Structural determinations of liquid semiconductors using extended X-ray absorption fine structure

1977 ◽  
Vol 55 (11) ◽  
pp. 1968-1974 ◽  
Author(s):  
E. D. Crozier ◽  
F. W. Lytle ◽  
D. E. Sayers ◽  
E. A. Stern
Keyword(s):  
Fine Structure ◽  
Disordered Systems ◽  
Structural Changes ◽  
Structural Information ◽  
Structural Rearrangement ◽  
Nearest Neighbour ◽  
X Ray ◽  
Absorption Fine ◽  
Amorphous States ◽  
X Ray Absorption

The extended fine structure in the X-ray absorption coefficient is dominated by the interference of the photoelectron scattered by atoms in the immediate neighbourhood of the atom which absorbs the X-ray photon and thus can provide structural information about ordered or disordered systems. In this paper it is demonstrated that Extended X-Ray Absorption Fine Structure (EXAFS) measurements can be made on liquid systems at high temperatures. The technique is illustrated with results for As2Se3 in the liquid and amorphous states for temperatures between 100 and 773 K. A Fourier analysis of the EXAFS data reveals that a major structural rearrangement does not occur in the nearest neighbour shell when As2Se3 is melted. However, small structural changes do occur at the melting point which, within the limitations of the present data, suggest a slight increase in the nearest neighbour As–Se distance, a decrease in the number of nearest neighbours, and a decrease in the nearest neighbour disorder term σ12.

X-ray absorption spectroscopy principles and practical use in materials analysis

2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Wolfgang Grünert ◽  
Konstantin Klementiev
Keyword(s):  
Fine Structure ◽  
Structural Analysis ◽  
Disordered Systems ◽  
Structural Information ◽  
Research Strategies ◽  
Edge Structure ◽  
X Ray ◽  
Absorption Fine ◽  
Wide Range ◽  
X Ray Absorption

AbstractThe X-ray Absorption Fine Structure (XAFS) with its subregions X-ray Absorption Near-edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) is a powerful tool for the structural analysis of materials, which is nowadays a standard component of research strategies in many fields. This review covers a wide range of topics related to its measurement and use: the origin of the fine structure, its analytical potential, derived from the physical basis, the environment for measuring XAFS at synchrotrons, including different measurement geometries, detection modes, and sample environments, e. g. for in-situ and operando work, the principles of data reduction, analysis, and interpretation, and a perspective on new methods for structure analysis combining X-ray absorption with X-ray emission. Examples for the application of XAFS have been selected from work with heterogeneous catalysts with the intention to demonstrate the strength of the method providing structural information about highly disperse and disordered systems, to illustrate pitfalls in the interpretation of results (e. g. by neglecting the averaged character of the information obtained) and to show how its merits can be further enhanced by combination with other methods of structural analysis and/or spectroscopy.

Structure study of the chalcogens and chalcogenides by X-ray absorption fine structure

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hiroyuki Ikemoto ◽  
Takafumi Miyanaga
Keyword(s):  
Fine Structure ◽  
Covalent Bond ◽  
Narrow Channel ◽  
Structure Study ◽  
Chain Structure ◽  
Covalent Bonds ◽  
X Ray ◽  
Absorption Fine ◽  
Amorphous States ◽  
X Ray Absorption

AbstractIn this review, we make a survey of the structure studies for the chalcogen elements and several chalcogenides in liquid, amorphous and nanosized state by using X-ray absorption fine structure (XAFS). The chalcogen elements have hierarchic structures; the chain structure constructed with the strong covalent bond as a primary structure, and the weaker interaction between chains as a secondary one. Existence of these two kinds of interactions induces exotic behaviors in the liquid, amorphous and nanosized state of the chalcogen and chalcogenides. XAFS is a powerful structure analysis technique for multi-element systems and the disordered materials, so it is suitable for the study of such as liquid, amorphous and nanosized mixtures. In section 2, the structures for the liquid state are discussed, which show the interesting semiconductor-metal transition depending on their temperatures and components. In section 3, the structure for the amorphous states are discussed. Especially, some of chalcogens and chalcogenides present the photostructural change, which is important industrial application. In section 4, the structures of nanosized state, nanoparticles and isolated chain confined into the narrow channel, are discussed. The studies of the nanoparticle and the isolated chain reveal the alternative role between the intrachain covalent bonds and the interchain interaction.

scholarly journals Nearest-neighbour distribution of distances in crystals from extended X-ray absorption fine structure

2017 ◽  
Vol 147 (4) ◽  
pp. 044503 ◽  
Author(s):  
P. Fornasini ◽  
R. Grisenti ◽  
M. Dapiaggi ◽  
G. Agostini ◽  
T. Miyanaga
Keyword(s):  
Fine Structure ◽  
Nearest Neighbour ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

scholarly journals Structural Change Analysis of Cerianite in Weathered Residual Rare Earth Ore by Mechanochemical Reduction Using X-Ray Absorption Fine Structure

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 267 ◽  
Author(s):  
Tatsuya Kato ◽  
Yuki Tsunazawa ◽  
Wenying Liu ◽  
Chiharu Tokoro
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Structural Change ◽  
Oxygen Vacancy ◽  
Structural Changes ◽  
Mechanochemical Reaction ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
Mechanochemical Reactions

Prolonged high-intensity grinding can modify the crystal structure of solid substances and/or induce chemical reaction, which is referred to as mechanochemical reaction. Such reactions can exert positive influences on hydrometallurgical processes, therefore, many researchers have applied mechanochemical reactions for metals dissolution from minerals. The mechanism of mechanochemical reaction has been investigated using solid analyses and simulations. Structural changes caused by mechanochemical reactions are not yet sufficiently clarified because the ground samples are amorphous. The objective of this study was to analyze structural changes of cerianite in weathered residual rare earth ore by mechanochemical reduction. The ore was ground by planetary ball milling for 10, 60 and 720 min. Structural change was analyzed by the X-ray absorption near-edge structure and extended x-ray absorption fine structure analysis at the cerium LIII- and K-edges. These analyses revealed that the structural change of cerianite in this ore induced by mechanochemical reduction involved oxygen vacancy production. The process of the oxygen vacancy formation was closely coupled with the quantum effect of localization–delocalization of the 4f electron of cerium.

scholarly journals Structural Change Analysis of Cerianite in Weathered Residual Rare Earth Ore by Mechanochemical Reduction Using X-ray Absorption Fine Structure

2019 ◽  
Author(s):  
Tatsuya Kato ◽  
Yuki Tsunazawa ◽  
Wenying Liu ◽  
Chiharu Tokoro
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Structural Change ◽  
Oxygen Vacancy ◽  
Structural Changes ◽  
Mechanochemical Reaction ◽  
Edge Structure ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Prolonged high-intensity grinding can modify the crystal structure of solid substances and/or induce chemical reaction, which is referred to as mechanochemical reaction. Such reactions can exert positive influences on hydrometallurgical processes, therefore, many researchers have applied mechanochemical reactions for metals dissolution from minerals. The mechanism of mechanochemical reaction has been investigated using solid analyses and simulations. Structural changes caused by mechanochemical reaction are not yet sufficiently clarified because the ground samples are amorphous. The objective of this study was to analyze structural changes of cerianite in weathered residual rare earth ore by mechanochemical reduction. Structural change was analyzed by x-ray absorption near-edge structure and extended x-ray absorption fine structure analysis at the cerium LIII- and K-edges. These analyses revealed that the structural change of cerianite in this ore induced by mechanochemical reduction involved oxygen vacancy production. The process of the oxygen vacancy formation was closely coupled with the quantum effect of localization–delocalization of the 4f electron of cerium.

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