Revealing ordering and structural changes at glass transition

2013 ◽  
Vol 1520 ◽  
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.

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.

Glass-transition temperature: Relation between low-frequency dynamics and medium-range order

1995 ◽  
Vol 51 (13) ◽  
pp. 8606-8609 ◽  
Author(s):  
Claire Levelut ◽  
Nabil Gaimes ◽  
Ferial Terki ◽  
Gérard Cohen-Solal ◽  
Jacques Pelous ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Low Frequency ◽  
Range Order ◽  
Temperature Relation ◽  
Medium Range Order ◽  
Medium Range

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: 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.

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