaging. A methodology is presented which determines crystal rotation parameters,i.e.instantaneous rotation axes and angles, from two unindexed Laue diffraction spots. Two-dimensional translation is obtained from dynamic imaging by a single camera. High-speed motion of crystals, including translation and rotation, can be tracked in real timeviasimultaneous imaging and diffraction.

  11. Dynamic crystal rotation resolved by high-speed synchrotron X-ray Laue diffraction

    PubMed Central

    Huang, J. W.; E, J. C.; Huang, J. Y.; Sun, T.; Fezzaa, K.; Luo, S. N.

    2016-01-01

    Dynamic compression experiments are performed on single-crystal Si under split Hopkinson pressure bar loading, together with simultaneous high-speed (250–350 ns resolution) synchrotron X-ray Laue diffraction and phase-contrast imaging. A methodology is presented which determines crystal rotation parameters, i.e. instantaneous rotation axes and angles, from two unindexed Laue diffraction spots. Two-dimensional translation is obtained from dynamic imaging by a single camera. High-speed motion of crystals, including translation and rotation, can be tracked in real time via simultaneous imaging and diffraction. PMID:27140150

  12. Diffraction-free light droplets for axially-resolved volume imaging.

    PubMed

    Antonacci, G; Domenico, G Di; Silvestri, S; DelRe, E; Ruocco, G

    2017-12-01

    An ideal direct imaging system entails a method to illuminate on command a single diffraction-limited region in a generally thick and turbid volume. The best approximation to this is the use of large-aperture lenses that focus light into a spot. This strategy fails for regions that are embedded deep into the sample, where diffraction and scattering prevail. Airy beams and Bessel beams are solutions of the Helmholtz Equation that are both non-diffracting and self-healing, features that make them naturally able to outdo the effects of distance into the volume but intrinsically do not allow resolution along the propagation axis. Here, we demonstrate diffraction-free self-healing three-dimensional monochromatic light spots able to penetrate deep into the volume of a sample, resist against deflection in turbid environments, and offer axial resolution comparable to that of Gaussian beams. The fields, formed from coherent mixtures of Bessel beams, manifest a more than ten-fold increase in their undistorted penetration, even in turbid milk solutions, compared to diffraction-limited beams. In a fluorescence imaging scheme, we find a ten-fold increase in image contrast compared to diffraction-limited illuminations, and a constant axial resolution even after four Rayleigh lengths. Results pave the way to new opportunities in three-dimensional microscopy.

  13. Beamline P02.1 at PETRA III for high-resolution and high-energy powder diffraction

    PubMed Central

    Dippel, Ann-Christin; Liermann, Hanns-Peter; Delitz, Jan Torben; Walter, Peter; Schulte-Schrepping, Horst; Seeck, Oliver H.; Franz, Hermann

    2015-01-01

    Powder X-ray diffraction techniques largely benefit from the superior beam quality provided by high-brilliance synchrotron light sources in terms of photon flux and angular resolution. The High Resolution Powder Diffraction Beamline P02.1 at the storage ring PETRA III (DESY, Hamburg, Germany) combines these strengths with the power of high-energy X-rays for materials research. The beamline is operated at a fixed photon energy of 60 keV (0.207 Å wavelength). A high-resolution monochromator generates the highly collimated X-ray beam of narrow energy bandwidth. Classic crystal structure determination in reciprocal space at standard and non-ambient conditions are an essential part of the scientific scope as well as total scattering analysis using the real space information of the pair distribution function. Both methods are complemented by in situ capabilities with time-resolution in the sub-second regime owing to the high beam intensity and the advanced detector technology for high-energy X-rays. P02.1’s efficiency in solving chemical and crystallographic problems is illustrated by presenting key experiments that were carried out within these fields during the early stage of beamline operation. PMID:25931084

  14. Structure of MnPO/sub 4/ x H/sub 2/O by synchrotron x-ray powder diffraction

    SciTech Connect

    Lightfoot, P.; Cheetham, A.K.; Sleight, A.W.

    1987-10-21

    The crystal structure of MnPO/sub 4/ x H/sub 2/O has been determined from high-resolution synchrotron X-ray powder diffraction data. The powder pattern was indexed on the basis of 20 accurately measured reflections by an automatic indexing program. Integrated intensities were obtained for 61 unambiguously indexed reflections and used to generate a Patterson map from which the position of the manganese atom was determined. The remaining non-hydrogen atoms were located by Fourier methods, and the hydrogen atom was placed geometrically and refined without constraints. Refinement of the entire diffraction profile, by the Rietveld method, converged to final agreement factors R/sub wp/ = 0.161, R/sub p/ = 0.122, and R/sub I/ = 0.047. The compound crystallizes in the monoclinic space group, C2c, with lattice parameters a = 6.912 (1) A, b = 7.470 (1) A, c = 7.357 (1) A, ..beta.. = 112.3 (1)/sup 0/, and Z = 4. The structure consists of axially distorted MnO/sub 6/ octahedra linked together, through the oxygen atom of the water molecule at a common vertex, to form zigzag-Mn-O-Mn-chains running parallel to (101). These chains are interconnected by PO/sub 4/ tetrahedra to form a continuous three-dimensional network. 27 references, 5 figures, 2 tables.

  15. Azine bridged silver coordination polymers: Powder X-ray diffraction route to crystal structure determination of silver benzotriazole

    SciTech Connect

    Rajeswaran, Manju . E-mail: manju.rajeswaran@kodak.com; Blanton, Thomas N.; Giesen, David J.; Whitcomb, David R.; Zumbulyadis, Nicholas; Antalek, Brian J.; Neumann, Marcus M.; Misture, Scott T.

    2006-04-15

    In continuation of our interest in solid-state structures of silver complexes of photographic importance, the structure for silver benzotriazole (AgBZT), has now been obtained. The preferred method for solving crystal structures is via single-crystal X-ray diffraction (XRD). However, for some materials, growing single crystals of appropriate size and quality is often difficult or even impossible. AgBZT is an example of such a silver complex with poor solubility. The usual routes to preparing single crystals using recrystallization from a cooperating solvent resulted in polycrystalline powder samples. We propose a crystal structure for AgBZT, solved from synchrotron X-ray powder diffraction data, using a direct-space Monte Carlo simulated annealing approach. AgBZT crystals are monoclinic (P2{sub 1} /c), with unit cell dimensions, a=14.8052(3) A, b=3.7498(4) A, c=12.3495(12) A, and {beta}=114.200(6){sup o}. The AgBZT complex is constructed from all three of the Benzotriazole (BZT) nitrogens bonding to a separate silver atom. As a consequence of this bonding mode, the structure is a highly cross-linked, coordination polymer.

  16. Real-time monitoring of laser powder bed fusion process using high-speed X-ray imaging and diffraction

    DOE PAGES

    Zhao, Cang; Fezzaa, Kamel; Cunningham, Ross W.; ...

    2017-06-15

    Here, we employ the high-speed synchrotron hard X-ray imaging and diffraction techniques to monitor the laser powder bed fusion (LPBF) process of Ti-6Al-4V in situ and in real time. We demonstrate that many scientifically and technologically significant phenomena in LPBF, including melt pool dynamics, powder ejection, rapid solidification, and phase transformation, can be probed with unprecedented spatial and temporal resolutions. In particular, the keyhole pore formation is experimentally revealed with high spatial and temporal resolutions. The solidification rate is quantitatively measured, and the slowly decrease in solidification rate during the relatively steady state could be a manifestation of the recalescencemore » phenomenon. The high-speed diffraction enables a reasonable estimation of the cooling rate and phase transformation rate, and the diffusionless transformation from β to α’ phase is evident. The data present here will facilitate the understanding of dynamics and kinetics in metal LPBF process, and the experiment platform established will undoubtedly become a new paradigm for future research and development of metal additive manufacturing.« less

  17. An Analysis of Shock-Compression in Mo-Si Powder Mixtures Using Recovery and Time-Resolved Measurements

    NASA Astrophysics Data System (ADS)

    Vandersall, Kevin S.; Thadhani, Naresh N.

    1999-06-01

    The densification and reaction characteristics in the Mo-Si system were investigated utilizing recovery experiments as well as time resolved measurements with in-situ stress gages. The starting sample in all cases consisted of statically pressed Mo + 2 Si powder mixtures ( ~55% TMD). The recovery experiments were performed using the Sandia Momma Bear and Momma Bear A fixtures with baratol and composition B explosives respectively. The instrumented experiments were performed in a capsule design similar to that of the Momma Bear, but modified to incorporate poly-vinyl di-flouride (PVDF) stress gages at the front and rear surfaces of the powder. These experiments were performed using a single stage gas gun in the velocity range of 500 m/s to 1 km/s. The instrumented experiments allow the crush strength, densification history, and reaction threshold to be mapped at increasing pressure to correlate with reaction observed in the recovery experiments.

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

    SciTech Connect

    Yun, Di; Miao, Yinbin; Xu, Ruqing; Mei, Zhigang; Mo, Kun; Mohamed, Walid; Ye, Bei; Pellin, Michael J.; Yacout, Abdellatif M.

    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 performed 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.

  19. Time-resolved measurements with streaked diffraction patterns from electrons generated in laser plasma wakefield

    NASA Astrophysics Data System (ADS)

    He, Zhaohan; Nees, John; Hou, Bixue; Krushelnick, Karl; Thomas, Alec; Beaurepaire, Benoît; Malka, Victor; Faure, Jérôme

    2013-10-01

    Femtosecond bunches of electrons with relativistic to ultra-relativistic energies can be robustly produced in laser plasma wakefield accelerators (LWFA). Scaling the electron energy down to sub-relativistic and MeV level using a millijoule laser system will make such electron source a promising candidate for ultrafast electron diffraction (UED) applications due to the intrinsic short bunch duration and perfect synchronization with the optical pump. Recent results of electron diffraction from a single crystal gold foil, using LWFA electrons driven by 8-mJ, 35-fs laser pulses at 500 Hz, will be presented. The accelerated electrons were collimated with a solenoid magnetic lens. By applying a small-angle tilt to the magnetic lens, the diffraction pattern can be streaked such that the temporal evolution is separated spatially on the detector screen after propagation. The observable time window and achievable temporal resolution are studied in pump-probe measurements of photo-induced heating on the gold foil.

  20. Apparatus and Techniques for Time-resolved Synchrotron X-ray Diffraction using Diamond Anvil Cells

    NASA Astrophysics Data System (ADS)

    Smith, J.; Sinogeikin, S. V.; Lin, C.; Rod, E.; Bai, L.; Shen, G.

    2015-12-01

    Complementary advances in synchrotron sources, x-ray optics, area detectors, and sample environment control have recently made possible many time-resolved experimental techniques for studying materials at extreme pressure and temperature conditions. The High Pressure Collaborative Access Team (HPCAT) at the Advanced Photon Source has made a sustained effort to assemble a powerful collection of high-pressure apparatus for time-resolved research, and considerable time has been invested in developing techniques for collecting high-quality time-resolved x-ray scattering data. Herein we present key aspects of the synchrotron beamline and ancillary equipment, including source considerations, rapid (de)compression apparatus, high frequency imaging detectors, and software suitable for processing large volumes of data. A number of examples are presented, including fast equation of state measurements, compression rate dependent synthesis of metastable states in silicon and germanium, and ultrahigh compression rates using a piezoelectric driven diamond anvil cell.

  1. Effect of microfibril twisting in theoretical powder diffraction studies of cellulose Iß

    USDA-ARS?s Scientific Manuscript database

    Previous studies of calculated diffraction patterns for cellulose crystallites have suggested that the distortions arising once models have been subjected to MD simulation are likely the result of dimensional changes induced by the empirical force field, but have been unable to determine to what ext...

  2. Super-resolving quantum radar: Coherent-state sources with homodyne detection suffice to beat the diffraction limit

    SciTech Connect

    Jiang, Kebei; Lee, Hwang; Gerry, Christopher C.; Dowling, Jonathan P.

    2013-11-21

    There has been much recent interest in quantum metrology for applications to sub-Raleigh ranging and remote sensing such as in quantum radar. For quantum radar, atmospheric absorption and diffraction rapidly degrades any actively transmitted quantum states of light, such as N00N states, so that for this high-loss regime the optimal strategy is to transmit coherent states of light, which suffer no worse loss than the linear Beer's law for classical radar attenuation, and which provide sensitivity at the shot-noise limit in the returned power. We show that coherent radar radiation sources, coupled with a quantum homodyne detection scheme, provide both longitudinal and angular super-resolution much below the Rayleigh diffraction limit, with sensitivity at shot-noise in terms of the detected photon power. Our approach provides a template for the development of a complete super-resolving quantum radar system with currently available technology.

  3. Time-Resolved Synchrotron X-ray Diffraction on Pulse Laser Heated Iron in Diamond Anvil Cell

    SciTech Connect

    Yoo, C S; Wei, H; Dias, R; Shen, G; Smith, J; Chen, J Y; Evans, W

    2011-09-21

    The authors present time-resolved synchrotron x-ray diffraction to probe the {var_epsilon}-{delta} phase transition of iron during pulse-laser heating in a diamond anvil cell. The system utilizes a monochromatic synchrotron x-ray beam, a two-dimensional pixel array x-ray detector and a dual beam, double side laser-heating system. Multiple frames of the diffraction images are obtained in real-time every 22 ms over 500 ms of the entire pulse heating period. The results show the structural evolution of iron phases at 17 GPa, resulting in thermal expansion coefficient 1/V({Delta}V/{Delta}T){sub p} = 7.1 * 10{sup -6}/K for {var_epsilon}-Fe and 2.4 * 10{sup -5}/K for {gamma}-Fe, as well as the evidence for metastability of {gamma}-Fe at low temperatures below the {var_epsilon}-{gamma} phase boundary.

  4. Development of Powder Diffraction Analysis Tools for aNanocrystalline Specimen: An Emphasis upon NiTi (Nitinol)

    SciTech Connect

    Owens, Erich; /Albion Coll. /SLAC

    2006-08-30

    Powder diffraction is a specialized technique whose investigatory limits are constrained by the scale of the crystallized substance being scanned versus the probe beam used. When disparate in scale, with the photon spot size larger than the crystal being probed, many are employed, the resulting diffraction image being cast from all possible incident angles, constructing {chi}-arcs containing information about the crystalline structure of the material under examination. Of particular interest to our collaboration is the structure of Nitinol, a superelastic Nickel-Titanium alloy, whose phase transformations and load bearing deformations can be studied by usage of diffraction, with wide sweeping biomedical uses. Analysis of this data is complicated by phase transformation and material fluorescence, which make difficult the computational modeling of the peaks within concentric {chi}-arcs. We endeavored to construct a series of computational tools (the amalgamation of them known as 2DPeakFinder) for refining and extracting this relevant data, toward the end of employing previously developed algorithms in the material's structural analysis. We succeeded to a large degree with the use of an iterative algorithm to navigate radial complexity of the signal and manage to retain a distinction between useful signal and superfluous background noise. The tools developed in this project are a small step in readily streamlining the analysis and physical modeling of a Nanocrystalline material's structural properties.

  5. The Oxford-Diamond In Situ Cell for studying chemical reactions using time-resolved X-ray diffraction.

    PubMed

    Moorhouse, Saul J; Vranješ, Nenad; Jupe, Andrew; Drakopoulos, Michael; O'Hare, Dermot

    2012-08-01

    A versatile, infrared-heated, chemical reaction cell has been assembled and commissioned for the in situ study of a range of chemical syntheses using time-resolved energy-dispersive X-ray diffraction (EDXRD) on Beamline I12 at the Diamond Light Source. Specialized reactor configurations have been constructed to enable in situ EDXRD investigation of samples under non-ambient conditions. Chemical reactions can be studied using a range of sample vessels such as alumina crucibles, steel hydrothermal autoclaves, and glassy carbon tubes, at temperatures up to 1200 °C.

  6. The Oxford-Diamond In Situ Cell for studying chemical reactions using time-resolved X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Moorhouse, Saul J.; Vranješ, Nenad; Jupe, Andrew; Drakopoulos, Michael; O'Hare, Dermot

    2012-08-01

    A versatile, infrared-heated, chemical reaction cell has been assembled and commissioned for the in situ study of a range of chemical syntheses using time-resolved energy-dispersive X-ray diffraction (EDXRD) on Beamline I12 at the Diamond Light Source. Specialized reactor configurations have been constructed to enable in situ EDXRD investigation of samples under non-ambient conditions. Chemical reactions can be studied using a range of sample vessels such as alumina crucibles, steel hydrothermal autoclaves, and glassy carbon tubes, at temperatures up to 1200 °C.

  7. Imaging of strain in laterally overgrown GaAs layers by spatially resolved x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Domagala, J. Z.; Czyzak, A.; Zytkiewicz, Z. R.

    2007-06-01

    Spatially resolved x-ray diffraction is used to analyze the strain in GaAs layers grown by liquid phase epitaxial lateral overgrowth (ELO) on SiO2-masked GaAs substrates. A downward tilt of ELO wings caused by their interaction with the mask is observed. The distribution of the tilt magnitude across the wings width is determined with micrometer-scale spatial resolution. A residual upward tilt originating from inhomogeneous Si dopant distribution in the ELO wing is found after mask removal. If a large area of the sample is studied, the technique provides precise information on the tilt of an individual wing and its distribution.

  8. Quantitative determination of mineral composition by powder x-ray diffraction

    DOEpatents

    Pawloski, G.A.

    1984-08-10

    An external standard intensity ratio method is used for quantitatively determining mineralogic compositions of samples by x-ray diffraction. The method uses ratios of x-ray intensity peaks from a single run. Constants are previously determined for each mineral which is to be quantitatively measured. Ratios of the highest intensity peak of each mineral to be quantified in the sample and the highest intensity peak of a reference mineral contained in the sample are used to calculate sample composition.

  9. Quantitative determination of mineral composition by powder X-ray diffraction

    DOEpatents

    Pawloski, Gayle A.

    1986-01-01

    An external standard intensity ratio method is used for quantitatively determining mineralogic compositions of samples by x-ray diffraction. The method uses ratios of x-ray intensity peaks from a single run. Constants are previously determined for each mineral which is to be quantitatively measured. Ratios of the highest intensity peak of each mineral to be quantified in the sample and the highest intensity peak of a reference mineral contained in the sample are used to calculate sample composition.

  10. Carrier-driven disordering in semiconductors: Time-resolved x-ray diffraction and density functional perturbation theory investigations

    NASA Astrophysics Data System (ADS)

    Hillyard, Patrick Brian

    Time-resolved x-ray science has opened the door to a previously inaccessible experimental world. Now the possibility of imaging ultrafast events with atomic spatial resolution is a reality. This dissertation highlights these new experimental techniques and uses them to study the effects of carrier photo-excitation in semiconductors using both time-resolved x-ray diffraction and time-resolved x-ray absorption spectroscopy. I have probed the ultrafast atomic disordering in InSb after intense photoexcitation with ultrafast x-ray diffraction measurements at the Sub-Picosecond Pulse Source (SPPS), The results indicate that three disordering regimes exist, depending on the photoinduced carrier density. At lower carrier densities, disordering occurs via a thermal mechanism, occurring on a picosecond time scale with the dominant relaxation mechanism being the transfer of energy from hot carriers to the lattice. At intermediate carrier density values, the potential energy surface flattens, allowing the atoms to move with the inertial room temperature velocities for approximately ~500 fs at which point other processes take over including thermal energy transfer, atomic collision, and diffusion. At higher carrier densities, it is observed that accelerated atomic disordering occurs, indicating the formation of a repulsive potential energy surface. These experimental observations are in contrast with previous theoretical work and therefore, I have performed calculations using Density Functional Perturbation Theory (DFPT) to more clearly outline the role of excited carriers in lattice destabilization. The calculations show that with increasing carrier density the transverse acoustic modes soften and the lattice destabilizes first in the (100) direction (X point) with 3.7% of the valence band electrons excited into the conduction band. Increasing the carrier density leads to the entire transverse acoustic mode becoming unstable, indicating a repulsive interatomic potential. A

  11. Exploiting powder X-ray diffraction for direct structure determination in structural biology: the P2X4 receptor trafficking motif YEQGL.

    PubMed

    Fujii, Kotaro; Young, Mark T; Harris, Kenneth D M

    2011-06-01

    We report the crystal structure of the 5-residue peptide acetyl-YEQGL-amide, determined directly from powder X-ray diffraction data recorded on a conventional laboratory X-ray powder diffractometer. The YEQGL motif has a known biological role, as a trafficking motif in the C-terminus of mammalian P2X4 receptors. Comparison of the crystal structure of acetyl-YEQGL-amide determined here and that of a complex formed with the μ2 subunit of the clathrin adaptor protein complex AP2 reported previously, reveals differences in conformational properties, although there are nevertheless similarities concerning aspects of the hydrogen-bonding arrangement and the hydrophobic environment of the leucine sidechain. Our results demonstrate the potential for exploiting modern powder X-ray diffraction methodology to achieve complete structure determination of materials of biological interest that do not crystallize as single crystals of suitable size and quality for single-crystal X-ray diffraction.

  12. Early age hydration and pozzolanic reaction in natural zeolite blended cements: Reaction kinetics and products by in situ synchrotron X-ray powder diffraction

    SciTech Connect

    Snellings, R.; Mertens, G.; Cizer, O.; Elsen, J.

    2010-12-15

    The in situ early-age hydration and pozzolanic reaction in cements blended with natural zeolites were investigated by time-resolved synchrotron X-ray powder diffraction with Rietveld quantitative phase analysis. Chabazite and Na-, K-, and Ca-exchanged clinoptilolite materials were mixed with Portland cement in a 3:7 weight ratio and hydrated in situ at 40 {sup o}C. The evolution of phase contents showed that the addition of natural zeolites accelerates the onset of C{sub 3}S hydration and precipitation of CH and AFt. Kinetic analysis of the consumption of C{sub 3}S indicates that the enveloping C-S-H layer is thinner and/or less dense in the presence of alkali-exchanged clinoptilolite pozzolans. The zeolite pozzolanic activity is interpreted to depend on the zeolite exchangeable cation content and on the crystallinity. The addition of natural zeolites alters the structural evolution of the C-S-H product. Longer silicate chains and a lower C/S ratio are deduced from the evolution of the C-S-H b-cell parameter.

  13. In-Situ Observations of Phase Transformations During Welding of 1045 Steel using Spatially Resolved and Time Resolved X-Ray Diffraction

    SciTech Connect

    Elmer, J; Palmer, T; DebRoy, T

    2005-10-28

    Synchrotron-based methods have been developed at Lawrence Livermore National Laboratory (LLNL) for the direct observation of microstructure evolution during welding. These techniques, known as spatially resolved (SRXRD) and time resolved (TRXRD) x-ray diffraction, allow in-situ experiments to be performed during welding and provide direct observations of high temperature phases that form under the intense thermal cycles that occur. This paper presents observations of microstructural evolution that occur during the welding of a medium carbon AISI 1045 steel, using SRXRD to map the phases that are present during welding, and TRXRD to dynamically observe transformations during rapid heating and cooling. SRXRD was further used to determine the influence of welding heat input on the size of the high temperature austenite region, and the time required to completely homogenize this region during welding. These data can be used to determine the kinetics of phase transformations under the steep thermal gradients of welds, as well as benchmark and verify phase transformation models.

  14. In Situ Synchrotron Powder Diffraction Studies of Reduction-Oxidation (Redox) Behavior of Iron Ores and Ilmenite

    NASA Astrophysics Data System (ADS)

    Ilyushechkin, Alexander Y.; Kochanek, Mark; Tang, Liangguang; Lim, Seng

    2017-04-01

    Phase transformations of two types of iron-based oxides (iron ore and industrial-grade ilmenite) were studied using synchrotron powder diffraction of the samples processed in reducing and oxidizing atmospheres at 1173 K (900 °C) and 1223 K (950 °C), respectively. In iron ore oxidation, the disappearance of the wustite and fayalite phases was followed by hematite growth and a decrease of the magnetite phase. The magnetite phase was partially recovered by treatment in a reducing atmosphere. Ilmenite oxidation initiated decomposition of the ilmenite phase with rapid growth of hematite and gradual growth of the pseudobrookite phase. In a reducing atmosphere, ilmenite was gradually recovered from pseudobrookite with a relatively fast initial decrease in rutile and hematite content. Under reducing conditions, there was interaction of iron ore with magnesio-ferrites in iron ore-ash mixture and interaction of ilmenite with silica by the formation of fayalite.

  15. Synchrotron powder diffraction characterization of the zeolite-based (p-N,N-dimethylnitroaniline-mordenite) guest-host phase.

    PubMed

    Porcher, Florence; Borissenko, Elena; Souhassou, Mohamed; Takata, Masaki; Kato, Kenichi; Rodriguez-Carvajal, Juan; Lecomte, Claude

    2008-12-01

    The crystal structure of a new phase consisting of the inclusion of the hyperpolarizable molecule p-N,N-dimethylnitroaniline (dimethyl-para-nitroaniline or dmpNA) in the large-pore zeolite mordenite (MOR) has been determined from high-resolution synchrotron powder diffraction at 300 and 90 K. The unit-cell parameters and space group at 300 K are similar to those of as-synthesized mordenite. The crystallographic study indicates that the MOR straight channels are almost fully loaded with molecules that are disordered over eight symmetry-related sites. As expected, the molecules are located in the large 12-membered ring channel, at the intersection with the secondary eight-membered channel with which they might form hydrogen bonds. The elongation axes (and then the dipole moments) of the molecules are slightly tilted (28.57 degrees ) from [001]. The configuration found suggests an interaction of dmpNA with framework O atoms through its methyl groups.

  16. In Situ Synchrotron Powder Diffraction Studies of Reduction-Oxidation (Redox) Behavior of Iron Ores and Ilmenite

    NASA Astrophysics Data System (ADS)

    Ilyushechkin, Alexander Y.; Kochanek, Mark; Tang, Liangguang; Lim, Seng

    2017-01-01

    Phase transformations of two types of iron-based oxides (iron ore and industrial-grade ilmenite) were studied using synchrotron powder diffraction of the samples processed in reducing and oxidizing atmospheres at 1173 K (900 °C) and 1223 K (950 °C), respectively. In iron ore oxidation, the disappearance of the wustite and fayalite phases was followed by hematite growth and a decrease of the magnetite phase. The magnetite phase was partially recovered by treatment in a reducing atmosphere. Ilmenite oxidation initiated decomposition of the ilmenite phase with rapid growth of hematite and gradual growth of the pseudobrookite phase. In a reducing atmosphere, ilmenite was gradually recovered from pseudobrookite with a relatively fast initial decrease in rutile and hematite content. Under reducing conditions, there was interaction of iron ore with magnesio-ferrites in iron ore-ash mixture and interaction of ilmenite with silica by the formation of fayalite.

  17. Synthesis and Neutron Powder Diffraction Structural Analysis of Oxidized Delafossite YCuO2.5

    SciTech Connect

    Garlea, Vasile O; Darie, Celine; Isnard, Olivier; Bordet, Pierre

    2006-01-01

    We report a study of the evolution of the structure of the delafossite-derived compounds YCuO{sub 2+{delta}} as a function of oxygen stoichiometry. The structural details of the oxygenated material YCuO{sub 2.5} were examined by means of high-resolution neutron powder diffraction. We confirmed that YCuO{sub 2.5} adopts an orthorhombic superstructure (a = {radical}3a{sub H}, b=c{sub H}, c=2a{sub H}) in which the anions are located at the center of corner-sharing triangles to form undulating chains of Cu{sup 2+} (s=1/2), running along a-axis direction.

  18. Compressibility of copper-oxygen bonds: a high-pressure neutron powder diffraction study of CuO

    NASA Astrophysics Data System (ADS)

    Ehrenberg, H.; McAllister, J. A.; Marshall, W. G.; Attfield, J. P.

    1999-08-01

    A high-pressure neutron powder diffraction study has been performed on CuO at room temperature for nine different pressures up to 8.8 GPa. Rietveld refinement gives very precise atomic parameters, enabling the copper-oxygen bond compressibility to be determined accurately. The Jahn-Teller elongated bond distance obeys icons/Journals/Common/kappa" ALT="kappa" ALIGN="TOP"/>Cu-O(p) = 0.0710(55)/(p+3.15(55) GPa) and is compared with the Cu-O bond compressibility in other materials. A Birch equation of state fitted to the experimental cell volume data gives K0 = 72(2) GPa, K0´ = 8.7(1.2) and V0 = 80.89(5) Å3.

  19. Observation of localized heating phenomena during microwave heating of mixed powders using in situ x-ray diffraction technique

    SciTech Connect

    Sabelström, N. Hayashi, M.; Watanabe, T.; Nagata, K.

    2014-10-28

    In materials processing research using microwave heating, there have been several observations of various phenomena occurring known as microwave effects. One significant example of such a phenomenon is increased reaction kinetics. It is believed that there is a possibility that this might be caused by localized heating, were some reactants would attain a higher than apparent temperature. To examine whether such thermal gradients are indeed possible, mixed powders of two microwave non-absorbers, alumina and magnesia, were mixed with graphite, a known absorber, and heated in a microwave furnace. During microwave irradiation, the local temperatures of the respective sample constituents were measured using an in situ x-ray diffraction technique. In the case of the alumina and graphite sample, a temperature difference of around 100 °C could be observed.

  20. Crystal structure of caesium di-hydrogen citrate from laboratory X-ray powder diffraction data and DFT comparison.

    PubMed

    Rammohan, Alagappa; Kaduk, James A

    2017-02-01

    The crystal structure of caesium di-hydrogen citrate, Cs(+)·H2C6H5O7(-), has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The coordination polyhedra of the nine-coordinate Cs(+) cations share edges to form chains along the a-axis. These chains are linked by corners along the c-axis. The un-ionized carb-oxy-lic acid groups form two different types of hydrogen bonds; one forms a helical chain along the c-axis, and the other is discrete. The hy-droxy group participates in both intra- and inter-molecular hydrogen bonds.

  1. Crystal structure of dirubidium hydrogen citrate from laboratory X-ray powder diffraction data and DFT comparison.

    PubMed

    Rammohan, Alagappa; Kaduk, James A

    2017-01-01

    The crystal structure of dirubidium hydrogen citrate, 2Rb(+)·HC6H5O7(2-), has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The un-ionized carb-oxy-lic acid group forms helical chains of very strong hydrogen bonds (O⋯O ∼ 2.42 Å) along the b axis. The hy-droxy group participates in a chain of intra- and inter-molecular hydrogen bonds along the c axis. These hydrogen bonds result in corrugated hydrogen-bonded layers in the bc plane. The Rb(+) cations are six-coordinate, and share edges and corners to form layers in the ab plane. The inter-layer contacts are composed of the hydro-phobic methyl-ene groups.

  2. X-ray powder diffraction study of the chloride-bromide systems of trivalent gadolinium, terbium, and ytterbium

    SciTech Connect

    Olejak-Chodan, M.; Lasocha, W.; Eick, H.A.

    1988-03-01

    The lanthanoid mixed halide systems, MCl/sub 3/-MBr/sub 3/, for M = Gd, Tb, and Yb, have been prepared by mixing and fusing the pure reactants and have been examined by X-ray powder diffraction procedures. For M = Gd, UCl/sub 3/, (P6/sub 3//m)-, PuBr/sub 3/ (Cmcm)- and AlCl/sub 3/ (C2/m)-type solid solutions regions were found. For M = Tb, PuBr/sub 3/- and AlCl/sub 3/-type solid solution regions were found. For M = Yb, AlCl/sub 3/- and FeCl/sub 3/-(R anti 3)-type solid solution areas were observed. Pure TbBr/sub 3/ appears to be isostructural with GdBr/sub 3/ rather than with DyBr/sub 3/. These systems are discussed and compared to related systems.

  3. Crystal structure of dirubidium hydrogen citrate from laboratory X-ray powder diffraction data and DFT comparison

    PubMed Central

    Rammohan, Alagappa; Kaduk, James A.

    2017-01-01

    The crystal structure of dirubidium hydrogen citrate, 2Rb+·HC6H5O7 2−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The un-ionized carb­oxy­lic acid group forms helical chains of very strong hydrogen bonds (O⋯O ∼ 2.42 Å) along the b axis. The hy­droxy group participates in a chain of intra- and inter­molecular hydrogen bonds along the c axis. These hydrogen bonds result in corrugated hydrogen-bonded layers in the bc plane. The Rb+ cations are six-coordinate, and share edges and corners to form layers in the ab plane. The inter­layer contacts are composed of the hydro­phobic methyl­ene groups. PMID:28083145

  4. Crystal structure of trirubidium citrate monohydrate from laboratory X-ray powder diffraction data and DFT comparison

    PubMed Central

    Kaduk, James A.

    2017-01-01

    The crystal structure of the title compound, 3Rb+·C6H5O7 3−·H2O, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The hy­droxy group participates in an intra­molecular hydrogen bond to the deprotonated central carboxyl­ate group with graph-set motif S(5). The water mol­ecule acts as a hydrogen-bond donor to both terminal and central carboxyl­ate O atoms. The three independent rubidium cations are seven-, six- and six-coordinate, with bond-valence sums of 0.84, 1.02, and 0.95, respectively. In the extended structure, their polyhedra share edges and corners to form a three-dimensional network. The hydro­phobic methyl­ene groups occupy channels along the b axis. PMID:28217348

  5. Crystal structure and electronic properties of two nimesulide derivatives: A combined X-ray powder diffraction and quantum mechanical study

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Abir; Ghosh, Soumen; Kankanala, Kavitha; Reddy, Vangala Ranga; Mukkanti, Khagga; Pal, Sarbani; Mukherjee, Alok K.

    2010-06-01

    Crystal structures of two nimesulide derivatives, C 13H 14O 3N 2S ( 2) and C 21H 16O 5N 2S ( 3), have been determined from X-ray powder diffraction data and their electronic structures were calculated at the DFT level. The optimized molecular geometries of 2 and 3 correspond closely to that obtained from the crystallographic analysis. Intermolecular hydrogen bonds and π… π stacking interactions form supramolecular assembly in both compounds. The HOMO-LUMO energy gap (>2.2 eV) indicates a high kinetic stability of both compounds. Although the compound 2 does not exhibit any anti-inflammatory activity, 3 can induce 34% edema inhibition in rat paws.

  6. Crystal structure of caesium di­hydrogen citrate from laboratory X-ray powder diffraction data and DFT comparison

    PubMed Central

    Kaduk, James A.

    2017-01-01

    The crystal structure of caesium di­hydrogen citrate, Cs+·H2C6H5O7 −, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The coordination polyhedra of the nine-coordinate Cs+ cations share edges to form chains along the a-axis. These chains are linked by corners along the c-axis. The un-ionized carb­oxy­lic acid groups form two different types of hydrogen bonds; one forms a helical chain along the c-axis, and the other is discrete. The hy­droxy group participates in both intra- and inter­molecular hydrogen bonds. PMID:28217327

  7. Abinitio powder x-ray diffraction and PIXEL energy calculations on thiophene derived 1,4 dihydropyridine

    SciTech Connect

    Karthikeyan, N. Sivakumar, K.; Pachamuthu, M. P.

    2016-05-06

    We focus on the application of powder diffraction data to get abinitio crystal structure determination of thiophene derived 1,4 DHP prepared by cyclocondensation method using solid catalyst. Crystal structure of the compound has been solved by direct-space approach on Monte Carlo search in parallel tempering mode using FOX program. Initial atomic coordinates were derived using Gaussian 09W quantum chemistry software in semi-empirical approach and Rietveld refinement was carried out using GSAS program. The crystal structure of the compound is stabilized by one N-H…O and three C-H…O hydrogen bonds. PIXEL lattice energy calculation was carried out to understand the physical nature of intermolecular interactions in the crystal packing, on which the total lattice energy is contributed into Columbic, polarization, dispersion, and repulsion energies.

  8. Crystal structure of penta­sodium hydrogen dicitrate from synchrotron X-ray powder diffraction data and DFT comparison

    PubMed Central

    Kaduk, James A.

    2017-01-01

    The crystal structure of penta­sodium hydrogen dicitrate, Na5H(C6H5O7)2, has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Each of the two independent citrate anions is joined into a dimer by very strong centrosymmetric O—H⋯O hydrogen bonds, with O⋯O distances of 2.419 and 2.409 Å. Four octa­hedrally coordinated Na+ ions share edges to form open layers parallel to the ab plane. A fifth Na+ ion in trigonal–bipyramidal coordination shares faces with NaO6 octahedra on both sides of these layers. PMID:28217360

  9. Abinitio powder x-ray diffraction and PIXEL energy calculations on thiophene derived 1,4 dihydropyridine

    NASA Astrophysics Data System (ADS)

    Karthikeyan, N.; Pachamuthu, M. P.; Sivakumar, K.

    2016-05-01

    We focus on the application of powder diffraction data to get abinitio crystal structure determination of thiophene derived 1,4 DHP prepared by cyclocondensation method using solid catalyst. Crystal structure of the compound has been solved by direct-space approach on Monte Carlo search in parallel tempering mode using FOX program. Initial atomic coordinates were derived using Gaussian 09W quantum chemistry software in semi-empirical approach and Rietveld refinement was carried out using GSAS program. The crystal structure of the compound is stabilized by one N-H…O and three C-H…O hydrogen bonds. PIXEL lattice energy calculation was carried out to understand the physical nature of intermolecular interactions in the crystal packing, on which the total lattice energy is contributed into Columbic, polarization, dispersion, and repulsion energies.

  10. X-Ray diffraction on large single crystals using a powder diffractometer

    SciTech Connect

    Jesche, A.; Fix, M.; Kreyssig, A.; Meier, W. R.; Canfield, P. C.

    2016-06-16

    Information on the lattice parameter of single crystals with known crystallographic structure allows for estimations of sample quality and composition. In many cases it is sufficient to determine one lattice parameter or the lattice spacing along a certain, high- symmetry direction, e.g. in order to determine the composition in a substitution series by taking advantage of Vegard’s rule. Here we present a guide to accurate measurements of single crystals with dimensions ranging from 200 μm up to several millimeter using a standard powder diffractometer in Bragg-Brentano geometry. The correction of the error introduced by the sample height and the optimization of the alignment are discussed in detail. Finally, in particular for single crystals with a plate-like habit, the described procedure allows for measurement of the lattice spacings normal to the plates with high accuracy on a timescale of minutes.

  11. X-Ray diffraction on large single crystals using a powder diffractometer

    DOE PAGES

    Jesche, A.; Fix, M.; Kreyssig, A.; ...

    2016-06-16

    Information on the lattice parameter of single crystals with known crystallographic structure allows for estimations of sample quality and composition. In many cases it is sufficient to determine one lattice parameter or the lattice spacing along a certain, high- symmetry direction, e.g. in order to determine the composition in a substitution series by taking advantage of Vegard’s rule. Here we present a guide to accurate measurements of single crystals with dimensions ranging from 200 μm up to several millimeter using a standard powder diffractometer in Bragg-Brentano geometry. The correction of the error introduced by the sample height and the optimizationmore » of the alignment are discussed in detail. Finally, in particular for single crystals with a plate-like habit, the described procedure allows for measurement of the lattice spacings normal to the plates with high accuracy on a timescale of minutes.« less

  12. X-Ray diffraction on large single crystals using a powder diffractometer

    SciTech Connect

    Jesche, A.; Fix, M.; Kreyssig, A.; Meier, W. R.; Canfield, P. C.

    2016-06-16

    Information on the lattice parameter of single crystals with known crystallographic structure allows for estimations of sample quality and composition. In many cases it is sufficient to determine one lattice parameter or the lattice spacing along a certain, high- symmetry direction, e.g. in order to determine the composition in a substitution series by taking advantage of Vegard’s rule. Here we present a guide to accurate measurements of single crystals with dimensions ranging from 200 μm up to several millimeter using a standard powder diffractometer in Bragg-Brentano geometry. The correction of the error introduced by the sample height and the optimization of the alignment are discussed in detail. Finally, in particular for single crystals with a plate-like habit, the described procedure allows for measurement of the lattice spacings normal to the plates with high accuracy on a timescale of minutes.

  13. Validation of molecular crystal structures from powder diffraction data with dispersion-corrected density functional theory (DFT-D)

    PubMed Central

    van de Streek, Jacco; Neumann, Marcus A.

    2014-01-01

    In 2010 we energy-minimized 225 high-quality single-crystal (SX) structures with dispersion-corrected density functional theory (DFT-D) to establish a quantitative benchmark. For the current paper, 215 organic crystal structures determined from X-ray powder diffraction (XRPD) data and published in an IUCr journal were energy-minimized with DFT-D and compared to the SX benchmark. The on average slightly less accurate atomic coordinates of XRPD structures do lead to systematically higher root mean square Cartesian displacement (RMSCD) values upon energy minimization than for SX structures, but the RMSCD value is still a good indicator for the detection of structures that deserve a closer look. The upper RMSCD limit for a correct structure must be increased from 0.25 Å for SX structures to 0.35 Å for XRPD structures; the grey area must be extended from 0.30 to 0.40 Å. Based on the energy minimizations, three structures are re-refined to give more precise atomic coordinates. For six structures our calculations provide the missing positions for the H atoms, for five structures they provide corrected positions for some H atoms. Seven crystal structures showed a minor error for a non-H atom. For five structures the energy minimizations suggest a higher space-group symmetry. For the 225 SX structures, the only deviations observed upon energy minimization were three minor H-atom related issues. Preferred orientation is the most important cause of problems. A preferred-orientation correction is the only correction where the experimental data are modified to fit the model. We conclude that molecular crystal structures determined from powder diffraction data that are published in IUCr journals are of high quality, with less than 4% containing an error in a non-H atom. PMID:25449625

  14. Solid state characterization and crystal structure from X-ray powder diffraction of two polymorphic forms of ranitidine base.

    PubMed

    de Armas, Héctor Novoa; Peeters, Oswald M; Blaton, Norbert; Van Gyseghem, Elke; Martens, Johan; Van Haele, Gerrit; Van Den Mooter, Guy

    2009-01-01

    Ranitidine hydrochloride (RAN-HCl), a known anti-ulcer drug, is the product of reaction between HCl and ranitidine base (RAN-B). RAN-HCl has been extensively studied; however this is not the case of the RAN-B. The solid state characterization of RAN-B polymorphs has been carried out using different analytical techniques (microscopy, thermal analysis, Fourier transform infrared spectrometry in the attenuated total reflection mode, (13)C-CPMAS-NMR spectroscopy and X-ray powder diffraction). The crystal structures of RAN-B form I and form II have been determined using conventional X-ray powder diffraction in combination with simulated annealing and whole profile pattern matching, and refined using rigid-body Rietveld refinement. RAN-B form I is a monoclinic polymorph with cell parameters: a = 7.317(2), b = 9.021(2), c = 25.098(6) A, beta = 95.690(1) degrees and space group P2(1)/c. The form II is orthorhombic: a = 31.252(4), b = 13.052(2), c = 8.0892(11) A with space group Pbca. In RAN-B polymorphs, the nitro group is involved in a strong intramolecular hydrogen bond responsible for the existence of a Z configuration in the enamine portion of the molecules. A tail to tail packing motif can be denoted via intermolecular hydrogen bonds. The crystal structures of RAN-B forms are compared to those of RAN-HCl polymorphs. RAN-B polymorphs are monotropic polymorphic pairs. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

  15. Validation of molecular crystal structures from powder diffraction data with dispersion-corrected density functional theory (DFT-D).

    PubMed

    van de Streek, Jacco; Neumann, Marcus A

    2014-12-01

    In 2010 we energy-minimized 225 high-quality single-crystal (SX) structures with dispersion-corrected density functional theory (DFT-D) to establish a quantitative benchmark. For the current paper, 215 organic crystal structures determined from X-ray powder diffraction (XRPD) data and published in an IUCr journal were energy-minimized with DFT-D and compared to the SX benchmark. The on average slightly less accurate atomic coordinates of XRPD structures do lead to systematically higher root mean square Cartesian displacement (RMSCD) values upon energy minimization than for SX structures, but the RMSCD value is still a good indicator for the detection of structures that deserve a closer look. The upper RMSCD limit for a correct structure must be increased from 0.25 Å for SX structures to 0.35 Å for XRPD structures; the grey area must be extended from 0.30 to 0.40 Å. Based on the energy minimizations, three structures are re-refined to give more precise atomic coordinates. For six structures our calculations provide the missing positions for the H atoms, for five structures they provide corrected positions for some H atoms. Seven crystal structures showed a minor error for a non-H atom. For five structures the energy minimizations suggest a higher space-group symmetry. For the 225 SX structures, the only deviations observed upon energy minimization were three minor H-atom related issues. Preferred orientation is the most important cause of problems. A preferred-orientation correction is the only correction where the experimental data are modified to fit the model. We conclude that molecular crystal structures determined from powder diffraction data that are published in IUCr journals are of high quality, with less than 4% containing an error in a non-H atom.

  16. X-ray powder diffraction study of poly/carbon monofluoride/, CF/1.12/

    NASA Technical Reports Server (NTRS)

    Mahajan, V. K.; Badachhape, R. B.; Margrave, J. L.

    1974-01-01

    Data from X-ray diffraction studies of the poly(carbon monofluoride) with empirical formula CF(1.09-1.15) are reported, and possible intercalation arrangements for the substance are discussed. The data do not conform to true hexagonal symmetry, indicating that the carbon atoms are not coplanar. Each bond angle of carbon is 118.8 deg, and the carbon-carbon distance is 1.47 A. The interlayer distance is 5.76 A. A total absence of (hkl) reflections in the X-ray pattern shows that the separate CF layers are not regularly arranged with respect to one another.

  17. Neutron powder diffraction study on the iron-based nitride superconductor ThFeAsN

    NASA Astrophysics Data System (ADS)

    Mao, Huican; Wang, Cao; Maynard-Casely, Helen E.; Huang, Qingzhen; Wang, Zhicheng; Cao, Guanghan; Li, Shiliang; Luo, Huiqian

    2017-03-01

    We report neutron diffraction and transport results on the newly discovered superconducting nitride ThFeAsN with T_c= 30 \\text{K} . No magnetic transition, but a weak structural distortion around 160 K, is observed by cooling from 300 K to 6 K. Analysis on the resistivity, Hall transport and crystal structure suggests that this material behaves as an electron optimally doped pnictide superconductor due to extra electrons from nitrogen deficiency or oxygen occupancy at the nitrogen site, which, together with the low arsenic height, may enhance the electron itinerancy and reduce the electron correlations, thus suppressing the static magnetic order.

  18. Investigation of recrystallization of amorphous trehalose through hot-humidity stage X-ray powder diffraction.

    PubMed

    Jójárt-Laczkovich, Orsolya; Katona, Gábor; Aigner, Zoltán; Szabó-Révész, Piroska

    2016-12-01

    The aim of this work was an investigation of the physical changes of the amorphous model material spray-dried trehalose through the use of various analytical techniques and to identify a suitable, rapid method able to quantify the changes. The crystallinity changes and recrystallization process of amorphous samples were investigated by hot-humidity stage X-ray powder diffractometry (HH-XRPD) with fresh samples, conventional X-ray powder diffractometry (XRPD) used stored samples and by differential scanning calorimetry (DSC). The data from the three methods were compared and the various forms of trehalose were analysed. HH-XRPD demonstrated that the recrystallization began at 40 and 60°C up to 45% RH and at 70°C up to 30% RH into dihydrate form. At 70°C up to 60% RH the anhydrous form of trehalose appeared too. Conventional XRPD results showed, that in the 28days stored samples the dihydrate form was detected at 40°C, 50% RH. Storage at 60°C, 40% RH resulted in the appearance of the anhydrous form and at 60°C, 50% RH both polymorphic forms were detected. By carrying out the DSC measurements at different temperatures the fraction of recrystallized trehalose dihydrate was detected. The recrystallization investigated by HH-XRPD and DSC followed Avrami kinetics, the calculated rate constants of isothermal crystallization (K) were same. Both HH-XRPD and conventional XRPD was suitable for the detection of the physical changes of the amorphous model material. DSC measurements showed similar results as HH-XRPD. Primarily HH-XRPD could be suggested for prediction, because the method is fast and every changes could be studied on one sample.

  19. Synchrotron powder diffraction simplified: The high-resolution diffractometer at 11-BM at the Advanced Photon Source

    NASA Astrophysics Data System (ADS)

    Ribaud, Lynn; Suchomel, Matthew; von Dreele, Robert; Toby, Brian

    2013-03-01

    Synchrotrons have revolutionized powder diffraction through higher resolution and sensitivity and much faster data collection. Few scientists beyond the synchrotron community make use of these capabilities. To help address this, the high resolution powder diffractometer beamline 11-BM at the APS offers rapid and easy mail-in access with world-class quality data 1. This instrument offers the highest resolution available in the Americas and is a free service for non-proprietary users 2. The instrument can collect a superb pattern in an hour, has an automated sample changer, and features variable temperature sample environments. Users of the mail-in program often receive their data within two weeks of sample receipt. The instrument is also available for on-site experiments requiring other conditions. Our poster will describe this instrument, highlight its capabilities, explain the types of measurements available, and discuss plans to improve access and available sample environments and collection protocols. More information about the 11-BM instrument and our mail-in program can be found at: http://11bm.xray.aps.anl.gov.

  20. Electronic structure of cesium butyratouranylate(VI) as derived from DFT-assisted powder X-ray diffraction data.

    PubMed

    Vologzhanina, Anna V; Savchenkov, Anton V; Dmitrienko, Artem O; Korlyukov, Alexander A; Bushmarinov, Ivan S; Pushkin, Denis V; Serezhkina, Larisa B

    2014-10-16

    Investigation of chemical bonding and electronic structure of coordination polymers that do not form high-quality single crystals requires special techniques. Here, we report the molecular and electronic structure of the first cesium butyratouranylate, Cs[UO(2)(n-C(3)H(7)COO)(3)][UO(2)(n-C(3)H(7)COO)(OH)(H2O)], as obtained from DFT-assisted powder X-ray diffraction data because of the low quality of crystalline sample. The topological analysis of the charge distribution within the quantum theory of atoms-in-molecules (QTAIM) space partitioning and the distribution of electron localization function (ELF) is reported. The constancy of atomic domain of the uranium(VI) atom at different coordination numbers (7 and 8) and the presence of three ELF maxima in equatorial plane of an uranyl cation attributed to the 6s and 6p electrons were demonstrated for the first time. Details of methodologies applied for additional verification of the correctness of powder XRD refinement (Voronoi atomic descriptors and the Morse restraints) are discussed.

  1. Tris(hydroxymethyl) aminomethane salt of ramipril: synthesis, structural characterization from X-ray powder diffraction and stability studies.

    PubMed

    Bhattacharya, Abir; Chattopadhyay, Basab; Chakraborty, Santu; Roy, Bhairab N; Singh, Girij P; Godbole, Himangshu M; Rananaware, Umesh B; Mukherjee, Alok K

    2012-11-01

    Tris(hydroxymethyl) aminomethane (tris) salt of API ramipril was synthesized, and characterized by FTIR, TG-DSC and ab initio X-ray powder structure analysis. The compound, ramipril-tris (II), crystallizes in the monoclinic space group P2(1) with a=24.3341(15), b=6.4645(5), c=9.5357(7) Å, β=96.917(3)° and V=1489.1(3) Å(3). The crystal structure has been determined from laboratory X-ray powder diffraction data using direct space global optimization strategy (simulated annealing) followed by the Rietveld refinement. A network of intermolecular OH…O, CH…N and CH…O hydrogen bonds between the ramipril-ramipril, tris-tris and ramipril-tris components in the compound generates a two-dimensional molecular assembly in (110) plane. A comparative study of solid-state stabilities of ramipril-tris (II) with that of ramipril (I) and ramipril-erbumine (III) indicates that ramipril-tris (II) is the most stable one among the three, and the conversion to impurity D after 72 h at 80 °C is only 1.5%. The solution phase analysis at different pH values also reveals a greater stability of ramipril-tris (II) over ramipril (I). Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Accurate unrestrained DDM refinement of crystal structures from highly distorted and low-resolution powder diffraction data.

    PubMed

    Solovyov, Leonid A

    2016-10-01

    The structure of benzene:ethane co-crystal at 90 K is refined with anisotropic displacement parameters without geometric restraints from high-resolution synchrotron X-ray powder diffraction (XRPD) data using the derivative difference method (DDM) with properly chosen weighting schemes. The average C-C bond precision achieved is 0.005 Å and the H-atom positions in ethane are refined independently. A new DDM weighting scheme is introduced that compensates for big distortions of experimental data. The results are compared with density functional theory (DFT) calculations reported by Maynard-Casely et al. [(2016). IUCrJ, 3, 192-199] where a rigid-body Rietveld refinement was also applied to the same dataset due to severe distortions of the powder pattern attributable to experimental peculiarities. For the crystal structure of 2-aminopyridinium fumarate-fumaric acid formerly refined applying 77 geometric restraints by Dong et al. [(2013). Acta Cryst. C69, 896-900], an unrestrained DDM refinement using the same XRPD pattern surprisingly gave two times narrower dispersion of interatomic distances.

  3. Field-induced alignment of a smectic-A phase: a time-resolved x-ray diffraction investigation.

    PubMed

    Bras, W; Emsley, J W; Levine, Y K; Luckhurst, G R; Seddon, J M; Timimi, B A

    2004-09-01

    The field-induced alignment of a smectic-A phase is, in principle, a complicated process involving the director rotation via the interaction with the field and the layer rotation via the molecular interactions. Time-resolved nuclear magnetic resonance spectroscopy has revealed this complexity in the case of the director alignment, but provides no direct information on the motion of the layers. Here we describe a time-resolved x-ray diffraction experiment using synchrotron radiation to solve the challenging problem of capturing the diffraction pattern on a time scale which is fast in comparison with that for the alignment of the smectic layers. We have investigated the alignment of the smectic-A phase of 4-octyl-4(')-cyanobiphenyl by a magnetic field. The experiment consists of creating a monodomain sample of the smectic-A phase by slow cooling from the nematic phase in a magnetic field with a flux density of 7 T. The sample is then turned quickly through an angle phi(0) about an axis parallel to the x-ray beam direction but orthogonal to the field. A sequence of two-dimensional small angle x-ray diffraction patterns are then collected at short time intervals. Experiments were carried out for different values of phi(0), and at different temperatures. The results show that the alignment behavior changes fundamentally when phi(0) exceeds 45 degrees, and that there is a sharp change in the alignment process when the temperature is less than 3 degrees C below the smectic-A-nematic transition. The results of the x-ray experiments are in broad agreement with the NMR results, but reveal major phenomena concerning the maintenance of the integrity of the smectic-A layer structure during the alignment process. (c) 2004 American Institute of Physics

  4. Structure determination of Ba5AlF13 by coupling electron, synchrotron and neutron powder diffraction, solid-state NMR and ab initio calculations.

    PubMed

    Martineau, Charlotte; Allix, Mathieu; Suchomel, Matthew R; Porcher, Florence; Vivet, François; Legein, Christophe; Body, Monique; Massiot, Dominique; Taulelle, Francis; Fayon, Franck

    2016-10-04

    The room temperature structure of Ba5AlF13 has been investigated by coupling electron, synchrotron and neutron powder diffraction, solid-state high-resolution NMR ((19)F and (27)Al) and first principles calculations. An initial structural model has been obtained from electron and synchrotron powder diffraction data, and its main features have been confirmed by one- and two-dimensional NMR measurements. However, DFT GIPAW calculations of the (19)F isotropic shieldings revealed an inaccurate location of one fluorine site (F3, site 8a), which exhibited unusual long F-Ba distances. The atomic arrangement was reinvestigated using neutron powder diffraction data. Subsequent Fourier maps showed that this fluorine atom occupies a crystallographic site of lower symmetry (32e) with partial occupancy (25%). GIPAW computations of the NMR parameters validate the refined structural model, ruling out the presence of local static disorder and indicating that the partial occupancy of this F site reflects a local motional process. Visualisation of the dynamic process was then obtained from the Rietveld refinement of neutron diffraction data using an anharmonic description of the displacement parameters to account for the thermal motion of the mobile fluorine. The whole ensemble of powder diffraction and NMR data, coupled with first principles calculations, allowed drawing an accurate structural model of Ba5AlF13, including site-specific dynamical disorder in the fluorine sub-network.

  5. A powder X-ray diffraction method for detection of polyprenylated benzophenones in plant extracts associated with HPLC for quantitative analysis.

    PubMed

    Martins, Felipe T; dos Santos, Marcelo H; Coelho, Carla P; Barbosa, Luiz C A; Dias, Gizelly C; Fracca, Mônica P; Neves, Person P; Stringheta, Paulo C; Doriguetto, Antônio C

    2011-02-20

    A robust, direct, rapid and non-destructive X-ray diffraction crystallography method to detect the polyprenylated benzophenones 7-epi-clusianone (1) and guttiferone A (2) in extracts from Garcinia brasiliensis is presented. Powder samples of benzophenones 1 and 2, dried hexane extracts from G. brasiliensis seeds and fruit's pericarp, and the dried ethanolic extract from G. brasiliensis seeds were unambiguously characterized by powder X-ray diffractometry. The calculated X-ray diffraction peaks from crystal structures of analytes 1 and 2, previously determined by single-crystal X-ray diffraction technique, were overlaid to those of the experimental powder diffractograms, providing a practical identification of these compounds in the analyzed material and confirming the pure contents of the powder samples. Using the X-ray diffraction crystallography method, the studied polyprenylated benzophenones were selectively and simultaneously detected in the extracts which were mounted directly on sample holder. In addition, reference materials of the analytes were not required for analyses since the crystal structures of the compounds are known. High performance liquid chromatography analyses also were comparatively carried out to quantify the analytes in the same plant extracts showing to be in agreement with X-ray diffraction crystallography method.

  6. Spatiotemporal reaction kinetics of an ultrafast photoreaction pathway visualized by time-resolved liquid x-ray diffraction.

    PubMed

    Kim, Tae Kyu; Lorenc, Maciej; Lee, Jae Hyuk; Lo Russo, Manuela; Kim, Joonghan; Cammarata, Marco; Kong, Qingyu; Noel, Sylvie; Plech, Anton; Wulff, Michael; Ihee, Hyotcherl

    2006-06-20

    We have studied the reaction dynamics for HgI(2) in methanol by using time-resolved x-ray diffraction (TRXD). Although numerous time-resolved spectroscopic studies have provided ample information about the early dynamics of HgI(2), a comprehensive reaction mechanism in the solution phase spanning from picoseconds up to microseconds has been lacking. Here we show that TRXD can provide this information directly and quantitatively. Picosecond optical pulses triggered the dissociation of HgI(2), and 100-ps-long x-ray pulses from a synchrotron probed the evolving structures over a wide temporal range. To theoretically explain the diffracted intensities, the structural signal from the solute, the local structure around the solute, and the hydrodynamics of bulk solvents were considered in the analysis. The results in this work demonstrate that the determination of transient states in solution is strongly correlated with solvent energetics, and TRXD can be used as an ultrafast calorimeter. It also is shown that a manifold of structural channels can be resolved at the same time if the measurements are accurate enough and that global analysis is applied. The rate coefficients for the reactions were obtained by fitting our model against the experimental data in one global fit including all q-values and time delays. The comparison between all putative reaction channels confirms that two-body dissociation is the dominant dissociation pathway. After this primary bond breakage, two parallel channels proceed. Transient HgI associates nongeminately with an iodine atom to form HgI(2), and I(2) is formed by nongeminate association of two iodine atoms.

  7. Data collection strategies for time-resolved X-ray free-electron laser diffraction, and 2-color methods

    PubMed Central

    Li, Chufeng; Schmidt, Kevin; Spence, John C.

    2015-01-01

    We compare three schemes for time-resolved X-ray diffraction from protein nanocrystals using an X-ray free-electron laser. We find expressions for the errors in structure factor measurement using the Monte Carlo pump-probe method of data analysis with a liquid jet, the fixed sample pump-probe (goniometer) method (both diffract-and-destroy, and below the safe damage dose), and a proposed two-color method. Here, an optical pump pulse arrives between X-ray pulses of slightly different energies which hit the same nanocrystal, using a weak first X-ray pulse which does not damage the sample. (Radiation damage is outrun in the other cases.) This two-color method, in which separated Bragg spots are impressed on the same detector readout, eliminates stochastic fluctuations in crystal size, shape, and orientation and is found to require two orders of magnitude fewer diffraction patterns than the currently used Monte Carlo liquid jet method, for 1% accuracy. Expressions are given for errors in structure factor measurement for the four approaches, and detailed simulations provided for cathepsin B and IC3 crystals. While the error is independent of the number of shots for the dose-limited goniometer method, it falls off inversely as the square root of the number of shots for the two-color and Monte Carlo methods, with a much smaller pre-factor for the two-color mode, when the first shot is below the damage threshold. PMID:26798813

  8. Studies of electron diffusion in photo-excited Ni using time-resolved X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Persson, A. I. H.; Jarnac, A.; Wang, Xiaocui; Enquist, H.; Jurgilaitis, A.; Larsson, J.

    2016-11-01

    We show that the heat deposition profile in a laser-excited metal can be determined by time-resolved X-ray diffraction. In this study, we investigated the electron diffusion in a 150 nm thick nickel film deposited on an indium antimonide substrate. A strain wave that mimics the heat deposition profile is generated in the metal and propagates into the InSb, where it influences the temporal profile of X-rays diffracted from InSb. We found that the strain pulse significantly deviated from a simple exponential profile, and that the two-temperature model was needed to reproduce the measured heat deposition profile. Experimental results were compared to simulations based on the two-temperature model carried out using commercial finite-element software packages and on-line dynamical diffraction tools. To reproduce the experimental data, the electron-phonon coupling factor was lowered compared to previously measured values. The experiment was carried out at a third-generation synchrotron radiation source using a high-brightness beam and an ultrafast X-ray streak camera with a temporal resolution of 3 ps.

  9. Anti-site mixing and magnetic properties of Fe3Co3Nb2 studied via neutron powder diffraction

    DOE PAGES

    Xu, Xiaoshan; Zhang, Xiaozhe; Yin, Yuewei; ...

    2016-11-02

    Here, we studied the crystal structure and magnetic properties of the rare-earth-free intermetallic compound Fe3Co3Nb2, which has recently been demonstrated to have potentially high magnetic anisotropy, using temperature-dependent neutron powder diffraction. Furthermore, the temperature dependence of the diffraction spectra reveals a magnetic transition between 300 and 400 K, in agreement with the magnetometry measurements. According to the structural refinement of the paramagnetic state and the substantial magnetic contribution to the diffuse scattering in the ferromagnetic state, the Fe/Co anti-site mixing is so strong that the site occupation for Fe and Co is almost random. The projection of the magnetic momentsmore » turned out to be non-zero along the c axis and in the a–b plane of Fe3Co3Nb2, most likely because of the exchange interactions between the randomly orientated nanograins in the samples. These findings suggest that future studies on the magnetism of Fe3Co3Nb2 need to take the Fe/Co anti-site mixing into account, and the exchange interactions need to be suppressed to obtain large remanence and coercivity.« less

  10. Magnetic phases in the Kagomé staircase compound Co3V2O8 studied using powder neutron diffraction

    NASA Astrophysics Data System (ADS)

    Wilson, N. R.; Petrenko, O. A.; Chapon, L. C.

    2007-03-01

    The low temperature properties of the Kagomé-type system Co3V2O8 have been studied by powder neutron diffraction both in zero field and in applied magnetic fields of up to 8T . Below 6K , the zero-field ground state is ferromagnetic with the magnetic moments aligned along the a axis. The size of the moment on one of the two Co sites, the so-called cross-tie site, is considerably reduced compared to the fully polarized state. The application of a magnetic field in this phase is found to rapidly enhance the cross-tie site magnetic moment, which reaches the expected value of ˜3μB by the maximum applied field of 8T . Different reorientation behaviors are found for the Co cross-tie and spine sites, suggesting a more pronounced easy-axis anisotropy for moments on the spine sites. Rietveld refinements reveal that a simple model, where the spins on both cross-tie and spine sites rotate in the ac plane in a magnetic field, reproduces the experimental diffraction patterns well. In addition, it is found that at higher temperatures and moderate magnetic fields, the incommensurate antiferromagnetic order, corresponding to a transverse sinusoidal modulation above 8K , is suppressed to be replaced by ferromagnetic order.

  11. A powder neutron diffraction study of the magnetic structure of FeV{sub 2}S{sub 4}

    SciTech Connect

    Powell, A.V.; Vaqueiro, P.; Ritter, C.

    1999-05-01

    Variable-temperature powder neutron diffraction data demonstrate that FeV{sub 2}S{sub 4} undergoes a transition to a long-range magnetically ordered state at 135(7) K, in agreement with magnetic susceptibility data. High-resolution neutron diffraction data collected at 1.9 K reveal that magnetic ordering results in a doubling of the crystallographic unit-cell dimensions (I2/m a = 5.8303(2), b = 3.2761(1), c = 11.2398(4) {angstrom}, {beta} = 92.046(2){degree}) in the a and c directions and that the magnetic structure is described by a propagation vector of ({1/2}, 0, {1/2}). Cations in an ordered defect layer, 76% of which are Fe(II), possess an average ordered moment of 1.86(5) {mu}{sub B}, which is directed at an angle of 75{degree} to the layer. Cation-cation interactions reduce the average moment of cations in the MS{sub 2} unit to 0.17(4) {mu}{sub B}. The complex magnetic structure involves essentially collinear antiferromagnetic ordering between nearest-neighbor cations.

  12. X-ray diffraction study of aluminum carbide powder to 50 GPa

    NASA Astrophysics Data System (ADS)

    Ji, Cheng; Ma, Yanzhang; Chyu, Ming-Chien; Knudson, Russell; Zhu, Hongyang

    2009-10-01

    The crystal structure and equation of state (EOS) of aluminum carbide (Al4C3) have been determined directly up to 50.1 GPa at room temperature by the synchrotron x-ray diffraction techniques. The results indicate that Al4C3 remained in rhombohedral structure under all tested pressure-temperature conditions and exhibited anisotropic compressibility, with the c-axis more compressible than the a-axis. Fitting the experimental data to third order Birch-Murnaghan EOS yields a bulk modulus of KOT=233±6 GPa with its pressure derivative KOT'=3.4±0.4, while the second-order EOS yields KOT=223±2 GPa.

  13. Calculations of single crystal elastic constants for yttria partially stabilised zirconia from powder diffraction data

    SciTech Connect

    Lunt, A. J. G. Xie, M. Y.; Baimpas, N.; Korsunsky, A. M.; Zhang, S. Y.; Kabra, S.; Kelleher, J.; Neo, T. K.

    2014-08-07

    Yttria Stabilised Zirconia (YSZ) is a tough, phase-transforming ceramic that finds use in a wide range of commercial applications from dental prostheses to thermal barrier coatings. Micromechanical modelling of phase transformation can deliver reliable predictions in terms of the influence of temperature and stress. However, models must rely on the accurate knowledge of single crystal elastic stiffness constants. Some techniques for elastic stiffness determination are well-established. The most popular of these involve exploiting frequency shifts and phase velocities of acoustic waves. However, the application of these techniques to YSZ can be problematic due to the micro-twinning observed in larger crystals. Here, we propose an alternative approach based on selective elastic strain sampling (e.g., by diffraction) of grain ensembles sharing certain orientation, and the prediction of the same quantities by polycrystalline modelling, for example, the Reuss or Voigt average. The inverse problem arises consisting of adjusting the single crystal stiffness matrix to match the polycrystal predictions to observations. In the present model-matching study, we sought to determine the single crystal stiffness matrix of tetragonal YSZ using the results of time-of-flight neutron diffraction obtained from an in situ compression experiment and Finite Element modelling of the deformation of polycrystalline tetragonal YSZ. The best match between the model predictions and observations was obtained for the optimized stiffness values of C11 = 451, C33 = 302, C44 = 39, C66 = 82, C12 = 240, and C13 = 50 (units: GPa). Considering the significant amount of scatter in the published literature data, our result appears reasonably consistent.

  14. Parallel readout multiwire proportional chambers for time resolved X-ray diffraction experiments

    NASA Astrophysics Data System (ADS)

    Faruqi, A. R.; Bond, C. C.

    1980-10-01

    Linear position sensitive detectors have been used for a number of years in X-ray diffraction studies from various types of muscle under different physiological conditions. Such detectors are mainly based on either an internal (RC) delay line or an external (LC) delay line for decoding positional information; the counting speed of the detectors is optimally matched to the available photon flux from laboratory based X-ray cameras. However, X-ray cameras based on synchrotron radiation provide photon fluxes which are greater by about three orders of magnitude. We describe in this paper an X-ray detection system based on parallel readout from a multiwire proportional chamber which offers high counting speeds and is designed to perform time slicing experiments with time resolutions down to 1 ms.

  15. Theory of time-resolved x-ray photoelectron diffraction from transient conformational molecules

    NASA Astrophysics Data System (ADS)

    Tsuru, Shota; Sako, Tokuei; Fujikawa, Takashi; Yagishita, Akira

    2017-04-01

    We formulate x-ray photoelectron diffraction (XPD) from molecules undergoing photochemical reactions induced by optical laser pulses, and then apply the formula to the simulation of time-dependent XPD profiles from both dissociating I2 molecules and bending C S2 molecules. The dependence of nuclear wave-packet motions on the intensity and shape of the optical laser pulses is examined. As a result, the XPD simulations based on such nuclear wave-packet calculations are observed to exhibit characteristic features, which are compared with the XPD profiles due to classical trajectories of nuclear motions. The present study provides a methodology toward creating "molecular movies" of ultrafast photochemical reactions by means of femtosecond XPD with x-ray free-electron lasers.

  16. Development of customised environmental chambers for time-resolved in situ diffraction studies

    NASA Astrophysics Data System (ADS)

    Styles, M. J.; Riley, D. P.

    2010-11-01

    In an effort to mitigate the expense and broaden the applicability of customised environment chambers, researchers at the University of Melbourne and the Australian Nuclear Science and Technology Organisation (ANSTO) have designed and are currently commissioning a modular reaction chamber, capable of separating the necessities of diffraction methodologies from those of the desired sample environment. The In Situ Reaction Chamber (ISRC) abstracts many of the details intrinsic to the diffractometer, allowing users to design inexpensive environmental inserts that may be readily customised to their individual needs. The first insert to be developed for use with the ISRC is a high temperature furnace capable of providing an oxidising sample environment up to 1600°C.

  17. Analysis of heat-affected zone phase transformations using in situ spatially resolved x-ray diffraction with synchrotron radiation

    SciTech Connect

    Elmer, J.W.; Wong, J.; Froeba, M.; Waide, P.A.; Larson, E.M.

    1996-03-01

    Spatially resolved X-ray diffraction (SRXRD) consists of producing a submillimeter size X-ray beam from an intense synchrotron radiation source to perform real-time diffraction measurements on solid materials. This technique was used int his study to investigate the crystal phases surrounding a liquid weld pool in commercial purity titanium and to determine the location of the phase boundary separating the high-temperature body-centered-cubic (bcc) {beta} phase from the low-temperature hexagonal-close-packed (hcp) {alpha} phase. The experiments were carried out at the Stanford Synchrotron Radiation Laboratory (SSRL) using a 0.25 x 0.50 mm X-ray probe that could be positioned with 10-{micro}m precision on the surface of a quasistationary gas tungsten arc weld (GTAW). The SRXRD results showed characteristic hcp, bcc, and liquid diffraction patterns at various points along the sample, starting from the base metal through the heat-affected zone (HAZ) and into the weld pool, respectively. Analyses of the SRXRD data show the coexistence of bcc and hcp phases in the partially transformed (outer) region of the HAZ and single-phase bcc in the fully transformed (inner) region of the HAZ. Postweld metallographic examinations of the HAZ, combined with a conduction-based thermal model of the weld, were correlated with the SRXRD results. Finally, analysis of the diffraction intensities of the hcp and bcc phases was performed on the SRXRD data to provide additional information about the microstructural conditions that may exist in the HAZ at temperature during welding. This work represents the first direct in situ mapping of phase boundaries in fusion welds.

  18. Sparsity-based super-resolved coherent diffraction imaging of one-dimensional objects

    NASA Astrophysics Data System (ADS)

    Sidorenko, Pavel; Kfir, Ofer; Shechtman, Yoav; Fleischer, Avner; Eldar, Yonina C.; Segev, Mordechai; Cohen, Oren

    2015-09-01

    Phase-retrieval problems of one-dimensional (1D) signals are known to suffer from ambiguity that hampers their recovery from measurements of their Fourier magnitude, even when their support (a region that confines the signal) is known. Here we demonstrate sparsity-based coherent diffraction imaging of 1D objects using extreme-ultraviolet radiation produced from high harmonic generation. Using sparsity as prior information removes the ambiguity in many cases and enhances the resolution beyond the physical limit of the microscope. Our approach may be used in a variety of problems, such as diagnostics of defects in microelectronic chips. Importantly, this is the first demonstration of sparsity-based 1D phase retrieval from actual experiments, hence it paves the way for greatly improving the performance of Fourier-based measurement systems where 1D signals are inherent, such as diagnostics of ultrashort laser pulses, deciphering the complex time-dependent response functions (for example, time-dependent permittivity and permeability) from spectral measurements and vice versa.

  19. Sparsity-based super-resolved coherent diffraction imaging of one-dimensional objects.

    PubMed

    Sidorenko, Pavel; Kfir, Ofer; Shechtman, Yoav; Fleischer, Avner; Eldar, Yonina C; Segev, Mordechai; Cohen, Oren

    2015-09-08

    Phase-retrieval problems of one-dimensional (1D) signals are known to suffer from ambiguity that hampers their recovery from measurements of their Fourier magnitude, even when their support (a region that confines the signal) is known. Here we demonstrate sparsity-based coherent diffraction imaging of 1D objects using extreme-ultraviolet radiation produced from high harmonic generation. Using sparsity as prior information removes the ambiguity in many cases and enhances the resolution beyond the physical limit of the microscope. Our approach may be used in a variety of problems, such as diagnostics of defects in microelectronic chips. Importantly, this is the first demonstration of sparsity-based 1D phase retrieval from actual experiments, hence it paves the way for greatly improving the performance of Fourier-based measurement systems where 1D signals are inherent, such as diagnostics of ultrashort laser pulses, deciphering the complex time-dependent response functions (for example, time-dependent permittivity and permeability) from spectral measurements and vice versa.

  20. Sparsity-based super-resolved coherent diffraction imaging of one-dimensional objects

    PubMed Central

    Sidorenko, Pavel; Kfir, Ofer; Shechtman, Yoav; Fleischer, Avner; Eldar, Yonina C.; Segev, Mordechai; Cohen, Oren

    2015-01-01

    Phase-retrieval problems of one-dimensional (1D) signals are known to suffer from ambiguity that hampers their recovery from measurements of their Fourier magnitude, even when their support (a region that confines the signal) is known. Here we demonstrate sparsity-based coherent diffraction imaging of 1D objects using extreme-ultraviolet radiation produced from high harmonic generation. Using sparsity as prior information removes the ambiguity in many cases and enhances the resolution beyond the physical limit of the microscope. Our approach may be used in a variety of problems, such as diagnostics of defects in microelectronic chips. Importantly, this is the first demonstration of sparsity-based 1D phase retrieval from actual experiments, hence it paves the way for greatly improving the performance of Fourier-based measurement systems where 1D signals are inherent, such as diagnostics of ultrashort laser pulses, deciphering the complex time-dependent response functions (for example, time-dependent permittivity and permeability) from spectral measurements and vice versa. PMID:26345495

  1. The determination of crystal structures of active pharmaceutical ingredients from X-ray powder diffraction data: a brief, practical introduction, with fexofenadine hydrochloride as example.

    PubMed

    Brüning, Jürgen; Schmidt, Martin U

    2015-06-01

    This study describes the general method for the determination of the crystal structures of active pharmaceutical ingredients (API) from powder diffraction data and demonstrates its use to determine the hitherto unknown crystal structure of fexofenadine hydrochloride, a third-generation antihistamine drug. Fexofenadine hydrochloride was subjected to a series of crystallisation experiments using re-crystallisation from solvents, gas diffusion, layering with an antisolvent and gel crystallisation. Powder diffraction patterns of all samples were recorded and inspected for polymorphism and for crystallinity. All samples corresponded to the same polymorph. The crystal structure was determined from an X-ray powder diffraction pattern using a real-space method with subsequent Rietveld refinement. The structure exhibits a two-dimensional hydrogen bond network. Crystal structures of API can be determined from X-ray powder diffraction data with good reliability. Fexofenadine exhibits only one polymorphic form, which is stabilised in the crystal by strong hydrogen bonds of the type (+)N-H···Cl(-), O-H···Cl(-), and between COOH groups. © 2015 Royal Pharmaceutical Society.

  2. Crystal Engineering on Industrial Diaryl Pigments Using Lattice Energy Minimizations and X-ray Powder Diffraction

    SciTech Connect

    Schmidt,M.; Dinnebier, R.; Kalkhof, H.

    2007-01-01

    Diaryl azo pigments play an important role as yellow pigments for printing inks, with an annual pigment production of more than 50,000 t. The crystal structures of Pigment Yellow 12 (PY12), Pigment Yellow 13 (PY13), Pigment Yellow 14 (PY14), and Pigment Yellow 83 (PY83) were determined from X-ray powder data using lattice energy minimizations and subsequent Rietveld refinements. Details of the lattice energy minimization procedure and of the development of a torsion potential for the biphenyl fragment are given. The Rietveld refinements were carried out using rigid bodies, or constraints. It was also possible to refine all atomic positions individually without any constraint or restraint, even for PY12 having 44 independent non-hydrogen atoms per asymmetric unit. For PY14 (23 independent non-hydrogen atoms), additionally all atomic isotropic temperature factors could be refined individually. PY12 crystallized in a herringbone arrangement with twisted biaryl fragments. PY13 and PY14 formed a layer structure of planar molecules. PY83 showed a herringbone structure with planar molecules. According to quantum mechanical calculations, the twisting of the biaryl fragment results in a lower color strength of the pigments, whereas changes in the substitution pattern have almost no influence on the color strength of a single molecule. Hence, the experimentally observed lower color strength of PY12 in comparison with that of PY13 and PY83 can be explained as a pure packing effect. Further lattice energy calculations explained that the four investigated pigments crystallize in three different structures because these structures are the energetically most favorable ones for each compound. For example, for PY13, PY14, or PY83, a PY12-analogous crystal structure would lead to considerably poorer lattice energies and lower densities. In contrast, lattice energy calculations revealed that PY12 could adopt a PY13-type structure with only slightly poorer energy. This structure was

  3. Generation and Propagation of a Picosecond Acoustic Pulse at a Buried Interface: Time-Resolved X-Ray Diffraction Measurements

    SciTech Connect

    Lee, S.H.; Cavalieri, A.L.; Fritz, D.M.; Swan, M.C.; Reis, D.A.; Hegde, R.S.; Reason, M.; Goldman, R.S.

    2005-12-09

    We report on the propagation of coherent acoustic wave packets in (001) surface oriented Al{sub 0.3}Ga{sub 0.7}As/GaAs heterostructure, generated through localized femtosecond photoexcitation of the GaAs. Transient structural changes in both the substrate and film are measured with picosecond time-resolved x-ray diffraction. The data indicate an elastic response consisting of unipolar compression pulses of a few hundred picosecond duration traveling along [001] and [001] directions that are produced by predominately impulsive stress. The transmission and reflection of the strain pulses are in agreement with an acoustic mismatch model of the heterostructure and free-space interfaces.

  4. 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

  5. Time-resolved X-ray diffraction studies of laser-induced acoustic wave propagation in bilayer metallic thin crystals

    SciTech Connect

    Er, Ali Oguz; Tang, Jau E-mail: prentzepis@ece.tamu.edu; Chen, Jie; Rentzepis, Peter M. E-mail: prentzepis@ece.tamu.edu

    2014-09-07

    Phonon propagation across the interface of a Cu/Ag(111) bilayer and transient lattice disorder, induced by a femtosecond 267 nm pulse, in Ag(111) crystal have been measured by means of time resolved X-ray diffraction. A “blast” force due to thermal stress induced by suddenly heated electrons is formed within two picoseconds after excitation and its “blast wave” propagation through the interface and Ag (111) crystal was monitored by the shift and broadening of the rocking curve, I vs. ω, as a function of time after excitation. Lattice disorder, contraction and expansion as well as thermal strain formation and wave propagation have also been measured. The experimental data and mechanism proposed are supported by theoretical simulations.

  6. Time-resolved x-ray diffraction and electrical resistance measurements of structural phase transitions in zirconium

    SciTech Connect

    Velisavljevic, N.; Sinogeikin, S.; Saavedra, R.; Chellappa, R. S.; Rothkirch, A.; Dattelbaum, D. M.; Konopkova, Z.; Liermann, H. -P.; Bishop, M.; Tsoi, G. M.; Vohra, Y. K.

    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 compression 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.

  7. Time-resolved x-ray diffraction study of photoinduced strains in h -LuFeO3 thin film

    NASA Astrophysics Data System (ADS)

    Sinha, Kishan; Jiang, Xuanyuan; Wang, Xiao; Dichiara, Anthony; Cheng, Xuemei; Li, Yuelin; Xu, Xiaoshan

    2015-03-01

    We have studied the structural response of epitaxially stabilized h-LuFeO3 (0001) thin film to above-band-gap optical excitation (pump) using time-resolved x-ray diffraction (probe) at picosecond time scale. The shift in (004) Bragg peak induced by a 390 nm excitation (30 ps duration) has been studied as a function of pump fluence and pump-probe time delay. The out-of-plane photoinduced lattice strain (Δc / c) exhibits a non-linear relation with fluence. The relaxation time is on the order of 1 ns. These observations suggest a relaxation mechanism that may be mediated by combined effects of charge recombination and phonon relaxation. This work at is supported by Nebraska EPESCoR (UNL), by NSF CAREER award (No. 1053854) (Bryn Mawr College), and by US-DOE, Office of Science, BES (No. DE-AC02-06CH11357) (ANL).

  8. Combustion synthesis in the Ni-Al-Nb ternary system: A Time-Resolved X-ray Diffraction study

    NASA Astrophysics Data System (ADS)

    Sytschev, Alexander E.; Kovalev, Dmitry Yu.; Vrel, Dominique; Vadchenko, Sergey G.

    Combustion synthesis of intermetallics, using the thermal explosion mode, in the Ni-Al-Nb ternary system is presented, with a 40:40:20 atomic ratio. The kinetic pathway is determined using Time-Resolved X-ray Diffraction, with a time-step resolution of 1 s and demonstrated a first formation of the B2 NiAl structure followed by progressive dissolution of Nb to yield NiAlNb intermetallic Laves phase, representing 35 w% of the final product. SEM observations show a double dendritic (coarse and fine) microstructure, resulting from eutectic crystallization. Due to a high cooling rate, Nb dissolution is not complete at the surface, and yields slightly more complex microstructure, including the Ni2AlNb Geissler phase, the (Ni,Al)2Nb Laves phase, and (Ni, Al)7Nb6.

  9. Hydrostatic Compression Curve for Triamino-Trinitrobenzene Determined to 13.0 GPa with Powder X-Ray Diffraction

    SciTech Connect

    Stevens, Lewis L.; Velisavljevic, Nenad; Hooks, Daniel E.; Dattelbaum, Dana M.

    2008-08-22

    Using powder X-ray diffraction in conjunction with a diamond anvil cell (DAC), the unit cell volume of triamino-trinitrobenzene (TATB) has been measured from ambient pressure to 13 GPa. The resultant isotherm is compared with previous theoretical (Byrd and Rice and Pastine and Bernecker) and experimental (Olinger and Cady) works. While all reports are consistent to approximately 2 GPa, our measurements reveal a slightly stiffer TATB material than reported by Olinger and Cady and an intermediate compressibility compared with the isotherms predicted by the two theoretical works. Analysis of the room temperature isotherm using the semi-empirical, Murnaghan, Birch-Murnaghan, and Vinet equations of state (EOS) provided a determination of the isothermal bulk modulus (K{sub 0}) and its pressure-derivative (K{sub 0}') for TATB. From these fits to our P-V isotherm, from ambient pressure to 8 GPa, the average results for the zero-pressure bulk modulus and its pressure derivative were found to be 14.7 GPa and 10.1, respectively. For comparison to shock experiments on pressed TATB powder and its plastic-bonded formulation PBX 9502 (95% TATB, 5% Kel-F 800), the isotherm was transformed to the pseudo-velocity U{sub s}-u{sub p} plane using the Rankine-Hugoniot jump conditions. This analysis provides an extrapolated bulk sound speed, c{sub 0}=1.70 km s{sup -1}, for TATB and its agreement with a previous determination (c{sub 0}=1.43 km s{sup -1}) is discussed. Furthermore, our P-V and corresponding U{sub s}-u{sub p} curves reveal a subtle cusp at approximately 8 GPa. This cusp is discussed in relation to similar observations made for the aromatic hydrocarbons anthracene, benzene and toluene, graphite, and trinitrotoluene (TNT).

  10. Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

    DOE PAGES

    Zhu, Yi; Cai, Zhonghou; Chen, Pice; ...

    2016-02-26

    Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase seperated regions. The ability to simultanousely track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of- the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiatedmore » at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, which is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. Lastly, the direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.« less

  11. Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

    PubMed Central

    Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J.; Jung, Il Woong; Walko, Donald A.; Dufresne, Eric M.; Jeong, Jaewoo; Samant, Mahesh G.; Parkin, Stuart S. P.; Freeland, John W.; Evans, Paul G.; Wen, Haidan

    2016-01-01

    Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems. PMID:26915398

  12. Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy.

    PubMed

    Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J; Jung, Il Woong; Walko, Donald A; Dufresne, Eric M; Jeong, Jaewoo; Samant, Mahesh G; Parkin, Stuart S P; Freeland, John W; Evans, Paul G; Wen, Haidan

    2016-02-26

    Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.

  13. Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J.; Jung, Il Woong; Walko, Donald A.; Dufresne, Eric M.; Jeong, Jaewoo; Samant, Mahesh G.; Parkin, Stuart S. P.; Freeland, John W.; Evans, Paul G.; Wen, Haidan

    2016-02-01

    Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.

  14. In-situ Characterization of Water-Gas Shift Catalysts using Time-Resolved X-ray Diffraction

    SciTech Connect

    Rodriguez, J.; Hanson, J; Wen, W; Wang, X; Brito, J; Martnez-Arias, A; Fernandez-Garca, M

    2009-01-01

    Time-resolved X-ray diffraction (XRD) has emerged as a powerful technique for studying the behavior of heterogeneous catalysts (metal oxides, sulfides, carbides, phosphides, zeolites, etc.) in-situ during reaction conditions. The technique can identify the active phase of a heterogeneous catalyst and how its structure changes after interacting with the reactants and products (80 K < T < 1200 K; P < 50 atm). In this article, we review a series of recent works that use in-situ time-resolved XRD for studying the water-gas shift reaction (WGS, CO + H2O ? H2 + CO2) over several mixed-metal oxides: CuMoO4, NiMoO4, Ce1-xCuxO2-d and CuFe2O4. Under reaction conditions the oxides undergo partial reduction. Neutral Cu0 (i.e. no Cu1+ or Cu2+ cations) and Ni0 are the active species in the catalysts, but interactions with the oxide support are necessary in order to obtain high catalytic activity. These studies illustrate the important role played by O vacancies in the mechanism for the WGS. In the case of Ce1-xCuxO2-d, Rietveld refinement shows expansions/contractions in the oxide lattice which track steps within the WGS process: CO(gas) + O(oxi) ? CO2(gas) + O(vac); H2O(gas) + O(vac) ? O(oxi) + H2(gas).

  15. EMCCD-Based Detector for Time-Resolved X-Ray Diffraction and Scattering Studies of Biological Specimens

    SciTech Connect

    Nagarkar, Vivek V.; Singh, Bipin; Guo, Liang; Gore, David; Irving, Thomas C.

    2007-11-26

    Third generation synchrotron sources such as the Advanced Photon Source (APS), Argonne, IL, are outstanding tools for X-ray diffraction and scattering studies of non-crystalline biological materials. However, these studies are hindered by the lack of detectors that provide multiple frames of detailed structural information on the millisecond time scale at the required high spatial resolution, and large active areas. Here we report the development of a cost effective detector for time-resolved small angle X-ray scattering (SAXS) using a cooled, fiberoptically coupled electron multiplying CCD (EMCCD), whose internal gain is selectable in real-time. The performance of the detector was evaluated using a Gd{sub 2}O{sub 2}S:Tb scintillator and was compared to a current state-of-the-art SAXS detector developed at Brandeis University. We also report our first results on the fabrication of a novel, microcolumnar, ZnSe(Te) scintillator that has a promise to provide very high emission efficiency of over 100,000 photons/MeV, high spatial resolution in excess of 10 lp/mm, and a fast decay time with virtually absent afterglow. Development of this scintillator will complement the EMCCD design, permitting the advances of a high spatial and temporal resolution, large area detector for time resolved applications.

  16. Time-resolved diffraction and interference: Young's interference with photons of different energy as revealed by time resolution.

    PubMed

    Garcia, N; Saveliev, I G; Sharonov, M

    2002-05-15

    We present time-resolved diffraction and two-slit interference experiments using a streak camera as a detector for femtosecond pulses of photons. These experiments show how the diffraction pattern is built by adding frames of a few photons to each frame. It is estimated that after 300 photons the diffraction pattern emerges. With time resolution we can check the speed of light and put an upper limit of 2 ps at our resolution to the time for wave function collapse in the quantum measurement process. We then produce interference experiments with photons of different energies impinging on the slits, i.e. we know which photon impinges on each slit. We show that for poor time resolution, no interference is observed, but for high time resolution, we have interference that is revealed as beats of 100 GHz frequency. The condition for interference is that the two pulses should overlap spatially at the detector, even if the pulses have different energies but are generated from the same pulse of the laser. The interference seems to be in agreement with classical theory at first sight. However, closer study and analysis of the data show deviations in the visibility of the interference fringes and of their phase. These experiments are discussed in connection with quantum mechanics and it may be concluded that the time resolution provides new data for understanding the longstanding and continuing arguments on wave-particle duality initiated by Newton, Young, Fresnel, Planck and others. A thought experiment is presented in the appendix to try to distinguish the photons at the detector by making it sensitive to colour.

  17. Two-dimensional time-resolved x-ray diffraction study of dual phase rapid solidification in steels

    NASA Astrophysics Data System (ADS)

    Yonemura, Mitsuharu; Osuki, Takahiro; Terasaki, Hidenori; Komizo, Yuichi; Sato, Masugu; Toyokawa, Hidenori; Nozaki, Akiko

    2010-01-01

    The high intensity heat source used for fusion welding creates steep thermal gradients of 100 °C/s from 1800 °C. Further, the influence of preferred orientation is important for the observation of a directional solidification that follows the dendrite growth along the ⟨100⟩ direction toward the moving heat source. In the present study, we observed the rapid solidification of weld metal at a time resolution of 0.01-0.1 s by a two-dimensional time-resolved x-ray diffraction (2DTRXRD) system for real welding. The diffraction rings were dynamically observed by 2DTRXRD with synchrotron energy of 18 keV while the arc passes over the irradiation area of the x-rays. The arc power output was 10 V-150 A, and the scan speed of the arc was 1.0 mm/s. The temperature rise in instruments was suppressed by a water-cooled copper plate under the specimen. Further, the temperature distribution of the weld metal was measured by a thermocouple and correlated with the diffraction patterns. Consequently, solidification and solid phase transformation of low carbon steels and stainless steels were observed during rapid cooling by 2DTRXRD. In the low carbon steel, the microstructure is formed in a two step process, (i) formation of crystallites and (ii) increase of crystallinity. In stainless steel, the irregular interface layer of δ/γ in the quenched metal after solidification is expected to show the easy movement of dendrites at a lower temperature. In carbide precipitation stainless steel, it is easy for NbC to grow on δ phase with a little undercooling. Further, a mistlike pattern, which differs from the halo pattern, in the fusion zone gave some indication of the possibilities to observe the nucleation and the early solidification by 2DTRXRD.

  18. Application of Powder Diffraction Methods to the Analysis of the Atomic Structure of Nanocrystals: The Concept of the Apparent Lattice Parameter (ALP)

    NASA Technical Reports Server (NTRS)

    Palosz, B.; Grzanka, E.; Gierlotka, S.; Stelmakh, S.; Pielaszek, R.; Bismayer, U.; Weber, H.-P.; Palosz, W.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The applicability of standard methods of elaboration of powder diffraction data for determination of the structure of nano-size crystallites is analysed. Based on our theoretical calculations of powder diffraction data we show, that the assumption of the infinite crystal lattice for nanocrystals smaller than 20 nm in size is not justified. Application of conventional tools developed for elaboration of powder diffraction data, like the Rietveld method, may lead to erroneous interpretation of the experimental results. An alternate evaluation of diffraction data of nanoparticles, based on the so-called 'apparent lattice parameter' (alp) is introduced. We assume a model of nanocrystal having a grain core with well-defined crystal structure, surrounded by a surface shell with the atomic structure similar to that of the core but being under a strain (compressive or tensile). The two structural components, the core and the shell, form essentially a composite crystal with interfering, inseparable diffraction properties. Because the structure of such a nanocrystal is not uniform, it defies the basic definitions of an unambiguous crystallographic phase. Consequently, a set of lattice parameters used for characterization of simple crystal phases is insufficient for a proper description of the complex structure of nanocrystals. We developed a method of evaluation of powder diffraction data of nanocrystals, which refers to a core-shell model and is based on the 'apparent lattice parameter' methodology. For a given diffraction pattem, the alp values are calculated for every individual Bragg reflection. For nanocrystals the alp values depend on the diffraction vector Q. By modeling different a0tomic structures of nanocrystals and calculating theoretically corresponding diffraction patterns using the Debye functions we showed, that alp-Q plots show characteristic shapes which can be used for evaluation of the atomic structure of the core-shell system. We show, that using a simple

  19. Application of Powder Diffraction Methods to the Analysis of the Atomic Structure of Nanocrystals: The Concept of the Apparent Lattice Parameter (ALP)

    NASA Technical Reports Server (NTRS)

    Palosz, B.; Grzanka, E.; Gierlotka, S.; Stelmakh, S.; Pielaszek, R.; Bismayer, U.; Weber, H.-P.; Palosz, W.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The applicability of standard methods of elaboration of powder diffraction data for determination of the structure of nano-size crystallites is analysed. Based on our theoretical calculations of powder diffraction data we show, that the assumption of the infinite crystal lattice for nanocrystals smaller than 20 nm in size is not justified. Application of conventional tools developed for elaboration of powder diffraction data, like the Rietveld method, may lead to erroneous interpretation of the experimental results. An alternate evaluation of diffraction data of nanoparticles, based on the so-called 'apparent lattice parameter' (alp) is introduced. We assume a model of nanocrystal having a grain core with well-defined crystal structure, surrounded by a surface shell with the atomic structure similar to that of the core but being under a strain (compressive or tensile). The two structural components, the core and the shell, form essentially a composite crystal with interfering, inseparable diffraction properties. Because the structure of such a nanocrystal is not uniform, it defies the basic definitions of an unambiguous crystallographic phase. Consequently, a set of lattice parameters used for characterization of simple crystal phases is insufficient for a proper description of the complex structure of nanocrystals. We developed a method of evaluation of powder diffraction data of nanocrystals, which refers to a core-shell model and is based on the 'apparent lattice parameter' methodology. For a given diffraction pattem, the alp values are calculated for every individual Bragg reflection. For nanocrystals the alp values depend on the diffraction vector Q. By modeling different a0tomic structures of nanocrystals and calculating theoretically corresponding diffraction patterns using the Debye functions we showed, that alp-Q plots show characteristic shapes which can be used for evaluation of the atomic structure of the core-shell system. We show, that using a simple

  20. Microstructure analysis of complex CuO/ZnO@carbon adsorbers: what are the limits of powder diffraction methods?

    PubMed

    Tseng, J C; Schmidt, W; Sager, U; Däuber, E; Pommerin, A; Weidenthaler, C

    2015-05-14

    Activate carbon impregnated with a mixture of copper oxide and zinc oxide performs well as active adsorber for NO2 removal in automotive cabin air filters. The oxide-loaded activated carbon exhibits superior long-term stability in comparison to pure activated carbon as has been shown in previous studies. The carbon material was loaded only with 2.5 wt% of each metal oxide. Characterization of the oxide nanoparticles within the pores of the activated carbon is difficult because of the rather low concentration of the oxides. Therefore, a systematic study was performed to evaluate the limits of line profile analysis of X-ray powder diffraction patterns. The method allows evaluation of crystalline domain size distributions, crystal defect concentrations and twinning probabilities of nanoscopic materials. Here, the analysis is hampered by the presence of several phases including more or less amorphous carbon. By using physical mixtures of defined copper oxide and zinc oxide particles with activated carbon, potential errors and limits could be identified. The contribution of the activated carbon to the scattering curve was modeled with a convolution of an exponential decay curve, a Chebyshev polynomial, and two Lorentzian peaks. With this approach, domain size distributions can be calculated that are shifted only by about 0.5-1.0 nm for very low loadings (≤4 wt%). Oxide loadings of 4 wt% and 5 wt% allow very reliable analyses from diffraction patterns measured in Bragg-Brentano and Debye-Scherrer geometry, respectively. For the real adsorber material, mean domain sizes have been calculated to be 2.8 nm and 2.4 nm before and after the NO2 removal tests.

  1. Structure of Calcium Aluminate Decahydrate (CaAl2O4.10D2O) from Neutron and X-ray Powder Diffraction Data

    SciTech Connect

    Christensen,A.; Lebech, B.; Sheptyakov, D.; Hanson, J.

    2007-01-01

    Calcium aluminate decahydrate is hexagonal with the space group P63/m and Z = 6. The compound has been named CaAl2O4{center_dot}10H2O (CAH10) for decades and is known as the product obtained by hydration of CaAl2O4 (CA) in the temperature region 273-288 K - one of the main components in high-alumina cements. The lattice constants depend on the water content. Several sample preparations were used in this investigation: one CAH10, three CAD10 and one CA(D/H)10, where the latter is a zero-matrix sample showing no coherent scattering contribution from the D/H atoms in a neutron diffraction powder pattern. The crystal structure including the positions of the H/D atoms was determined from analyses of four neutron diffraction powder patterns by means of the ab initio crystal structure determination program FOX and the FULLPROF crystal structure refinement program. Additionally, eight X-ray powder diffraction patterns (Cu K[alpha]1 and synchrotron X-rays) were used to establish phase purity. The analyses of these combined neutron and X-ray diffraction data clearly show that the previously published positions of the O atoms in the water molecules are in error. Thermogravimetric analysis of the CAD10 sample preparation used for the neutron diffraction studies gave the composition CaAl2(OD)8(D2O)2{center_dot}2.42D2O. Neutron and X-ray powder diffraction data gave the structural formula CaAl2(OX)8(X2O)2{center_dot}[gamma]X2O (X = D, H and D/H), where the [gamma] values are sample dependent and lie between 2.3 and 3.3.

  2. An investigation of mineral dynamics in frozen seawater brines by direct measurement with synchrotron X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Butler, Benjamin Miles; Kennedy, Hilary

    2015-08-01

    Frozen seawater is a composite material with a sponge-like structure. The framework of the structure is composed of pure ice, and within the pores exists a concentrated seawater brine. When the temperature is reduced, the volume of this residual brine decreases, while its salinity increases. As a result of the paired changes to temperature and salinity, the brine eventually becomes supersaturated with respect to a mineral, resulting in the precipitation of microscopic crystals throughout the ice structure. Due to experimental constraints, the current understanding about the formation of these minerals relies on the analysis of the residual brine, rather than the mineral phase. Here synchrotron X-ray powder diffraction was used to assess the dynamics that occur between ice, brine, and mineral phases within frozen seawater brines that were subjected to cooling and warming at subzero temperatures. The method was able to detect crystalline phases of ice, mirabilite (Na2SO4·10H2O), and hydrohalite (NaCl·2H2O). Results illustrate a highly dynamic geochemical environment where ice-brine-mineral interactions tend toward an equilibrium crystallization process, which supports the process of seawater freezing that is described by the Gitterman Pathway and FREZCHEM model. This study highlights the power of synchrotron techniques in observing the mineralogical dynamics of inaccessible environmental systems.

  3. Limits of visual detection for finasteride polymorphs in prepared binary mixtures: analysis by X-ray powder diffraction.

    PubMed

    Bezzon, Vinícius D N; Antonio, Selma G; Paiva-Santos, Carlos O

    2014-11-01

    Finasteride (FNT) is a drug that inhibits human enzyme type II 5α-reductase that metabolizes testosterone into dihydrotestosterone. There are two enantiotropic polymorphs with known crystal structure: designated as forms I and II. Identification and control of these polymorphic forms in mixtures can be performed using X-ray powder diffraction (XRPD) data and Rietveld method (RM). As experimental conditions may limit the detection of minority phases in mixtures, it is interesting to show what are these limits for some usual and one high-resolution equipment. So, in this work, we discuss the parameters to find the limit of the detection in binary mixtures of forms I and II of FNT according to each experimental condition. The samples analyzed were binary mixtures prepared with anhydrous polymorphs of the drug FNT. These samples were measured in four diffractometers with different experimental condition. These equipments represent the main resolutions generally used for drug analysis by XRPD. For the development of this work, a batch of form I was obtained pure, and another batch with forms I and II was used to obtain pure form II by heat treatment. Depending on the experimental condition, the polymorphs could be detected in a proportion as low as 0.5 wt%. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:3567-3575, 2014.

  4. Using Neutron Diffraction to Investigate Texture Evolution During Consolidation of Deuterated Triaminotrinitrobenzene (d-TATB) Explosive Powder

    DOE PAGES

    Luscher, Darby J.; Yeager, John D.; Clausen, Bjørn; ...

    2017-05-14

    Triaminotrinitrobenzene (TATB) is a highly anisotropic molecular crystal used in several plastic-bonded explosive (PBX) formulations. A complete understanding of the orientation distribution of TATB particles throughout a PBX charge is required to understand spatially variable, anisotropic macroscale properties of the charge. Although texture of these materials can be measured after they have been subjected to mechanical or thermal loads, measuring texture evolution in situ is important in order to identify mechanisms of crystal deformation and reorientation used to better inform thermomechanical models. Neutron diffraction measurements were used to estimate crystallographic reorientation while deuterated TATB (d-TATB) powder was consolidated into amore » cylindrical pellet via a uniaxial die-pressing operation at room temperature. Both the final texture of the pressed pellet and the in situ evolution of texture during pressing were measured, showing that the d-TATB grains reorient such that (001) poles become preferentially aligned with the pressing direction. A compaction model is used to predict the evolution of texture in the pellet during the pressing process, finding that the original model overpredicted the texture strength compared to these measurements. The theory was extended to account for initial particle shape and pore space, bringing the results into good agreement with the data.« less

  5. In situ neutron powder diffraction investigation of the hydration of tricalcium aluminate in the presence of gypsum

    SciTech Connect

    Hartman, M.R. . E-mail: michael.hartman@nist.gov; Berliner, R.

    2005-11-15

    The hydration of a 1:3 molar ratio of tricalcium aluminate, Ca{sub 3}Al{sub 2}O{sub 6}, to gypsum, CaSO{sub 4}.2D{sub 2}O, was investigated at temperatures of 25, 50, and 80 deg. C using time-of-flight powder neutron diffraction combined with multiphase Rietveld structural refinement. It was shown that ettringite, Ca{sub 6}[Al(OD){sub 6}]{sub 2}(SO{sub 4}){sub 3}.{approx}26D{sub 2}O, was the first and only hydration product of the system, in contrast to a prior investigation which suggested the occurrence of a precursor phase prior to the formation of ettringite. Kinetics data showed that the hydration reaction is very sensitive to temperature: hydration at 25 deg. C was characterized by a single kinetic regime while hydration at higher temperatures consisted of two distinct kinetic regimes. The presence of two kinetic regimes was attributed to a change in either the dimensionality of the growth process or a change in the rate controlling mechanism in the hydration reaction.

  6. Coherent 3D nanostructure of γ-Al2O3: Simulation of whole X-ray powder diffraction pattern

    NASA Astrophysics Data System (ADS)

    Pakharukova, V. P.; Yatsenko, D. A.; Gerasimov, E. Yu.; Shalygin, A. S.; Martyanov, O. N.; Tsybulya, S. V.

    2017-02-01

    The structure and nanostructure features of nanocrystalline γ-Al2O3 obtained by dehydration of boehmite with anisotropic platelet-shaped particles were investigated. The original models of 3D coherent nanostructure of γ-Al2O3 were constructed. The models of nanostructured γ-Al2O3 particles were first confirmed by a direct simulation of powder X-Ray diffraction (XRD) patterns using the Debye Scattering Equation (DSE) with assistance of high-resolution transmission electron microscopy (HRTEM) study. The average crystal structure of γ-Al2O3 was shown to be tetragonally distorted. The experimental results revealed that thin γ-Al2O3 platelets were heterogeneous on a nanometer scale and nanometer-sized building blocks were separated by partially coherent interfaces. The XRD simulation results showed that a specific packing of the primary crystalline blocks in the nanostructured γ-Al2O3 particles with formation of planar defects on {001}, {100}, and {101} planes nicely accounted for pronounced diffuse scattering, anisotropic peak broadening and peak shifts in the experimental XRD pattern. The identified planar defects in cation sublattice seem to be described as filling cation non-spinel sites in existing crystallographic models of γ-Al2O3 structure. The overall findings provided an insight into the complex nanostructure, which is intrinsic to the metastable γ-Al2O3 oxide.

  7. X-ray Powder Diffraction in Conservation Science: Towards Routine Crystal Structure Determination of Corrosion Products on Heritage Art Objects.

    PubMed

    Dinnebier, Robert E; Fischer, Andrea; Eggert, Gerhard; Runčevski, Tomče; Wahlberg, Nanna

    2016-06-08

    The crystal structure determination and refinement process of corrosion products on historic art objects using laboratory high-resolution X-ray powder diffraction (XRPD) is presented in detail via two case studies. The first material under investigation was sodium copper formate hydroxide oxide hydrate, Cu4Na4O(HCOO)8(OH)2∙4H2O (sample 1) which forms on soda glass/copper alloy composite historic objects (e.g., enamels) in museum collections, exposed to formaldehyde and formic acid emitted from wooden storage cabinets, adhesives, etc. This degradation phenomenon has recently been characterized as "glass induced metal corrosion". For the second case study, thecotrichite, Ca3(CH3COO)3Cl(NO3)2∙6H2O (sample 2), was chosen, which is an efflorescent salt forming needlelike crystallites on tiles and limestone objects which are stored in wooden cabinets and display cases. In this case, the wood acts as source for acetic acid which reacts with soluble chloride and nitrate salts from the artifact or its environment. The knowledge of the geometrical structure helps conservation science to better understand production and decay reactions and to allow for full quantitative analysis in the frequent case of mixtures.

  8. Using neutron powder diffraction and first-principles calculations to understand the working mechanisms of porous coordination polymer sorbents.

    PubMed

    Chevreau, Hubert; Duyker, Samuel G; Peterson, Vanessa K

    2015-12-01

    Metal-organic frameworks (MOFs) are promising solid sorbents, showing gas selectivity and uptake capacities relevant to many important applications, notably in the energy sector. To improve and tailor the sorption properties of these materials for such applications, it is necessary to gain an understanding of their working mechanisms at the atomic and molecular scale. Specifically, it is important to understand how features such as framework porosity, topology, chemical functionality and flexibility underpin sorbent behaviour and performance. Such information is obtained through interrogation of structure-function relationships, with neutron powder diffraction (NPD) being a particularly powerful characterization tool. The combination of NPD with first-principles density functional theory (DFT) calculations enables a deep understanding of the sorption mechanisms, and the resulting insights can direct the future development of MOF sorbents. In this paper, experimental approaches and investigations of two example MOFs are summarized, which demonstrate the type of information and the understanding into their functional mechanisms that can be gained. Such information is critical to the strategic design of new materials with targeted gas-sorption properties.

  9. The ab-initio crystal structure determination of UPd 2Sn by synchrotron X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Marezio, M.; Cox, D. E.; Rossel, C.; Maple, M. B.

    1988-09-01

    The structure of the heavy-fermion compound UPd 2Sn has been determined by synchrotron x-ray radiation powder diffraction techniques. It is orthorhombic, space group Pnma [lattice parameters a = 9.9787(1), b = 4.58843(5), c = 6.89166(8) Å at room temperature] and Z = 4. All atoms, one U, one Sn, and two Pd are in 4d special positions at (x {1}/{4} z). The refinements were carried out by the Rietveld method with a pseudo-Voigt peak shape function. The final conventional R factors were: R wp = 21.3% and R E = 14.3%. The U positions in the unit cell were unequivocally located, but because of the similarity in x-ray scattering factors it was not possible to determine whether the Pd atoms and the Sn atoms are ordered or disordered on the other three sites. The structural arrangement of UPd 2Sn is of either MnCu 2Al, or ordered NaTl, or disordered Fe 3Al type, all these structures being cubic and b.c.c. related. The orthorhombic distortion is large and is probably due to a size effect of the U atoms which would be in a mixed ( {3+}/{4+}) valence state.

  10. Analysis of an industrial production suspension of Bacillus lentus subtilisin crystals by powder diffraction: a powerful quality-control tool.

    PubMed

    Frankaer, Christian G; Moroz, Olga V; Turkenburg, Johan P; Aspmo, Stein I; Thymark, Majbritt; Friis, Esben P; Stahl, Kenny; Nielsen, Jens E; Wilson, Keith S; Harris, Pernille

    2014-04-01

    A microcrystalline suspension of Bacillus lentus subtilisin (Savinase) produced during industrial large-scale production was analysed by X-ray powder diffraction (XRPD) and X-ray single-crystal diffraction (MX). XRPD established that the bulk microcrystal sample representative of the entire production suspension corresponded to space group P212121, with unit-cell parameters a = 47.65, b = 62.43, c = 75.74 Å, equivalent to those for a known orthorhombic crystal form (PDB entry 1ndq). MX using synchrotron beamlines at the Diamond Light Source with beam dimensions of 20 × 20 µm was subsequently used to study the largest crystals present in the suspension, with diffraction data being collected from two single crystals (∼20 × 20 × 60 µm) to resolutions of 1.40 and 1.57 Å, respectively. Both structures also belonged to space group P2(1)2(1)2(1), but were quite distinct from the dominant form identified by XRPD, with unit-cell parameters a = 53.04, b = 57.55, c = 71.37 Å and a = 52.72, b = 57.13, c = 65.86 Å, respectively, and refined to R = 10.8% and Rfree = 15.5% and to R = 14.1% and Rfree = 18.0%, respectively. They are also different from any of the forms previously reported in the PDB. A controlled crystallization experiment with a highly purified Savinase sample allowed the growth of single crystals of the form identified by XRPD; their structure was solved and refined to a resolution of 1.17 Å with an R of 9.2% and an Rfree of 11.8%. Thus, there are at least three polymorphs present in the production suspension, albeit with the 1ndq-like microcrystals predominating. It is shown how the two techniques can provide invaluable and complementary information for such a production suspension and it is proposed that XRPD provides an excellent quality-control tool for such suspensions.

  11. Time-Resolved In Situ X-ray Diffraction Reveals Metal-Dependent Metal-Organic Framework Formation.

    PubMed

    Wu, Yue; Henke, Sebastian; Kieslich, Gregor; Schwedler, Inke; Yang, Miaosen; Fraser, Duncan A X; O'Hare, Dermot

    2016-11-02

    Versatility in metal substitution is one of the key aspects of metal-organic framework (MOF) chemistry, allowing properties to be tuned in a rational way. As a result, it important to understand why MOF syntheses involving different metals arrive at or fail to produce the same topological outcome. Frequently, conditions are tuned by trial-and-error to make MOFs with different metal species. We ask: is it possible to adjust synthetic conditions in a systematic way in order to design routes to desired phases? We have used in situ X-ray powder diffraction to study the solvothermal formation of isostructural M2 (bdc)2 dabco (M=Zn, Co, Ni) pillared-paddlewheel MOFs in real time. The metal ion strongly influences both kinetics and intermediates observed, leading in some cases to multiphase reaction profiles of unprecedented complexity. The standard models used for MOF crystallization break down in these cases; we show that a simple kinetic model describes the data and provides important chemical insights on phase selection.

  12. Neutron powder diffraction study of the layer organic-inorganic hybrid iron(II) methylphosphonate-hydrate, Fe[(CD 3PO 3)(D 2O)

    NASA Astrophysics Data System (ADS)

    Léone, Philippe; Bellitto, Carlo; Bauer, Elvira M.; Righini, Guido; André, Gilles; Bourée, Françoise

    2008-11-01

    The crystal and magnetic structures of the hybrid organic-inorganic layer compound Fe[(CD 3PO 3)(D 2O)] have been studied by neutron powder diffraction as a function of temperature down to 1.5 K. The neutron diffraction pattern recorded at 200 K shows that the fully deuterated compound crystallizes in one of the two known forms of the undeuterated Fe[(CH 3PO 3)(H 2O)]. The crystal structure is orthorhombic, space group Pmn2 1, with the following unit-cell parameters: a=5.7095(1) Å, b=8.8053(3) Å and c=4.7987(1) Å; Z=2. The crystal structure remains unchanged on cooling from 200 to 1.5 K. Moreover, at low temperature, Fe[(CD 3PO 3)(D 2O)] shows a commensurate magnetic structure ( k=(0,0,0)). As revealed by bulk susceptibility measurements on Fe[(CH 3PO 3)(H 2O)], the magnetic structure corresponds to a canted antiferromagnet with a critical temperature TN=25 K. Neutron powder diffraction reveals that below TN=23.5 K the iron magnetic moments in Fe[(CD 3PO 3)(D 2O)] are antiferromagnetically coupled and oriented along the b-axis, perpendicular to the inorganic layers. No ferromagnetic component is observable in the neutron powder diffraction experiment, due to its too small value (<0.1 μB).

  13. Analyzing solution-phase time-resolved x-ray diffraction data by isolated-solute models

    SciTech Connect

    Lee, Jae Hyuk; Kim, Kyoung Hwan; Kim, Tae Kyu; Lee, Youhong; Ihee, Hyotcherl

    2006-11-07

    Extracting transient structural information of a solute from time-resolved x-ray diffraction (TRXD) data is not trivial because the signal from a solution contains not only the solute-only term as in the gas phase, but also solvent-related terms. To obtain structural insights, the diffraction signal in q space is often Fourier sine transformed (FT) into r space, and molecular dynamics (MD) simulation-aided signal decomposition into the solute, cage, and solvent terms has so far been indispensable for a clear-cut assignment of structural features. Here we present a convenient method of comparative structural analysis without involving MD simulations by incorporating only isolated-species models for the solute. FT is applied to both the experimental data and candidate isolated-solute models, and comparison of the correlation factors between the experimental FT and the model FTs can distinguish the best candidate among isolated-solute models for the reaction intermediates. The low q region whose influence by solvent-related terms is relatively high can be further excluded, and this mode of truncated Fourier transform (TFT) improves the correlation factors and facilitates the comparison. TFT analysis has been applied to TRXD data on the photodissociation of C{sub 2}H{sub 4}I{sub 2} in two different solvents (methanol and cyclohexane), HgI{sub 2} in methanol, and I{sub 3}{sup -} in methanol excited at 267 nm. The results are consistent with previous conclusions for C{sub 2}H{sub 4}I{sub 2} in methanol and HgI{sub 2} in methanol, and the new TRXD data reveal that the C{sub 2}H{sub 4}I transient radical has a bridged structure in cyclohexane and I{sub 3}{sup -} in methanol decomposes into I+I{sub 2}{sup -} upon irradiation at 267 nm. This TFT method should greatly simplify the analysis because it bypasses MD simulations.

  14. Intercalation chemistry in a LDH system: anion exchange process and staging phenomenon investigated by means of time-resolved, in situ X-ray diffraction.

    PubMed

    Taviot-Guého, Christine; Feng, Yongjun; Faour, Azzam; Leroux, Fabrice

    2010-07-14

    Using time-resolved, in situ energy-dispersive X-ray diffraction (EDXRD), the formation of interstratified LDH structures, with alternate interlayer spaces occupied by different anions, have been demonstrated during anion exchange reactions. Novel hybrid LDH nanostructures can thus be prepared, combining the physicochemical properties of two intercalated anions plus those of the LDH host. A general trend is that inorganic-inorganic anion exchange reactions occur in a one-step process while inorganic-organic exchanges may proceed via a second-stage intermediate, suggesting that staging occurs partly as a result of organic-inorganic separation. Yet, other influencing parameters must be considered such as LDH host composition, LDH affinity for different anions and LDH particle size as well as extrinsic parameters like the reaction temperature. Hence, a correlation between the occurrence of staging phenomenon and the difficulty of the exchange of the initial anion is observed, suggesting that staging is needed to overcome the energy barrier in the case of the exchange by organic anions. Notwithstanding the LiAl(2) system, staging has mainly been observed with Zn(2)Cr LDH host so far, a peculiar LDH composition with a unique Zn/Cr ratio of two and a local order of the cations within the hydroxide layers. The formation of a higher order-staged intermediate than stage two, observed during the exchange reaction of CO(3)(2-) or SO(4)(2-) anions with Zn(2)Cr-tartrate, is in favour of a Daumas-Herold model although this model implies a bending of LDH layers. The analysis of the X-ray powder diffraction pattern of Zn(2)Cr-Cl/tartrate second-stage intermediate, isolated almost as a pure phase during the exchange of Cl(-) with tartrate anions in Zn(2)Cr LDH, indicates a disorder in the stacking sequence and a relative proportion of the two kinds of interlayers slightly different from 50/50. Besides, the microstructural analysis of the XRD pattern reveals a great reduction of the

  15. Comparison of Shock-Deformed Carbonate Samples to Unshocked Carbonate Samples Using X-ray Powder Diffraction

    NASA Astrophysics Data System (ADS)

    Huson, S.; Foit, F.; Pope, M.

    2006-12-01

    Previous studies of carbonate minerals from meteorite impact craters have revealed broader X-ray powder diffraction (XRD) peaks when compared to those of unshocked mineral standards. In this study XRD patterns of shocked minerals from an impact crater are compared to those subjected to terrestrial tectonic processes as well as to undeformed mineral standards from our in-house collection. Shocked dolostone and limestone samples were collected from the central uplift and eroded crater rim of Sierra Madera, a well-exposed, complex impact crater located in west Texas. Unshocked samples of dolostone and limestone were collected from the Mission Canyon Formation of the Madison Limestone Group of southwest Montana and western Wyoming. The Mission Canyon Formation was deposited in a shallow shelf environment during the Mississippian, subsequently buried to varying depths, and deformed during the Laramide and Sevier orogenies in the Cretaceous. These samples are therefore excellent representatives for "normal" terrestrial tectonic processes. Samples were powdered, sieved through a 63 μm mesh sieve to ensure a uniform size, and sifted onto a vaseline coated zero background plate to reduce preferred orientation of grains. Patterns were collected over the range from 15° 120° 2θ with a step width of 0.02° 2θ and count-time of 10s per step. All patterns were analyzed using MDI Jade 7.0 software. Generally, samples collected in the field have XRD patterns that are not as sharp as the mineral standard patterns. With both shocked and unshocked samples, those containing dolomite show more XRD peak broadening than those without dolomite and at least one pattern of an unshocked dolostone sample is indistinguishable from a shocked dolostone pattern. However, dolostone samples in general are problematic. Previous researchers reported that the amount of magnesium in calcite may affect grinding properties and, therefore, influence XRD peak broadening. Currently, it is not always

  16. High pressure neutron powder diffraction study of Fe1-xCrx with and without hydrogen exposure

    SciTech Connect

    Rivin, Oleg; Amir Broide; Maskova, Sylvie; Lucas, Matthew; Hen, Amir; Orion, Itzhak; Salhov, Shai; Shandalov, Michael; Moreira Dos Santos, Antonio F.; Molaison, Jamie J.; Chen, Zhiqiang; Halevy, Itzhak

    2014-12-23

    The crystal structure of Fe1-xCrx(x = 0, 0.2 and 0.4) materials, with and without exposure to Hydrogen, is investigated using neutron powder diffraction under the applied external high-pressure. Above a certain applied pressure, PC, a structural phase transition, from cubic to hexagonal symmetry, is observed, in agreement with previous x-ray diffraction results. The PC values exhibit an increase with x increase. The possibility for an evolution of a magnetic structure with pressure, x and Hydrogen exposure, is examined. Finally, a broadening of the angular profile of the (200) reflection (cubic phase) is identified and reported.

  17. Time-resolved X-ray diffraction microprobe studies of the conversion of cellulose I to ethylenediamine-cellulose I

    SciTech Connect

    Nishiyama, Yoshiharu; Wada, Masahisa; Hanson, B. Leif; Langan, Paul

    2010-08-03

    Structural changes during the treatment of films of highly crystalline microfibers of Cladophora cellulose with ethylenediamine (EDA) have been studied by time-resolved X-ray microprobe diffraction methods. As EDA penetrates the sample and converts cellulose I to EDA-cellulose I, the measured profile widths of reflections reveal changes in the shapes and average dimensions of cellulose I and EDA-cellulose I crystals. The (200) direction of cellulose I is most resistant to EDA penetration, with EDA penetrating most effectively at the hydrophilic edges of the hydrogen bonded sheets of cellulose chains. Most of the cellulose chains in the initial crystals of cellulose I are incorporated into crystals of EDA-cellulose I. The size of the emerging EDA-cellulose I crystals is limited to about half of their size in cellulose I, most likely due to strains introduced by the penetration of EDA molecules. There is no evidence of any gradual structural transition from cellulose I to EDA-cellulose I involving a continuously changing intermediate phase. Rather, the results point to a rapid transition to EDA-cellulose I in regions of the microfibrils that have been penetrated by EDA.

  18. Crystal structures of deuterated sodium molybdate dihydrate and sodium tungstate dihydrate from time-of-flight neutron powder diffraction.

    PubMed

    Fortes, A Dominic

    2015-07-01

    Time-of-flight neutron powder diffraction data have been measured from ∼90 mol% deuterated isotopologues of Na2MoO4·2H2O and Na2WO4·2H2O at 295 K to a resolution of sin (θ)/λ = 0.77 Å(-1). The use of neutrons has allowed refinement of structural parameters with a precision that varies by a factor of two from the heaviest to the lightest atoms; this contrasts with the X-ray based refinements where precision may be > 20× poorer for O atoms in the presence of atoms such as Mo and W. The accuracy and precision of inter-atomic distances and angles are in excellent agreement with recent X-ray single-crystal structure refinements whilst also completing our view of the hydrogen-bond geometry to the same degree of statistical certainty. The two structures are isotypic, space-group Pbca, with all atoms occupying general positions, being comprised of edge- and corner-sharing NaO5 and NaO6 polyhedra that form layers parallel with (010) inter-leaved with planes of XO4 (X = Mo, W) tetra-hedra that are linked by chains of water mol-ecules along [100] and [001]. The complete structure is identical with the previously described molybdate [Capitelli et al. (2006 ▸). Asian J. Chem. 18, 2856-2860] but shows that the purported three-centred inter-action involving one of the water mol-ecules in the tungstate [Farrugia (2007 ▸). Acta Cryst. E63, i142] is in fact an ordinary two-centred 'linear' hydrogen bond.

  19. Study of desorbed hydrogen-decrepitated anisotropic Nd-Fe-B powder using x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Meisner, G. P.; Panchanathan, V.

    1994-11-01

    The instrinsic magnetic coercivity (H(sub ci)) of Nd-Fe-B-based permanent magnet material is profoundly affected by hydrogen absorbed during the hydrogen decrepitation (HD) process for producing anisotropic powders from bulk anisotropic hot-deformed MAGNEQUENCH (MQ) magnets. Hydrogen (H) content and x-ray diffraction measurements clarify the effects of H and desorption temperature (T(sub d)) on the intrinsic magnetic anisotropy (IMA) of the Nd2Fe14B-type phase and the nature of the intergranular phases, both of which are crucial for high H(sub ci). The Nd-rich intergranular phase disproportionates during HD, initially forming a microcrystalline Nd-hydride phase, possibly Nd2H5. For T(sub d) less than or equal to 220 C, H remains in the Nd2Fe14B-type phase, severely degrading the IMA, which causes a low H(sub ci). For 220 C less than or equal to T(sub d) less than or equal to 250 C, enough H desorbs from the Nd2Fe14B-type phase and the IMA recovers its large prehydrided value, and the microstructure supports a high H(sub ci) less than or equal to 10 kOe in spite of the H disproportionated interfgranular phase. Only for T(sub d) greater than 250 C is H(sub ci) degraded by the microstructure, corresponding to further H desorption and the microcrystalline Nd-hydride phase becoming well-crystallized NdH2. The NdH2 phase decomposes with continued H desorption and at T(sub d) greater than 580 C recombines to reform the Nd-rich intergranular phase of prehydrided MQ material. H is completely desorbed above 580 C and H(sub ci) greater than 11 kOe, nearly that of the prehydrided MQ magnets.

  20. Crystal structures of deuterated sodium molybdate dihydrate and sodium tungstate dihydrate from time-of-flight neutron powder diffraction

    PubMed Central

    Fortes, A. Dominic

    2015-01-01

    Time-of-flight neutron powder diffraction data have been measured from ∼90 mol% deuterated isotopologues of Na2MoO4·2H2O and Na2WO4·2H2O at 295 K to a resolution of sin (θ)/λ = 0.77 Å−1. The use of neutrons has allowed refinement of structural parameters with a precision that varies by a factor of two from the heaviest to the lightest atoms; this contrasts with the X-ray based refinements where precision may be > 20× poorer for O atoms in the presence of atoms such as Mo and W. The accuracy and precision of inter­atomic distances and angles are in excellent agreement with recent X-ray single-crystal structure refinements whilst also completing our view of the hydrogen-bond geometry to the same degree of statistical certainty. The two structures are isotypic, space-group Pbca, with all atoms occupying general positions, being comprised of edge- and corner-sharing NaO5 and NaO6 polyhedra that form layers parallel with (010) inter­leaved with planes of XO4 (X = Mo, W) tetra­hedra that are linked by chains of water mol­ecules along [100] and [001]. The complete structure is identical with the previously described molybdate [Capitelli et al. (2006 ▸). Asian J. Chem. 18, 2856–2860] but shows that the purported three-centred inter­action involving one of the water mol­ecules in the tungstate [Farrugia (2007 ▸). Acta Cryst. E63, i142] is in fact an ordinary two-centred ‘linear’ hydrogen bond. PMID:26279871

  1. A comparative study of the use of powder X-ray diffraction, Raman and near infrared spectroscopy for quantification of binary polymorphic mixtures of piracetam.

    PubMed

    Croker, Denise M; Hennigan, Michelle C; Maher, Anthony; Hu, Yun; Ryder, Alan G; Hodnett, Benjamin K

    2012-04-07

    Diffraction and spectroscopic methods were evaluated for quantitative analysis of binary powder mixtures of FII(6.403) and FIII(6.525) piracetam. The two polymorphs of piracetam could be distinguished using powder X-ray diffraction (PXRD), Raman and near-infrared (NIR) spectroscopy. The results demonstrated that Raman and NIR spectroscopy are most suitable for quantitative analysis of this polymorphic mixture. When the spectra are treated with the combination of multiplicative scatter correction (MSC) and second derivative data pretreatments, the partial least squared (PLS) regression model gave a root mean square error of calibration (RMSEC) of 0.94 and 0.99%, respectively. FIII(6.525) demonstrated some preferred orientation in PXRD analysis, making PXRD the least preferred method of quantification. Copyright © 2012 Elsevier B.V. All rights reserved.

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

    SciTech Connect

    Pauling, L. )

    1988-07-01

    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.

  3. Investigation of the Surface Stress in SiC and Diamond Nanocrystals by In-situ High Pressure Powder Diffraction Technique

    NASA Technical Reports Server (NTRS)

    Palosz, B.; Stelmakh, S.; Grzanka, E.; Gierlotka, S.; Zhao, Y.; Palosz, W.

    2003-01-01

    The real atomic structure of nanocrystals determines key properties of the materials. For such materials the serious experimental problem lies in obtaining sufficiently accurate measurements of the structural parameters of the crystals, since very small crystals constitute rather a two-phase than a uniform crystallographic phase system. As a result, elastic properties of nanograins may be expected to reflect a dual nature of their structure, with a corresponding set of different elastic property parameters. We studied those properties by in-situ high-pressure powder diffraction technique. For nanocrystalline, even one-phase materials such measurements are particularly difficult to make since determination of the lattice parameters of very small crystals presents a challenge due to inherent limitations of standard elaboration of powder diffractograms. In this investigation we used our methodology of the structural analysis, the 'apparent lattice parameter' (alp) concept. The methodology allowed us to avoid the traps (if applied to nanocrystals) of standard powder diffraction evaluation techniques. The experiments were performed for nanocrystalline Sic and GaN powders using synchrotron sources. We applied both hydrostatic and isostatic pressures in the range of up to 40 GPa. Elastic properties of the samples were examined based on the measurements of a change of the lattice parameters with pressure. The results show a dual nature of the mechanical properties (compressibilities) of the materials, indicating a complex, core-shell structure of the grains.

  4. Investigation of the Surface Stress in SiC and Diamond Nanocrystals by In-situ High Pressure Powder Diffraction Technique

    NASA Technical Reports Server (NTRS)

    Palosz, B.; Stelmakh, S.; Grzanka, E.; Gierlotka, S.; Zhao, Y.; Palosz, W.

    2003-01-01

    The real atomic structure of nanocrystals determines key properties of the materials. For such materials the serious experimental problem lies in obtaining sufficiently accurate measurements of the structural parameters of the crystals, since very small crystals constitute rather a two-phase than a uniform crystallographic phase system. As a result, elastic properties of nanograins may be expected to reflect a dual nature of their structure, with a corresponding set of different elastic property parameters. We studied those properties by in-situ high-pressure powder diffraction technique. For nanocrystalline, even one-phase materials such measurements are particularly difficult to make since determination of the lattice parameters of very small crystals presents a challenge due to inherent limitations of standard elaboration of powder diffractograms. In this investigation we used our methodology of the structural analysis, the 'apparent lattice parameter' (alp) concept. The methodology allowed us to avoid the traps (if applied to nanocrystals) of standard powder diffraction evaluation techniques. The experiments were performed for nanocrystalline Sic and GaN powders using synchrotron sources. We applied both hydrostatic and isostatic pressures in the range of up to 40 GPa. Elastic properties of the samples were examined based on the measurements of a change of the lattice parameters with pressure. The results show a dual nature of the mechanical properties (compressibilities) of the materials, indicating a complex, core-shell structure of the grains.

  5. Shock-induced chemical reactions in titanium{endash}silicon powder mixtures of different morphologies: Time-resolved pressure measurements and materials analysis

    SciTech Connect

    Thadhani, N.N.; Graham, R.A.; Royal, T.; Dunbar, E.; Anderson, M.U.; Holman, G.T.

    1997-08-01

    The response of porous titanium (Ti) and silicon (Si) powder mixtures with small, medium, and coarse particle morphologies is studied under high-pressure shock loading, employing postshock materials analysis as well as nanosecond, time-resolved pressure measurements. The objective of the work was to provide an experimental basis for development of models describing shock-induced solid-state chemistry. The time-resolved measurements of stress pulses obtained with piezoelectric polymer (poly-vinyl-di-flouride) pressure gauges provided extraordinary sensitivity for determination of rate-dependent shock processes. Both techniques showed clear evidence for shock-induced chemical reactions in medium-morphology powders, while fine and coarse powders showed no evidence for reaction. It was observed that the medium-morphology mixtures experience simultaneous plastic deformation of both Ti and Si particles. Fine morphology powders show particle agglomeration, while coarse Si powders undergo extensive fracture and entrapment within the plastically deformed Ti; such processes decrease the propensity for initiation of shock-induced reactions. The change of deformation mode between fracture and plastic deformation in Si powders of different morphologies is a particularly critical observation. Such a behavior reveals the overriding influence of the shock-induced, viscoplastic deformation and fracture response, which controls the mechanochemical nature of shock-induced solid-state chemistry. The present work in conjunction with our prior studies, demonstrates that the initiation of chemical reactions in shock compression of powders is controlled by solid-state mechanochemical processes, and cannot be qualitatively or quantitatively described by thermochemical models. {copyright} {ital 1997 American Institute of Physics.}

  6. Shock-induced chemical reactions in titanium-silicon powder mixtures of different morphologies: Time-resolved pressure measurements and materials analysis

    NASA Astrophysics Data System (ADS)

    Thadhani, N. N.; Graham, R. A.; Royal, T.; Dunbar, E.; Anderson, M. U.; Holman, G. T.

    1997-08-01

    The response of porous titanium (Ti) and silicon (Si) powder mixtures with small, medium, and coarse particle morphologies is studied under high-pressure shock loading, employing postshock materials analysis as well as nanosecond, time-resolved pressure measurements. The objective of the work was to provide an experimental basis for development of models describing shock-induced solid-state chemistry. The time-resolved measurements of stress pulses obtained with piezoelectric polymer (poly-vinyl-di-flouride) pressure gauges provided extraordinary sensitivity for determination of rate-dependent shock processes. Both techniques showed clear evidence for shock-induced chemical reactions in medium-morphology powders, while fine and coarse powders showed no evidence for reaction. It was observed that the medium-morphology mixtures experience simultaneous plastic deformation of both Ti and Si particles. Fine morphology powders show particle agglomeration, while coarse Si powders undergo extensive fracture and entrapment within the plastically deformed Ti; such processes decrease the propensity for initiation of shock-induced reactions. The change of deformation mode between fracture and plastic deformation in Si powders of different morphologies is a particularly critical observation. Such a behavior reveals the overriding influence of the shock-induced, viscoplastic deformation and fracture response, which controls the mechanochemical nature of shock-induced solid-state chemistry. The present work in conjunction with our prior studies, demonstrates that the initiation of chemical reactions in shock compression of powders is controlled by solid-state mechanochemical processes, and cannot be qualitatively or quantitatively described by thermochemical models.

  7. Angle Resolved Photoelectron and Auger Electron Diffraction as a Structural Probe for Surfaces, Interfaces, and Epitaxial Films.

    NASA Astrophysics Data System (ADS)

    Li, Hong

    The recently developed techniques of angle-resolved photoelectron and Auger electron diffraction (ARXPD/AED) have shown promise in identifying the structures of epitaxial films. This is due to the realization that electrons scattered by other atoms are enhanced along the forward direction. In this dissertation research, we have further investigated the capabilities of the ARXPD/AED technique. First, the complete polar angle distribution of the Auger electron intensity from Cu(001) was measured from the (100) to the (110) azimuth. The presentation of the ARAED in the form of a contour map clearly shows the relationship of the constructive and destructive interference of electron scattering to the crystallographic index of the crystal. Secondly, the angular distributions of electron emissions with initial states of 3p, 3d, 4d, and the Auger emission with electron kinetic energies ranging from 348 eV to 1477 eV were measured for single crystal Ag(001). The results show that all of these electron emissions have similar electron forward scattering enhancements along the directions of nearest and next nearest neighbour atoms in the crystal. The forward scattering enhancements do not shift as the electron kinectic energy changes. The ARXPD/AED combined with low energy electron diffraction (LEED) has been demonstrated to be a very powerful technique in probing both the long range order and the short range order of the epitaxial films. The epitaxial films studied include Co on Cu(001), Fe on Ag(001), Co on Ag(001), and Co on an ultra-thin film of Fe(001), which was epitaxially grown on Ag(001). We find that up to 20 ML thickness of high quality metastable fcc Co can be stabilized on Cu(001) at room temperature. We have directly verified that the Fe on Ag(001) is bcc. The Co on Ag(001) is neither bcc nor fcc for coverages of less than 3 ML. Thick films of Co on Ag(001) are disordered, of which a very small portion has a local structure of bcc. The bcc Co phases has been

  8. Single-crystal and synchrotron x-ray powder diffraction study of the one-dimensial orthorhombic polymer phase of C[sub 60}.

    SciTech Connect

    Papoular, R. J.; Toby, B. H.; Davydov, V. A.; Rakhmanina, A. V.; Dzyabchenko,, A.; Allouchi,, H.; Agafonov, V.; X-Ray Science Division; Leon Brillouin Lab.; Vereshchagin Inst. of High-Presure Physics; Karpov Inst. of Physical Chemistry; Labo. de Synthese Physco-Chimique et Therapeutique; Lab. d'Electrodynamique des Materiaux Avances

    2008-07-20

    The 1D-orthorhombic polymer phase of C{sub 60} was originally mentioned in 1995. The present work provides the first direct experimental quantitative evidences of the 1D-polymer chains, clearly seen by single-crystal diffraction. Geometrical details of the [2+2]-cycloaddition rings are compared with those of C{sub 60} dimers and 2D-polymers. Another key structural parameter is the angle of rotation {Psi} of the 1D chains about the polymerization axis. Single-crystal diffraction yields {Psi} {approx} 78{sup o}, whereas accurate synchrotron powder diffraction independently produces a similar {Psi} {approx} 73{sup o}. These values are in qualitative agreement with a former theoretical prediction ({Psi} {approx} 61{sup o}).

  9. X-ray powder diffraction of high-absorption materials at the XRD1 beamline off the best conditions: Application to (Gd, Nd)5Si4 compounds

    NASA Astrophysics Data System (ADS)

    Carvalho, A. M. G.; Nunes, R. S.; Coelho, A. A.

    2017-03-01

    Representative compounds of the new family of magnetic materials Gd5-xNdxSi4 were analyzed by X-ray diffraction at the XRD1 beamline at LNLS. To reduce X-ray absorption, thin layers of the powder samples were mounted outside the capillaries and measured in Debye-Scherrer geometry as usual. The X-ray diffraction analyses and the magnetometry results indicate that the behavior of the magnetic transition temperature as a function of Nd content may be directly related to the average of the four smallest interatomic distances between different rare earth sites of the majority phase of each compound. The quality and consistency of the results show that the XRD1 beamline is able to perform satisfactory X-ray diffraction experiments on high-absorption materials even off the best conditions.

  10. Visualizing structural dynamics of aluminum and iron under laser shock compression with time-resolved X-ray diffraction method

    NASA Astrophysics Data System (ADS)

    Takagi, S.; Ichiyanagi, K.; Fukaya, R.; Syunsuke, N.; Kawai, N.; Kazutaka, N.; Kyono, A.; Nobumasa, F.; Adachi, S. I.

    2016-12-01

    Understanding the characterization of Earth's materials under shock compression is indispensable to comprehend the dynamics of the Earth such as fault movement in the crust, deep earthquake in the mantle, and meteorite collision. We investigated structural dynamics of aluminum and iron polycrystalline materials under laser shock compression by using the nanosecond time-resolved X-ray diffraction (TR-XRD) with the high power Nd:Glass laser system installed at the NW14A beamline, Photon Factory Advanced Ring (PF-AR), High Energy Accelerator Research Organization (KEK), Japan. The Nd:Glass laser system as the shock wave device was composed of the oscillator system (Q-switch Nd:YAG laser) and three stages amplifiers. The pulse width, wavelength, repetition rate, and energy of the Nd:Glass laser were 12 ns, 1064 nm, 9.46 Hz, and 16 J/pulse, respectively. The laser system was synchronized with the rf master clock of the PF-AR. A monochromatic X-ray with the energy of 15.68 keV and pulse width of 100 ps was employed as a probe source. We utilized a polycrystalline aluminum foil with the thickness of 100 mm and an iron foil of 20 mm as target materials. TR-XRD patterns of aluminum exhibited continuous structural change during the shock-wave loading up to 14.19 ns (Fig.1). No phase transition was observed during the compression. The shock compression pressure was estimated to be reached at least 10 GPa. The iron, on the other hand, underwent the α (bcc)-ɛ (hcp) phase transition at 13 GPa. In this presentation, we will discuss the details of structural dynamics under shock compression, and report the shock compressed crystal structures analyzed by XRD patterns and shock wave profiles.

  11. Testing the limits of sensitivity in a solid-state structural investigation by combined X-ray powder diffraction, solid-state NMR, and molecular modelling.

    PubMed

    Filip, Xenia; Borodi, Gheorghe; Filip, Claudiu

    2011-10-28

    A solid state structural investigation of ethoxzolamide is performed on microcrystalline powder by using a multi-technique approach that combines X-ray powder diffraction (XRPD) data analysis based on direct space methods with information from (13)C((15)N) solid-state Nuclear Magnetic Resonance (SS-NMR) and molecular modeling. Quantum chemical computations of the crystal were employed for geometry optimization and chemical shift calculations based on the Gauge Including Projector Augmented-Wave (GIPAW) method, whereas a systematic search in the conformational space was performed on the isolated molecule using a molecular mechanics (MM) approach. The applied methodology proved useful for: (i) removing ambiguities in the XRPD crystal structure determination process and further refining the derived structure solutions, and (ii) getting important insights into the relationship between the complex network of non-covalent interactions and the induced supra-molecular architectures/crystal packing patterns. It was found that ethoxzolamide provides an ideal case study for testing the accuracy with which this methodology allows to distinguish between various structural features emerging from the analysis of the powder diffraction data.

  12. Time-and-state resolved spectroscopy, diffraction, and circular dichroism in core photoelectron emission from clean and oxygen-covered W(110)

    SciTech Connect

    Ynzunza, Ramon Xavier

    1998-10-01

    Several aspects of core-level photoelectron emission fi-om solid surfaces as excited by high-brightness variable-polarization synchrotrons radiation have been studied with a new beamline and experimental station at the Advanced Light Source in Berkeley. These include: resolution of different chemical states and site types via high-resolution photoelectron spectroscopy (PS), the use of state-resolved photoelectron difllaction (PD) to determine local atomic geometries, and the observation and analysis of circular dichroism (CD) effects in photoelectron diffraction. These methods have been applied to clean and oxygen-exposed surfaces of W(110). Full-solid-angle photoelectron diffraction from clean W(110) was measured, with the surface and bulk atoms being clearly resolved.

  13. Simultaneous Differential Scanning Calorimetry-Synchrotron X-ray Powder Diffraction: A Powerful Technique for Physical Form Characterization in Pharmaceutical Materials.

    PubMed

    Clout, Alexander; Buanz, Asma B M; Prior, Timothy J; Reinhard, Christina; Wu, Yue; O'Hare, Dermot; Williams, Gareth R; Gaisford, Simon

    2016-10-18

    We report a powerful new technique: hyphenating synchrotron X-ray powder diffraction (XRD) with differential scanning calorimetry (DSC). This is achieved with a simple modification to a standard laboratory DSC instrument, in contrast to previous reports which have involved extensive and complex modifications to a DSC to mount it in the synchrotron beam. The high-energy X-rays of the synchrotron permit the recording of powder diffraction patterns in as little as 2 s, meaning that thermally induced phase changes can be accurately quantified and additional insight on the nature of phase transitions obtained. Such detailed knowledge cannot be gained from existing laboratory XRD instruments, since much longer collection times are required. We demonstrate the power of our approach with two model systems, glutaric acid and sulfathiazole, both of which show enantiotropic polymorphism. The phase transformations between the low and high temperature polymorphs are revealed to be direct solid-solid processes, and sequential refinement against the diffraction patterns obtained permits phase fractions at each temperature to be calculated and unit cell parameters to be accurately quantified as a function of temperature. The combination of XRD and DSC has further allowed us to identify mixtures of phases which appeared phase-pure by DSC.

  14. Investigation of phase evolution of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) by in situ synchrotron high-temperature powder diffraction

    SciTech Connect

    Ouyang, Xin; Huang, Saifang; Zhang, Weijun; Cao, Peng; Huang, Zhaohui; Gao, Wei

    2014-03-15

    In situ synchrotron X-ray powder diffraction was used to study the high-temperature phase evolution of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) precursors prepared via solid-state and sol–gel methods. After the precursors are heated to 1225 °C, the CCTO phase is the main phase observed in the calcined powder, with the presence of some minor impurities. Comparing the two precursors, we found that the onset temperature for the CCTO phase formation is 800 °C in the sol–gel precursor, lower than that in the solid-state precursor (875 °C). Intermediate phases were only observed in the sol–gel precursor. Both precursors are able to be calcined to sub-micrometric sized powders. Based on the synchrotron data along with differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), the phase formation sequence and mechanism during calcination are proposed in this study. -- Graphical abstract: The in situ synchrotron HT-XRD patterns of CCTO sol–gel and solid-state precursor. Highlights: • Phase formation sequence/mechanism in two CCTO precursors has been established. • Formation temperature of CCTO via sol–gel method is lower than solid-state method. • Intermediate phases are only observed in the sol–gel precursor. • Both precursors are able to be calcined into sub-micrometric sized powders.

  15. L-Lysine: exploiting powder X-ray diffraction to complete the set of crystal structures of the 20 directly encoded proteinogenic amino acids.

    PubMed

    Williams, P Andrew; Hughes, Colan E; Harris, Kenneth D M

    2015-03-23

    During the last 75 years, crystal structures have been reported for 19 of the 20 directly encoded proteinogenic amino acids in their natural (enantiomerically pure) form. The crystal structure is now reported for the final member of this set: L-lysine. As crystalline L-lysine has a strong propensity to incorporate water under ambient atmospheric conditions to form a hydrate phase, the pure (non-hydrate) crystalline phase can be obtained only by dehydration under rigorously anhydrous conditions, resulting in a microcrystalline powder sample. For this reason, modern powder X-ray diffraction methods have been exploited to determine the crystal structure in this final, elusive case. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Single-crystal and humidity-controlled powder diffraction study of the breathing effect in a metal-organic framework upon water adsorption/desorption.

    PubMed

    Aríñez-Soriano, Javier; Albalad, Jorge; Vila-Parrondo, Christian; Pérez-Carvajal, Javier; Rodríguez-Hermida, Sabina; Cabeza, Aurelio; Juanhuix, Jordi; Imaz, Inhar; Maspoch, Daniel

    2016-05-26

    Herein we report a study on water adsorption/desorption-triggered single-crystal to single-crystal transformations in a MOF, by single-crystal and humidity-controlled powder X-ray diffraction and water-sorption measurements. We identified a gate-opening effect at a relative humidity of 85% upon water adsorption, and a gate-closure effect at a relative humidity of 55 to 77% upon water desorption. This reversible breathing effect between the "open" and the "closed" structures of the MOF involves the cleavage and formation of several coordination bonds.

  17. (Z)-3-Methyl-N-(7-nitroacridin-3-yl)-2,3-dihydro-1,3-benzothiazol-2-imine from laboratory powder diffraction data.

    PubMed

    Vallcorba, Oriol; Latorre, Sonia; Alcobé, Xavier; Miravitlles, Carles; Rius, Jordi

    2011-11-01

    The title compound, C(21)H(14)N(4)O(2)S, belongs to a family of molecules possessing nonlinear optical properties in solution. Its structure has been solved from laboratory X-ray powder diffraction data using a new direct-space structure solution method, where the atomic coordinates are directly used as parameters and the molecular geometry is described by restraints. The molecular packing is controlled by two systems of π-π interactions and one weak edge-to-face interaction.

  18. Strategies for reducing preferred orientation and strain in powder samples for high-pressure synchrotron X-ray diffraction in diamond-anvil cells

    SciTech Connect

    Tschauner, Oliver; McClure, Jason; Nicol, Malcolm

    2010-07-20

    Among the many problems associated with high-pressure X-ray diffraction from polycrystalline samples in the diamond-anvil cell are strain and preferred orientation. A method is presented for efficiently reducing preferred orientation of powder samples compressed in diamond-anvil cells to pressures in excess of 20 GPa. This method may be successfully applied to samples of yield strength higher than alkalihalides. In addition, the problem of strain is discussed using ice-VII as an example and as an illustration of the importance of laser heating as a method of minimizing strain.

  19. Effect of chlorine in clay-mineral specimens prepared on silver metal-membrane mounts for X-ray powder diffraction analysis

    USGS Publications Warehouse

    Poppe, L.J.; Commeau, J.A.; Pense, G.M.

    1989-01-01

    Silver metal-membrane filters are commonly used as substrates in the preparation of oriented clay-mineral specimens for X-ray powder diffraction (XRD). The silver metal-membrane filters, however, present some problems after heat treatment if either the filters or the samples contain significant amounts of chlorine. At elevated temperature, the chloride ions react with the silver substrate to form crystalline compounds. These compounds change the mass-absorption coefficient of the sample, reducing peak intensities and areas and, therefore, complicating the semiquantitative estimation of clay minerals. A simple procedure that eliminates most of the chloride from a sample and the silver metal-membrane substrate is presented here.

  20. Synthesis and ab initio X-ray powder diffraction structure of the new alkali and alkali earth metal borate NaCa(BO3).

    PubMed

    Wu, L; Chen, X L; Li, X Z; Dai, L; Xu, Y P; Zhao, M

    2005-03-01

    A sodium calcium borate, NaCaBO3, has been synthesized by the solid-state reaction method and the structure solved from X-ray powder diffraction data. The compound crystallizes in space group Pmmn and has a desired structure type containing isolated planar BO3(3-) anions. Mixed occupancy is found to exist in the Ca site, with partial replacement by Na. One Ca/Na mixed atom and one Na atom are at sites with mm2 symmetry, and a second Ca/Na mixed atom, an Na atom, two B and two O atoms are on mirror planes.

  1. Disorder in the composite crystal structure of the manganese `disilicide' MnSi1.73 from powder X-ray diffraction data.

    PubMed

    Akselrud, L; Cardoso Gil, R; Wagner-Reetz, M; Grin, Yu

    2015-12-01

    The crystal structure of the higher manganese silicide MnSi1.7 (known in the literature as HMS) is investigated in samples with different compositions obtained by different techniques at temperatures not higher than 1273 K. Powder X-ray diffraction was applied. The crystal structure is described as incommensurate composite. In addition to the ordered model already known in the literature, the partial disorder in the silicon substructure was detected and described introducing an additional atomic site with a different modulation function.

  2. Pressure-Induced Structural Evolution and Elastic Behaviour of Na{6}Cs{2}Ga{6}Ge{6}O{24} Variant of Cancrinite: A Synchrotron Powder Diffraction Study

    SciTech Connect

    Diego Gatta, G.; Lee, Y

    2008-01-01

    The elastic behaviour and the pressure (P) induced structural evolution of Na6Cs2Ga6Ge6O24 Ge(OH)6, a synthetic compound isotypic with cancrinite (CAN topology), have been investigated up to 5.01(5) GPa by means of in situ X-ray synchrotron powder diffraction with a diamond anvil cell and using a nominally penetrating hydrous P-transmitting medium (methanol:ethanol:water = 16:3:1). No evidence of phase-transition was observed within the P-range investigated.

  3. A general method for baseline-removal in ultrafast electron powder diffraction data using the dual-tree complex wavelet transform

    PubMed Central

    René de Cotret, Laurent P.; Siwick, Bradley J.

    2016-01-01

    The general problem of background subtraction in ultrafast electron powder diffraction (UEPD) is presented with a focus on the diffraction patterns obtained from materials of moderately complex structure which contain many overlapping peaks and effectively no scattering vector regions that can be considered exclusively background. We compare the performance of background subtraction algorithms based on discrete and dual-tree complex (DTCWT) wavelet transforms when applied to simulated UEPD data on the M1–R phase transition in VO2 with a time-varying background. We find that the DTCWT approach is capable of extracting intensities that are accurate to better than 2% across the whole range of scattering vector simulated, effectively independent of delay time. A Python package is available. PMID:28083543

  4. Neutron powder thermo-diffraction: a very useful tool for the study of crystallisation kinetics and phase segregation in metastable materials

    NASA Astrophysics Data System (ADS)

    Gorria, P.; Martínez-Blanco, D.; Blanco, J. A.; Garitaonandia, J. S.; Campo, J.; Smith, R. I.

    2004-05-01

    This paper gives an overview of what kind of information and how deep can we go into the structure determination of materials, in metastable states, using neutron powder thermo-diffraction, whether temperature induced crystallisation and phase segregation processes have to be completely understood. We have obtained, by means of high energy ball milling technique, four different Fe-based compounds, showing unique characteristics (nanostructured Fe, FeNi alloys, FeCu solid solutions and FeZr amorphous alloys). In situ neutron diffraction experiments have been carried out in the temperature range between 300 and 1220 K in order to study the great variety of structural changes that takes place in these compounds.

  5. A combined approach for characterisation of fresh and brined vine leaves by X-ray powder diffraction, NMR spectroscopy and direct infusion high resolution mass spectrometry.

    PubMed

    Rizzuti, Antonino; Caliandro, Rocco; Gallo, Vito; Mastrorilli, Piero; Chita, Giuseppe; Latronico, Mario

    2013-12-01

    X-ray powder diffraction was combined, for the first time, with Nuclear Magnetic Resonance spectroscopy and direct infusion mass spectrometry to characterise fresh and brined grape leaves. Covariance analysis of data generated by the three techniques was performed with the aim to correlate information deriving from the solid part with those obtained for soluble metabolites. The results obtained indicate that crystalline components can be correlated to the metabolites contained in the grape leaves, paving the way to the use of X-ray diffraction analysis for food fingerprinting purposes. Moreover it was ascertained that, differently from most of the metabolites present in the fresh vine leaves, linolenic acid (an omega-3-fatty acid) and quercetin-3-O-glucuronide (a polyphenol metabolite) do not undergo sensible degradation during the brining process, which is used as preservative method for the grape leaves.

  6. Magnetic and electronic orderings in orthorhombic RMnO3 (R=Tm, Lu) studied by resonant soft x-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Garganourakis, M.; Bodenthin, Y.; de Souza, R. A.; Scagnoli, V.; Dönni, A.; Tachibana, M.; Kitazawa, H.; Takayama-Muromachi, E.; Staub, U.

    2012-08-01

    Resonant soft x-ray powder diffraction experiments on orthorhombic TmMnO3 and LuMnO3 are presented. Experiments were performed in the vicinity of the Tm M5 and the Mn L2,3 edges to study the Tm and Mn magnetic moments, respectively. These experiments show that for the heavy rare-earth perovskite with an E-type ordered ground state, the Tm magnetic moments order already in the nonferroelectric incommensurate magnetic phase. Additionally, deviations from the collinear E-type Mn magnetic structure at low temperatures are found for both compounds. These experiments show the power of resonant soft x-ray diffraction, extended to polycrystalline 4f materials.

  7. Direct Observations of Austenite, Bainite and Martensite Formation During Arc Welding of 1045 Steel using Time Resolved X-Ray Diffraction

    SciTech Connect

    Elmer, J; Palmer, T; Babu, S; Zhang, W; DebRoy, T

    2004-02-17

    In-situ Time Resolved X-Ray Diffraction (TRXRD) experiments were performed during stationary gas tungsten arc (GTA) welding of AISI 1045 C-Mn steel. These synchrotron-based experiments tracked, in real time, phase transformations in the heat-affected zone of the weld under rapid heating and cooling conditions. The diffraction patterns were recorded at 100 ms intervals, and were later analyzed using diffraction peak profile analysis to determine the relative fraction of ferrite ({alpha}) and austenite ({gamma}) phases in each diffraction pattern. Lattice parameters and diffraction peak widths were also measured throughout the heating and cooling cycle of the weld, providing additional information about the phases that were formed. The experimental results were coupled with a thermofluid weld model to calculate the weld temperatures, allowing time-temperature transformation kinetics of the {alpha} {yields} {gamma} phase transformation to be evaluated. During heating, complete austenitization was observed in the heat affected zone of the weld and the kinetics of the {alpha} {yields} {gamma} phase transformation were modeled using a Johnson-Mehl-Avrami (JMA) approach. The results from the 1045 steel weld were compared to those of a 1005 low carbon steel from a previous study. Differences in austenitization rates of the two steels were attributed to differences in the base metal microstructures, particularly the relative amounts of pearlite and the extent of the allotriomorphic ferrite phase. During weld cooling, the austenite transformed to a mixture of bainite and martensite. In situ diffraction was able to distinguish between these two non-equilibrium phases based on differences in their lattice parameters and their transformation rates, resulting in the first real time x-ray diffraction observations of bainite and martensite formation made during welding.

  8. Crystal structures of eight mono-methyl alkanes (C26–C32) via single-crystal and powder diffraction and DFT-D optimization

    PubMed Central

    Brooks, Lee; Brunelli, Michela; Pattison, Philip; Jones, Graeme R.; Fitch, Andrew

    2015-01-01

    The crystal structures of eight mono-methyl alkanes have been determined from single-crystal or high-resolution powder X-ray diffraction using synchrotron radiation. Mono-methyl alkanes can be found on the cuticles of insects and are believed to act as recognition pheromones in some social species, e.g. ants, wasps etc. The molecules were synthesized as pure S enantiomers and are (S)-9-methylpentacosane, C26H54; (S)-9-methylheptacosane and (S)-11-methylheptacosane, C28H58; (S)-7-methylnonacosane, (S)-9-methylnonacosane, (S)-11-methylnonacosane and (S)-13-methylnonacosane, C30H62; and (S)-9-methylhentriacontane, C32H66. All crystallize in space group P21. Depending on the position of the methyl group on the carbon chain, two packing schemes are observed, in which the molecules pack together hexagonally as linear rods with terminal and side methyl groups clustering to form distinct motifs. Carbon-chain torsion angles deviate by less than 10° from the fully extended conformation, but with one packing form showing greater curvature than the other near the position of the methyl side group. The crystal structures are optimized by dispersion-corrected DFT calculations, because of the difficulties in refining accurate structural parameters from powder diffraction data from relatively poorly crystalline materials. PMID:26306191

  9. High temperature neutron powder diffraction study of the Cu12Sb4S13 and Cu4Sn7S16 phases

    NASA Astrophysics Data System (ADS)

    Lemoine, Pierric; Bourgès, Cédric; Barbier, Tristan; Nassif, Vivian; Cordier, Stéphane; Guilmeau, Emmanuel

    2017-03-01

    Ternary copper-containing sulfides Cu12Sb4S13 and Cu4Sn7S16 have attracted considerable interest since few years due to their high-efficiency conversion as absorbers for solar energy and promising thermoelectric materials. We report therein on the decomposition study of Cu12Sb4S13 and Cu4Sn7S16 phases using high temperature in situ neutron powder diffraction. Our results obtained at a heating rate of 2.5 K/min indicate that: (i) Cu12Sb4S13 decomposes above ≈792 K into Cu3SbS3, and (ii) Cu4Sn7S16 decomposes above ≈891 K into Sn2S3 and a copper-rich sulfide phase of sphalerite ZnS-type structure with an assumed Cu3SnS4 stoichiometry. Both phase decompositions are associated to a sulfur volatilization. While the results on Cu12Sb4S13 are in fair agreement with recent published data, the decomposition behavior of Cu4Sn7S16 differs from other studies in terms of decomposition temperature, thermal stability and products of reaction. Finally, the crystal structure refinements from neutron powder diffraction data are reported and discussed for the Cu4Sn7S16 and tetrahedrite Cu12Sb4S13 phases at 300 K, and for the high temperature form of skinnerite Cu3SbS3 at 843 K.

  10. Raman scattering and X-ray powder diffraction studies of hydrate layered perovskites: dirubidium aquapentafluoromanganate(III) and dipotassium aquapentafluoroferrate(III)

    SciTech Connect

    Galicka, Karolina; Slodczyk, Aneta; Ratuszna, Alicja; Daniel, Philippe; Malecki, Grzegorz

    2004-06-08

    The structural and vibrational properties of above mentioned crystals were determined using X-ray powder diffraction and Raman scattering experiments. At room temperature hydrate layered perovskites: Rb{sub 2}MnF{sub 5}{center_dot}H{sub 2}O and K{sub 2}FeF{sub 5}{center_dot}H{sub 2}O exhibit orthorhombic--Cmcm (D{sub 2h}{sup 17}) and monoclinic--C2/c (C{sub 2h}{sup 6}) symmetry. Their structure is built up of MnF{sub 6} or FeF{sub 5}{center_dot}H{sub 2}O octahedra forming trans-linked zig-zag chains or hydrogen bonded zig-zag chains along the major crystallographic direction [0 0 1], respectively. To confirm crystal structures and to describe lattice dynamics of these compounds the vibrational normal modes (in {gamma} point of first Brillouin zone) were calculated on the base of the group theory analysis and compared with the spectra obtained from Raman scattering experiments. A relatively good reliability was obtained for both X-ray powder diffraction and Raman scattering.

  11. 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.

  12. Structural properties of Pb{sub 3}Mn{sub 7}O{sub 15} determined from high-resolution synchrotron powder diffraction

    SciTech Connect

    Rasch, Julia C.E.; Sheptyakov, D.V.; Schefer, J.; Keller, L.; Boehm, M.; Gozzo, F.; Volkov, N.V.; Sablina, K.A.; Petrakovskii, G.A.; Grimmer, H.; Conder, K.; Loeffler, J.F.

    2009-05-15

    We report on the crystallographic structure of the layered compound Pb{sub 3}Mn{sub 7}O{sub 15}. Previous analysis based on laboratory X-ray data at room temperature gave contradictory results in terms of the description of the unit cell. Motivated by recent magnetic bulk measurements of this system [N.V. Volkov, K.A. Sablina, O.A. Bayukov, E.V. Eremin, G.A. Petrakovskii, D.A. Velikanov, A.D. Balaev, A.F. Bovina, P. Boni, E. Clementyev, J. Phys. Condens. Matter 20 (2008) 055217], we re-investigated the chemical structure with high-resolution synchrotron powder diffraction at temperatures between 15 and 295 K. Our results show that the crystal structure of stoichiometric Pb{sub 3}Mn{sub 7}O{sub 15} has a pronounced 2-dimensional character and can be described in the orthorhombic space group Pnma. - The crystal structure of Pb{sub 3}Mn{sub 7}O{sub 15} has been reinvestigated by synchrotron powder diffraction. The compound crystallizes in the orthorhombic space group Pnma and shows no structural transition between 15 and 295 K.

  13. High temperature phase stability in Li0.12Na0.88NbO3: A combined powder X-ray and neutron diffraction study

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Krishna, P. S. R.; Shinde, A. B.; Jayakrishnan, V. B.; Mittal, R.; Sastry, P. U.; Chaplot, S. L.

    2015-09-01

    The phase stabilities of ecofriendly piezoelectric material of lithium doped sodium niobate for composition Li0.12Na0.88NbO3 (LNN12) have been investigated by a combination of powder X-ray and neutron diffraction techniques in the temperature range of 300-1100 K. We observed interesting changes with appearance or disappearance of the super-lattice reflections in the powder diffraction patterns. Unambiguous experimental evidence is shown for coexistence of paraelectric and ferroelectric orthorhombic phases in the temperature range of 525 K to 675 K. We identified the correct crystal structure of LNN12 with temperature and correlated it with observed anomaly in the physical properties. Identification of crystal structure also helps in the mode assignments in Raman and infrared spectroscopies. We argued that application of chemical pressure as a result of Li substitution in NaNbO3 matrix favors the freezing of zone centre phonons in contrast to the freezing of zone boundary phonons in pure NaNbO3 with the variation of temperature.

  14. Structure Determination of Ca 3HfSi 2O 9 and Ca 3ZrSi 2O 9 from Powder Diffraction

    NASA Astrophysics Data System (ADS)

    Plaister, J. R.; Jansen, J.; de Graaff, R. A. G.; IJdo, D. J. W.

    1995-03-01

    The crystal structure of Ca 3HfSi 2O 9 has been determined from X-ray powder diffraction data using a recently developed software package in order to find individual intensities from overlapping reflections. The Hf atoms were found from the Patterson map, while Ca atoms were found in a subsequent heavy atom Fourier map. The other atoms were determined by trial and error using the Rietveld method. The atomic parameters for Ca 3ZrSi 2O 9 were determined from neutron powder diffraction data with the structure of Ca 3HfSi 2O 9 use as the trial model. Ca 3HfSi 2O 9, a = 7.3517(4)Å, b = 10.1489(11) Å, c = 10.4319(12)Å, β = 91.(184(7)°, P2 1/ c, and Z = 4; Ca 3ZrSi 2O 9, a = 7.3603(1)Å, b = 10.1766(3) Å, c = 10.4514(3) Å, β = 90.875(2)°, P2 1/ c, and Z = 4. The structure contains ribbons of edge-sharing octahedra parallel to [100]. The structure of these compounds is nearly the same as that of BeY 2O 4, substituting Si 2O groups for 2 Be and doubling the a-axis. The mineral cuspidine (Ca 4Si 2O 7(F,OH) 2) has a very similar structure as well.

  15. Rietveld Analysis of X-ray Powder Diffraction Patterns as a Potential Tool for the Identification of Impact-deformed Carbonate Rocks

    SciTech Connect

    Huson, Sarah A.; Foit, Franklin F.; Watkinson, A. J.; Pope, Michael C.

    2009-11-01

    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.

  16. Crystal structures of eight mono-methyl alkanes (C26-C32) via single-crystal and powder diffraction and DFT-D optimization.

    PubMed

    Brooks, Lee; Brunelli, Michela; Pattison, Philip; Jones, Graeme R; Fitch, Andrew

    2015-09-01

    The crystal structures of eight mono-methyl alkanes have been determined from single-crystal or high-resolution powder X-ray diffraction using synchrotron radiation. Mono-methyl alkanes can be found on the cuticles of insects and are believed to act as recognition pheromones in some social species, e.g. ants, wasps etc. The molecules were synthesized as pure S enantiomers and are (S)-9-methylpentacosane, C26H54; (S)-9-methylheptacosane and (S)-11-methylheptacosane, C28H58; (S)-7-methylnonacosane, (S)-9-methylnonacosane, (S)-11-methylnonacosane and (S)-13-methylnonacosane, C30H62; and (S)-9-methylhentriacontane, C32H66. All crystallize in space group P21. Depending on the position of the methyl group on the carbon chain, two packing schemes are observed, in which the molecules pack together hexagonally as linear rods with terminal and side methyl groups clustering to form distinct motifs. Carbon-chain torsion angles deviate by less than 10° from the fully extended conformation, but with one packing form showing greater curvature than the other near the position of the methyl side group. The crystal structures are optimized by dispersion-corrected DFT calculations, because of the difficulties in refining accurate structural parameters from powder diffraction data from relatively poorly crystalline materials.

  17. A combined solid-state NMR and synchrotron x-ray diffraction powder study on the structure of the antioxidant(+)-catechin 4.5 hydrate.

    SciTech Connect

    Harper, J. K.; Doebbler, J. A.; Jaccques, E.; Grant, D. M.; Von Dreele, R. B.; Univ. of Utah

    2010-03-10

    Analyses combining X-ray powder diffraction (XRD) and solid-state NMR (SSNMR) data can now provide crystal structures in challenging powders that are inaccessible by traditional methods. The flavonoid catechin is an ideal candidate for these methods, as it has eluded crystallographic characterization despite extensive study. Catechin was first described nearly two centuries ago, and its powders exhibit numerous levels of hydration. Here, synchrotron XRD data provide all heavy-atom positions in (+)-catechin 4.5-hydrate and establish the space group as C2. SSNMR data ({sup 13}C tensor and {sup 1}H/{sup 13}C correlation) complete the conformation by providing catechin's five OH hydrogen orientations. Since 1903, this phase has been erroneously identified as a 4.0 hydrate, but XRD and density data establish that this discrepancy is due to the facile loss of the water molecule located at a Wyckoff special position in the unit cell. A final improvement to heavy-atom positions is provided by a geometry optimization of bond lengths and valence angles with XRD torsion angles held constant. The structural enhancement in this final structure is confirmed by the significantly improved fit of computed {sup 13}C tensors to experimental data.

  18. Time- and angle-resolved x-ray diffraction to probe structural and chemical evolution during Al-Ni intermetallic reactions

    SciTech Connect

    Yoo, Choong-Shik; Wei, Haoyan; Chen, Jing-Yin; Shen, Guoyin; Chow, Paul; Xiao, Yuming

    2011-12-09

    We present novel time- and angle-resolved x-ray diffraction (TARXD) capable of probing structural and chemical evolutions during rapidly propagating exothermic intermetallic reactions between Ni-Al multilayers. The system utilizes monochromatic synchrotron x-rays and a two-dimensional (2D) pixel array x-ray detector in combination of a fast-rotating diffraction beam chopper, providing a time (in azimuth) and angle (in distance) resolved x-ray diffraction image continuously recorded at a time resolution of {approx}30 {micro}s over a time period of 3 ms. Multiple frames of the TARXD images can also be obtained with time resolutions between 30 and 300 {micro}s over three to several hundreds of milliseconds. The present method is coupled with a high-speed camera and a six-channel optical pyrometer to determine the reaction characteristics including the propagation speed of 7.6 m/s, adiabatic heating rate of 4.0 x 10{sup 6} K/s, and conductive cooling rate of 4.5 x 10{sup 4} K/s. These time-dependent structural and temperature data provide evidences for the rapid formation of intermetallic NiAl alloy within 45 {micro}s, thermal expansion coefficient of 1.1 x 10{sup -6} K for NiAl, and crystallization of V and Ag{sub 3}In in later time.

  19. Time- and angle-resolved x-ray diffraction to probe structural and chemical evolution during Al-Ni intermetallic reactions.

    PubMed

    Yoo, Choong-Shik; Wei, Haoyan; Chen, Jing-Yin; Shen, Guoyin; Chow, Paul; Xiao, Yuming

    2011-11-01

    We present novel time- and angle-resolved x-ray diffraction (TARXD) capable of probing structural and chemical evolutions during rapidly propagating exothermic intermetallic reactions between Ni-Al multilayers. The system utilizes monochromatic synchrotron x-rays and a two-dimensional (2D) pixel array x-ray detector in combination of a fast-rotating diffraction beam chopper, providing a time (in azimuth) and angle (in distance) resolved x-ray diffraction image continuously recorded at a time resolution of ~30 μs over a time period of 3 ms. Multiple frames of the TARXD images can also be obtained with time resolutions between 30 and 300 μs over three to several hundreds of milliseconds. The present method is coupled with a high-speed camera and a six-channel optical pyrometer to determine the reaction characteristics including the propagation speed of 7.6 m/s, adiabatic heating rate of 4.0 × 10(6) K/s, and conductive cooling rate of 4.5 × 10(4) K/s. These time-dependent structural and temperature data provide evidences for the rapid formation of intermetallic NiAl alloy within 45 μs, thermal expansion coefficient of 1.1 × 10(-6) K for NiAl, and crystallization of V and Ag(3)In in later time.

  20. Time-resolved x-ray diffraction experiments to examine the elastic-plastic transition in shocked magnesium-doped LiF

    NASA Astrophysics Data System (ADS)

    Jensen, B. J.; Gupta, Y. M.

    2008-07-01

    Time-resolved x-ray diffraction measurements were used to examine the lattice deformation during elastic-plastic deformation in Mg-doped (approximately 100 ppm) LiF single crystals shocked along [100]. The magnesium impurities significantly increase the elastic limit of the LiF crystals, as compared to the low values observed for ultrapure LiF crystals, leading to a large amplitude elastic wave and significant stress relaxation behind the elastic wave. The objective of the current work was to examine lattice deformation throughout this wave profile using time-resolved, x-ray diffraction methods (2 ns resolution) for plate impact experiments to gain insight into time-dependent, elastic-plastic deformation at the microscopic level. The diffraction data were analyzed using an x-ray model coupled to an existing wave propagation code that incorporated dislocation mechanisms for elastic-plastic deformation including stress relaxation. All experimental results revealed a uniaxial lattice compression at the elastic wave front followed by a rapid transition toward isotropic unit cell compression during stress relaxation. Furthermore, comparison between the experimental data and the calculated streak records indicated that the lattice transition proceeds at a faster rate than predicted by the model. Further implications of these results are discussed.

  1. Structure determination of homoleptic AuI, AgI, and CuI aryl/alkylethynyl coordination polymers by X-ray powder diffraction.

    PubMed

    Chui, Stephen S Y; Ng, Miro F Y; Che, Chi-Ming

    2005-03-04

    This article describes the structure determination of five homoleptic d(10) metal-aryl/alkylacetylides [RC triple bond CM] (M=Cu, R=tBu 1, nPr 2, Ph 3; R=Ph, M=Ag 4; Au 5) by using X-ray single-crystal and powder diffraction. Complex 1.C6H6 reveals an unusual Cu20 catenane cluster structure that has various types of tBuC triple bond C-->Cu coordination modes. By using this single-crystal structure as a starting model for subsequent Rietveld refinement of X-ray powder diffraction data, the structure of the powder synthesized from CuI and tBuC triple bond CH was found to have the same structure as 1. Complex 2 has an extended sheet structure consisting of discrete zig-zag Cu4 subunits connected through bridging nPrC triple bond C groups. Complex 3 forms an infinite chain structure with extended Cu-Cu ladders (Cu-Cu=2.49(4)-2.83(2) A). The silver(I) congener 4 is iso-structural to 3 (average Ag-Ag distance 3.11 A), whereas the gold(I) analogue 5 forms a Au...Au honeycomb network with PhC triple bond C pillars (Au-Au=2.98(1)-3.26(1) A). Solid-state properties including photoluminescence, nu(C triple bond C) stretching frequencies and thermal stability of these polymeric systems are discussed in the context of the determined structures.

  2. An in situ sample environment reaction cell for spatially resolved x-ray absorption spectroscopy studies of powders and small structured reactors

    SciTech Connect

    Zhang, Chu; Gustafson, Johan; Merte, Lindsay R.; Evertsson, Jonas; Norén, Katarina; Carlson, Stefan; Svensson, Håkan; Carlsson, Per-Anders

    2015-03-15

    An easy-to-use sample environment reaction cell for X-ray based in situ studies of powders and small structured samples, e.g., powder, pellet, and monolith catalysts, is described. The design of the cell allows for flexible use of appropriate X-ray transparent windows, shielding the sample from ambient conditions, such that incident X-ray energies as low as 3 keV can be used. Thus, in situ X-ray absorption spectroscopy (XAS) measurements in either transmission or fluorescence mode are facilitated. Total gas flows up to about 500 ml{sub n}/min can be fed while the sample temperature is accurately controlled (at least) in the range of 25–500 °C. The gas feed is composed by a versatile gas-mixing system and the effluent gas flow composition is monitored with mass spectrometry (MS). These systems are described briefly. Results from simultaneous XAS/MS measurements during oxidation of carbon monoxide over a 4% Pt/Al{sub 2}O{sub 3} powder catalyst are used to illustrate the system performance in terms of transmission XAS. Also, 2.2% Pd/Al{sub 2}O{sub 3} and 2% Ag − Al{sub 2}O{sub 3} powder catalysts have been used to demonstrate X-ray absorption near-edge structure (XANES) spectroscopy in fluorescence mode. Further, a 2% Pt/Al{sub 2}O{sub 3} monolith catalyst was used ex situ for transmission XANES. The reaction cell opens for facile studies of structure-function relationships for model as well as realistic catalysts both in the form of powders, small pellets, and coated or extruded monoliths at near realistic conditions. The applicability of the cell for X-ray diffraction measurements is discussed.

  3. Possibilities and limitations of synchrotron X-ray powder diffraction with double crystal and double multilayer monochromators for microscopic speciation studies

    NASA Astrophysics Data System (ADS)

    De Nolf, Wout; Jaroszewicz, Jakub; Terzano, Roberto; Lind, Ole Christian; Salbu, Brit; Vekemans, Bart; Janssens, Koen; Falkenberg, Gerald

    2009-08-01

    The performance of a combined microbeam X-ray fluorescence/X-ray powder diffraction (XRF/XRPD) measurement station at Hamburger Synchrotronstrahlungslabor (HASYLAB) Beamline L is discussed in comparison to that at European Synchrotron Radiation Facility (ESRF) ID18F/ID22. The angular resolution in the X-ray diffractograms is documented when different combinations of X-ray source, optics and X-ray diffraction detectors are employed. Typical angular resolution values in the range 0.3-0.5° are obtained at the bending magnet source when a 'pink' beam form of excitation is employed. A similar setup at European Synchrotron Radiation Facility beamlines ID18F and ID22 allows to reach angular resolution values of 0.1-0.15°. In order to document the possibilities and limitations for speciation of metals in environmental materials by means of Hamburger Synchrotronstrahlungslabor Beamline L X-ray fluorescence/X-ray powder diffraction setup, two case studies are discussed, one involved in the identification of the crystal phases in which heavy metals such as chromium, iron, barium and lead are present in polluted soils of an industrial site (Val Basento, Italy) and another involved in the speciation of uranium in depleted uranium particles (Ceja Mountains, Kosovo). In the former case, the angular resolution is sufficient to allow identification of most crystalline phases present while in the latter case, it is necessary to dispose of an angular resolution of ca. 0.2° to distinguish between different forms of oxidized uranium.

  4. In situ powder X-ray diffraction, synthesis, and magnetic properties of the defect zircon structure ScVO(4-x).

    PubMed

    Shafi, Shahid P; Kotyk, Matthew W; Cranswick, Lachlan M D; Michaelis, Vladimir K; Kroeker, Scott; Bieringer, Mario

    2009-11-16

    We report the formation pathway of ScVO(4) zircon from ScVO(3) bixbyite with emphasis on the synthesis and stability of the novel intermediate defect zircon phase ScVO(4-x) (0.0 < x powder X-ray diffraction. The oxidation of ScVO(3) to ScVO(4) involves two intermediates of composition ScVO(3.5+y) (0.00 powder X-ray diffraction, neutron diffraction, and bulk magnetic susceptibility data as well as (45)Sc and (51)V solid state NMR spectroscopy. ScVO(4-x) can only be obtained by oxidation of ScVO(3) or ScVO(3.5+y) while the reduction of ScVO(4) does not yield the novel defect structure. Mechanistic insights into the oxidative formation of ScVO(4) via the defect structure are presented.

  5. Structural Transitions in Nanosized Zn0.97Al0.03O Powders under High Pressure Analyzed by in Situ Angle-Dispersive X-ray Diffraction

    PubMed Central

    Lin, Chih-Ming; Liu, Hsin-Tzu; Zhong, Shi-Yao; Hsu, Chia-Hung; Chiu, Yi-Te; Tai, Ming-Fong; Juang, Jenh-Yih; Chuang, Yu-Chun; Liao, Yen-Fa

    2016-01-01

    Nanosized aluminum-doped zinc oxide Zn1−xAlxO (AZO) powders (AZO-NPs) with x = 0.01, 0.03, 0.06, 0.09 and 0.11 were synthesized by chemical precipitation method. The thermogravimetric analysis (TGA) indicated that the precursors were converted to oxides from hydroxides near 250 °C, which were then heated to 500 °C for subsequent thermal processes to obtain preliminary powders. The obtained preliminary powders were then calcined at 500 °C for three hours. The structure and morphology of the products were measured and characterized by angle-dispersive X-ray diffraction (ADXRD) and scanning electron microscopy (SEM). ADXRD results showed that AZO-NPs with Al content less than 11% exhibited würtzite zinc oxide structure and there was no other impurity phase in the AZO-NPs, suggesting substitutional doping of Al on Zn sites. The Zn0.97Al0.03O powders (A3ZO-NPs) with grain size of about 21.4 nm were used for high-pressure measurements. The in situ ADXRD measurements revealed that, for loading run, the pressure-induced würtzite (B4)-to-rocksalt (B1) structural phase transition began at 9.0(1) GPa. Compared to the predicted phase-transition pressure of ~12.7 GPa for pristine ZnO nanocrystals of similar grain size (~21.4 nm), the transition pressure for the present A3ZO-NPs exhibited a reduction of ~3.7 GPa. The significant reduction in phase-transition pressure is attributed to the effects of highly selective site occupation, namely Zn2+ and Al3+, were mainly found in tetrahedral and octahedral sites, respectively. PMID:28773683

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

    SciTech Connect

    Storm, Mie Møller 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 thermal 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.

  7. New large volume hydrothermal reaction cell for studying chemical processes under supercritical hydrothermal conditions using time-resolved in situ neutron diffraction.

    PubMed

    Ok, Kang Min; O'Hare, Dermot; Smith, Ronald I; Chowdhury, Mohammed; Fikremariam, Hanna

    2010-12-01

    The design and testing of a new large volume Inconel pressure cell for the in situ study of supercritical hydrothermal syntheses using time-resolved neutron diffraction is introduced for the first time. The commissioning of this new cell is demonstrated by the measurement of the time-of-flight neutron diffraction pattern for TiO(2) (Anatase) in supercritical D(2)O on the POLARIS diffractometer at the United Kingdom's pulsed spallation neutron source, ISIS, Rutherford Appleton Laboratory. The sample can be studied over a wide range of temperatures (25-450 °C) and pressures (1-355 bar). This novel apparatus will now enable us to study the kinetics and mechanisms of chemical syntheses under extreme environments such as supercritical water, and in particular to study the crystallization of a variety of technologically important inorganic materials.

  8. New large volume hydrothermal reaction cell for studying chemical processes under supercritical hydrothermal conditions using time-resolved in situ neutron diffraction

    NASA Astrophysics Data System (ADS)

    Ok, Kang Min; O'Hare, Dermot; Smith, Ronald I.; Chowdhury, Mohammed; Fikremariam, Hanna

    2010-12-01

    The design and testing of a new large volume Inconel pressure cell for the in situ study of supercritical hydrothermal syntheses using time-resolved neutron diffraction is introduced for the first time. The commissioning of this new cell is demonstrated by the measurement of the time-of-flight neutron diffraction pattern for TiO2 (Anatase) in supercritical D2O on the POLARIS diffractometer at the United Kingdom's pulsed spallation neutron source, ISIS, Rutherford Appleton Laboratory. The sample can be studied over a wide range of temperatures (25-450 °C) and pressures (1-355 bar). This novel apparatus will now enable us to study the kinetics and mechanisms of chemical syntheses under extreme environments such as supercritical water, and in particular to study the crystallization of a variety of technologically important inorganic materials.

  9. Time-resolved resonant soft x-ray diffraction with free-electron lasers: Femtosecond dynamics across the Verwey transition in magnetite

    SciTech Connect

    Pontius, N.; Kachel, T.; Schuessler-Langeheine, C.; Schlotter, W. F.; Beye, M.; Sorgenfrei, F.; Wurth, W.; Chang, C. F.; Foehlisch, A.; Berglund, M.; Metcalf, P.

    2011-05-02

    Resonant soft x-ray diffraction (RSXD) with femtosecond (fs) time resolution is a powerful tool for disentangling the interplay between different degrees of freedom in strongly correlated electron materials. It allows addressing the coupling of particular degrees of freedom upon an external selective perturbation, e.g., by an optical or infrared laser pulse. Here, we report a time-resolved RSXD experiment from the prototypical correlated electron material magnetite using soft x-ray pulses from the free-electron laser FLASH in Hamburg. We observe ultrafast melting of the charge-orbital order leading to the formation of a transient phase, which has not been observed in equilibrium.

  10. When combined X-ray and polarized neutron diffraction data challenge high-level calculations: spin-resolved electron density of an organic radical.

    PubMed

    Voufack, Ariste Bolivard; Claiser, Nicolas; Lecomte, Claude; Pillet, Sébastien; Pontillon, Yves; Gillon, Béatrice; Yan, Zeyin; Gillet, Jean Michel; Marazzi, Marco; Genoni, Alessandro; Souhassou, Mohamed

    2017-08-01

    Joint refinement of X-ray and polarized neutron diffraction data has been carried out in order to determine charge and spin density distributions simultaneously in the nitronyl nitroxide (NN) free radical Nit(SMe)Ph. For comparison purposes, density functional theory (DFT) and complete active-space self-consistent field (CASSCF) theoretical calculations were also performed. Experimentally derived charge and spin densities show significant differences between the two NO groups of the NN function that are not observed from DFT theoretical calculations. On the contrary, CASSCF calculations exhibit the same fine details as observed in spin-resolved joint refinement and a clear asymmetry between the two NO groups.

  11. X-ray diffraction study of W-B elemental powder mixtures after high-energy ball-milling.

    NASA Astrophysics Data System (ADS)

    Stubičar, Mirko; Tonejc, Antun; Stubičar, Nada

    Very high temperatures are needed to prepare W-B compounds. However, the results obtained in this study demonstrate a possibility of inducing the formation of W2B, WB or WB4 tungsten borides, in air and at room temperature, using the high-energy ball-mill treatment on appropriate compositions of the W-B elemental powder mixtures. The present results throw a new light on the synthesis of tungsten borides, and on the accuracy of the equilibrium W-B phase diagram.

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

    NASA Astrophysics Data System (ADS)

    Storm, Mie Møller; Johnsen, Rune E.; Norby, Poul

    2016-08-01

    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 thermal 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.

  13. In-situ high-pressure powder X-ray diffraction study of α-zirconium phosphate.

    PubMed

    Readman, Jennifer E; Lennie, Alistair; Hriljac, Joseph A

    2014-06-01

    The high-pressure structural chemistry of α-zirconium phosphate, α-Zr(HPO4)2·H2O, was studied using in-situ high-pressure diffraction and synchrotron radiation. The layered phosphate was studied under both hydrostatic and non-hydrostatic conditions and Rietveld refinement carried out on the resulting diffraction patterns. It was found that under hydrostatic conditions no uptake of additional water molecules from the pressure-transmitting medium occurred, contrary to what had previously been observed with some zeolite materials and a layered titanium phosphate. Under hydrostatic conditions the sample remained crystalline up to 10 GPa, but under non-hydrostatic conditions the sample amorphized between 7.3 and 9.5 GPa. The calculated bulk modulus, K0 = 15.2 GPa, showed the material to be very compressible with the weak linkages in the structure of the type Zr-O-P.

  14. A time resolved high energy X-ray diffraction study of cooling liquid SiO2.

    PubMed

    Skinner, L B; Benmore, C J; Weber, J K R; Wilding, M C; Tumber, S K; Parise, J B

    2013-06-14

    The evolution of the X-ray structure factor and corresponding pair distribution function of SiO2 has been measured upon cooling from the melt using high energy X-ray diffraction combined with aerodynamic levitation. Small changes in the position of the average Si-O bond distance and peak width are found to occur at ~1500(100) K in the region of the calorimetric glass transition temperature, T(g) and the observed density minima. At higher temperatures deviations from linear behavior are seen in the first sharp diffraction peak width, height and area at around 1750(50) K, which coincides with the reported density maximum around 1.2T(g).

  15. Time-Resolved Diffraction Profiles and Atomic Dynamics in Short-Pulse Laser-Induced Structural Transformations: Molecular Dynamics Study

    DTIC Science & Technology

    2006-05-16

    Touloukian , Thermophysical Properties of Matter, Vol. 4: Specific Heat: Metallic Elements and Alloys IFI/Plenum, New York, 1970. 31Y. S. Touloukian ...Thermophysical Properties of Matter, Vol. 12: Thermal Expansion: Metallic Elements and Alloys IFI/Plenum, New York, 1975. 32S. I. Anisimov and B...nm aluminum films irradiated with 120 fs laser pulses.11 The diffraction intensity over a range of scattering vectors was measured in this work

  16. Quadrupole lamp furnace for high temperature (up to 2050 K) synchrotron powder x-ray diffraction studies in air in reflection geometry

    SciTech Connect

    Sarin, P.; Yoon, W.; Jurkschat, K.; Zschack, P.; Kriven, W. M.

    2006-09-15

    A four-lamp thermal image furnace has been developed to conduct high temperature x-ray diffraction in reflection geometry on oxide ceramic powder samples in air at temperatures {<=}2050 K using synchrotron radiation. A refractory crucible made of Pt20%Rh alloy was used as a specimen holder. A material with well characterized lattice expansion properties was used as an internal crystallographic thermometer to determine the specimen temperature and displacement. The performance of the apparatus was verified by measurement of the thermal expansion properties of CeO{sub 2}, MgO, and Pt which were found to be within {+-}3% of the acceptable values. The advantages, limitations, and important considerations of the instrument developed are discussed.

  17. Polymorphism of ceramide 6: a vibrational spectroscopic and X-ray powder diffraction investigation of the diastereomers of N-(alpha-hydroxyoctadecanoyl)-phytosphingosine.

    PubMed

    Raudenkolb, Steve; Wartewig, Siegfried; Neubert, R H H

    2005-01-01

    A preparative chromatographic method was developed for the quantitative isolation of the diastereomers of synthetic N-(alpha-hydroxyoctadecanoyl)-phytosphingosine (DL-CER6). The L- and the D-compound were studied each by means X-ray powder diffraction, FT-Raman and FT-IR spectroscopy. The diastereomers exhibit different thermotropic polymorphism. Three lamellar crystalline and a lamellar liquid crystalline phase were found for L-CER6. The natural occurring D-CER6 forms an Lalpha phase with a larger repeating distance than the L-CER6. The two lamellar crystalline phases of the D-compound have a significant larger dimension than those of the L-compound. The addition of water lowers the phase transition temperatures but does not induce structural changes such as incorporation into the lamellar sheets.

  18. High pressure synthesis, structure solution and Rietveld refinement of polycrystalline (Ba,K)VS{sub 3} from x-ray powder diffraction data

    SciTech Connect

    Poulsen, N.J.

    1997-12-01

    The quasi-one-dimensional hexagonal perovskites BaVS{sub 3} and BaVSe{sub 3} are susceptible to doping under high pressure. At 3 GPa, 900 C, barium was replaced with potassium, and mixed chalcogenides BaV(Se,S){sub 3} were stabilized. X-ray powder diffraction revealed that the product from the high-pressure synthesis was dominated by strain. The potassium-rich samples swiftly absorbed water in humid air. Rietveld analysis and assumption of Vegard`s law indicated that selenium can replace sulfur in all ratios, whereas potassium only partially replaces barium. In this paper, the synthesis and Rietveld refinements results for the sulfides are reported.

  19. Hydrogen molecule binding to unsaturated metal sites in metal-organic frameworks studied by neutron powder diffraction and inelastic neutron scattering

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Brown, Craig; Neumann, Dan; Dinca, Mircea; Long, Jeffrey; Peterson, Vanessa; Kepert, Cameron

    2007-03-01

    Metal organic framework (MOF) materials have shown considerable potential for hydrogen storage arising from very large surface areas. However, the low binding energy of hydrogen molecules limits its storage capability to very low temperatures (< 77 K), which is impractical for industrial applications. Using neutron powder diffraction (NPD), we have characterized the hydrogen adsorption sites in a selected series of MOF materials with exposed unsaturated metal ions. Direct binding between the unsaturated metal ions and hydrogen molecules is observed and responsible for the enhanced initial hydrogen adsorption enthalpy. The different metals centers in these MOFs show different binding strength and interaction distances between the hydrogen molecule and metal ions. The organic linker also affects the overall H2 binding strength. Inelastic neutron scattering spectra of H2 in these MOFs are also discussed.

  20. Functional biocompatible magnetite-cellulose nanocomposite fibrous networks: Characterization by fourier transformed infrared spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy analysis

    NASA Astrophysics Data System (ADS)

    Habibi, Neda

    2015-02-01

    The preparation and characterization of functional biocompatible magnetite-cellulose nano-composite fibrous material is described. Magnetite-cellulose nano-composite was prepared by a combination of the solution-based formation of magnetic nano-particles and subsequent coating with amino celluloses. Characterization was accomplished using X-ray powder diffraction (XRD), fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. The peaks of Fe3O4 in the XRD pattern of nanocomposite confirm existence of the nanoparticles in the amino cellulose matrix. Magnetite-cellulose particles exhibit an average diameter of roughly 33 nm as demonstrated by field emission scanning electron microscopy. Magnetite nanoparticles were irregular spheres dispersed in the cellulose matrix. The vibration corresponding to the Nsbnd CH3 functional group about 2850 cm-1 is assigned in the FTIR spectra. Functionalized magnetite-cellulose nano-composite polymers have a potential range of application as targeted drug delivery system in biomedical field.

  1. Molecular and crystalline structures of three (S)-4-alkoxycarbonyl-2-azetidinones containing long alkyl side chains from synchrotron X-ray powder diffraction data.

    PubMed

    Seijas, Luis E; Mora, Asiloé J; Delgado, Gerzon E; López-Carrasquero, Francisco; Báez, María E; Brunelli, Michela; Fitch, Andrew N

    2009-12-01

    The (S)-4-alkoxo-2-azetidinecarboxylic acids are optically active beta-lactam derivatives of aspartic acid, which are used as precursors of carbapenem-type antibiotics and poly-beta-aspartates. The crystal structures of three (S)-4-alkoxo-2-azetidinecarboxylic acids with alkyl chains with 10, 12 and 16 C atoms were solved using parallel tempering and refined against the X-ray powder diffraction data using the Rietveld method. The azetidinone rings in the three compounds display a pattern of asymmetrical bond distances and an almost planar conformation; these characteristics are compared with periodic solid-state, gas-phase density-functional theory (DFT) calculations and MOGUL average bond distances and angles from the CSD. The compounds pack along [001] as corrugated sheets separated by approximately 4.40 A and connected by hydrogen bonds of the type N-H...O.

  2. Validation of missed space-group symmetry in X-ray powder diffraction structures with dispersion-corrected density functional theory.

    PubMed

    Hempler, Daniela; Schmidt, Martin U; van de Streek, Jacco

    2017-08-01

    More than 600 molecular crystal structures with correct, incorrect and uncertain space-group symmetry were energy-minimized with dispersion-corrected density functional theory (DFT-D, PBE-D3). For the purpose of determining the correct space-group symmetry the required tolerance on the atomic coordinates of all non-H atoms is established to be 0.2 Å. For 98.5% of 200 molecular crystal structures published with missed symmetry, the correct space group is identified; there are no false positives. Very small, very symmetrical molecules can end up in artificially high space groups upon energy minimization, although this is easily detected through visual inspection. If the space group of a crystal structure determined from powder diffraction data is ambiguous, energy minimization with DFT-D provides a fast and reliable method to select the correct space group.

  3. Phase transition of synthetic zinc ferrite spinel (ZnFe2O4) at high pressure, from synchrotron X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Levy, D.; Pavese, A.; Hanfland, M.

    Synthetic Zn-ferrite (ideally ZnFe2O4; mineral name: franklinite) was studied up to 37GPa, by X-ray powder diffraction at ESRF (Grenoble, France), on the ID9 beamline; high pressure was achieved by means of a DAC. The P-V equation of state of franklinite was investigated using the Birch-Murnaghan function, and the elastic properties thus inferred [K0=166.4(+/-3.0) GPa K0'=9.3(+/-0.6) K0''=-0.22GPa-1] are compared with earlier determinations for MgAl-spinel and magnetite. The structural behaviour of Zn-ferrite as a function of pressure was studied by Rietveld refinements, and interpreted in the light of a phase transition from spinel to either CaTi2O4- or MnFe2O4-like structure; this transformation occurs above 24GPa.

  4. Magnetic interactions in HoCr1-xFexO3 (x = 0, 0.2) investigated by neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Liu, Xinzhi; Hao, Lijie; Ma, Xiaobai; Wang, Chin-Wei; Klose, Frank; Liu, Yuntao; Sun, Kai; Li, Yuqing; Chen, Dongfeng

    2017-07-01

    The temperature dependent magnetism of Fe-doped rare earth orthochromite HoCr1-xFexO3(x = 0, 0.2) was investigated by neutron powder diffraction. It is found that the magnetism of Cr(Fe)3+ can be well understood within mean field theory, while the ordering of Ho3+ was induced by the Cr(Fe)3+ sublattice and can be satisfyingly described by an effective S = 1/2 model. The absences of both the most common GxFz configuration of Cr3+ and the ordering of Ho3+ caused by Ho-Ho interaction evidence a strong Ho3+-Cr3+ interaction which dominates this system. On the other hand, a remarkable magnetoelastic strain was observed accompanying the Cr(Fe)3+ ordering. An analysis based on the equation of state with a Grüneisen approximation was performed and revealed magnetic origin of this strain.

  5. Vacancy-induced nanoscale phase separation in KxFe2–ySe₂ single crystals evidenced by Raman scattering and powder x-ray diffraction

    DOE PAGES

    Lazarević, N.; Abeykoon, M.; Stephens, P. W.; ...

    2012-08-06

    Polarized Raman scattering spectra of KxFe2–ySe₂ were analyzed in terms of peculiarities of both I4/m and I4/mmm space group symmetries. The presence of the Raman active modes from both space group symmetries (16 Raman-active modes of the I4/m phase and two Raman-active modes of the I4/mmm phase) confirmed the existence of two crystallographic domains with different space group symmetry in a KxFe2–ySe₂ sample. High-resolution synchrotron powder x-ray diffraction structural refinement of the same sample confirmed the two-phase description, and determined the atomic positions and occupancies for both domains.

  6. Crystal structure of silica-ZSM-12 by the combined use of high-resolution solid-state MAS NMR spectroscopy and synchrotron x-ray powder diffraction

    SciTech Connect

    Fyfe, C.A.; Kokotailo, G.T. ); Gies, H.; Marler, B. ); Cox, D.E. )

    1990-05-03

    The crystal structure of the synthetic zeolite silica-ZSM-12, 56 SiO{sub 2}, has been solved by the combined use of high-resolution solid-state MAS NMR spectroscopy and high-resolution synchrotron X-ray powder diffraction ZSM-12 crystallizes in the monoclinic space group C2/c with a{sub 0} = 24.863 {angstrom}, b{sub 0} = 5.012 {angstrom}, c{sub 0} = 24.328 {angstrom}, and {beta} = 107.7{degree}. The zeolite host structure is built from corner-linked SiO{sub 4} tetrahedra to give a three-dimensional 4-connected net. The pores of the structure are one-dimensional channels that do not intersect, with 12-membered ring pore openings of approximately 5.6 {times} 7.7 {angstrom}. The structure of ZSM-12 is frequently twinned with (100) as the twin plane, which indicates a new zeolite structure type.

  7. Quadrupole lamp furnace for high temperature (up to 2050 K) synchrotron powder x-ray diffraction studies in air in reflection geometry.

    SciTech Connect

    Sarin, P.; Yoon, W.; Jurkschat, K.; Zschack, P.; Kriven, W. M.; Univ. of Illinois; Frederick-Seitz Materials Research Lab.

    2006-09-01

    A four-lamp thermal image furnace has been developed to conduct high temperature x-ray diffraction in reflection geometry on oxide ceramic powder samples in air at temperatures {le} 2050 K using synchrotron radiation. A refractory crucible made of Pt20%Rh alloy was used as a specimen holder. A material with well characterized lattice expansion properties was used as an internal crystallographic thermometer to determine the specimen temperature and displacement. The performance of the apparatus was verified by measurement of the thermal expansion properties of CeO{sub 2}, MgO, and Pt which were found to be within {+-} 3% of the acceptable values. The advantages, limitations, and important considerations of the instrument developed are discussed.

  8. Investigation by laser induced breakdown spectroscopy, X-ray fluorescence and X-ray powder diffraction of the chemical composition of white clay ceramic tiles from Veliki Preslav

    NASA Astrophysics Data System (ADS)

    Blagoev, K.; Grozeva, M.; Malcheva, G.; Neykova, S.

    2013-01-01

    The paper presents the results of the application of laser induced breakdown spectroscopy, X-ray fluorescence spectrometry, and X-ray powder diffraction in assessing the chemical and phase composition of white clay decorative ceramic tiles from the medieval archaeological site of Veliki Preslav, a Bulgarian capital in the period 893-972 AC, well-known for its original ceramic production. Numerous white clay ceramic tiles with highly varied decoration, produced for wall decoration of city's churches and palaces, were found during the archaeological excavations in the old capital. The examination of fourteen ceramic tiles discovered in one of the city's monasteries is aimed at characterization of the chemical profile of the white-clay decorative ceramics produced in Veliki Preslav. Combining different methods and comparing the obtained results provides complementary information regarding the white-clay ceramic production in Veliki Preslav and complete chemical characterization of the examined artefacts.

  9. Exploring the structural changes on excitation of a luminescent organic bromine-substituted complex by in-house time-resolved pump-probe diffraction

    PubMed Central

    Basuroy, Krishnayan; Chen, Yang; Sarkar, Sounak; Benedict, Jason; Coppens, Philip

    2017-01-01

    The structural changes accompanying the excitation of the luminescent dibromobenzene derivative, 1,4-dibromo-2,5-bis(octyloxy)benzene, have been measured by in-house monochromatic time-resolved (TR) diffraction at 90 K. Results show an increment of the very short intermolecular Br•••Br contact distance from 3.290 Å to 3.380 Å. Calculations show the Br…Br interaction to be strongly repulsive in both the Ground and Excited states but significantly relaxed by the lengthening of the contact distance on excitation. The stability of the crystals is attributed to the many weak C-H···Br and C-H···π intermolecular interactions. The study described is the first practical application of In-House Time-Resolved diffraction, made possible by the continuing increase in the brightness of X-ray sources and the sensitivity of our detectors. PMID:28382318

  10. Exploring the structural changes on excitation of a luminescent organic bromine-substituted complex by in-house time-resolved pump-probe diffraction

    DOE PAGES

    Basuroy, Krishnayan; Chen, Yang; Sarkar, Sounak; ...

    2017-03-09

    The structural changes accompanying the excitation of the luminescent dibromobenzene derivative, 1,4-dibromo-2,5-bis(octyloxy)benzene, have been measured by in-house monochromatic time-resolved (TR) diffraction at 90 K. Results show an increment of the very short intermolecular Br•••Br contact distance from 3.290 Å to 3.380 Å. These calculations show the Br…Br interaction to be strongly repulsive in both the Ground and Excited states but significantly relaxed by the lengthening of the contact distance on excitation. The stability of the crystals is attributed to the many weak C-H···Br and C-H···π intermolecular interactions. Our study described is the first practical application of In-House Time-Resolved diffraction, mademore » possible by the continuing increase in the brightness of X-ray sources and the sensitivity of our detectors.« less

  11. Maximum Entropy Method and Charge Flipping, a Powerful Combination to Visualize the True Nature of Structural Disorder from in situ X-ray Powder Diffraction Data

    SciTech Connect

    Samy, A.; Dinnebier, R; van Smaalen, S; Jansen, M

    2010-01-01

    In a systematic approach, the ability of the Maximum Entropy Method (MEM) to reconstruct the most probable electron density of highly disordered crystal structures from X-ray powder diffraction data was evaluated. As a case study, the ambient temperature crystal structures of disordered {alpha}-Rb{sub 2}[C{sub 2}O{sub 4}] and {alpha}-Rb{sub 2}[CO{sub 3}] and ordered {delta}-K{sub 2}[C{sub 2}O{sub 4}] were investigated in detail with the aim of revealing the 'true' nature of the apparent disorder. Different combinations of F (based on phased structure factors) and G constraints (based on structure-factor amplitudes) from different sources were applied in MEM calculations. In particular, a new combination of the MEM with the recently developed charge-flipping algorithm with histogram matching for powder diffraction data (pCF) was successfully introduced to avoid the inevitable bias of the phases of the structure-factor amplitudes by the Rietveld model. Completely ab initio electron-density distributions have been obtained with the MEM applied to a combination of structure-factor amplitudes from Le Bail fits with phases derived from pCF. All features of the crystal structures, in particular the disorder of the oxalate and carbonate anions, and the displacements of the cations, are clearly obtained. This approach bears the potential of a fast method of electron-density determination, even for highly disordered materials. All the MEM maps obtained in this work were compared with the MEM map derived from the best Rietveld refined model. In general, the phased observed structure factors obtained from Rietveld refinement (applying F and G constraints) were found to give the closest description of the experimental data and thus lead to the most accurate image of the actual disorder.

  12. Single-crystal X-ray and powder neutron diffraction of ThB 2C (ThB 2C-type)

    NASA Astrophysics Data System (ADS)

    Rogl, Peter; Fischer, Peter

    1989-02-01

    The crystal structure of ThB 2C was determined using single-crystal X-ray and powder neutron diffraction data. ThB 2C crystallizes in the rhombohedral space group R overline3m with a = 0.66761(23), c = 1.13760(31) nm, {c}/{a} = 1.704, V = 0.4391 nm 3, Z = 9 . X-ray intensity data were obtained from a four-circle diffractometer; the structure was solved by Patterson methods and refined by full-matrix least-squares calculation. R = {∑|ΔF|}/{∑|F o| } = 0.034 for an asymmetric set of 219 independent reflections (| Fo| > 2 σ( Fo)). Precise nonmetal atom parameters and bond distances have been derived from room-temperature neutron powder diffraction data employing the Rietveld-Young profile analysis method. The reliability value of the neutron refinement was RI = 0.067. The crystal structure of ThB 2C is a new structure type with slightly puckered 6 3-Th-metal layers alternating with nonmetal layers each composed of hexagons of boron atoms, the hexagons being linked by carbon atoms. Boron atoms are in a triangular prismatic metal surrounding of a tetrakaidekahedral coordination |Th 6B 2C 1|B, whereas carbon atoms occupy the center points of quadratic bipyramids |Th 4B 2|C. The crystal structure of ThB 2C derives from the AlB 2-type structure with carbon atoms entering the boron nets to form a 2∞ - (6B) · (6B(3C)) 2 layer.

  13. In situ x-ray and neutron powder diffraction study of LaNi5-xSnx-H systems

    NASA Technical Reports Server (NTRS)

    Bowman, Robert C., Jr.; Nakamara, Yumiko; Akiba, Etsuo

    2004-01-01

    This paper will present results of in situ XRD measurements of LaNi4.75Sn0.25 .during the initial absorption-desorption cycle, These measurements were performed under a similar condition to that for LaNi4.75Al0.25 previously reported [1]. The data were analyzed by the Rietveld method. Lattice parameter change and strain formation accompanying hydride phase formation and decomposition will be discussed. In addition, results of in situ neutron diffraction of LaNi4.78Sn0.22, focusing on hydrogen occupation in the hydride phase, will be presented.

  14. X-Ray Diffraction.

    ERIC Educational Resources Information Center

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  15. Revealing the powdering methods of black makeup in Ancient Egypt by fitting microstructure based Fourier coefficients to the whole x-ray diffraction profiles of galena

    NASA Astrophysics Data System (ADS)

    Ungár, T.; Martinetto, P.; Ribárik, G.; Dooryhée, E.; Walter, Ph.; Anne, M.

    2002-02-01

    Galena (PbS) is a major ingredient in ancient Egyptian eye makeup. The microstructure of PbS in Egyptian cosmetic powders is used as a fingerprint and is matched with the microstructures produced artificially in geological galena minerals. The microstructure of PbS is determined by x-ray diffraction peak profile analysis in terms of dislocation density, crystallite size, and size distribution. High-resolution powder diffractograms were measured at the ESRF Grenoble synchrotron source with high resolution and high peak-to-background ratios. The Fourier coefficients of the first nine measured reflections of galena are fitted using physically based Fourier coefficients of strain and size functions. Strain anisotropy is accounted for by the dislocation model of the mean square strain. The x-ray data are supplemented by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs, and are compared with archæological documents. It enables us to describe the procedures of eye makeup manufacturing in the Middle and New Kingdoms of Egypt some 2000 years before Christ.

  16. Evidence from x-ray and neutron powder diffraction patterns that the so-called icosahedral and decagonal quasicrystals of MnAl/sub 6/ and other alloys are twinned cubic crystals

    SciTech Connect

    Pauling, L.

    1987-06-01

    It is shown that the x-ray powder diffraction patterns of rapidly quenched MnAl/sub 6/ and Mg/sub 32/(Al,Zn)/sub 49/ and the neutron powder diffraction pattern of MnAl/sub 5/ are compatible with the proposed 820-atom primitive cubic structure. The values found for the edge of the unit cube are 23.365 A (x-ray) and 23.416 A (neutron) for MnAl/sub 6/ and 24.313 A (x-ray) for Mg/sub 32/(Al,Zn)/sub 49/.

  17. Time-resolved neutron diffraction investigation of the effect of hydrogen on the high- Tc superconductor YBa 2Cu 3O 7-δ

    NASA Astrophysics Data System (ADS)

    Balagurov, A. M.; Mironova, G. M.; Rudnickij, L. A.; Galkin, V. Ju.

    1990-12-01

    The results of a time-resolved neutron diffraction investigation of the interaction of hydrogen flow with the high- Tc superconductor YBa 2Cu 3O 7-δ are presented. The experiment was carried out on the TOF diffractometer DN-2 at the reactor IBR-2 in Dubna. Hydrogenation was performed on small pieces of 1-2-3 ceramics which were enclosed inside a quartz tube. The sample was heated up to 350°C at a constant rate of 5°C/min. Diffraction patterns were collected every 3 min within the dhkl-interval of 1-20 Å. Up to 220°C the refinement yielded the well-known orthorhombic phase of the 1-2-3 structure without any remarkable reduction of the ( b- a)/( a+ b) ratio. Below this temperature the only change in the specimen was a gradual increase of the incoherent background which occured even at room temperature. Once the temperature of 220°C was reached, sample degradation took place as evidence by precipitation of metallic copper, a drastic increase of background and widening of the diffraction peaks. Simultaneously, the occupancy of O(4)+ O(5) sites fell to 0.6. No evidence was found for the formation of a solid solution of hydrogen in 1-2-3 structure.

  18. In-situ Time-Resolved Neutron Diffraction Measurements of Microstructure Variations during Friction Stir Welding in a 6061-T6 Aluminum Alloy

    SciTech Connect

    Woo, Wan Chuck; Wang, Xun-Li; Ungar, Prof Tomas; Feng, Zhili; David, Stan A; Clausen, B; Hubbard, Camden R

    2008-01-01

    The microstructure change is one of the most important research areas in the friction stir welding (FSW). However, direct observation of microstructure changes during FSW has been extremely challenging because many measurement techniques are inapplicable. Recently developed in-situ time-resolved neutron diffraction methodology, which drastically improves the temporal resolution of neutron diffraction, enables to observe the transient microstructure changes during FSW. We installed a portable FSW system in the Spectrometer for MAterials Research at Temperature and Stress (SMARTS) at Los Alamos Neutron Science Center and the FSW was made on 6.35mm-thickness 6061-T6 Al alloy plate. At the same time, the neutron beam was centered on the mid-plane of the Al plate at 8 mm from the tool center (underneath the tool shoulder) and the diffraction peak was continuously measured during welding. The peak broadening analysis has been performed using the Williamson-Hall Method. The result shows that the dislocation density of about 3.2 x 10^15 m-2 duing FSW, which is the significant increse compared to the before (4.5 x 10^14 m-2) and after (4.0 x 10^14 m-2) the FSW. The quantitatively analysis of the grain structure can provide an insight to understand the transient variation of the microstructure during FSW.

  19. Anti-site mixing and magnetic properties of Fe3Co3Nb2 studied via neutron powder diffraction

    SciTech Connect

    Xu, Xiaoshan; Zhang, Xiaozhe; Yin, Yuewei; Balasubramanian, Balamurugan; Das, Bhaskar; Liu, Yaohua; Huq, Ashfia; Sellmyer, David

    2016-11-02

    Here, we studied the crystal structure and magnetic properties of the rare-earth-free intermetallic compound Fe3Co3Nb2, which has recently been demonstrated to have potentially high magnetic anisotropy, using temperature-dependent neutron powder diffraction. Furthermore, the temperature dependence of the diffraction spectra reveals a magnetic transition between 300 and 400 K, in agreement with the magnetometry measurements. According to the structural refinement of the paramagnetic state and the substantial magnetic contribution to the diffuse scattering in the ferromagnetic state, the Fe/Co anti-site mixing is so strong that the site occupation for Fe and Co is almost random. The projection of the magnetic moments turned out to be non-zero along the c axis and in the a–b plane of Fe3Co3Nb2, most likely because of the exchange interactions between the randomly orientated nanograins in the samples. These findings suggest that future studies on the magnetism of Fe3Co3Nb2 need to take the Fe/Co anti-site mixing into account, and the exchange interactions need to be suppressed to obtain large remanence and coercivity.

  20. Static and Dynamical Structural Investigations of Metal-Oxide Nanocrystals by Powder X-ray Diffraction: Colloidal Tungsten Oxide as a Case Study

    SciTech Connect

    Caliandro, Rocco; Sibillano, Teresa; Belviso, B. Danilo; Scarfiello, Riccardo; Dooryhee, Eric; Manca, Michele; Cozzoli, P. Davide

    2016-02-02

    In this study, we have developed a general X-ray powder diffraction (XPD) methodology for the simultaneous structural and compositional characterization of inorganic nanomaterials. The approach is validated on colloidal tungsten oxide nanocrystals (WO3-x NCs), as a model polymorphic nanoscale material system. Rod-shaped WO3-x NCs with different crystal structure and stoichiometry are comparatively investigated under an inert atmosphere and after prolonged air exposure. An initial structural model for the as-synthesized NCs is preliminarily identified by means of Rietveld analysis against several reference crystal phases, followed by atomic pair distribution function (PDF) refinement of the best-matching candidates (static analysis). Subtle stoichiometry deviations from the corresponding bulk standards are revealed. NCs exposed to air at room temperature are monitored by XPD measurements at scheduled time intervals. The static PDF analysis is complemented with an investigation into the evolution of the WO3-x NC structure, performed by applying the modulation enhanced diffraction technique to the whole time series of XPD profiles (dynamical analysis). Prolonged contact with ambient air is found to cause an appreciable increase in the static disorder of the O atoms in the WO3-x NC lattice, rather than a variation in stoichiometry. Finally, the time behavior of such structural change is identified on the basis of multivariate analysis.

  1. Synthesis, solid-state NMR, and X-ray powder diffraction characterization of group 12 coordination polymers, including the first example of a C-mercuriated pyrazole.

    PubMed

    Masciocchi, Norberto; Galli, Simona; Alberti, Enrica; Sironi, Angelo; Di Nicola, Corrado; Pettinari, Claudio; Pandolfo, Luciano

    2006-10-30

    Cadmium and mercury acetates have been reacted with pyrazole (Hpz) and 3,5-dimethylpyrazole (Hdmpz), affording distinct mixed-ligand species, selectively prepared upon slightly modifying the reaction conditions. Two polymorphs of [{Cd(mu-ac)2(Hpz)2}n], as well as the [{Cd(mu-ac)2(Hdmpz)2}n] species (Hac = acetic acid), were obtained by solution chemistry, while the two-dimensional [{Cd3(mu3-ac)4(mu-pz)2(Hpz)2}n] and [{Cd(mu-ac)(mu-pz)}n] polymers were prepared upon controlled thermal treatment of one of the [{Cd(mu-ac)2(Hpz)2}n] forms. Two mercury derivatives, [{Hg3(mu-ac)3(mu-pz)3}n] and [{Hg(ac)(mu-dmpz)}n], were also prepared, the latter containing one-dimensional chains of Hg(II) ions bridged by C-mercuriated Hdmpz ligands. All their crystal structures (but one) were determined by powder diffraction methods using conventional X-ray laboratory equipment, supported by 13C CPMAS NMR measurements. The latter method helped in assigning a C-metalated nature to an amorphous material of [Hg(ac)(pz)] formula, obtained by employing EtOH as a solvent. A few other Hdmpz-containing cadmium acetates were also prepared, but their polyphasic nature, evidenced by diffraction methods, hampered their complete structural characterization.

  2. Structure determination of the crystalline phase of n-butanol by powder X-ray diffraction and study of intermolecular associations by Raman spectroscopy.

    PubMed

    Derollez, Patrick; Hédoux, Alain; Guinet, Yannick; Danède, Florence; Paccou, Laurent

    2013-04-01

    X-ray powder diffraction patterns of n-butanol at 110 K and the isothermal transformation above the glass transition temperature of the supercooled liquid into the glacial state were recorded with a laboratory diffractometer. The starting structural model of the crystalline stable phase was found by a Monte-Carlo simulated annealing method. The final structure was obtained through Rietveld refinements with soft restraints on the interatomic bond lengths and angles. The cell is triclinic with space group P1 and contains two molecules. The width of the Bragg peaks is interpreted by a phenomenological microstructural approach in terms of anisotropic strain effects. The study of the hydrogen bonds by Raman spectroscopy shows the existence of two main kinds of hydrogen bonds in the crystal, in agreement with the structure obtained by diffraction. The glacial state resulting from an abortive crystallization is composed of microcrystallites of the stable phase coexisting with non-transformed supercooled liquid. Crystalline features of the glacial state were determined as closely connected to the microstructural description of the crystal, leading to information about the origin of the glacial state.

  3. Static and Dynamical Structural Investigations of Metal-Oxide Nanocrystals by Powder X-ray Diffraction: Colloidal Tungsten Oxide as a Case Study

    DOE PAGES

    Caliandro, Rocco; Sibillano, Teresa; Belviso, B. Danilo; ...

    2016-02-02

    In this study, we have developed a general X-ray powder diffraction (XPD) methodology for the simultaneous structural and compositional characterization of inorganic nanomaterials. The approach is validated on colloidal tungsten oxide nanocrystals (WO3-x NCs), as a model polymorphic nanoscale material system. Rod-shaped WO3-x NCs with different crystal structure and stoichiometry are comparatively investigated under an inert atmosphere and after prolonged air exposure. An initial structural model for the as-synthesized NCs is preliminarily identified by means of Rietveld analysis against several reference crystal phases, followed by atomic pair distribution function (PDF) refinement of the best-matching candidates (static analysis). Subtle stoichiometry deviationsmore » from the corresponding bulk standards are revealed. NCs exposed to air at room temperature are monitored by XPD measurements at scheduled time intervals. The static PDF analysis is complemented with an investigation into the evolution of the WO3-x NC structure, performed by applying the modulation enhanced diffraction technique to the whole time series of XPD profiles (dynamical analysis). Prolonged contact with ambient air is found to cause an appreciable increase in the static disorder of the O atoms in the WO3-x NC lattice, rather than a variation in stoichiometry. Finally, the time behavior of such structural change is identified on the basis of multivariate analysis.« less

  4. Static and Dynamical Structural Investigations of Metal-Oxide Nanocrystals by Powder X-ray Diffraction: Colloidal Tungsten Oxide as a Case Study.

    PubMed

    Caliandro, Rocco; Sibillano, Teresa; Belviso, B Danilo; Scarfiello, Riccardo; Hanson, Jonathan C; Dooryhee, Eric; Manca, Michele; Cozzoli, P Davide; Giannini, Cinzia

    2016-03-03

    We have developed a general X-ray powder diffraction (XPD) methodology for the simultaneous structural and compositional characterization of inorganic nanomaterials. The approach is validated on colloidal tungsten oxide nanocrystals (WO3-x NCs), as a model polymorphic nanoscale material system. Rod-shaped WO3-x NCs with different crystal structure and stoichiometry are comparatively investigated under an inert atmosphere and after prolonged air exposure. An initial structural model for the as-synthesized NCs is preliminarily identified by means of Rietveld analysis against several reference crystal phases, followed by atomic pair distribution function (PDF) refinement of the best-matching candidates (static analysis). Subtle stoichiometry deviations from the corresponding bulk standards are revealed. NCs exposed to air at room temperature are monitored by XPD measurements at scheduled time intervals. The static PDF analysis is complemented with an investigation into the evolution of the WO3-x NC structure, performed by applying the modulation enhanced diffraction technique to the whole time series of XPD profiles (dynamical analysis). Prolonged contact with ambient air is found to cause an appreciable increase in the static disorder of the O atoms in the WO3-x NC lattice, rather than a variation in stoichiometry. The time behavior of such structural change is identified on the basis of multivariate analysis.

  5. High-throughput and time-resolved energy-dispersive X-ray diffraction (EDXRD) study of the formation of CAU-1-(OH)2: microwave and conventional heating.

    PubMed

    Ahnfeldt, Tim; Moellmer, Jens; Guillerm, Vincent; Staudt, Reiner; Serre, Christian; Stock, Norbert

    2011-05-27

    Aluminium dihydroxyterephthalate [Al(8)(OH)(4)(OCH(3))(8)(BDC(OH)(2))(6)]⋅x H(2)O (denoted CAU-1-(OH)(2)) was synthesized under solvothermal conditions and characterized by X-ray powder diffraction, IR spectroscopy, sorption measurements, as well as thermogravimetric and elemental analysis. CAU-1-(OH)(2) is isoreticular to CAU-1 and its pores are lined with OH groups. It is stable under ambient conditions and in water, and it exhibits permanent porosity and two types of cavities with effective diameters of approximately 1 and 0.45 nm. The crystallization of CAU-1-(OH)(2) was studied by in situ energy-dispersive X-ray diffraction (EDXRD) experiments in the 120-145 °C temperature range. Two heating methods-conventional and microwave-were investigated. The latter leads to shorter induction periods as well as shorter reaction times. Whereas CAU-1-(OH)(2) is formed at all investigated temperatures using conventional heating, it is only observed below 130 °C using microwave heating. The calculation of the activation energy of the crystallization of CAU-1-(OH)(2) exhibits similar values for microwave and conventional synthesis. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Neutron powder diffraction study of the crystal and magnetic structures of BiNiO{sub 3} at low temperature

    SciTech Connect

    Carlsson, Sandra J.E.; Azuma, Masaki; Shimakawa, Yuichi; Takano, Mikio; Hewat, Alan; Attfield, J. Paul

    2008-03-15

    The crystal and magnetic structures of the charge ordered perovskite BiNiO{sub 3} have been studied at temperatures from 5 to 300 K using neutron diffraction. Rietveld analysis of the data shows that the structure remains triclinic (space group P1-bar) throughout the whole temperature range. Bond-valence sum calculations based on the Bi-O and Ni-O bond distances confirm that the charge distribution is Bi{sup 3+}{sub 0.5}Bi{sup 5+}{sub 0.5}Ni{sup 2+}O{sub 3} down to 5 K. The magnetic cell is identical to that of the triclinic superstructure and a G-type antiferromagnetic model gives a good fit to the magnetic intensities, with an ordered Ni{sup 2+} moment of 1.76(3) {mu}{sub B} at 5 K. However, BiNiO{sub 3} is ferrimagnetic due to the inexact cancellation of opposing, inequivalent moments in the low symmetry cell. - Graphical abstract: A neutron diffraction study shows that the perovskite BiNiO{sub 3} retains the unusual charge distribution Bi{sup 3+}{sub 0.5}Bi{sup 5+}{sub 0.5}Ni{sup 2+}O{sub 3} down to 5 K. The Ni{sup 2+} moments are ordered in the G-type antiferromagnetic arrangement shown; however, BiNiO{sub 3} is ferrimagnetic due to the inexact cancellation of the four inequivalent moments in the triclinic unit cell.

  7. Thermoelastic study of nanolayered structures using time-resolved X-ray diffraction at high repetition rate

    NASA Astrophysics Data System (ADS)

    Navirian, H. A.; Schick, D.; Gaal, P.; Leitenberger, W.; Shayduk, R.; Bargheer, M.

    2014-01-01

    We investigate the thermoelastic response of a nanolayered sample composed of a metallic SrRuO3 electrode sandwiched between a ferroelectric Pb(Zr0.2Ti0.8)O3 film with negative thermal expansion and a SrTiO3 substrate. SrRuO3 is rapidly heated by fs-laser pulses with 208 kHz repetition rate. Diffraction of X-ray pulses derived from a synchrotron measures the transient out-of-plane lattice constant c of all three materials simultaneously from 120 ps to 5 μs with a relative accuracy up to Δc/c = 10-6. The in-plane propagation of sound is essential for understanding the delayed out-of-plane compression of Pb(Zr0.2Ti0.8)O3.

  8. The Surprising Outburst Behavior of Z Canis Majoris, and Resolving the Alpha Oph Companion Near the Diffraction limit

    NASA Astrophysics Data System (ADS)

    Hinkley, Sasha; Pope, Benjamin; Martinache, Frantz; Hillenbrand, Lynne; Kraus, Adam L.; Ireland, Michael; Oppenheimer, Ben R.; Rice, Emily L.; Monnier, John D.; Tuthill, Peter; Latyshev, Alexey

    2015-01-01

    We present recent high resolution Palomar and Keck observations on two intriguing binary star systems: Z Canis Majoris and Alpha Ophiuchus. We have obtained near-infrared Keck and Palomar photometry and spectra for each component of the Z Canis Majoris system, a very young binary composed of an FU Ori object and a Herbig Ae/Be object. Our high angular resolution photometry of this very young (~1 Myr) binary conclusively determines that the outburst was due solely to the embedded Herbig Ae/Be member, supporting results from earlier works. Further, our high-resolution K-band spectra during a quiescent phase definitively demonstrate that the 2.294 micron CO absorption feature seen in composite spectra of the system is due solely to the FU Ori component, while a prominent CO emission feature at the same wavelength, long suspected to be associated with the innermost regions of a circumstellar accretion disk, can be assigned to the Herbig Ae/Be member. These findings greatly clarify previous analyses of the origin of the CO emission in this complex system. In a different study, we detected the faint companion to the star Alpha Ophiuchus using the Palomar 5m Hale Telescope Adaptive Optics system combined with kernel phase interferometry, a recently-developed post-processing technique for high contrast imaging. The technique of kernel phase interferometry has never before been used to detect faint companions to nearby stars using ground-based observations. Our Palomar observations detect the Alpha Oph companion passing near its periastron point with separation of only ~130 miliarcseconds, close to the Palomar infrared diffraction limit. Alpha Oph is a particularly important binary system with the primary star rotating close to its breakup velocity. Thus, establishing the host star mass with high precision through dynamical orbital analysis is extremely valuable. This technique holds great promise for detecting high contrast objects at, or just inside, the formal

  9. [Study on X-ray powder diffraction of various structured zinc titanate prepared by the method of direct precipitation].

    PubMed

    Guo, Jian; Wang, Zhi-hua; Tao, Dong-liang; Guo, Guang-sheng

    2007-05-01

    Zinc titanate powders were prepared from Ti(SO4)2, Zn(NO3)2 x (6)H2O and (NH4)2CO3 by the method of direct precipitation. The effects of reaction conditions on the structure of zinc titanate were studied. The sample was analyzed by means of XRD and TG-DTA. The structure of zinc titanate was affected by the reaction subsequence of the formation of titanic acid and zinc carbonate. In the reaction system where titanic acid was generated earlier, collision reaction occurred between the generated zinc carbonate molecule and the surrounding titanic acid molecule. When titanic acid was generated earlier and precipitant (NH4)2CO3 was sufficient, Zn2Ti3O8 was obtained because of the sufficient collision reaction and superfluous titanic acid. In the reaction system where zinc carbonate was generated earlier, collision reaction occurred between the generated titanic acid molecule and the surrounding zinc carbonate molecule. When zinc carbonate was generated earlier and precipitant (NH4)2CO3 was sufficient, Zn2TiO4 was obtained because of the sufficient collision reaction and superfluous zinc carbonate. In addition, the kinds and structure of the production were affected by the dosage of precipitant and the reaction temperature. Zn2Ti3O8 or Zn2TiO4 could be obtained easier when using more precipitant or higher reaction temperature which could cause more sufficient collision reaction. ZnTiO3 could be obtained under the conditions of less precipitant and lower reaction temperature.

  10. Quantitative phase analysis from powder diffraction using de Rietveld method in hydrogen storage alloys based on TiCr

    NASA Astrophysics Data System (ADS)

    Martinez, A.; Bellon, D.; Reina, L.

    2016-08-01

    Hydrogen storage is one of the important steps in the implementation of the hydrogen economy; metal hydrides are a promising way to achieve this goal. We present in this work the use of Rietveld analysis to characterize structurally TiCr-based alloys that are able to store hydrogen. TiCruV09, TiCrL1V0.45Nb0.45, TiCr1.1V0.2 Nb0.8, TiCr1.1Nb0.9 alloys were synthesized in an arc furnace under argon atmosphere. The analysis of phases was developed by X-Ray Diffraction (XRD) for further refinement of both the two lattice parameters and the percentage of the phases. Our results confirmed that a structure bcc, mostly combined with a small percentage of Laves phases, leads to obtain important properties in this area. Rietveld analysis was performed by the Fullprof program and this program allows us to obtain the different structural parameters.

  11. Local ordering of Jahn-Teller orbitals in LiNiO2 by neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Chung, Jae-Ho; Egami, Takeshi; Shamoto, Shin-Ichi; Proffen, Thomas; Ghorayeb, Andre

    2004-03-01

    The orbital state of LiNiO2 has been controversial, since there is no signature of long-range Jahn-Teller distortion, unlike NaNiO2 that shows ferromagnetic orbital order. We have neutron pair distribution function analysis to reveal important features, such as the local J-T distortion, the sharp oxygen-oxygen distance correlations, and unusual temperature dependence. These observations can be explained by a local ordering of Ni^3+ Jahn-Teller orbitals, where three neighboring 3d_z^2-r^2/3 orbitals share an oxygen site to form a trimer. Under this arrangement, it is expected that a medium-range elastic field will induce a curvature on NiO2 layers, which frustrates long-range order and is consistent with the systematic peak broadening observed in the neutron diffraction profiles. We propose that this local ordering is the basis for the complex magnetic properties observed in this material.

  12. Molecular Visualization of Methane - Carbon Dioxide Solid Solution in Gas Hydrates by High Resolution Neutron Powder Diffraction

    NASA Astrophysics Data System (ADS)

    Everett, M.; Rawn, C.; Huq, A.; Chakoumakos, B. C.; Phelps, T. J.

    2012-12-01

    The exchange of CO2 for CH4 in natural gas hydrates could produce energy from untapped sources while at the same time sequestering CO2. In addition to the energy and environmental aspects the solid solution of (CH4)1-x(CO2)x 5.75H2O provides a framework inclusion structure that enables the scientific study of how two molecules that differ greatly in their bonding, shape, coordination and molecular weight can influence the structure and properties of the compound and interact with the framework that occludes the molecules. Samples synthesized by cooling liquid water pressurized with either pure CH4 or CO2 or mixtures of the two gases to temperatures where hydrate formation occurs have been studied using high-resolution neutron diffraction. Static images of the nuclear scattering density of the free moving gas molecules have been determined. Cage occupants and occupancies, the volume change of the unit cell and the individual cages based on composition have been determined.

  13. Coherent femtosecond low-energy single-electron pulses for time-resolved diffraction and imaging: A numerical study

    SciTech Connect

    Paarmann, A.; Mueller, M.; Ernstorfer, R.; Gulde, M.; Schaefer, S.; Schweda, S.; Maiti, M.; Ropers, C.; Xu, C.; Hohage, T.; Schenk, F.

    2012-12-01

    We numerically investigate the properties of coherent femtosecond single electron wave packets photoemitted from nanotips in view of their application in ultrafast electron diffraction and non-destructive imaging with low-energy electrons. For two different geometries, we analyze the temporal and spatial broadening during propagation from the needle emitter to an anode, identifying the experimental parameters and challenges for realizing femtosecond time resolution. The simple tip-anode geometry is most versatile and allows for electron pulses of several ten of femtosecond duration using a very compact experimental design, however, providing very limited control over the electron beam collimation. A more sophisticated geometry comprising a suppressor-extractor electrostatic unit and a lens, similar to typical field emission electron microscope optics, is also investigated, allowing full control over the beam parameters. Using such a design, we find {approx}230 fs pulses feasible in a focused electron beam. The main limitation to achieve sub-hundred femtosecond time resolution is the typical size of such a device, and we suggest the implementation of more compact electron optics for optimal performance.

  14. Thermoelastic study of nanolayered structures using time-resolved X-ray diffraction at high repetition rate

    SciTech Connect

    Navirian, H. A.; Schick, D. Leitenberger, W.; Bargheer, M.; Gaal, P.; Shayduk, R.

    2014-01-13

    We investigate the thermoelastic response of a nanolayered sample composed of a metallic SrRuO{sub 3} electrode sandwiched between a ferroelectric Pb(Zr{sub 0.2}Ti{sub 0.8})O{sub 3} film with negative thermal expansion and a SrTiO{sub 3} substrate. SrRuO{sub 3} is rapidly heated by fs-laser pulses with 208 kHz repetition rate. Diffraction of X-ray pulses derived from a synchrotron measures the transient out-of-plane lattice constant c of all three materials simultaneously from 120 ps to 5 μs with a relative accuracy up to Δc/c = 10{sup −6}. The in-plane propagation of sound is essential for understanding the delayed out-of-plane compression of Pb(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}.

  15. Synthesis, structure, and catalytic properties of the layered oxide SbOReO[sub 4][center dot]2H[sub 2]O: Location of hydrogen-atom positions by powder neutron diffraction

    SciTech Connect

    Harrison, W.T.A. ); McManus, A.V.P. ); Kaminsky, M.P. ); Cheetham, A.K. )

    1993-11-01

    A new hydrated antimony rhenium oxide, SbOReO[sub 4][center dot]2H[sub 2]O, has been prepared by hydrothermal methods and fully characterized by powder neutron diffraction. The structure consists of double layers built up from infinite, interconnected arrays of [SbO[sup +

  16. Time-resolved x-ray diffraction and Raman studies of the phase transition mechanisms of methane hydrate

    SciTech Connect

    Hirai, Hisako Kadobayashi, Hirokazu; Hirao, Naohisa; Ohishi, Yasuo; Ohtake, Michika; Yamamoto, Yoshitaka; Nakano, Satoshi

    2015-01-14

    The mechanisms by which methane hydrate transforms from an sI to sH structure and from an sH to filled-ice Ih structure were examined using time-resolved X-ray diffractometry (XRD) and Raman spectroscopy in conjunction with charge-coupled device camera observation under fixed pressure conditions. The XRD data obtained for the sI–sH transition at 0.8 GPa revealed an inverse correlation between sI and sH, suggesting that the sI structure is replaced by sH. Meanwhile, the Raman analysis demonstrated that although the 12-hedra of sI are retained, the 14-hedra are replaced sequentially by additional 12-hedra, modified 12-hedra, and 20-hedra cages of sH. With the sH to filled-ice Ih transition at 1.8 GPa, both the XRD and Raman data showed that this occurs through a sudden collapse of the sH structure and subsequent release of solid and fluid methane that is gradually incorporated into the filled-ice Ih to complete its structure. This therefore represents a typical reconstructive transition mechanism.

  17. Thermal expansion of anatase and rutile between 300 and 575 K using synchrotron powder X-ray diffraction

    SciTech Connect

    Hummer,D.; Heaney, P.; Post, J.

    2007-01-01

    High-precision unit-cell parameters for the TiO2 polymorphs anatase and rutile at temperatures between 300 and 575 K have been determined using Rietveld analysis of synchrotron powder XRD data. Polynomial models were used to express the tetragonal unit-cell parameters as a function of absolute temperature, with a (anatase)=1.759 37x10-8xT2+6.418 16x10-6xT+3.779 84, c (anatase)=6.6545x10-8xT2+4.0464x10-5xT+9.4910, V (anatase)=2.237 58x10-6xT2+1.027 77x10-3xT+135.602, a (rutile)=-6.636 42x10-11xT3+1.005 01x10-7xT2-1.009 9310-5xT+4.586 34, c (rutile)=-4.115 50x10-11xT3+6.405 94x10-8xT2+4.675 61x10-7T+2.951 81, and V (rutile)=-2.7790x10-9xT3+4.2386x10-6xT2-3.3551x10-4xT+62.100. The polynomial expressions were used to calculate linear (alpha) and volume (beta) thermal expansion coefficients of anatase and rutile between 300 and 575 K. At 298.15 K, these values were alphaa=4.46943x10-6 K-1, alphac=8.4283x10-6 K-1, and beta=17.3542x10-6 K-1 for anatase, and alphaa=6.99953x10-6 K-1, alphac=9.36625x10-6 K-1, and beta=28.680x10-6 K-1 for rutile.

  18. Lattice-level observation of the elastic-to-plastic relaxation process with subnanosecond resolution in shock-compressed Ta using time-resolved in situ Laue diffraction

    DOE PAGES

    Wehrenberg, C. E.; Comley, A. J.; Barton, N. R.; ...

    2015-09-29

    We report direct lattice level measurements of plastic relaxation kinetics through time-resolved, in-situ Laue diffraction of shock-compressed single-crystal [001] Ta at pressures of 27-210 GPa. For a 50 GPa shock, a range of shear strains is observed extending up to the uniaxial limit for early data points (<0.6 ns) and the average shear strain relaxes to a near steady state over ~1 ns. For 80 and 125 GPa shocks, the measured shear strains are fully relaxed already at 200 ps, consistent with rapid relaxation associated with the predicted threshold for homogeneous nucleation of dislocations occurring at shock pressure ~65 GPa.more » The relaxation rate and shear stresses are used to estimate the dislocation density and these quantities are compared to the Livermore Multiscale Strength model as well as various molecular dynamics simulations.« less

  19. Communication: The formation of rarefaction waves in semiconductors after ultrashort excitation probed by grazing incidence ultrafast time-resolved x-ray diffraction

    PubMed Central

    Höfer, S.; Kämpfer, T.; Förster, E.; Stöhlker, T.; Uschmann, I.

    2016-01-01

    We explore the InSb-semiconductor lattice dynamics after excitation of high density electron-hole plasma with an ultrashort and intense laser pulse. By using time resolved x-ray diffraction, a sub-mÅ and sub-ps resolution was achieved. Thus, a strain of 4% was measured in a 3 nm thin surface layer 2 ps after excitation. The lattice strain was observed for the first 5 ps as exponentially decaying, changing rapidly by time and by depth. The observed phenomena can only be understood assuming nonlinear time dependent laser absorption where the absorption depth decreases by a factor of twenty compared to linear absorption. PMID:27704034

  20. The complementary nature of x-ray photoelectron spectroscopy and angle-resolved x-ray diffraction part II: Analysis of oxides on dental alloys

    NASA Astrophysics Data System (ADS)

    Kerber, S. J.; Barr, T. L.; Mann, G. P.; Brantley, W. A.; Papazoglou, E.; Mitchell, J. C.

    1998-06-01

    X-ray photoelectron spectroscopy (XPS) and angle-resolved x-ray diffraction (ARXRD) were used to analyze the oxide layer on three palladium-gallium-based dental casting alloys. The oxide layers were approximately 10 Μm thick. The use of the techniques helped to determine which mechanism was responsible for oxide formation—either (a) oxide layer growth via diffusion of oxygen through the scale to the metal, causing the scale to grow at the metal-oxide interface, or (b) an oxide layer formed by metal ions diffusing through the scale to the surface and reacting with oxygen, causing the scale to grow at the oxide-air interface. The oxide growth mechanisms were correlated to previous layer adhesion results determined with biaxial flexure testing.

  1. Ultrafast Formation of a Charge Density Wave State in 1 T -TaS2 : Observation at Nanometer Scales Using Time-Resolved X-Ray Diffraction

    NASA Astrophysics Data System (ADS)

    Laulhé, C.; Huber, T.; Lantz, G.; Ferrer, A.; Mariager, S. O.; Grübel, S.; Rittmann, J.; Johnson, J. A.; Esposito, V.; Lübcke, A.; Huber, L.; Kubli, M.; Savoini, M.; Jacques, V. L. R.; Cario, L.; Corraze, B.; Janod, E.; Ingold, G.; Beaud, P.; Johnson, S. L.; Ravy, S.

    2017-06-01

    Femtosecond time-resolved x-ray diffraction is used to study a photoinduced phase transition between two charge density wave (CDW) states in 1 T -TaS2 , namely the nearly commensurate (NC) and the incommensurate (I) CDW states. Structural modulations associated with the NC-CDW order are found to disappear within 400 fs. The photoinduced I-CDW phase then develops through a nucleation and growth process which ends 100 ps after laser excitation. We demonstrate that the newly formed I-CDW phase is fragmented into several nanometric domains that are growing through a coarsening process. The coarsening dynamics is found to follow the universal Lifshitz-Allen-Cahn growth law, which describes the ordering kinetics in systems exhibiting a nonconservative order parameter.

  2. Revisited: Decomposition or melting? Formation mechanism investigation of LiCoO2 via in-situ time-resolved X-ray diffraction.

    PubMed

    Wicker, Scott A; Walker, Edwin H

    2013-02-18

    We report the first in-situ time-resolved X-ray diffraction investigation in conjunction with a non-isothermal kinetic study using the model-free isoconversional kinetic method to determine the formation mechanism for the solid-state synthesis of electrochemically active LiCoO(2) from Li(2)CO(3) and Co(3)O(4). Detailed information on the phase evolution as well as thermal events during the heating process was clearly observed, explained, and supported. This investigation provides structural as well as kinetic evidence for a multistep reaction and proposes the first plausible formation mechanism for the solid-state synthesis of LiCoO(2).

  3. Ultrafast Formation of a Charge Density Wave State in 1T-TaS_{2}: Observation at Nanometer Scales Using Time-Resolved X-Ray Diffraction.

    PubMed

    Laulhé, C; Huber, T; Lantz, G; Ferrer, A; Mariager, S O; Grübel, S; Rittmann, J; Johnson, J A; Esposito, V; Lübcke, A; Huber, L; Kubli, M; Savoini, M; Jacques, V L R; Cario, L; Corraze, B; Janod, E; Ingold, G; Beaud, P; Johnson, S L; Ravy, S

    2017-06-16

    Femtosecond time-resolved x-ray diffraction is used to study a photoinduced phase transition between two charge density wave (CDW) states in 1T-TaS_{2}, namely the nearly commensurate (NC) and the incommensurate (I) CDW states. Structural modulations associated with the NC-CDW order are found to disappear within 400 fs. The photoinduced I-CDW phase then develops through a nucleation and growth process which ends 100 ps after laser excitation. We demonstrate that the newly formed I-CDW phase is fragmented into several nanometric domains that are growing through a coarsening process. The coarsening dynamics is found to follow the universal Lifshitz-Allen-Cahn growth law, which describes the ordering kinetics in systems exhibiting a nonconservative order parameter.

  4. Reversible phase transition in laser-shocked 3Y-TZP ceramics observed via nanosecond time-resolved x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Hu, Jianbo; Ichiyanagi, Kouhei; Takahashi, Hiroshi; Koguchi, Hiroaki; Akasaka, Takeaki; Kawai, Nobuaki; Nozawa, Shunsuke; Sato, Tokushi; Sasaki, Yuji C.; Adachi, Shin-ichi; Nakamura, Kazutaka G.

    2012-03-01

    The high-pressure phase stability of the metastable tetragonal zirconia is still under debate. The transition dynamics of shocked Y2O3 (3 mol. %) stabilized tetragonal zirconia ceramics under laser-shock compression has been directly studied using nanosecond time-resolved x-ray diffraction. The martensitic phase transformation to the monoclinic phase, which is the stable phase for pure zirconia at ambient pressure and room temperature, has been observed during compression at 5 GPa within 20 ns without any intermediates. This monoclinic phase reverts back to the tetragonal phase during pressure release. The results imply that the stabilization effect due to the addition of Y2O3 is to some extent negated by the shear stress under compression.

  5. Evolution of polytypism in GaAs nanowires during growth revealed by time-resolved in situ x-ray diffraction.

    PubMed

    Schroth, Philipp; Köhl, Martin; Hornung, Jean-Wolfgang; Dimakis, Emmanouil; Somaschini, Claudio; Geelhaar, Lutz; Biermanns, Andreas; Bauer, Sondes; Lazarev, Sergey; Pietsch, Ullrich; Baumbach, Tilo

    2015-02-06

    In III-V nanowires the energetic barriers for nucleation in the zinc blende or wurtzite arrangement are typically of a similar order of magnitude. As a result, both arrangements can occur in a single wire. Here, we investigate the evolution of this polytypism in self-catalyzed GaAs nanowires on Si(111) grown by molecular beam epitaxy with time-resolved in situ x-ray diffraction. We interpret our data in the framework of a height dependent Markov model for the stacking in the nanowires. In this way, we extract the mean sizes of faultless wurtzite and zinc blende segments-a key parameter of polytypic nanowires-and their temporal evolution during growth. Thereby, we infer quantitative information on the differences of the nucleation barriers including their evolution without requiring a model of the nucleus.

  6. Development of a fast pixel array detector for use in microsecond time-resolved x-ray diffraction

    SciTech Connect

    Barna, S.L.; Gruner, S.M.; Shepherd, J.A.

    1995-08-01

    A large-area pixel x-ray detector is being developed to collect eight successive frames of wide dynamic range two-dimensional images at 200kHz rates. Such a detector, in conjunction with a synchrotron radiation x-ray source, will enable time-resolved x-ray studies of proteins and other materials on time scales which have previously been inaccessible. The detector will consist of an array of fully-depleted 150 micron square diodes connected to a CMOS integrated electronics layer with solder bump-bonding. During each framing period, the current resulting from the x-rays stopped in the diodes is integrated in the electronics layer, and then stored in one of eight storage capacitors underneath the pixel. After the last frame, the capacitors are read out at standard data transmission rates. The detector has been designed for a well-depth of at least 10,000 x-rays (at 20keV), and a noise level of one x-ray. Ultimately, the authors intend to construct a detector with over one million pixels (1024 by 1024). They present the results of their development effort and various features of the design. The electronics design is discussed, with special attention to the performance requirements. The choice and design of the detective diodes, as they relate to x-ray stopping power and charge collection, are presented. An analysis of various methods of bump bonding is also presented. Finally, the authors discuss the possible need for a radiation-blocking layer, to be placed between the electronics and the detective layer, and various methods they have pursued in the construction of such a layer.

  7. Characterisation of the UFXC32k hybrid pixel detector for time-resolved pump-probe diffraction experiments at Synchrotron SOLEIL

    NASA Astrophysics Data System (ADS)

    Dawiec, A.; Maj, P.; Ciavardini, A.; Gryboś, P.; Laulhé, C.; Menneglier, C.; Szczygieł, R.

    2017-03-01

    The experimental set-up for time-resolved studies of ultra-fast photo-induced structural dynamics at the Synchrotron SOLEIL is based on a general pump-probe scheme that has been developed and implemented on the CRISTAL hard X-ray diffraction beamline [1,2]. In a so-called pump-probe cycle, the sample is excited with an ultra-short laser pulse of ≈40 fs duration (the pump), and induced changes in its atomic structure are studied by measuring, with a precisely controlled delay, a diffraction pattern from a single pulse of synchrotron radiation (the probe) with a 2-D pixel detector. An improvement to the classical scheme is proposed, where the sample's response is probed at two different delays after each laser excitation. The first measurement at short delays allows studying the photo-induced dynamics. The second one is a reference measurement taken after sample's relaxation, which permits detection of drifts in the experimental conditions (e.g. beam misalignment, sample degradation). A hybrid pixel detector with a very fast readout time, a high dynamic range and extended linearity was tested to achieve the experiment objectives. In this paper, the first results obtained with the UFXC32k single photon counting detector are presented.

  8. Electric-field-induced lattice distortion in epitaxial BiFeO3 thin films as determined by in situ time-resolved x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Nakashima, Seiji; Sakata, Osami; Funakubo, Hiroshi; Shimizu, Takao; Ichinose, Daichi; Takayama, Kota; Imai, Yasuhiko; Fujisawa, Hironori; Shimizu, Masaru

    2017-08-01

    Time-resolved X-ray diffraction (XRD) with synchrotron radiation while applying continuous voltage pulses was employed to investigate the electric-field-induced lattice distortion of an epitaxial BiFeO3 (BFO) thin film in a Pt/BFO (1 μm)/SrRuO3 (50 nm)/vicinal SrTiO3 (001) structure. XRD-reciprocal space maps based on the BFO 003, 114, and 1 1 ¯ 4 diffraction spots with and without the application of +15 V (150 kV/cm) to the capacitor demonstrated simultaneous electric-field-induced lattice distortion and crystallographic rotation in the BFO thin film. In response to the application of +15 V, the BFO lattice elongated by 0.08% along the [001]BFO direction and compressed by 0.05% along the [110]BFO direction. In addition, the BFO crystals were rotated by 0.01° along the [ 1 ¯1 ¯ 0]STO direction as a result of electric-field-induced lattice distortion under epitaxial strain along the vertical direction at the step edges of the vicinal substrate.

  9. Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

    SciTech Connect

    Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J.; Jung, II Woong; Walko, Donald A.; Dufresne, Eric M.; Jaewoo, Jeong; Samant, Mahesh G.; Parkin, Stuart S. P.; Freeland, John W.; Evans, Paul G.; Wen, Haidan

    2016-02-26

    Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase seperated regions. The ability to simultanousely track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of- the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, which is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. Lastly, the direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.

  10. H2 Production Through the Water-gas Shift Reaction: An In situ Time-resolved X-ray Diffraction Investigation of Manganese OMS-2 Catalyst

    SciTech Connect

    Hanson, J.C.; Sithambaram, S.; Wen, W.; Njagi, E.; Shen, X.-F.; Suib, S.L.

    2010-10-01

    Manganese oxide octahedral molecular sieve (OMS-2) catalyst prepared by the reflux method was investigated for hydrogen generation via the water-gas shift reaction. Catalysts were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), The Brunauer-Emmett-Teller (BET) surface area and determination of average oxidation state (AOS). The OMS-2 catalyst showed very good catalytic activity for the water-gas shift reaction to generate hydrogen under laboratory conditions. An in situ study was conducted to monitor the structural changes in the catalyst during the water-gas shift reaction using synchrotron radiation-based time-resolved X-ray diffraction (TR-XRD). During the water-gas shift reaction, the mixed valent OMS-2 catalyst undergoes a structural transformation to form Mn{sub 2}O{sub 3} and finally to form MnO. The study showed that OMS-2 catalysts can be used as inexpensive catalysts for hydrogen generation.

  11. H2 production Through the Water-gas Shift Reaction: An in Situ Time-resolved X-ray Diffraction Investigation of Manganese OMS-2 Catalyst

    SciTech Connect

    Sithambaram, S.; Wen, W; Njagi, E; Shen, X; Hanson, J; Suib, S

    2010-01-01

    Manganese oxide octahedral molecular sieve (OMS-2) catalyst prepared by the reflux method was investigated for hydrogen generation via the water-gas shift reaction. Catalysts were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), The Brunauer-Emmett-Teller (BET) surface area and determination of average oxidation state (AOS). The OMS-2 catalyst showed very good catalytic activity for the water-gas shift reaction to generate hydrogen under laboratory conditions. An in situ study was conducted to monitor the structural changes in the catalyst during the water-gas shift reaction using synchrotron radiation-based time-resolved X-ray diffraction (TR-XRD). During the water-gas shift reaction, the mixed valent OMS-2 catalyst undergoes a structural transformation to form Mn{sub 2}O{sub 3} and finally to form MnO. The study showed that OMS-2 catalysts can be used as inexpensive catalysts for hydrogen generation.

  12. Time-resolved changes in equatorial x-ray diffraction and stiffness during rise of tetanic tension in intact length-clamped single muscle fibers.

    PubMed

    Cecchi, G; Griffiths, P J; Bagni, M A; Ashley, C C; Maeda, Y

    1991-06-01

    We report the first time-resolved x-ray diffraction studies on tetanized intact single muscle fibers of the frog. The 10, 11, 20, 21, 30, and Z equatorial reflections were clearly resolved in the relaxed fiber. The preparation readily withstood 100 1-s duration (0.4-s beam exposure) tetani at 4 degrees C (less than 4% decline of force and no deterioration in the 10, 11 equatorial intensity ratio at rest or during activation). Equatorial intensity changes (10 and 11) and fiber stiffness led tension (t1/2 lead 20 ms at 4 degrees C) during the tetanus rise and lagged during the isometric phase of relaxation. These findings support the existence of a low force cross-bridge state during the rise of tetanic tension and isometric relaxation that is not evident at the tetanus plateau. In "fixed end" tetani lattice expansion occurred with a time course similar to stiffness during the tetanus rise. During relaxation, lattice spacing increased slightly, while the sarcomere length remained isometric, but underwent large changes after the "shoulder" of tension. Under length clamp control, lattice expansion during the tetanus rise was reduced or abolished, and compression (2%) of the lattice was observed. A lattice compression is predicted by certain cross-bridge models of force generation (Schoenberg, M. 1980. Biophys. J. 30:51-68; Schoenberg, M. 1980. Biophys. J. 30:69-78).

  13. Direct measurement of critical resolved shear stress of prismatic and basal slip in polycrystalline Ti using high energy X-ray diffraction microscopy

    DOE PAGES

    Wang, L.; Zheng, Z.; Phukan, H.; ...

    2017-05-07

    Knowledge of the critical resolved shear stress (CRSS) values of different slip modes is important for accurately modeling plastic deformation of hexagonal materials. Here, we demonstrate that CRSS can be directly measured with an in-situ high energy X-ray diffraction microscopy (HEDM) experiment. A commercially pure Ti tensile specimen was deformed up to 2.6% strain. In-situ far-field HEDM experiments were carried out to track the evolution of crystallographic orientations, centers of masses, and stress states of 1153 grains in a material volume of 1.1mm×1mm×1mm. Predominant prismatic slip was identified in 18 grains, where the orientation change occurred primarily by rotation aroundmore » the c-axis during specimen deformation. By analyzing the resolved shear stress on individual slip systems, the estimated CRSS for prismatic slip is 96±18 MPa. Predominant basal slip was identified in 22 other grains, where the 2 orientation change occurred primarily by tilting the c-axis about an axis in the basal plane. The estimated CRSS for basal slip is 127±33 MPa. The ratio of CRSSbasal/CRSSprismatic is in the range of 1.7-2.1. From indirect assessment, the CRSS for pyramidal < c+a > slip is likely greater than 240MPa. Lastly, grain size and free surface effects on the CRSS value in different grains are also examined.« less

  14. Neutron powder diffraction study of Pb 2Sr 2YCu 3O 8, the prototype of a new family of superconductors

    NASA Astrophysics Data System (ADS)

    Cava, R. J.; Marezio, M.; Krajewski, J. J.; Peck, W. F.; Santoro, A.; Beech, F.

    1989-02-01

    The structure of Pb 2Sr 2YCu 3O 8 has been analyzed with powder neutron diffraction techniques and profile analysis. The results of this study confirm the general structural features determined by X-ray single-crystal methods. The material has pseudo tetragonal symmetry, but is orthorhombic, space group Cmmm with lattice parameters a=5.3933(2), b=5.4311(2), and c=15.7334(6)Å. The orthorhombic distortion is caused by the disordering in the ab plane of the oxygen atoms of the PbO layers over the general position of the space group, with x=0.275(5) and y=0.402(5) Å. The structure of this compound can be derived from that of YBa 2Cu 3O 6 by substituting the Cu layers with blocks of … PbO.Cu.PbO… . Of the two Cu atoms in the asymmetric unit, one has two fold coordination while the other has five fold pyramidal coordination with the apex elongated along the c-axis.

  15. Operando Synchrotron X-ray Powder Diffraction and Modulated-Excitation Infrared Spectroscopy Elucidate the CO2 Promotion on a Commercial Methanol Synthesis Catalyst.

    PubMed

    Martin, Oliver; Mondelli, Cecilia; Cervellino, Antonio; Ferri, Davide; Curulla-Ferré, Daniel; Pérez-Ramírez, Javier

    2016-09-05

    Optimal amounts of CO2 are added to syngas to boost the methanol synthesis rate on Cu-ZnO-Al2 O3 in the industrial process. The reason for CO2 promotion is not sufficiently understood at the particle level due to the catalyst complexity and the high demands of characterization under true reaction conditions. Herein, we applied operando synchrotron X-ray powder diffraction and modulated-excitation infrared spectroscopy on a commercial catalyst to gain insights into its morphology and surface chemistry. These studies unveiled that Cu and ZnO agglomerate and ZnO particles flatten under CO/H2 and/or CO2 /H2 . Under the optimal CO/CO2 /H2 mixture, sintering is prevented and ZnO crystals adopt an elongated shape due to the minimal presence of the H2 O byproduct, enhancing the water-gas shift activity and thus the methanol production. Our results provide a rationale to the CO2 promotion emphasizing the importance of advanced analytical methods to establish structure-performance relations in heterogeneous catalysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Characterization by X-Ray Absorption, X-Ray Powder Diffraction, and Magnetic Susceptibility of Cu Zn Co Al Containing Hydroxycarbonates, Oxycarbonates, Oxides, and Their Products of Reduction

    NASA Astrophysics Data System (ADS)

    Porta, Piero; Morpurgo, Simone; Pettiti, Ida

    1996-02-01

    Copper-zinc-cobalt-aluminium-containing crystalline hydroxycarbonates having hydrotalcite structure have been prepared by coprecipitation. X-ray powder diffraction (XRPD), magnetic susceptibility, and extended X-ray absorption fine structure (EXAFS) indicate that Cu2+, Zn2+, and Co2+are present in an octahedral environment. Calcination of the hydroxycarbonates at 723 K produces quasi-amorphous oxycarbonates where Cu2+and Co2+still retain octahedral coordination and cobalt is almost completely oxidized to Co3+. The coordination of Zn2+, at this stage, is intermediate between the octahedral one of the precursors and the tetrahedral one of ZnO and Zn-based spinels. Further calcination at 973 K produces a mixture of crystalline oxides such as CuO, ZnO, CuAl2O4, ZnAl2O4, and ZnCo2O4. EXAFS analysis of these samples indicates that copper is mainly in a fourfold coordination (although two longer Cu-O distances are also detected), zinc is tetrahedral, and cobalt (as Co3+) is essentially octahedral. EXAFS and XANES investigations performed afterin situreduction (10% H2/N2, at 523 and 623 K) on the oxycarbonates and oxides reveal that the total Cu2+→ Cu0reduction occurs only at 623 K in both series of samples, Co3+is reduced to Co2+only at 623 K in the oxycarbonates, and Zn2+is never reduced.

  17. In situ synchrotron X-ray powder diffraction for studying the role of induced structural defects on the thermoluminescence mechanism of nanocrystalline LiF.

    PubMed

    El Ashmawy, Mostafa; Amer, Hany; Abdellatief, Mahmoud

    2016-03-01

    The correlation between the thermoluminescence (TL) response of nanocrystalline LiF and its microstructure was studied. To investigate the detailed TL mechanism, the glow curves of nanocrystalline LiF samples produced by high-energy ball-milling were analyzed. The microstructure of the prepared samples was analyzed by synchrotron X-ray powder diffraction (XRPD) at room temperature. Then, the microstructure of a representative pulverized sample was investigated in detail by performing in situ XRPD in both isothermal and non-isothermal modes. In the present study, the dislocations produced by ball-milling alter the microstructure of the lattice where the relative concentration of the vacancies, responsible for the TL response, changes with milling time. An enhancement in the TL response was recorded for nanocrystalline LiF at high-temperature traps (after dislocations recovery starts >425 K). It is also found that vacancies are playing a major role in the dislocations recovery mechanism. Moreover, the interactions among vacancies-dislocations and/or dislocations-dislocations weaken the TL response.

  18. From antiferromagnetism to superconductivity in Fe1+yTe1-xSex (0≤x≤0.20) : Neutron powder diffraction analysis

    NASA Astrophysics Data System (ADS)

    Martinelli, A.; Palenzona, A.; Tropeano, M.; Ferdeghini, C.; Putti, M.; Cimberle, M. R.; Nguyen, T. D.; Affronte, M.; Ritter, C.

    2010-03-01

    The nuclear and magnetic structures of Fe1+yTe1-xSex (0≤x≤0.20) compounds was analyzed between 2 and 300 K by means of Rietveld refinement of neutron powder diffraction data. Samples with x≤0.075 undergo a tetragonal to monoclinic phase transition at low temperature, whose critical temperature decreases with increasing Se content; this structural transition is strictly coupled to a long-range antiferromagnetic ordering at the Fe site. Both the transition to a monoclinic phase and the long-range antiferromagnetism are suppressed for 0.10≤x≤0.20 . The onset of the structural and of the magnetic transition remains coincident with the increase in Se substitution. The low-temperature monoclinic crystal structure has been revised. Superconductivity arises for x≥0.05 , therefore a significant region where superconductivity and long-range antiferromagnetism coexist is present in the pseudobinary FeTe-FeSe phase diagram.

  19. Structural studies of Ni{sub 2+x}Mn{sub 1-x}Ga by powder x-ray diffraction and total energy calculations

    SciTech Connect

    Banik, S.; Bhardwaj, S.; Lalla, N. P.; Awasthi, A. M.; Sathe, V.; Phase, D. M.; Barman, S. R.; Ranjan, R.; Pandey, D.; Chakrabarti, A.; Mukhopadhyay, P. K.

    2007-03-01

    The crystal structure of Ni{sub 2+x}Mn{sub 1-x}Ga has been studied as a function of composition (x) by powder x-ray diffraction. For Ni{sub 2.24}Mn{sub 0.75}Ga, where one-fourth of the Mn atoms are replaced by Ni, the experimentally determined lattice constants are in good agreement with theoretical equilibrium lattice constants calculated by minimization of total energy using full potential linearized augmented plane-wave method. For 0.15{<=}x{<=}0.35, a nonmodulated tetragonal martensitic phase is obtained at room temperature, whose lattice constant c increases and a decreases linearly with increasing x following Vegard's law. A 7M modulated monoclinic phase is obtained for x=0.2 due to annealing. The small width of the hysteresis of the martensitic transition shows its thermoelastic nature that is the characteristic of a shape memory alloy. Phase coexistence is observed for 0.1{<=}x{<=}0.15 at room temperature, confirming the first-order nature of the martensitic transition.

  20. Revealing the Formation Mechanism and Effect of Pressure on the Magnetic Order of Multiferroic BiMn2O5 Through Neutron Powder Diffraction

    NASA Astrophysics Data System (ADS)

    Dang, N. T.; Kozlenko, D. P.; Kichanov, S. E.; Jabarov, S. G.; Mammadov, A. I.; Mekhtieva, R. Z.; Phan, T. L.; Smotrakov, V. G.; Eremkin, V. V.; Savenko, B. N.

    2017-02-01

    The crystal and magnetic structures of the strong magnetoelectric BiMn2O5 have been studied as a function of pressure up to 5.7 GPa in the temperature range from 10 K to 60 K by means of neutron powder diffraction. The results reveal that the Pbam orthorhombic crystal structure remains unchanged in the investigated thermodynamic range. At ambient pressure, a long-range commensurate antiferromagnetic (AFM) phase with propagation vector q = (1/2, 0, 1/2) formed below T N = 41(2) K, accompanied by anomalies in the temperature dependence of structural parameters including the lattice parameters, interatomic distances, and bond angles. This AFM phase remained stable in the studied pressure range, and the relevant pressure coefficient of the Néel temperature was determined to be 3.0(4) K/GPa. No incommensurate AFM phase was detected. The magnetic properties of BiMn2O5 and their difference from most other RMn2O5 compounds were analyzed in terms of competing exchange interactions.

  1. Rietveld refinement of the semiconducting system Bi{sub 2-x}Fe{sub x}Te{sub 3} from X-ray powder diffraction

    SciTech Connect

    Adam, Alia

    2007-12-04

    The semiconducting system Bi{sub 2-x}Fe{sub x}Te{sub 3} (x = 0.0, 0.02, 0.04 and 0.08) was synthesized at 1000 deg. C for 30 h. The scanning electron microscope (SEM) image reveals the tendency of the Bi{sub 2-x}Fe{sub x}Te{sub 3} system to form a sheet structure with more pronounced alignment and to enhance the formation of some microstructure tubes. The structure of the system under study was refined on the basis of X-ray powder diffraction data using the Rietveld method. The analysis revealed the complete miscibility of Fe in the Bi{sub 2}Te{sub 3} matrix and hence the formation of single phase. The system crystallizes in the space group R-3m [1 6 6]. The lattice parameters and the unit cell size slightly change by the incorporation of Fe. The refinement of instrumental and structural parameters led to reliable values for the R{sub B}, R{sub F} and Chi{sup 2}.

  2. The Stoichiometry of Synthetic Alunite as a Function of Hydrothermal Aging Investigated by Solid-State NMR Spectroscopy, Powder X-ray Diffraction and Infrared Spectroscopy

    SciTech Connect

    Grube, Elisabeth; Nielsen, Ulla Gro

    2015-05-01

    The stoichiometry of a series of synthetic alunite [nominally KAl3(SO4)2(OH)6] samples prepared by hydrothermal methods as a function of reaction time (1–31 days) has been investigated by powder X-ray diffraction, Fourier transform infrared spectroscopy as well as solid-state 1H and 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The 1H MAS NMR spectra recorded at high magnetic field (21.1 T, 900 MHz) allowed for a clear separation of the different proton environments and for quantitative determination of the aluminum vacancy concentration as a function of time. The concentration of structural defects determined from, i.e., aluminum vacancies was reduced from 4 to 1 %, as the reaction time was extended from one to 31 days based on 1H MAS NMR. This was further supported by an increase of the unit cell parameter c, which is indicative of the relative concentration of potassium defects present, from 17.261(1) to 17.324(5) Å. Solid-state 27Al MAS NMR revealed a decrease in the defect concentration as a function of time and showed the presence of 7–10 % impurities in the samples.

  3. On the estimation of statistical uncertainties on powder diffraction and small-angle scattering data from two-dimensional X-ray detectors

    SciTech Connect

    Yang, X.; Juhás, P.; Billinge, S. J. L.

    2014-07-19

    Optimal methods are explored for obtaining one-dimensional powder pattern intensities from two-dimensional planar detectors with good estimates of their standard deviations. Methods are described to estimate uncertainties when the same image is measured in multiple frames as well as from a single frame. The importance of considering the correlation of diffraction points during the integration and the resampling process of data analysis is shown. It is found that correlations between adjacent pixels in the image can lead to seriously overestimated uncertainties if such correlations are neglected in the integration process. Off-diagonal entries in the variance–covariance (VC) matrix are problematic as virtually all data processing and modeling programs cannot handle the full VC matrix. It is shown that the off-diagonal terms come mainly from the pixel-splitting algorithm used as the default integration algorithm in many popular two-dimensional integration programs, as well as from rebinning and resampling steps later in the processing. When the full VC matrix can be propagated during the data reduction, it is possible to get accurate refined parameters and their uncertainties at the cost of increasing computational complexity. However, as this is not normally possible, the best approximate methods for data processing in order to estimate uncertainties on refined parameters with the greatest accuracy from just the diagonal variance terms in the VC matrix is explored.

  4. X-ray powder diffraction, spectroscopic study, dielectric properties and thermal analysis of new doped compound TiGa0.67Te2.33O8

    NASA Astrophysics Data System (ADS)

    Smaoui, S.; Ben Aribia, W.; Kabadou, A.; Abdelmouleh, M.

    2017-04-01

    A novel mixed valence tellurium oxide, TiGa0.67Te2.33O8, was synthesized and its crystal structure determined using the X-ray powder diffraction technique. The obtained oxide was found to crystallize in a cubic unit-cell, Ia 3 bar space group, with the lattice parameter a = 10.9557(1) Å. Rietveld refinement of the structure led to ultimate confidence factors Rp = 7.63 and Rwp = 6.71. This structure was based on slabs containing groups of (Te/Ga)O4 joined by the metal cations Ti4+. The structure analysis showed a cation ordering of Te4+ and Te6+ yielding a TiGa2/3Te7/3O8 formula. The IR and RAMAN spectra confirmed the presence of the TiO6 and (Te/Ga)O4 groups. The dielectric anomalies observed at 500 K were attributed to the mixed valence structure, arising from the mixed-valence Te6+/Te4+. We detected only one peak in thermal behavior by the DTA/TG analysis; which implied a melting reaction.

  5. Germanate with three-dimensional 12 × 12 × 11-ring channels solved by X-ray powder diffraction with charge-flipping algorithm.

    PubMed

    Xu, Yan; Liu, Leifeng; Chevrier, Daniel M; Sun, Junliang; Zhang, Peng; Yu, Jihong

    2013-09-16

    A new open-framework germanate, denoted as GeO-JU90, was prepared by the hydrothermal synthesis method using 1,5-bis(methylpyrrolidinium)pentane dihydroxide as the organic structure-directing agent (SDA). The structure of GeO-JU90 was determined from synchrotron X-ray powder diffraction (XRPD) data using the charge-flipping algorithm. It revealed a complicated framework structure containing 11 Ge atoms in the asymmetric unit. The framework is built of 7-connected Ge7 clusters and additional tetrahedral GeO3(OH) units forming a new three-dimensional interrupted framework with interesting 12 × 12 × 11-ring intersecting channels. The Ge K-edge extended X-ray absorption fine structure (EXAFS) analysis was performed to provide the local structural information around Ge atoms, giving rise to a first-shell contribution from about 4.2(2) O atoms at the average distance of 1.750(8) Å. The guest species in the channels were subsequently determined by the simulated annealing method from XRPD data combining with other characterization techniques, e.g., (13)C NMR spectroscopy, infrared spectroscopy (FTIR), compositional analyses, and thermogravimetric analysis (TGA). Crystallographic data |(C15N2H32)(NH4)|[Ge11O21.5(OH)4], orthorhombic Ama2 (No. 40), a = 37.82959 Å, b = 15.24373 Å, c = 12.83659 Å, and Z = 8.

  6. Synchrotron powder X-ray diffraction and structural analysis of Eu0.5La0.5FBiS2-x Se x

    NASA Astrophysics Data System (ADS)

    Nagasaka, K.; Jinno, G.; Miura, O.; Miura, A.; Moriyoshi, C.; Kuroiwa, Y.; Mizuguchi, Y.

    2017-07-01

    Eu0.5La0.5FBiS2-x Se x is a new BiS2-based superconductor system. In Eu0.5La0.5FBiS2-x Se x , electron carriers are doped to the BiS2 layer by the substitution of Eu by La. Bulk superconductivity in this system is induced by increasing the in-plane chemical pressure, which is controlled by the Se concentration (x). In this study, we have analysed the crystal structure of Eu0.5La0.5FBiS2-x Se x using synchrotron powder diffraction and the Rietveld refinement. The precise determination of the structural parameters and thermal factors suggest that the emergence of bulk superconductivity in Eu0.5La0.5FBiS2-x Se x is achieved by the enhanced in-plane chemical pressure and the decrease in in-plane disorder.

  7. Functional biocompatible magnetite-cellulose nanocomposite fibrous networks: Characterization by fourier transformed infrared spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy analysis.

    PubMed

    Habibi, Neda

    2015-02-05

    The preparation and characterization of functional biocompatible magnetite-cellulose nano-composite fibrous material is described. Magnetite-cellulose nano-composite was prepared by a combination of the solution-based formation of magnetic nano-particles and subsequent coating with amino celluloses. Characterization was accomplished using X-ray powder diffraction (XRD), fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. The peaks of Fe3O4 in the XRD pattern of nanocomposite confirm existence of the nanoparticles in the amino cellulose matrix. Magnetite-cellulose particles exhibit an average diameter of roughly 33nm as demonstrated by field emission scanning electron microscopy. Magnetite nanoparticles were irregular spheres dispersed in the cellulose matrix. The vibration corresponding to the NCH3 functional group about 2850cm(-1) is assigned in the FTIR spectra. Functionalized magnetite-cellulose nano-composite polymers have a potential range of application as targeted drug delivery system in biomedical field. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Anomalous Thermal Expansion of HoCo0.5Cr0.5O3 Probed by X-ray Synchrotron Powder Diffraction

    NASA Astrophysics Data System (ADS)

    Hreb, Vasyl; Vasylechko, Leonid; Mykhalichko, Vitaliya; Prots, Yurii

    2017-07-01

    Mixed holmium cobaltite-chromite HoCo0.5Cr0.5O3 with orthorhombic perovskite structure (structure type GdFeO3, space group Pbnm) was obtained by solid state reaction of corresponding oxides in air at 1373 K. Room- and high-temperature structural parameters were derived from high-resolution X-ray synchrotron powder diffraction data collected in situ in the temperature range of 300-1140 K. Analysis of the results obtained revealed anomalous thermal expansion of HoCo0.5Cr0.5O3, which is reflected in a sigmoidal temperature dependence of the unit cell parameters and in abnormal increase of the thermal expansion coefficients with a broad maxima near 900 K. Pronounced anomalies are also observed for interatomic distances and angles within Co/CrO6 octahedra, tilt angles of octahedra and atomic displacement parameters. The observed anomalies are associated with the changes of spin state of Co3+ ions and insulator-metal transition occurring in HoCo0.5Cr0.5O3.

  9. Plumbonacrite identified by X-ray powder diffraction tomography as a missing link during degradation of red lead in a Van Gogh painting.

    PubMed

    Vanmeert, Frederik; Van der Snickt, Geert; Janssens, Koen

    2015-03-16

    Red lead, a semiconductor pigment used by artists since antiquity, is known to undergo several discoloration phenomena. These transformations are either described as darkening of the pigment caused by the formation of either plattnerite (β-PbO2) or galena (PbS) or as whitening by which red lead is converted into anglesite (PbSO4) or (hydro)cerussite (2 PbCO3⋅Pb(OH)2; PbCO3). X-ray powder diffraction tomography, a powerful analytical method that allows visualization of the internal distribution of different crystalline compounds in complex samples, was used to investigate a microscopic paint sample from a Van Gogh painting. A very rare lead mineral, plumbonacrite (3 PbCO3⋅Pb(OH)2⋅PbO), was revealed to be present. This is the first reported occurrence of this compound in a painting dating from before the mid 20th century. It constitutes the missing link between on the one hand the photoinduced reduction of red lead and on the other hand (hydro)cerussite, and thus sheds new light on the whitening of red lead. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A study of nitrogenation of a NdFe{sub 12-x}Mo{sub x} compound by in situ neutron powder diffraction.

    SciTech Connect

    Ding, Y.; Lin, J.; Loong, C.-K.; Short, S. M.

    1997-11-18

    The effects on the crystal lattice of a NdFe{sub 12{minus}x}Mo{sub x}(x {approx_equal} 1.7) compound which contained {approximately}12 vol% of bcc-Fe were studied by neutron powder diffraction during controlled nitrogenation over the 25-600 C temperature range. The sample inside the furnace was connected to a closed volume of ultra-pure nitrogen gas while neutron data were collected over regular time intervals during sequential heating. Substantial nitrogen absorption occurred between 500 to 600 C. During the nitrogenation process the NdFe{sub 12{minus}x}Mo{sub x}N{sub y} lattice expanded while the bcc-Fe lattice contracted. An increasing decomposition of the compound into bcc-Fe at 600 C was observed. The average size of the NdFe{sub 12{minus}x}Mo{sub x}N{sub y} crystalline grains decreased starting at {approximately}300 C, reaching a minimum at {approximately}500 C and then increased markedly at higher temperatures. The development of lattice strains, on the other hand, showed an opposite trend, i.e., a maximum at 500 C. A correlation of structural modification of the crystalline phases and the nitrogenation process is discussed.

  11. Crystal structure of dicesium hydrogen citrate from laboratory single-crystal and powder X-ray diffraction data and DFT comparison.

    PubMed

    Rammohan, Alagappa; Sarjeant, Amy A; Kaduk, James A

    2017-02-01

    The crystal structure of dicesium hydrogen citrate, 2Cs(+)·C6H6O7(2-), has been solved using laboratory X-ray single-crystal diffraction data, refined using laboratory powder X-ray data, and optimized using density functional techniques. The Cs(+) cation is nine-coordinate, with a bond-valence sum of 0.92 valence units. The CsO9 coordination polyhedra share edges and corners to form a three-dimensional framework. The citrate anion is located on a mirror plane. Its central hy-droxy/carboxyl-ate O-H⋯O hydrogen bond is short, and (unusually) inter-molecular. The centrosymmetric end-end carboxyl-ate hydrogen bond is exceptionally short (O⋯O = 2.416 Å) and strong. These hydrogen bonds contribute 16.5 and 21.7 kcal mol(-1), respectively, to the crystal energy. The hydro-phobic methyl-ene groups occupy pockets in the framework.

  12. The Structure of High Pressure Ca(OD) 2II from Powder Neutron Diffraction: Relationship to the ZrO 2and EuI 2Structures

    NASA Astrophysics Data System (ADS)

    Leinenweber, Kurt; Partin, Dan E.; Schuelke, Udo; O'Keeffe, Michael; Von Dreele, Robert B.

    1997-09-01

    The "unquenchable" high pressure form of Ca(OD) 2[Ca(OH) 2II] has been synthesized at 9 GPa and 400°C and recovered to ambient pressure at cryogenic temperatures. The structure was determined from powder neutron diffraction data using the Rietveld technique. The symmetry is monoclinic P2 1/ cwith a=5.3979(4) Å, b=6.0931(4) Å, c=5.9852(4) Å, β=103.581(6)°, Z=4 at 1 atm and 11 K. Rwp=2.8%, Rp=1.9%, reduced χ2=6.6. for 117 variables. The calcium and oxygen substructure is intermediate between that in α-PbO 2and that in fluorite; it was previously described as isostructural with baddeleyite (ZrO 2), but it is more accurately described as isostructural with EuI 2. This structure is distinguished by the presence of a 3 6anion net parallel to (100). Only one of the two kinds of D atoms in the structure shows appreciable hydrogen bonding to O, with a second neighbor D … O distance of 1.91 Å, and an O-D … O angle of 153.2°; the other D atom has 3 second-neighbor oxygens near 2.6 Å away.

  13. Pulsed supercritical synthesis of anatase TiO₂ nanoparticles in a water-isopropanol mixture studied by in situ powder X-ray diffraction.

    PubMed

    Rostgaard Eltzholtz, Jakob; Tyrsted, Christoffer; Ørnsbjerg Jensen, Kirsten Marie; Bremholm, Martin; Christensen, Mogens; Becker-Christensen, Jacob; Brummerstedt Iversen, Bo

    2013-03-21

    A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania nanoparticles were synthesized in a 50/50 mixture of water and isopropanol near and above the critical point of water (P = 250 bar, T = 300, 350, 400, 450, 500 and 550 °C). The evolution of the reaction product was followed by sequentially recording PXRD patterns with a time resolution of less than two seconds. The crystallite size of titania is found to depend on both temperature and residence time, and increasing either parameter leads to larger crystallites. A simple adjustment of either temperature or residence time provides a direct method for gram scale production of anatase nanoparticles of average crystallite sizes between 7 and 35 nm, thus giving the option of synthesizing tailor-made nanoparticles. Modeling of the in situ growth curves using an Avrami growth model gave an activation energy of 66(19) kJ mol(-1) for the initial crystallization. The in situ PXRD data also provide direct information about the size dependent macrostrain in the nanoparticles and with decreasing crystallite size the unit cell contracts, especially along the c-direction. This agrees well with previous ex situ results obtained for hydrothermal synthesis of titania nanoparticles.

  14. Anomalous Thermal Expansion of HoCo0.5Cr0.5O3 Probed by X-ray Synchrotron Powder Diffraction.

    PubMed

    Hreb, Vasyl; Vasylechko, Leonid; Mykhalichko, Vitaliya; Prots, Yurii

    2017-12-01

    Mixed holmium cobaltite-chromite HoCo0.5Cr0.5O3 with orthorhombic perovskite structure (structure type GdFeO3, space group Pbnm) was obtained by solid state reaction of corresponding oxides in air at 1373 K. Room- and high-temperature structural parameters were derived from high-resolution X-ray synchrotron powder diffraction data collected in situ in the temperature range of 300-1140 K. Analysis of the results obtained revealed anomalous thermal expansion of HoCo0.5Cr0.5O3, which is reflected in a sigmoidal temperature dependence of the unit cell parameters and in abnormal increase of the thermal expansion coefficients with a broad maxima near 900 K. Pronounced anomalies are also observed for interatomic distances and angles within Co/CrO6 octahedra, tilt angles of octahedra and atomic displacement parameters. The observed anomalies are associated with the changes of spin state of Co(3+) ions and insulator-metal transition occurring in HoCo0.5Cr0.5O3.

  15. Obtaining aluminas from the thermal decomposition of their different precursors: An {sup 27}Al MAS NMR and X-ray powder diffraction studies

    SciTech Connect

    Chagas, L.H.; De Carvalho, G.S.G.; San Gil, R.A.S.; Chiaro, S.S.X.; Leitão, A.A.; Diniz, R.

    2014-01-01

    Graphical abstract: - Highlights: • We synthesized three precursors of alumina from different methods. • The calcination of the precursors generated several alumina polymorphs. • XRD and NMR were used for structural investigation of the polymorphs. • The synthesis route determines the structural and textural properties of the solids. - Abstract: A commercial sample of Boehmite was used as precursor of alumina polymorphs. For comparison, three other precursors were synthesized from different methods. Particularly, the use of excess of urea promoted a very crystalline form of basic aluminum carbonate. The characteristics of the four precursors were investigated by thermal, vibrational and X-ray powder diffraction (XRD) analysis. Additionally, the nuclear magnetic resonance, with magic angle spinning ({sup 27}Al MAS NMR), was used to verify the coordination of aluminum cations. Each precursor was calcined at various temperatures generating alumina polymorphs, which were structurally analyzed by XRD and {sup 27}Al MAS NMR. Due to interest in catalysis supports, special attention was given to the γ-Al{sub 2}O{sub 3} phase, which in addition to structural investigation was subjected to textural analysis. The results showed that, from different synthesis procedures and common route of calcination, one can obtain materials with the same composition but with different structural and textural properties, which in turn can significantly influence the performance of a supported catalyst.

  16. Characterisation of Incommensurate Bi2+xSr2-xCuOz by X-Ray Powder Diffraction and Oxygen Content Determinations

    NASA Astrophysics Data System (ADS)

    Sinclair, D. C.; Irvine, J. T. S.; West, A. R.

    1990-11-01

    The composition-temperature stability region of the solid solution Bi2+xSr2-xCuOz, phase R, has been determined. At 800°C, 0.15powder diffraction pattern can be indexed using a pseudo-tetragonal subcell, a{=}b{=}5.390(1), c{=}24.59 Å, with a supercell vector q* given by q*{=}nδ b*-n\\varepsilon c*, where δ{=}0.21, \\varepsilon{=}0.55, for x{=}0.30 and n{=}1, 2\\cdots. Both a and \\varepsilon increased with x, c decreased with x and δ was independent of x. The excess oxygen content, α, was determined to be (0.18± 0.02) by citrate iodometry and was independent of x. The total oxygen content z, given by z{=}6+x/2+α, was confirmed to be 6.33± 0.04, for x{=}0.30, by hydrogen reduction thermogravimetry.

  17. Formation of γ-Fe 2O 3 nanoparticles and vacancy ordering: An in situ X-ray powder diffraction study

    NASA Astrophysics Data System (ADS)

    Jørgensen, Jens-Erik; Mosegaard, Lene; Thomsen, Line E.; Jensen, Torben R.; Hanson, Jonathan C.

    2007-01-01

    The formation of maghemite, γ-Fe 2O 3 nanoparticles has been studied by in situ X-ray powder diffraction. The maghemite was formed by thermal decomposition of an amorphous precursor compound made by reacting lauric acid, CH 3(CH 2) 10COOH with Fe(NO 3) 3·9H 2O. It has been shown that cubic γ-Fe 2O 3 was formed directly from the amorphous precursor and that vacancy ordering starts about 45 min later at 305 °C resulting in a tripled unit cell along the c-axis. The kinetics of grain growth was found to obey a power law with growth exponents n equal to 0.136(6) and 0.103(5) at 305 and 340 °C, respectively. Particles with average sizes of 12 and 13 nm were obtained in 86 and 76 min at 305 and 340 °C, respectively. The structure of cubic and vacancy ordered phases of γ-Fe 2O 3 was studied at 305 °C by Rietveld refinements.

  18. Quantitative study of solid-state acid-base reactions between polymorphs of flufenamic acid and magnesium oxide using X-ray powder diffraction.

    PubMed

    Chen, Xiaoming; Stowell, Joseph G; Morris, Kenneth R; Byrn, Stephen R

    2010-03-11

    The purpose of this study is to investigate solid-state acid-base reactions between polymorphs of flufenamic acid (FFA) and magnesium oxide (MgO) using X-ray powder diffraction (XRPD). Polymorphs of FFA were blended with MgO and stored under conditions of 96.5% RH and 89% RH at 40 degrees C. The disappearance of FFA and production of magnesium flufenamate were monitored by XRPD. It was observed that the reactions between FFA and MgO proceeded following the Jander equation. Form I of FFA is more reactive with MgO than Form III. Differential accessibility of reactive groups is hypothesized as one of the reasons that Form I is more reactive than Form III. It was noted that the reaction between FFA and MgO could be mitigated by adding another acidic excipient such as polyacrylic acid to prevent the acid-base reaction with FFA. The effectiveness of polyacrylic acid was impacted by the mixing order of the tertiary mixture. Mixing polyacrylic acid and MgO first provided the most significant protection. In conclusion, solid-state acid-base reactions could be investigated using XRPD. Different forms may have distinct reactivity. Acid-base reactions in the solid state could be mitigated through the addition of another "shielding" excipient. Copyright 2009 Elsevier B.V. All rights reserved.

  19. Quasi-hydrostatic X-ray powder diffraction study of the low- and high-pressure phases of CaWO4 up to 28 GPa

    NASA Astrophysics Data System (ADS)

    Vilaplana, R.; Lacomba-Perales, R.; Gomis, O.; Errandonea, D.; Meng, Y.

    2014-10-01

    We have studied CaWO4 under compression using Ne as pressure-transmitting medium at room temperature by means of synchrotron X-ray powder diffraction. We have found that CaWO4 beyond 8.8 GPa transforms from its low-pressure tetragonal structure (scheelite) into a monoclinic structure (fergusonite). The high-pressure phase remains stable up to 28 GPa and the low-pressure phase is totally recovered after full decompression. The pressure dependence of the unit-cell parameters, as well as the pressure-volume equation of state, has been determined for both phases. Compared with previous studies, we found in our quasi-hydrostatic experiments a different behavior for the unit-cell parameters of the fergusonite phase and a different transition pressure. These facts suggest that deviatoric stresses influence on the high-pressure structural behavior of CaWO4 as previously found in related compounds. The reported experiments also provide information on the pressure dependence of interatomic bond distances, shedding light on the transition mechanisms.

  20. X-Ray Powder Diffraction Data for Na8(AlSiO4)6(ReO4)2

    SciTech Connect

    McCready, David E.; Mattigod, Shas V.; Young, James S.; McGrail, B. Peter

    2004-01-31

    X-ray powder diffraction data for a new zeolite, Na8(AlSiO4)6(ReO4)2, are reported. Rietveld refinement shows this compound adopts the primitive cubic structure of sodalite (Space Group , #218) with a = 9.1528 (1) Å. The calculated value of the reference intensity ratio (RIR, or I/Ic) is 7.54. The experimental density (Dm) is 2.98 ± 0.10 g/cm3, in agreement with the calculated density (Dx) of 3.029 g/cm3. Chemical analysis of Na8(AlSiO4)6(ReO4)2 gives its composition as 11.7 ± 1.6 wt % Na; 10.7 ± 0.2 wt % Al; 11.6 ± 0.9 wt % Si; 30.6 ± 1.2 wt % Re, which compares favorably with the theoretical composition of 13.2 wt % Na, 11.6 wt% Al, 12.1 wt% Si; 26.6 wt % Re. In addition, scanning electron microscopy reveals a doubly terminated trapezohedral crystal morphology for Na8(AlSiO4)6(ReO4)2, which is typical of sodalite.

  1. Electron paramagnetic resonance, scanning electron microscopy with energy dispersion X-ray spectrometry, X-ray powder diffraction, and NMR characterization of iron-rich fired clays.

    PubMed

    Presciutti, Federica; Capitani, Donatella; Sgamellotti, Antonio; Brunetti, Brunetto Giovanni; Costantino, Ferdinando; Viel, Stéphane; Segre, Annalaura

    2005-12-01

    The aim of this study is to clarify the structure of an iron-rich clay and the structural changes involved in the firing process as a preliminary step to get information on ancient ceramic technology. To this purpose, illite-rich clay samples fired at different temperatures were characterized using a multitechnique approach, i.e., by electron paramagnetic resonance, scanning electron microscopy with electron dispersion X-ray spectrometry, X-ray powder diffraction, magic angle spinning and multiple quantum magic angle spinning NMR. During firing, four main reaction processes occur: dehydration, dehydroxylation, structural breakdown, and recrystallization. When the results are combined from all characterization methods, the following conclusions could be obtained. Interlayer H2O is located close to aluminum in octahedral sites and is driven off at temperatures lower than 600 degrees C. Between 600 and 700 degrees C dehydroxylation occurs whereas, between 800 and 900 degrees C, the aluminum in octahedral sites disappears, due to the breakdown of the illite structure, and all iron present is oxidized to Fe3+. In samples fired at 1000 and 1100 degrees C iron clustering was observed as well as large single crystals of iron with the occurrence of ferro- or ferrimagnetic effects. Below 900 degrees C the aluminum in octahedral sites presents a continuous distribution of chemical shift, suggesting the presence of slightly distorted sites. Finally, over the whole temperature range, the presence of at least two tetrahedral aluminum sites was revealed, characterized by different values of the quadrupolar coupling constant.

  2. Determination of tacrolimus crystalline fraction in the commercial immediate release amorphous solid dispersion products by a standardized X-ray powder diffraction method with chemometrics.

    PubMed

    Rahman, Ziyaur; Siddiqui, Akhtar; Bykadi, Srikant; Khan, Mansoor A

    2014-11-20

    Clinical performance of an amorphous solid dispersion (ASD) drug product is related to the amorphous drug content because of the greater bioavailability of this form of the drug than its crystalline form. Therefore, it is paramount to monitor the amorphous and the crystalline fractions in the ASD products. The objective of the present investigation was to study the feasibility of using a standardized X-ray powder diffraction (XRPD) in conjunction with chemometric methods to quantitate the amorphous and crystalline fraction of the drug in several tacrolimus ASD products. Three ASD products were prepared in which drug to excipients ratios ranged from 1:19 to 1:49. The amorphous and crystalline drug products were mixed in various proportions so that amorphous/crystalline tacrolimus in the samples vary from 0 to 100%. XRPD of the samples of the drug products were collected, and PLSR and PCR chemometric methods were applied to the data. The R(2) was greater than '0.987' for all the models and bias in the models were statistically insignificant (p>0.05). RMSEP and SEP values were smaller for PLSR models than PCR models. The models prediction capabilities were good and can predict as low as 10% when drug to excipient ratio is as high as 1:49. In summary, XRPD and chemometric provide powerful analytical tools to monitor the crystalline fractions of the drug in the ASD products.

  3. Antisolvent crystallization of pharmaceutical excipients from aqueous solutions and the use of preferred orientation in phase identification by powder X-ray diffraction.

    PubMed

    Crisp, J L; Dann, S E; Blatchford, C G

    2011-04-18

    Crystallization of lactose from 10% (w/v) aqueous solutions was investigated with the use of polar antisolvents. Crystal growth was observed at 50-65% antisolvent content and showed a morphological transition from a polyhedral to needle-like habit with increasing antisolvent content, which coincided with a polymorphic transition from alpha lactose monohydrate (Lα·H(2)O) to beta lactose (Lβ). Where dehydrating antisolvents were employed such as methanol and ethanol, evidence of Lα·H(2)O dehydration to form Lα(S) was also observed at 95% antisolvent content. Powder X-ray diffraction (PXRD) analysis of the crystals highlighted the preferred orientation effects exhibited by large crystals of this kind, indicating the difficulties experienced by the non-specialist when performing phase identification of lactose polymorphs. The same studies were applied to raffinose pentahydrate, trehalose dihydrate and mannitol to assess the effects of crystallization conditions on other pharmaceutical excipients. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Analysis of a nanocrystalline polymer dispersion of ebselen using solid-state NMR, Raman microscopy, and powder X-ray diffraction.

    PubMed

    Vogt, Frederick G; Williams, Glenn R

    2012-07-01

    Nanocrystalline drug-polymer dispersions are of significant interest in pharmaceutical delivery. The purpose of this work is to demonstrate the applicability of methods based on two-dimensional (2D) and multinuclear solid-state NMR (SSNMR) to a novel nanocrystalline pharmaceutical dispersion of ebselen with polyvinylpyrrolidone-vinyl acetate (PVP-VA), after initial characterization with other techniques. A nanocrystalline dispersion of ebselen with PVP-VA was prepared and characterized by powder X-ray diffraction (PXRD), confocal Raman microscopy and mapping, and differential scanning calorimetry (DSC), and then subjected to detailed 1D and 2D SSNMR analysis involving ¹H, ¹³C, and ⁷⁷Se isotopes and ¹H spin diffusion. PXRD was used to show that dispersion contains nanocrystalline ebselen in the 35-60 nm size range. Confocal Raman microscopy and spectral mapping were able to detect regions where short-range interactions may occur between ebselen and PVP-VA. Spin diffusion effects were analyzed using 2D SSNMR experiments and are able to directly detect interactions between ebselen and the surrounding PVP-VA. The methods used here, particularly the 2D SSNMR methods based on spin diffusion, provided detailed structural information about a nanocrystalline polymer dispersion of ebselen, and should be useful in other studies of these types of materials.

  5. Quantifying low amorphous or crystalline amounts of alpha-lactose-monohydrate using X-ray powder diffraction, near-infrared spectroscopy, and differential scanning calorimetry.

    PubMed

    Fix, I; Steffens, K J

    2004-05-01

    Efficient and accurate quantification of low amorphous and crystalline contents within pharmaceutical materials still remains a challenging task in the pharmaceutical industry. Since X-ray powder diffraction (XRPD) equipment has improved in recent years, our aim was 1) to investigate the possibility of substantially lowering the detection limits of amorphous or crystalline material to about 1% or 0.5% w/w respectively by applying conventional Bragg Brentano optics, combined with a fast and simple evaluation technique; 2) to perform these measurements within a short time to make it suitable for routine analysis; and 3) to subject the same data sets to a partial least squares regression (PLSR) in order to investigate whether it is possible to improve accuracy and precision compared to the standard integration method. Near-infrared spectroscopy (NIRS) and differential scanning calorimetry (DSC) were chosen as reference method. As model substance, alpha lactose monohydrate was chosen to create calibration curves based on predetermined mixtures of highly crystalline and amorphous substance. In contrast to DSC, XRPD and NIRS revealed an excellent linearity, precision, and accuracy with the percent of crystalline amount and a detectability down to about 0.5% w/w. Chemometric evaluation (partial least squares regression) applied to the XRPD data further improved the quality of our calibration.

  6. The interplay between the lattice and magnetism in La(Fe11.4Al1.6)C0.02 studied by powder neutron diffraction

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Cui; He, Lun-Hua; Wang, Hai; Liu, Rong-Deng; Wang, Fang-Wei

    2012-04-01

    The crystallographic structure and magnetic properties of La(Fe11.4Al1.6)C0.02 are studied by magnetic measurement and powder neutron diffraction with temperature and applied magnetic field. Rietveld refinement shows that La(Fe11.4Al1.6)C0.02 crystallizes into the cubic NaZn13-type with two different Fe sites: FeI (8b) and FeII (96i), and that Al atoms preferentially occupy the FeII site. A ferromagnetic state can be induced at a medial temperature of 39 K-139 K by an external magnetic field of 0.7 T, and a large lattice is correspondingly found at 100 K and 0.7 T. In all other conditions, La(Fe11.4Al1.6)C0.02 has no net magnetization in the paramagnetic (T > TN = 182 K) or antiferromagnetic states, and thus keeps its small lattice. Analysis of the Fe—Fe bond length indicates that the ferromagnetic state prefers longer Fe—Fe distances.

  7. Crystal structure of dicesium hydrogen citrate from laboratory single-crystal and powder X-ray diffraction data and DFT comparison

    PubMed Central

    Rammohan, Alagappa; Sarjeant, Amy A.; Kaduk, James A.

    2017-01-01

    The crystal structure of dicesium hydrogen citrate, 2Cs+·C6H6O7 2−, has been solved using laboratory X-ray single-crystal diffraction data, refined using laboratory powder X-ray data, and optimized using density functional techniques. The Cs+ cation is nine-coordinate, with a bond-valence sum of 0.92 valence units. The CsO9 coordination polyhedra share edges and corners to form a three-dimensional framework. The citrate anion is located on a mirror plane. Its central hy­droxy/carboxyl­ate O—H⋯O hydrogen bond is short, and (unusually) inter­molecular. The centrosymmetric end-end carboxyl­ate hydrogen bond is exceptionally short (O⋯O = 2.416 Å) and strong. These hydrogen bonds contribute 16.5 and 21.7 kcal mol−1, respectively, to the crystal energy. The hydro­phobic methyl­ene groups occupy pockets in the framework. PMID:28217349

  8. Crystal structure of carnidazole form II from synchrotron X-ray powder diffraction: structural comparison with form I, the hydrated form and the low energy conformations in vacuo.

    PubMed

    de Armas, Héctor Novoa; Peeters, Oswald M; Blaton, Norbert; Van den Mooter, Guy; De Ridder, Dirk J A; Schenk, Henk

    2006-10-01

    The crystal structure of carnidazole form II, O-methyl [2-(2-methyl-5-nitro-1H-imidazole-1-yl)ethyl]thiocarbamate, has been determined using synchrotron X-ray powder diffraction in combination with simulated annealing and whole profile pattern matching, and refined by the Rietveld method. For structure solution, 12 degrees of freedom were defined: one motion group and six torsions. Form II crystallizes in space group P2(1)/n, Z=4, with unit cell parameters after Rietveld refinement: a=13.915(4), b=8.095(2), c=10.649(3) A, beta=110.83(1) degrees, and V=1121.1(5) A3. The two polymorphic forms, as well as the hydrate, crystallize in the monoclinic space group P2(1)/n having four molecules in the cell. In form II, the molecules are held together by forming two infinite zig-zag chains via hydrogen bonds of the type N--H...N, the same pattern as in form I. A conformational study of carnidazole, at semiempirical PM3 level, was performed using stochastic approaches based on modification of the flexible torsion angles. The values of the torsion angles for the molecules of the two polymorphic forms and the hydrate of carnidazole are compared to those obtained from the conformational search. Form I and form II are enantiotropic polymorphic pairs this agrees with the fact that the two forms are conformational polymorphs.

  9. The use of in situ powder X-ray diffraction in the investigation of dolomite as a potential reversible high-temperature CO2 sorbent.

    PubMed

    Readman, Jennifer E; Blom, Richard

    2005-03-21

    We report the use of gas sorption experiments and in situ powder X-ray diffraction to study the use of dolomite (MgCa(CO3)2) as a potential reversible high-temperature CO2 sorbent. When dolomite is treated in inert atmosphere at 900 degrees C it decomposes into separate CaO and MgO rich phases and dolomite is never reformed pon CO2 sorption. Gas sorption studies show that the calcined dolomite can go through several cycles of CO2 sorption/desorption in a reversible manner, however, the sorption capacity diminishes with each cycle. Only calcium seems to be involved in the CO2 sorption, while MgO acts as a carrier for the calcium phase. Some evidence of magnesium contamination of the calcium phase was found. BET and SEM measurements were carried out to find differences in the surface area/particle morphology that may explain similarities in the sorption capacities of dolomite and calcite (CaCO3).

  10. Thermal expansion and cation partitioning of MnFe2O4 (Jacobsite) from 1.6 to 1276 K studied by using neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Levy, Davide; Pastero, Linda; Hoser, Andreas; Viscovo, Gabriele

    2015-01-01

    MnFe2O4 is a low-cost and stable magnetic spinel ferrite. In this phase, the influence of the inversion degree on the magnetic properties is still not well understood. To understand this relationship, Mn-ferrite was synthesized by a chemical co-precipitation method modified in our laboratory and studied by using the Neutron Powder Diffraction from 1.6 K to 1243 K. A full refinement of both crystal and magnetic structures was performed in order to correlate the high-temperature cation partitioning, the Curie transition and the structure changes of the Mn-ferrite. In this work three main temperature intervals are detected, characterized by different Mn-ferrite behaviors: first, ranging from 1.6 K to 573 K, where MnFe2O4 is magnetic; second, from 573 K to 623 K, where MnFe2O4 becomes paramagnetic without cation partitioning; and lastly, from 673 K to 1243 K, where cation partitioning occurs.

  11. Crystal structure of α- and β-Na{sub 2}U{sub 2}O{sub 7}: From Rietveld refinement using powder neutron diffraction data

    SciTech Connect

    IJdo, D.J.W. Akerboom, S.; Bontenbal, A.

    2015-01-15

    The crystal structures of α- and β-Na{sub 2}U{sub 2}O{sub 7} have been determined from neutron powder diffraction. At 293 K, the compound α-Na{sub 2}U{sub 2}O{sub 7} has a monoclinic unit cell, space group P2{sub 1}/a, with a=12.7617(14) Å, b=7.8384(10) Å, c=6.8962(9) Å, β=111.285(9)°, and Z=4. At 773 K, β-Na{sub 2}U{sub 2}O{sub 7} is also monoclinic, space group C2/m, with a=12.933(1) Å, b=7.887(1) Å, c=6.9086(8) Å, β=110.816(10)°, and Z=4. The structures can be described by layers U{sub 2}O{sub 7}{sup 2−} built from corner linked deformed UO{sub 6} octahedra with pentagonal UO{sub 7} bipyramids in between linked with common edges to each other and to the octahedra. The Na atoms occupy the interlayer space. The Na{sub 2}U{sub 2}O{sub 7} layers are similar as in K{sub 2}U{sub 2}O{sub 7}, but with a different stacking sequence of the layers. The layers in β-Na{sub 2}U{sub 2}O{sub 7} are more symmetric. The relationship with the compounds A{sub 2}U{sub 2}O{sub 7} (A=K, Rb, and Cs) is discussed. - Graphical abstract: The U{sub 2}O{sub 7} layer of α-Na{sub 2}U{sub 2}O{sub 7} (left) at 293 K and of β-Na{sub 2}U{sub 2}O{sub 7} (right) at 773 K determined by neutron diffraction. Some Na atoms between the layers are visible. - Highlights: • Na{sub 2}U{sub 2}O{sub 7} has been prepared by means of a solid state reaction. • The structure has been determined using neutron diffraction. • At 293 K, the compound adopts a monoclinic structure with space group P2{sub 1}/a. • The structure at 773 K is closely related, and is described in the space group C2/m.

  12. Temperature- and moisture-dependent studies on alunogen and the crystal structure of meta-alunogen determined from laboratory powder diffraction data.

    PubMed

    Kahlenberg, Volker; Braun, Doris E; Krüger, Hannes; Schmidmair, Daniela; Orlova, Maria

    2017-01-01

    Starting from a synthetic sample with composition Al2(SO4)3·16.6H2O, the high-temperature- and moisture-dependent behavior of alunogen has been unraveled by TGA measurements, in situ powder X-ray diffraction as well as by gravimetric moisture sorption/desorption studies. Heating experiments using the different techniques show that alunogen undergoes a first dehydration process already starting at temperatures slightly above 40 °C. The crystalline product of the temperature-induced dehydration corresponds to the synthetic equivalent of meta-alunogen and has the following chemical composition: Al2(SO4)3·13.8H2O or Al2(SO4)3(H2O)12·1.8H2O. At 90 °C a further reaction can be monitored resulting in the formation of an X-ray amorphous material. The sequence of "amorphous humps" in the patterns persists up to 250 °C, where a re-crystallization process is indicated by a sudden appearance of a larger number of sharp Bragg peaks. Phase analysis confirmed this compound to be anhydrous Al2(SO4)3. Furthermore, meta-alunogen can be also obtained from alunogen at room temperature when stored at relative humidities (RH) lower than 20 %. The transformation is reversible, however, water sorption of meta-alunogen to alunogen and the corresponding desorption reaction show considerable hysteresis. For RH values above 80 %, deliquescence of the material was observed. Structural investigations on meta-alunogen were performed using a sample that has been stored at dry conditions (0 % RH) over phosphorus pentoxide. Powder diffraction data were acquired on an in-house high-resolution diffractometer in transmission mode using a sealed glass capillary as sample holder. Indexing resulted in a triclinic unit cell with the following lattice parameters: a = 14.353(6) Å, b = 12.490(6) Å, c = 6.092(3) Å, α = 92.656(1)°, β = 96.654(1)°, γ = 100.831(1)°, V = 1062.8(8) Å(3) and Z = 2. These data correct earlier findings suggesting an orthorhombic cell. Ab

  13. Temperature- and moisture-dependent studies on alunogen and the crystal structure of meta-alunogen determined from laboratory powder diffraction data

    NASA Astrophysics Data System (ADS)

    Kahlenberg, Volker; Braun, Doris E.; Krüger, Hannes; Schmidmair, Daniela; Orlova, Maria

    2017-02-01

    Starting from a synthetic sample with composition Al2(SO4)3·16.6H2O, the high-temperature- and moisture-dependent behavior of alunogen has been unraveled by TGA measurements, in situ powder X-ray diffraction as well as by gravimetric moisture sorption/desorption studies. Heating experiments using the different techniques show that alunogen undergoes a first dehydration process already starting at temperatures slightly above 40 °C. The crystalline product of the temperature-induced dehydration corresponds to the synthetic equivalent of meta-alunogen and has the following chemical composition: Al2(SO4)3·13.8H2O or Al2(SO4)3(H2O)12·1.8H2O. At 90 °C a further reaction can be monitored resulting in the formation of an X-ray amorphous material. The sequence of "amorphous humps" in the patterns persists up to 250 °C, where a re-crystallization process is indicated by a sudden appearance of a larger number of sharp Bragg peaks. Phase analysis confirmed this compound to be anhydrous Al2(SO4)3. Furthermore, meta-alunogen can be also obtained from alunogen at room temperature when stored at relative humidities (RH) lower than 20 %. The transformation is reversible, however, water sorption of meta-alunogen to alunogen and the corresponding desorption reaction show considerable hysteresis. For RH values above 80 %, deliquescence of the material was observed. Structural investigations on meta-alunogen were performed using a sample that has been stored at dry conditions (0 % RH) over phosphorus pentoxide. Powder diffraction data were acquired on an in-house high-resolution diffractometer in transmission mode using a sealed glass capillary as sample holder. Indexing resulted in a triclinic unit cell with the following lattice parameters: a = 14.353(6) Å, b = 12.490(6) Å, c = 6.092(3) Å, α = 92.656(1)°, β = 96.654(1)°, γ = 100.831(1)°, V = 1062.8(8) Å3 and Z = 2. These data correct earlier findings suggesting an orthorhombic cell. Ab-initio structure solution in

  14. Temperature- and moisture-dependent studies on alunogen and the crystal structure of meta-alunogen determined from laboratory powder diffraction data

    NASA Astrophysics Data System (ADS)

    Kahlenberg, Volker; Braun, Doris E.; Krüger, Hannes; Schmidmair, Daniela; Orlova, Maria

    2016-09-01

    Starting from a synthetic sample with composition Al2(SO4)3·16.6H2O, the high-temperature- and moisture-dependent behavior of alunogen has been unraveled by TGA measurements, in situ powder X-ray diffraction as well as by gravimetric moisture sorption/desorption studies. Heating experiments using the different techniques show that alunogen undergoes a first dehydration process already starting at temperatures slightly above 40 °C. The crystalline product of the temperature-induced dehydration corresponds to the synthetic equivalent of meta-alunogen and has the following chemical composition: Al2(SO4)3·13.8H2O or Al2(SO4)3(H2O)12·1.8H2O. At 90 °C a further reaction can be monitored resulting in the formation of an X-ray amorphous material. The sequence of "amorphous humps" in the patterns persists up to 250 °C, where a re-crystallization process is indicated by a sudden appearance of a larger number of sharp Bragg peaks. Phase analysis confirmed this compound to be anhydrous Al2(SO4)3. Furthermore, meta-alunogen can be also obtained from alunogen at room temperature when stored at relative humidities (RH) lower than 20 %. The transformation is reversible, however, water sorption of meta-alunogen to alunogen and the corresponding desorption reaction show considerable hysteresis. For RH values above 80 %, deliquescence of the material was observed. Structural investigations on meta-alunogen were performed using a sample that has been stored at dry conditions (0 % RH) over phosphorus pentoxide. Powder diffraction data were acquired on an in-house high-resolution diffractometer in transmission mode using a sealed glass capillary as sample holder. Indexing resulted in a triclinic unit cell with the following lattice parameters: a = 14.353(6) Å, b = 12.490(6) Å, c = 6.092(3) Å, α = 92.656(1)°, β = 96.654(1)°, γ = 100.831(1)°, V = 1062.8(8) Å3 and Z = 2. These data correct earlier findings suggesting an orthorhombic cell. Ab-initio structure solution in

  15. Structural characterization of iron oxide/hydroxide nanoparticles in nine different parenteral drugs for the treatment of iron deficiency anaemia by electron diffraction (ED) and X-ray powder diffraction (XRPD).

    PubMed

    Fütterer, S; Andrusenko, I; Kolb, U; Hofmeister, W; Langguth, P

    2013-12-01

    Drug products containing iron oxide and hydroxide nanoparticles (INPs) are important for the treatment of iron deficiency anaemia. Pharmaceuticals prepared by the complexation of different kinds of INPs and carbohydrates have different physicochemical and biopharmaceutic characteristics. The increasing number of parenteral non-biological complex drugs (NBCD) containing iron requires physicochemical methods for characterization and enabling of cross comparisons. In this context the structure and the level of crystallinity of the iron phases may be connected to the in vitro and in vivo dissolution rates, which etiologically determine the therapeutic and toxic effects. X-ray powder diffraction (XRPD) and electron diffraction (ED) methods were used in order to investigate the nine different parenteral iron formulations Ferumoxytol (Feraheme(®)), sodium ferric gluconate sucrose (Ferrlecit(®)), iron sucrose (Venofer(®)), low molecular weight iron dextran (CosmoFer(®)), low molecular weight iron dextran (Infed(®)), high molecular weight iron dextran (Ironate(®)), high molecular weight iron dextran (Dexferrum(®)), iron carboxymaltose (Ferinject(®)) and iron isomaltoside 1000 (Monofer(®)). The iron phase in CosmoFer(®), Ferinject(®), Monofer(®), Infed(®), Ironate(®) and Dexferrum(®) was identified as Akaganéite/Akaganéite-like (β-FeOOH), with low amounts of chloride. By combining results of both methods the iron oxide in Feraheme(®) was identified as Magnetite (Fe3O4) with spinel-like structure. Ferrlecit(®) and Venofer(®) were difficult to analyze due to the low degree of crystallinity, but the iron phase seems to fit Lepidocrocite/Lepidocrocite-like (γ-FeOOH) or an amorphous kind of structure. The structural information on the type of iron oxide or hydroxide together with the particle size allows predicting the stability of the different complexes including their labile iron content. The combination of ED and XRPD methods is a very helpful approach

  16. Combustion front dynamics in the combustion synthesis of refractory metal carbides and di-borides using time-resolved X-ray diffraction.

    PubMed

    Wong, Joe; Larson, E M; Waide, P A; Frahm, R

    2006-07-01

    A compact diffraction-reaction chamber, using a 2-inch photodiode array detector, has been employed to investigate the chemical dynamics at the combustion front of a selected series of refractory metal carbides and di-borides from their constituent element reactants as well as binary products from B4C as a reactant. These systems are denoted as (i) M + C --> MC; (ii) M + 2B --> MB2; and (iii) 3M + B4C --> 2MB2 + MC, where M = Ti, Zr, Nb, Hf or Ta. Time-resolved X-ray diffraction using intense synchrotron radiation at frame rates up to 10 frames s(-1) (or 100 ms frame(-1)) was employed. The combustion reactions were found to complete within 200-400 ms. In contrast to the Ta + C --> TaC combustion system studied earlier, in which a discernible intermediate sub-carbide phase was first formed, reacted further and disappeared to yield the final TaC product, no intermediate sub-carbide or sub-boride was detected in the current systems. Combustion for the Ti, Zr and Hf systems involved a liquid phase, in which the adiabatic temperatures Tad are well above the melting points of the respective reactant metals and have a typical combustion front velocity of 5-6 mm s(-1). The Nb and Ta systems have lower Tad, involving no liquid phase. These are truly solid combustion systems and have a lower combustion front velocity of 1-2 mm s(-1). The current study opens up a new avenue to chemical dynamics and macrokinetic investigations of high-temperature solid-state reactions.

  17. Direct Observations of Phase Transitions in Ti-6Al-4V Alloy Transient Welds using Time Resolved X-Ray Diffraction

    SciTech Connect

    Elmer, J W; Palmer, T A; Babu, S S; Zhang, W; Debroy, T

    2003-11-11

    Time Resolved X-Ray Diffraction (TRXRD) experiments were used to directly observe phase transformations occurring during gas tungsten arc spot welding of Ti-6Al-4V. These in-situ x-ray diffraction experiments tracked the evolution of the {alpha} {yields} {beta} {yields} L {yields} {beta} {yields} {alpha}/{alpha}{prime} phase transformation sequence in real time during rapid weld heating and cooling. Three different weld locations were examined, providing kinetic information about phase transformations in the fusion zone (FZ) and heat affected zone (HAZ) under different heating and cooling rates and at different temperatures. The TRXRD data were further coupled with the results of thermodynamic calculations of phase equilibria and numerical modeling to compute the weld temperatures. The results suggest that significant superheat is required above the {beta} transus temperature to complete the {alpha} {yields} {beta} transformation at all locations during weld heating, and that the amount of superheat decreases with distance from the center of the weld where the heating rates are lower. Johnson-Mehl-Avrami modeling of the weld heating kinetics produced a set of parameters that allowed the prediction of the {alpha} {yields} {beta} phase transformation rate at each location, but were not successful in determining a definitive mechanism for the transformation. The {beta} {yields} {alpha} transformation during weld cooling in the HAZ was shown to initiate at the {beta} transus temperature and reach completion below the Ms temperature, producing substantial {alpha}{prime}martensite. In the FZ, the {beta} {yields} {alpha} transformation during weld cooling was shown to initiate below the Ms temperature, and to completely transform the microstructure to {alpha}{prime} martensite.

  18. Analysis of the average poly-cyclic aromatic unit in a meta-anthracite coal using conventional x-ray powder diffraction and intensity separation methods

    SciTech Connect

    Wertz, D.L.; Bissell, M.

    1994-12-31

    X-ray characterizations of coals and coal products have occurred for many years. Hirsch and Cartz measured the diffraction from several coals over the reciprocal space region from s = 0.12 {angstrom}{sup -1} to 7.5 {angstrom}{sup -1} where s = (4{pi}/{lambda}) sin{Theta}. In these studies, a 9 cm powder camera was used to study the high angle region, and a transmission type focusing camera equipped with a LiF monochromator was used for the low angle measurements. They reported that the height of the graphene peak measured for each coal is proportional to the % carbon in the coals. Hirsch also suggested that the ontyberem anthracite has a lamellar diameter of ca. 16 {angstrom} corresponding to an aromatic lamellae of ca. C{sub 87}. For coals with lower carbon content, Hirsch proposed much smaller lamellae; C{sub 19} for a coal with 80% carbon, and C{sub 24} for a coal with 89% carbon. The subject coal for this study is a meta-anthracite which was derived from the Portsmouth, RI mine. The Narragansett Basin contains anthracite and meta-anthracite coals of Pennsylvanian Age. The Basin was a techtonically active non-marine coal-forming basin which has been impacted by several tectonic events. Because of the importance placed by coal scientists no correctly characterizing the nature of the micro-level structural cluster(s) in coals and because of improvements in both x-ray experimentation capabilities and computing power, we have measured the x-ray diffraction and scattering produced from irradiation of this meta-anthracite coal which contains about 94% aromatic carbon. The goal of our study is to determine the intra-planar, and where possible, inter-planar structural details of coals. To accomplish this goal we have utilized the methods normally used for the molecular analysis of non-crystalline condensed phases such as liquids, solutions, and amorphous solids. Reported herein are the results obtained from the high angle x-ray analysis of this coal.

  19. Pulsed supercritical synthesis of anatase TiO2 nanoparticles in a water-isopropanol mixture studied by in situ powder X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Eltzholtz, Jakob Rostgaard; Tyrsted, Christoffer; Jensen, Kirsten Marie Ørnsbjerg; Bremholm, Martin; Christensen, Mogens; Becker-Christensen, Jacob; Iversen, Bo Brummerstedt

    2013-02-01

    A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania nanoparticles were synthesized in a 50/50 mixture of water and isopropanol near and above the critical point of water (P = 250 bar, T = 300, 350, 400, 450, 500 and 550 °C). The evolution of the reaction product was followed by sequentially recording PXRD patterns with a time resolution of less than two seconds. The crystallite size of titania is found to depend on both temperature and residence time, and increasing either parameter leads to larger crystallites. A simple adjustment of either temperature or residence time provides a direct method for gram scale production of anatase nanoparticles of average crystallite sizes between 7 and 35 nm, thus giving the option of synthesizing tailor-made nanoparticles. Modeling of the in situ growth curves using an Avrami growth model gave an activation energy of 66(19) kJ mol-1 for the initial crystallization. The in situ PXRD data also provide direct information about the size dependent macrostrain in the nanoparticles and with decreasing crystallite size the unit cell contracts, especially along the c-direction. This agrees well with previous ex situ results obtained for hydrothermal synthesis of titania nanoparticles.A new step in supercritical nanoparticle synthesis, the pulsed supercritical synthesis reactor, is investigated in situ using synchrotron powder X-ray diffraction (PXRD) to understand the formation of nanoparticles in real time. This eliminates the common problem of transferring information gained during in situ studies to subsequent laboratory reactor conditions. As a proof of principle, anatase titania

  20. Ultrafast time-resolved electron diffraction revealing the nonthermal dynamics of near-UV photoexcitation-induced amorphization in Ge2Sb2Te5

    PubMed Central

    Hada, Masaki; Oba, Wataru; Kuwahara, Masashi; Katayama, Ikufumi; Saiki, Toshiharu; Takeda, Jun; Nakamura, Kazutaka G.

    2015-01-01

    Because of their robust switching capability, chalcogenide glass materials have been used for a wide range of applications, including optical storages devices. These phase transitions are achieved by laser irradiation via thermal processes. Recent studies have suggested the potential of nonthermal phase transitions in the chalcogenide glass material Ge2Sb2Te5 triggered by ultrashort optical pulses; however, a detailed understanding of the amorphization and damage mechanisms governed by nonthermal processes is still lacking. Here we performed ultrafast time-resolved electron diffraction and single-shot optical pump-probe measurements followed by femtosecond near-ultraviolet pulse irradiation to study the structural dynamics of polycrystalline Ge2Sb2Te5. The experimental results present a nonthermal crystal-to-amorphous phase transition of Ge2Sb2Te5 initiated by the displacements of Ge atoms. Above the fluence threshold, we found that the permanent amorphization caused by multi-displacement effects is accompanied by a partial hexagonal crystallization. PMID:26314613