Medium-range order in amorphous materials

1988 ◽  
Vol 106 (1-3) ◽  
pp. 291-300 ◽  
Author(s):  
Ladislav Červinka
Keyword(s):  
Amorphous Materials ◽  
Range Order ◽  
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.

Fluctuation Microscopy: A New Class of Microscopy Techniques for Probing Medium Range Order in Amorphous Materials

1998 ◽  
Vol 4 (S2) ◽  
pp. 702-703
Author(s):  
J. M. Gibson ◽  
M. M. J. Treacy ◽  
P. M. Voyles
Keyword(s):  
Long Range ◽  
Short Range ◽  
Amorphous Materials ◽  
Short Range Order ◽  
Nearest Neighbor ◽  
Range Order ◽  
Regular Tetrahedron ◽  
Long Range Order ◽  
Medium Range Order ◽  
Medium Range

Amorphous materials are devoid of periodic long range order, but at the nearest-neighbor level they possess a high degree of short-range order. In amorphous tetrahedral semiconductors, such as Si and Ge, this short-range order arises because each atom attempts to satisfy four bonds arranged as a regular tetrahedron. It is the rotations about each bond, from the second-nearest-neighbor outwards, that result in the loss of long-range order. It is apparent from modeling of amorphous materials, that there is considerable flexibility as to how rapidly the medium-range-order diminishes. The continuous random network (CRN) is a hypothetical tetrahedral extended structure wherein the atoms possess full four-connected coordination, but have minimal medium-range order. However, real amorphous materials infrequently exhibit true CRN-like topologies. Traditionally, diffraction has been used to study short- and medium-range order in amorphous materials. Assuming kinematical scattering, and that every atom has a similar environment, a radial distribution function (RDF) can be extracted which is sensitive only to the averaged atom pair-correlations out to ∼1 nm.

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.

scholarly journals Short and Medium-Range Order in Liquid Ternary Al80Co10Ni10, Al72.5Co14.5Ni13, and Al65Co17.5Ni17.5 Alloys

2010 ◽  
Vol 65 (1-2) ◽  
pp. 123-131 ◽  
Author(s):  
Oleksandr S. Roik ◽  
Oleksiy Samsonnikov ◽  
Volodymyr Kazimirov ◽  
Volodymyr Sokolskii
Keyword(s):  
Three Dimensional ◽  
Range Order ◽  
Ternary Alloys ◽  
X Ray Diffraction ◽  
Medium Range Order ◽  
Intermediate Range Order ◽  
Transition Metal Atoms ◽  
Medium Range ◽  
Three Dimensional Models ◽  
Co Alloys

AbstractA local short-to-intermediate range order of liquid Al80Co10Ni10, Al72.5Co14.5Ni13, and Al65Co17.5Ni17.5 alloys was examined by X-ray diffraction and the reverse Monte Carlo modelling. The comprehensive analysis of three-dimensional models of the liquid ternary alloys was performed by means of the Voronoi-Delaunay method. The existence of a prepeak on the S(Q) function of the liquid alloys is caused by medium range ordering of 3d-transition metal atoms in dense-packed polytetrahedral clusters at temperatures close to the liquidus. The non-crystalline clusters, represented by aggregates of pentagons that consist of good tetrahedra, and chemical short-range order lead to the formation of the medium range order in the liquid binary Al-Ni, Al-Co and ternary Al-Ni-Co alloys.

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