scholarly journals Fluctuation Microscopy: What is it?

2005 ◽  
Vol 13 (5) ◽  
pp. 20-21 ◽  
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.

Medium-Range Order in Metallic Glasses Studied by Fluctuation Microscopy

2001 ◽  
Vol 7 (S2) ◽  
pp. 1260-1261
Author(s):  
Jing Li ◽  
Xiaofeng Gu ◽  
T. C. Hufnagel
Keyword(s):  
Metallic Glasses ◽  
Atomic Structure ◽  
Amorphous Semiconductors ◽  
Range Order ◽  
Disordered Materials ◽  
Specimen Preparation ◽  
Covalent Bonds ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Microscopy

Atomic structure on the 1-2 nm scale, often referred to as “medium-range order” (MRO), is of great importance for understanding the properties of disordered materials. It is, however, difficult to adequately characterize medium-range order. Fluctuation microscopy is a newly developed TEM technique that has successfully been employed to characterize MRO in amorphous semiconductors. The predominance of highly directional covalent bonds leads naturally to the presence of MRO in amorphous semiconductors. For metallic glasses, however, the bonding is primarily metallic and nondirectional. Thus, it is not readily apparent whether MRO would exist, or whether fluctuation microscopy is a useful tool for studying the structure of metallic glasses. in this work we report the use of fluctuation microscopy to identify differing degrees of MRO in Zr-based bulk metallic glasses; the MRO depends on the alloy content and the method of TEM specimen preparation.

Fluctuation X-ray Microscopy for Measuring Medium-Range Order

2004 ◽  
Vol 840 ◽  
Author(s):  
Lixin Fan ◽  
Ian McNulty ◽  
David Paterson ◽  
Michael M.J. Treacy ◽  
J. Murray Gibson
Keyword(s):  
Amorphous Materials ◽  
Structural Changes ◽  
Real Space ◽  
Polystyrene Latex ◽  
Range Order ◽  
Disordered Materials ◽  
X Ray ◽  
Novel Approach ◽  
Wide Range ◽  
Medium Range

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.

scholarly journals Revealing hidden medium-range order in amorphous materials using topological data analysis

2020 ◽  
Vol 6 (37) ◽  
pp. eabc2320
Author(s):  
Søren S. Sørensen ◽  
Christophe A. N. Biscio ◽  
Mathieu Bauchy ◽  
Lisbeth Fajstrup ◽  
Morten M. Smedskjaer
Keyword(s):  
Data Analysis ◽  
Amorphous Materials ◽  
Persistent Homology ◽  
Amorphous Solids ◽  
Range Order ◽  
Silicate Glasses ◽  
Topological Data Analysis ◽  
Medium Range Order ◽  
Medium Range ◽  
Topological Data

Despite the numerous technological applications of amorphous materials, such as glasses, the understanding of their medium-range order (MRO) structure—and particularly the origin of the first sharp diffraction peak (FSDP) in the structure factor—remains elusive. Here, we use persistent homology, an emergent type of topological data analysis, to understand MRO structure in sodium silicate glasses. To enable this analysis, we introduce a self-consistent categorization of rings with rigorous geometrical definitions of the structural entities. Furthermore, we enable quantitative comparison of the persistence diagrams by computing the cumulative sum of all points weighted by their lifetime. On the basis of these analysis methods, we show that the approach can be used to deconvolute the contributions of various MRO features to the FSDP. More generally, the developed methodology can be applied to analyze and categorize molecular dynamics data and understand MRO structure in any class of amorphous solids.

scholarly journals Fluctuation Microscopy Studies Of Aluminum Oxides Exposed To CL Ions

2002 ◽  
Vol 738 ◽  
Author(s):  
Xidong Chen ◽  
John Sullivan ◽  
Charles Barbour ◽  
Craig Johnson ◽  
Guangwen Zhou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Aluminum Oxide ◽  
Amorphous Material ◽  
Range Order ◽  
Aluminum Oxides ◽  
Medium Range Order ◽  
Microscopy Technique ◽  
Medium Range ◽  
Fluctuation Microscopy ◽  
Physical Changes

ABSTRACTFluctuation electron microscopy studies have been performed on several aluminum oxides exposed to different electrochemical conditions. Little is known about amorphous aluminum oxide structures and their relationship with their passivation behaviors. Corrosion studies have shown that exposure of aluminum oxide films to Cl ions in solution reduces the oxide's passivity, and this results in the onset of pitting corrosion. The physical changes that occur in the oxide as a result of Cl exposure have not been previously identified due to the difficulty in investigating the structure of this amorphous material. Fluctuation microscopy is a new electron microscopy technique that is able to detect the presence of medium range order structures in amorphous systems. In this paper, we will report fluctuation microscopy results on amorphous aluminum oxides that have been exposed to Cl ions in solution and compare them with oxides that have seen no electrolyte exposure or that have been exposed to electrolytes that do not contain Cl-,such as SO42- containing electrolytes. We will also compare the Cl-exposed oxides with oxides that have been implanted with Cl ions. The differences in pitting behaviors for these oxidesare consistent with our previous speculation on the effect of medium range order on the passivation behavior of aluminum oxides grown using ozone.

Fluctuation microscopy: a probe of medium range order

2005 ◽  
Vol 68 (12) ◽  
pp. 2899-2944 ◽  
Author(s):  
M M J Treacy ◽  
J M Gibson ◽  
L Fan ◽  
D J Paterson ◽  
I McNulty
Keyword(s):  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Fluctuation Microscopy

Fluctuation Microscopy Studies of Medium-range Order Structures in Amorphous Tetrahedral Semiconductors

2000 ◽  
Vol 638 ◽  
Author(s):  
Xidong Chen ◽  
J. Murray Gibson ◽  
John Sullivan ◽  
Tom Friedmann ◽  
Paul Voyles
Keyword(s):  
Thermal Annealing ◽  
Random Network ◽  
Carbon Films ◽  
Range Order ◽  
Diamond Like Carbon ◽  
Medium Range Order ◽  
Microscopy Technique ◽  
Medium Range ◽  
Annealing Effects ◽  
Fluctuation Microscopy

AbstractWe applied fluctuation microscopy technique to study medium-range order in tetrahedral semiconductor materials, such as amorphous silicon, amorphous diamond-like carbon films. It is shown that this technique is very sensitive to local structure changes in the medium range order and promises solutions to open questions that cannot be answered by current techniques. For asdeposited amorphous germanium and silicon, we previously identified a fine-grain para-crystallite structure [1, 2], which will be relaxed into a lower-energy continuous random network structure after thermal annealing. With the same fluctuation microscopy technique, we however found that thermal annealing introduces medium-range order in amorphous diamond-like carbon films. Future studies will be focused on modeling and systematic exploration of annealing effects.

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