Fluctuation X-ray Microscopy for Measuring Medium-Range Order

ABSTRACTMany x-ray techniques exist to probe long- and short-range order in matter, in real space by imaging and in reciprocal space by diffraction and scattering. However, measuring mediumrange order (MRO) in disordered materials is a long-standing problem. Based on fluctuation electron microscopy, which was applied successfully to the understanding of MRO in amorphous materials, we have developed fluctuation x-ray microscopy (FXM). This novel approach offers quantitative insight into medium-range correlations in materials at nanometer and larger length scales. It examines spatially resolved fluctuations in the intensity of a series of x-ray speckle patterns. The speckle variance depends on higher order correlations that are more sensitive to MRO. Systematically measuring the speckle variance as function of the momentum transfer and x-ray illumination size produces a fluctuation map that contains information about the degree of MRO and the correlation length. This approach can be used for the exploration of MRO and subtle spatial structural changes in a wide range of disordered materials from soft condensed matter to nanowire arrays, semiconductor quantum dot arrays and magnetic materials. It will also help us to understand the mechanisms of order-disorder transitions and may lead to control of ordering, which is important in developing ordered structures tailored for particular applications. A theory for FXM and preliminary experimental results from polystyrene latex spheres are discussed in this paper.

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Fluctuation Microscopy: What is it?

Microscopy Today ◽

10.1017/s1551929500053761 ◽

2005 ◽

Vol 13 (5) ◽

pp. 20-21 ◽

Cited By ~ 5

Author(s):

Michael M. J. Treacy

Keyword(s):

Amorphous Materials ◽

Range Order ◽

Disordered Materials ◽

Atomic Ordering ◽

Thin Sample ◽

Length Scales ◽

Medium Range Order ◽

Medium Range ◽

Fluctuation Microscopy

Fluctuation microscopy is the enigmatic name given to an otherwise straightforward technique for studying medium range order in highly disordered materials. By medium range, we mean atomic ordering at length scales within the range 0.5-2.0 nm, where traditional imaging and diffraction techniques have the most difficulty detecting structural correlations in amorphous materials. Puzzlement over fluctuation microscopy generally arises not because of the "microscopy" part of the name, but because of the "fluctuation" part. What, exactly, is fluctuating? And, why does it fluctuate?The fluctuations are simply the variations in scattering between small sub-volumes within a thin sample. These are usually not timevarying fluctuations (although they could be), but instead they are the position-varying fluctuations in local diffraction.

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Revealing ordering and structural changes at glass transition

MRS Proceedings ◽

10.1557/opl.2013.112 ◽

2013 ◽

Vol 1520 ◽

Cited By ~ 5

Author(s):

Michael I. Ojovan

Keyword(s):

Glass Transition ◽

Amorphous Materials ◽

Structural Changes ◽

Range Order ◽

Medium Range Order ◽

Disordered Structure ◽

Bonding System ◽

Liquid Transition ◽

Medium Range

ABSTRACTOrdering types in the disordered structure of amorphous materials and structural changes which occur at glass-liquid transition are discussed revealing medium range order and reduction of topological signature of bonding system.

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Medium-Range Order of Amorphous Silicon Germanium Alloys: Small-Angle X-Ray Scattering Study

Japanese Journal of Applied Physics ◽

10.1143/jjap.28.l1092 ◽

1989 ◽

Vol 28 (Part 2, No. 7) ◽

pp. L1092-L1095 ◽

Cited By ~ 18

Author(s):

Shin-ichi Muramatsu ◽

Toshikazu Shimada ◽

Hiroshi Kajiyama ◽

Kazufumi Azuma ◽

Takeshi Watanabe ◽

...

Keyword(s):

Amorphous Silicon ◽

Small Angle ◽

Silicon Germanium ◽

Range Order ◽

Medium Range Order ◽

X Ray ◽

X Ray Scattering ◽

Medium Range ◽

Scattering Study ◽

Amorphous Silicon Germanium

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Temperature dependence of amorphous magnesium carbonate structure studied by PDF and XAFS analyses

Scientific Reports ◽

10.1038/s41598-021-02261-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Gen-ichiro Yamamoto ◽

Atsushi Kyono ◽

Satoru Okada

Keyword(s):

Temperature Dependence ◽

Three Dimensional ◽

Magnesium Carbonate ◽

Range Order ◽

Edge Structure ◽

Medium Range Order ◽

X Ray ◽

Medium Range ◽

Mineral Trapping ◽

X Ray Absorption

AbstractMineral trapping through the precipitation of carbonate minerals is a potential approach to reduce CO2 accumulation in the atmosphere. The temperature dependence of amorphous magnesium carbonate (AMC), a precursor of crystalline magnesium carbonate hydrates, was investigated using synchrotron X-ray scattering experiments with atomic pair distribution function (PDF) and X-ray absorption fine structure analysis. PDF analysis revealed that there were no substantial structural differences among the AMC samples synthesized at 20, 60, and 80 °C. In addition, the medium-range order of all three AMC samples was very similar to that of hydromagnesite. Stirring in aqueous solution at room temperature caused the AMC sample to hydrate immediately and form a three-dimensional hydrogen-bonding network. Consequently, it crystallized with the long-range structural order of nesquehonite. The Mg K-edge X-ray absorption near-edge structure spectrum of AMC prepared at 20 °C was very similar to that of nesquehonite, implying that the electronic structure and coordination geometry of Mg atoms in AMC synthesized at 20 °C are highly similar to those in nesquehonite. Therefore, the short-range order (coordination environment) around the Mg atoms was slightly modified with temperature, but the medium-range order of AMC remained unchanged between 20 and 80 °C.

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High-Energy Small- and Wide-Angle X-Ray Scattering: A Versatile Tool for Materials Analysis

X-Rays in Mechanical Engineering Applications ◽

10.1115/imece2004-62458 ◽

2004 ◽

Author(s):

Jonathan Almer

Keyword(s):

High Energy ◽

Real Space ◽

Wide Angle ◽

X Ray ◽

Study Materials ◽

X Ray Scattering ◽

Angle Scattering ◽

Wide Range ◽

Versatile Tool ◽

Ray Scattering

Acquisition of microstructural information during realistic service conditions is an ongoing need for fundamental materials insight and computational input. In addition, for engineering applications it is often important to be able to study materials over a wide range of penetration depths, from the surface to bulk. In this presentation we discuss developments at the Sector 1-ID beamline of the Advanced Photon Source (APS) to utilize high-energy x-ray scattering for such studies. The use of high-energies (~80 keV) provides a highly penetrating probe, with sampling depths up to several mm in most materials. Through the development and use of high-energy optics, we can perform both small- and wide-angle scattering (SAXS/WAXS), to probe a large range of sample dimensions in reciprocal space (ranging from Angstroms to hundreds of nanometers), with real space resolutions ranging from microns to mm.

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In Situ Studies of the Processing of Sol-Gel Produced Amorphous Materials Using Xanes, Saxs and Curved Image Plate XRD

MRS Proceedings ◽

10.1557/proc-590-119 ◽

1999 ◽

Vol 590 ◽

Author(s):

DM Pickup ◽

G Mountjoy ◽

RJ Newport ◽

ME Smith ◽

GW Wallidge ◽

...

Keyword(s):

Amorphous Materials ◽

Sol Gel ◽

Heat Treatments ◽

Silica Gels ◽

Ex Situ ◽

High Count ◽

X Ray ◽

Image Plate ◽

Wide Range

ABSTRACTSol-gel produced mixed oxide materials have been extensively studied using conventional, ex situ structural techniques. Because the structure of these materials is complex and dependent on preparation conditions, there is much to be gained from in situ techniques: the high brightness of synchrotron x-ray sources makes it possible to probe atomic structure on a short timescale, and hence in situ. Here we report recent results for mixed titania- (and some zirconia-) silica gels and xerogels. Titania contents were in the range 8–18 mol%, and heat treatments up to 500°C were applied. The results have been obtained from intrinsically rapid synchrotron x-ray experiments: i) time-resolved small angle scattering, using a quadrant detector, to follow the initial stages of aggregation between the sol and the gel; ii) the use of a curved image plate detector in diffraction, which allowed the simultaneous collection of data across a wide range of scattering at high count rate, to study heat treatments; and iii) x-ray absorption spectroscopy to explore the effects of ambient moisture on transition metal sites.

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A scanning Kelvin probe for synchrotron investigations: thein situdetection of radiation-induced potential changes

Journal of Synchrotron Radiation ◽

10.1107/s0909049511047066 ◽

2011 ◽

Vol 19 (1) ◽

pp. 48-53 ◽

Cited By ~ 4

Author(s):

Bekir Salgin ◽

Dirk Vogel ◽

Diego Pontoni ◽

Heiko Schröder ◽

Bernd Schönberger ◽

...

Keyword(s):

High Performance ◽

Structural Changes ◽

Kelvin Probe ◽

X Ray ◽

Scanning Kelvin Probe ◽

Wide Range ◽

First Results ◽

Radiation Induced ◽

Set Up

A wide range of high-performance X-ray surface/interface characterization techniques are implemented nowadays at every synchrotron radiation source. However, these techniques are not always `non-destructive' because possible beam-induced electronic or structural changes may occur during X-ray irradiation. As these changes may be at least partially reversible, anin situtechnique is required for assessing their extent. Here the integration of a scanning Kelvin probe (SKP) set-up with a synchrotron hard X-ray interface scattering instrument for thein situdetection of work function variations resulting from X-ray irradiation is reported. First results, obtained on bare sapphire and sapphire covered by a room-temperature ionic liquid, are presented. In both cases a potential change was detected, which decayed and vanished after switching off the X-ray beam. This demonstrates the usefulness of a SKP forin situmonitoring of surface/interface potentials during X-ray materials characterization experiments.

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