X-ray Microdiffraction Study Research Articles

Ray Tracing Simulation of X-ray Microdiffraction Beamline on the Inverse Compton Source

This paper deals with the simulation of output beam parameters of the inverse Compton X-ray Source (ICS). The simulation takes into account the main parameters of the laser and electron beams, such as their pulse shapes, polarization properties as well as the angular and energy dispersion of the electrons. The layout of the presented ICS and X-ray optical beamline is dedicated to X-ray micro-diffraction studies. To maintain the axial symmetry of output X-ray beams at different photon energies, the beamline monochromator is based on a single crystal installed in the Borrmann transparency condition.

Distinct conformers of amyloid beta accumulate in the neocortex of patients with rapidly progressive Alzheimer's disease

Amyloid beta (Aβ) deposition in the neocortex is a major hallmark of Alzheimer's disease (AD), but the extent of deposition does not readily explain phenotypic diversity and rate of disease progression. The prion strain–like model of disease heterogeneity suggests the existence of different conformers of Aβ. We explored this paradigm using conformation-dependent immunoassay (CDI) for Aβ and conformation-sensitive luminescent conjugated oligothiophenes (LCOs) in AD cases with variable progression rates. Mapping the Aβ conformations in the frontal, occipital, and temporal regions in 20 AD patients with CDI revealed extensive interindividual and anatomical diversity in the structural organization of Aβ with the most significant differences in the temporal cortex of rapidly progressive AD. The fluorescence emission spectra collected in situ from Aβ plaques in the same regions demonstrated considerable diversity of spectral characteristics of two LCOs—quatroformylthiophene acetic acid and heptaformylthiophene acetic acid. Heptaformylthiophene acetic acid detected a wider range of Aβ deposits, and both LCOs revealed distinct spectral attributes of diffuse and cored plaques in the temporal cortex of rapidly and slowly progressive AD and less frequent and discernible differences in the frontal and occipital cortex. These and CDI findings indicate a major conformational diversity of Aβ accumulating in the neocortex, with the most notable differences in temporal cortex of cases with shorter disease duration, and implicate distinct Aβ conformers (strains) in the rapid progression of AD.

In-situ X-ray micro-diffraction study of the metal–insulator phase transition in VO$$_2$$ particles

In-situ X-ray micro-diffraction study of the metal–insulator phase transition in VO$$_2$$ particles

Localized strain profile in surface electrode array for programmable composite multiferroic devices

We investigate localized in-plane strains on the microscale, induced by arrays of biased surface electrodes patterned on piezoelectrics. Particular focus is given to the influence that adjacent electrode pairs have on one another to study the impact of densely packed electrode arrays. We present a series of X-ray microdiffraction studies to reveal the spatially resolved micrometer-scale strain distribution. The strain maps with micrometer-scale resolution highlight how the local strain profile in square regions up to 250 × 250 μm2 in size is affected by the surface electrodes that are patterned on ferroelectric single-crystal [Pb(Mg1/3Nb2/3)O3]x-[PbTiO3]1−x. The experimental measurements and simulation results show the influence of electrode pair distance, positioning of the electrode pair, including the angle of placement, and neighboring electrode pair arrangements on the strength and direction of the regional strain. Our findings are relevant to the development of microarchitected strain-mediated multiferroic devices. The electrode arrays could provide array-addressable localized strain control for applications including straintronic memory, probabilistic computing platforms, microwave devices, and magnetic-activated cell sorting platforms.

Synchrotron x-ray microdiffraction study of residual stresses in BaTiO3 films deposited at room temperature by aerosol deposition

The residual stress through the thickness of a BaTiO3 ceramic film deposited on steel substrate at room temperature with aerosol deposition has been analyzed using synchrotron x-ray microdiffraction. A gradient in stress distribution was evident through the film and the maximum biaxial compressive stress of −800 MPa was observed at the film-substrate interface. Heat-treatment was found to relax the internal compressive stress, due to thermal expansion mismatch between the film and substrate. Variation in ferroelectric response was correlated to the change in stress state by thermal treatment. This analysis is crucial for development of micro-and nanoelectronic devices with AD films.

Shear-induced precursors in polyethylene: An in-situ synchrotron radiation scanning X-ray microdiffraction study

Localized shear flow was imposed by pulling glass fiber in polyethylene (PE) melt below and above its equilibrium melting point (141.6 °C). Immediately after the cessation of shear, the structure around the fiber was investigated with in-situ synchrotron radiation scanning X-ray microdiffraction (SR-μSXRD), which had spot area of 4.2 × 4.5 μm2 and step size of 6 μm. Results indicate that crystalline precursors are induced below equilibrium melting point, as evidenced by the occurrence of crystalline diffractions. Whilst at temperature above equilibrium melting point, no crystalline diffraction is observed. SR-μSXRD measurements on the crystallization behaviors at 127 °C after shearing at 145 °C suggest that non-crystalline precursors are induced, which is supported by three evidences. (i) The occurrence of crystallization near the fiber surface implies shear-induced formation of precursors at 145 °C since the fiber has no ability to induce crystallization at quiescent condition; (ii) No crystalline diffraction is detected immediately after cessation of shear at 145 °C; (iii) The necessity of induction time for the precursors to transform into crystalline nuclei further demonstrates the non-crystalline nature of precursors. The concentration of precursors is observed to reduce with increasing shearing temperature, as evidenced by twisting degree of lamellar crystals after isothermally crystallized at 127 °C.

Cancrinite–vishnevite solid solution from Cinder Lake (Manitoba, Canada): crystal chemistry and implications for alkaline igneous rocks

AbstractThis paper presents a microbeam (electron microprobe, Raman spectroscopic and X-ray microdiffraction) study of cancrinite-group minerals of relevance to alkaline igneous rocks. A solid solution is known to exist between cancrinite and vishnevite with the principal substitutions being CO32- by SO42- and Ca for Na. In the present study, several intermediate members of the cancrinite–vishnevite series from a syenitic intrusion at Cinder Lake (Manitoba, Canada), were used to examine how chemical variations in this series affect their spectroscopic and structural characteristics. The Cinder Lake samples deviate from the ideal cancrinite-vishnevite binary owing to the presence of cation vacancies. The only substituent elements detectable by electron microprobe are K, Sr and Fe (0.03-0.70, 0-0.85 and 0-0.45 wt.% respective oxides). The following Raman bands are present in the spectra of these minerals: ∼631 cm-1 and ∼984-986 cm-1 [SO42- vibration modes]; ∼720-774 cm -1 and ∼1045-1060 cm -1 [CO32- vibration modes]; and ∼3540 cm -1 and 3591 cm -1 [H2O vibration modes]. Our study shows a clear relationship between the chemical composition and Raman characteristics of intermediate members of the cancrinite-vishnevite series, especially with regard to stretching modes of the CO32- and SO42- anions. From cancrinite-poor (Ccn65) to cancrinite-dominant (Ccn913) compositions, the SO42- vibration modes disappear from the Raman spectrum, giving way to CO32- modes. X-ray microdiffraction results show a decrease in unit-cell parameters towards cancrinite-dominant compositions: a = 12.664 (1) Å, c = 5.173(1) Å for vishnevite (Ccn22); a = 12.613 (1) Å, c = 5.132(1) Å for cancrinite (Ccn71). Our results demonstrate that Raman spectroscopy and X-ray microdiffraction are effective for in situ identification of microscopic grains of cancrinite-vishnevite where other methods (e.g. infrared spectroscopy) are inapplicable. The petrogenetic implications of cancrinite-vishnevite relations for tracing early- to late-stage evolution of alkaline magmas are discussed.

Finite Element Simulation and X-Ray Microdiffraction Study of Strain Partitioning in a Layered Nanocomposite

The depth-dependent strain partitioning across the interfaces in the growth direction of the NiAl/Cr(Mo) nanocomposite between the Cr and NiAl lamellae was directly measured experimentally and simulated using a finite element method (FEM). Depth-resolved X-ray microdiffraction demonstrated that in the as-grown state both Cr and NiAl lamellae grow along the 111 direction with the formation of as-grown distinct residual ~0.16% compressive strains for Cr lamellae and ~0.05% tensile strains for NiAl lamellae. Three-dimensional simulations were carried out using an implicit FEM. First simulation was designed to study residual strains in the composite due to cooling resulting in formation of crystals. Strains in the growth direction were computed and compared to those obtained from the microdiffraction experiments. Second simulation was conducted to understand the combined strains resulting from cooling and mechanical indentation of the composite. Numerical results in the growth direction of crystal were compared to experimental results confirming the experimentally observed trends.

Multiscale twin hierarchy in NiMnGa shape memory alloys with Fe and Cu

X-ray microdiffraction and scanning electron microscopy studies reveal 10M martensitic structure with a highly correlated multiscale twin hierarchy organization in NiMnGaFeCu shape memory alloys. High compatibility is found at the twin interfaces resulting in a highly correlated twinned lattice orientation across several laminate levels. The lattice unit cell is described as monoclinic I-centered with a=4.28Å, b=4.27Å, c=5.40Å, γ=78.5°. The modulation is found parallel to the b axis. Thin tapered needle-like lamellae and branching are observed near the twin boundaries.

X-ray micro-diffraction studies on biological samples at the BioCAT Beamline 18-ID at the Advanced Photon Source.

The small source sizes of third-generation synchrotron sources are ideal for the production of microbeams for diffraction studies of crystalline and non-crystalline materials. While several such facilities have been available around the world for some time now, few have been optimized for the handling of delicate soft-tissue specimens under cryogenic conditions. Here the development of a new X-ray micro-diffraction instrument at the Biophysics Collaborative Access Team beamline 18-ID at the Advanced Photon Source, and its use with newly developed cryo-diffraction techniques for soft-tissue studies, are described. The combination of the small beam sizes delivered by this instrument, the high delivered flux and successful cryo-freezing of rat-tail tendon has enabled us to record data to better than 4 Å resolution. The ability to quickly raster scan samples in the beam allows selection of ordered regions in fibrous samples for markedly improved data quality. Examples of results of experiments obtainable using this instrument are presented.

In situ X-ray microdiffraction study of deformation-induced phase transformation in 304 austenitic stainless steel

The traditional phenomenological crystallographic theory of martensitic transformations can only explain the change in the shape and crystallographic orientation of a martensitic plate within a single parent crystal. It cannot predict the detailed transformation scenario for preferred selections of martensitic variants or the contributions of partial slip/twinning to local lattice distortion, especially in polycrystalline metals/alloys that exhibit grain-to-grain interactions throughout deformation-induced phase transformation. In this work, synchrotron-based X-ray microdiffraction was used to characterize changes in the local orientation, morphology and strain distribution inside individual martensitic plates, as well as the effect of parent orientation on variant selection in bulk polycrystalline 304 stainless steel (SS) during in situ uniaxial tensile loading at the low temperature of 210K. It was directly verified that the martensitic phase transformation in the studied 304 SS has two stages, transformation first from γ to ε in the nanoscaled lamella, and then from ε to α′ in the microbands. The selection of martensitic variants was predicted well by the minimum strain work criterion. Phase transformation-induced stress relaxation was evidenced by fluctuations in the (111) plane lattice strain accompanied by a strain gradient inside the martensitic plate, indicating a load transfer from the transformed grain to its neighbor. This leads to good stress/strain accommodation, as stresses can dissipate from the matrix into martensitic plates and nearby grains. Our experimental observations and theoretical analysis provide an in-depth understanding of the micromechanical behavior, particularly phase transformation-induced plasticity enhancement, of metals containing the metastable phase.

X-ray micro-diffraction studies of heterogeneous interfaces between cementitious materials and geological formations

In the present study the challenge of analyzing complex micro X-ray diffraction (microXRD) patterns from cement–clay interfaces has been addressed. In order to extract the maximum information concerning both the spatial distribution and the crystal structure type associated with each of the many diffracting grains in heterogeneous, polycrystalline samples, an approach has been developed in which microXRD was applied to thin sections which were rotated in the X-ray beam. The data analysis, performed on microXRD patterns collected from a filled vein of a cement–clay interface from the natural analogue in Maqarin (Jordan), and a sample from a two-year-old altered interface between cement and argillaceous rock, demonstrate the potential of this method.

Cross-sectional X-ray microdiffraction study of a thick AlN film grown on a trench-patterned AlN/α-Al2O3 template

X-ray microdiffraction (XRMD) measurements using the AlN 22¯01 and 12¯10 Bragg reflections were performed to determine the cross-sectional distribution of local residual strain and twisting of crystal domains for a thick AlN film grown on a trench-patterned AlN/α-Al2O3 template. The distribution of the strain components in the [0001] and [112¯0] directions, which are perpendicular to the trench lines, was strongly influenced by the presence of voids caused by the trench pattern. The strains in the [11¯00] and [112¯0] directions determined using the two Bragg reflections were found to be significantly different, and this was shown to be the result of twisting of the crystal domains about the [0001] axis under the influence of anisotropic shear stress in the prismatic planes.

Structural Consequences of Ferroelectric Nanolithography

Domains of remnant polarization can be written into ferroelectrics with nanoscale precision using scanning probe nanolithography techniques such as piezoresponse force microscopy (PFM). Understanding the structural effects accompanying this process has been challenging due to the lack of appropriate structural characterization tools. Synchrotron X-ray nanodiffraction provides images of the domain structure written by PFM into an epitaxial Pb(Zr,Ti)O(3) thin film and simultaneously reveals structural effects arising from the writing process. A coherent scattering simulation including the superposition of the beams simultaneously diffracted by multiple mosaic blocks provides an excellent fit to the observed diffraction patterns. Domains in which the polarization is reversed from the as-grown state have a strain of up to 0.1% representing the piezoelectric response to unscreened surface charges. An additional X-ray microdiffraction study of the photon-energy dependence of the difference in diffracted intensity between opposite polarization states shows that this contrast has a crystallographic origin. The sign and magnitude of the intensity contrast between domains of opposite polarization are consistent with the polarization expected from PFM images and with the writing of domains through the entire thickness of the ferroelectric layer. The strain induced by writing provides a significant additional contribution to the increased free energy of the written domain state with respect to a uniformly polarized state.

X-ray Microdiffraction Study on Crystallinity of Micron-Sized Ge Films Selectively Grown on Si(001) Substrates

Using X-ray microdiffraction with a focused beam size of about 0.4 × 1.0 μm2, we investigated the strain relaxation and crystallinity of Ge thin films with areas of 2 × 2 μm2 and 250 × 250 μm2 grown on Si (001) substrates with SiO2 standard shallow-trench-isolation patterning. Results showed slower progression of strain relaxation in the 2 × 2 μm2 Ge films compared to the 250 × 250 μm2 films, which can be attributed to the effects of the SiO2 side walls during annealing.

X-ray Microdiffraction Study on Crystallinity of Micron-Sized Ge Films Selectively Grown on Si(001) Substrates

not Available.

Time-resolved x-ray microdiffraction studies of phase transformations during rapidly propagating reactions in Al/Ni and Zr/Ni multilayer foils

We showed how intermetallic formation reactions can be studied under rapid heating (106–107 K s−1) using x-ray microdiffraction with temporal resolution on microsecond time scales. Rapid heating was achieved by initiating an exothermic reaction in multilayer foils comprising alternating nanoscale layers of elemental metals. The reaction occurred in a front ∼100 μm wide which propagated across the foil at ∼1–10 m s−1. By using synchrotron x-rays focused to a small spot (60 μm diameter) and a fast pixel-array detector, we were able to track the evolution of phases in the reaction front during the initial heating transient, which occurred in approximately 1 ms, through cooling over a period of hundreds of milliseconds. In Al/Ni multilayer foils, the first phases to form were an Al-rich liquid and the cubic intermetallic AlNi (which likely formed by nucleation from the liquid). In foils of overall composition AlNi, this is the stable intermetallic and the only phase to form. In foils of composition Al3Ni2, during cooling we observed a peritectic reaction between AlNi and the remaining liquid to form Al3Ni2, which is the stable phase at room temperature and the final product of the reaction. This is in contrast to the sequence of phases under slow heating, where we observed formation of nonequilibrium Al9N2 first and do not observe formation of a liquid phase or the AlNi intermetallic. We also observed formation of an amorphous phase (along with crystalline ZrNi) during rapid heating of Zr/Ni multilayers, but in this system the temperature of the reaction front never reached the lowest liquidus temperature on the Zr–Ni phase diagram. This implies that the amorphous phase we observed was not a liquid arising from melting of a crystalline phase. We suggest instead that a Zr-rich amorphous solid formed due to solid-state interdiffusion, which then transformed to a supercooled liquid when the temperature exceeded the glass transition temperature. Formation of the supercooled liquid presumably facilitated continued rapid intermixing, which may be necessary to sustain a self-propagating reaction front in this system.

X-ray microdiffraction and EBSD study of FSP induced structural/phase transitions in a Ni-based superalloy

Severe plastic deformation during Friction Stir Processing (FSP) of an IN738 Ni-based superalloy was studied by means of X-ray polychromatic microdiffraction, EBSD, scanning electron and optical microscopies. Modeling of the physical properties and phase composition was also performed. Several distinct zones are formed during FSP including a stir zone (SZ), a thermal-mechanical affected zone (TMAZ) and a heat affected zone (HAZ). Each zone has distinct microstructure after FSP. The initial dendrite structure is preserved in the HAZ, while strengthening γ′-phase particles partially dissolve and coagulate. Plastic deformation of the base material dendrites takes place in the TMAZ and a large number of geometrically necessary dislocations are formed. The extent of deformation increases toward the SZ and the dendrite structure is completely destroyed in the SZ and replaced by a fine submicrocrystallinne microstructure.

Plastic deformation in Al (Cu) interconnects stressed by electromigration and studied by synchrotron polychromatic x-ray microdiffraction

We report here an in-depth synchrotron radiation based white beam x-ray microdiffraction study of plasticity in individual grains of an Al (Cu) interconnect during the early stage of electromigration (EM). The study shows a rearrangement of the geometrically necessary dislocations (GNDs) in bamboo typed grains during that stage. We find that about 90% of the GNDs are oriented so that their line direction is the closest to the current flow direction. In nonbamboo typed grains, the Laue peak positions shift, indicating that the grains rotate. An analysis in terms of force directions has been carried out and is consistent with observed EM induced grain rotation and bending.

X-ray microdiffraction and strain gradient crystal plasticity studies of geometrically necessary dislocations near a Ni bicrystal grain boundary

We compare experimental measurements of inhomogeneous plastic deformation in a Ni bicrystal with crystal plasticity simulations. Polychromatic X-ray microdiffraction, orientation imaging microscopy and scanning electron microscopy, were used to characterize the geometrically necessary dislocation distribution of the bicrystal after uniaxial tensile deformation. Changes in the local crystallographic orientations within the sample reflect its plastic response during the tensile test. Elastic strain in both grains increases near the grain boundary. Finite element simulations were used to understand the influence of initial grain orientation and structural inhomogeneities on the geometrically necessary dislocations arrangement and distribution and to understand the underlying materials physics.