Diffraction anomalous fine structure study of iron/iron oxide nanoparticles

2009 ◽  
Vol 42 (4) ◽  
pp. 642-648 ◽  
Author(s):  
Carlo Meneghini ◽  
Federico Boscherini ◽  
Luca Pasquini ◽  
Hubert Renevier
Keyword(s):  
Fine Structure ◽  
Local Structure ◽  
Structural Disorder ◽  
Structure Study ◽  
Nanocrystalline Powders ◽  
Oxide Shell ◽  
Iron Iron ◽  
Diffraction Peaks ◽  
Diffraction Patterns ◽  
High Degree

Diffraction anomalous fine structure is a recently developed technique which can provide a measurement of the local structure of a given element in a particular phase or crystallographic site. Most previous investigations have applied the technique to bulk solids, thin films, and nano-dots or wires on crystalline substrates. In this paper, the technique is applied to highly disordered nanometre-sized Fe/Fe oxide core–shell nanocrystalline powders, the diffraction patterns of which exhibit weak and greatly broadened diffraction peaks. Focusing on the oxide shell diffraction peaks, a qualitative analysis of the near-edge spectral region and a quantitative analysis of the extended energy region are provided; in particular, good quality fittings of the extended range spectra are obtained. The local structure is selectively probed around the tetrahedral and octahedral sites of the oxide shell, finding the presence of a high degree of structural disorder. This study demonstrates that diffraction anomalous fine structure can now be fruitfully applied to nanocrystalline powders.

scholarly journals Exafs Studies of Multilayer Interfaces

1988 ◽  
Vol 143 ◽  
Author(s):  
S. M. Heald ◽  
G. M. Lamble
Keyword(s):  
Fine Structure ◽  
Standing Wave ◽  
Structural Disorder ◽  
Interface Structure ◽  
X Ray ◽  
Absorption Fine ◽  
High Degree ◽  
X Ray Absorption ◽  
Multilayer Materials

AbstractImportant for the understanding of multilayer materials is a determination of their interface structure. The extended x-ray absorption fine structure (EXAFS) technique can be useful, particularly for interfaces with a high degree of structural disorder. This paper reviews the application of EXAFS to multilayers, and describes the standing wave enhancement of the EXAFS from multilayer interfaces. Examples are given for W-C and Ni- Ti multilayers.

Extended X-Ray Absorption Fine Structure Study on Local Structure around Fe Atoms in Fe/Ag Granular Materials

1994 ◽  
Vol 33 (Part 1, No. 7A) ◽  
pp. 4090-4093 ◽  
Author(s):  
Masaki Sakurai ◽  
Salah A. Makhlouf ◽  
Kenji Sumiyama ◽  
Kimio Wakoh ◽  
Kenji Suzuki
Keyword(s):  
Fine Structure ◽  
Granular Materials ◽  
Local Structure ◽  
Structure Study ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

An extended X-ray absorption fine structure study of amorphous and crystalline germanium

1981 ◽  
Vol 59 (7) ◽  
pp. 876-882 ◽  
Author(s):  
E. D. Crozier ◽  
A. J. Seary
Keyword(s):  
Fine Structure ◽  
Random Network ◽  
Structural Disorder ◽  
Structure Study ◽  
Additional Contribution ◽  
Many Body ◽  
X Ray ◽  
Absorption Fine ◽  
Body Potential ◽  
X Ray Absorption

Extended X-ray absorption fine structure (EXAFS) results are presented for amorphous and crystalline Ge at temperatures ranging from 83 to 1085 K. Specific tests for the detection of asymmetry in the distribution of atoms are examined. In amorphous Ge the distribution of nearest neighbours is found to be Gaussian. In crystalline Ge at the highest temperatures studied a small asymmetry in the distribution of nearest atoms, attributed to anharmonicity in the effective two-body potential, must be included explicitly in the EXAFS analysis to determine changes in nearest neighbour distances to an accuracy of ± 0.01 Å. The temperature dependence of the disorder parameter σ12 in crystalline Ge is found to obey an Einstein model, contrary to earlier work. The structure of amorphous Ge is found to be consistent with a continuous random network of distorted tetrahedra in which the dynamic contribution to σ12(T) is given by the same force-constant law as in crystalline Ge. The static structural disorder provides an additional contribution to a σ12(T) which decreases as the crystalline temperature is approached. Many-body contributions to the reduction of the amplitude of the EXAFS interference function in amorphous and crystalline Ge are also determined empirically.

Local structure study of dilute Er in III–V semiconductors by fluorescence EXAFS

1998 ◽  
Vol 5 (3) ◽  
pp. 1061-1063 ◽  
Author(s):  
H. Ofuchi ◽  
D. Kawamura ◽  
J. Tsuchiya ◽  
N. Matsubara ◽  
M. Tabuchi ◽  
...  
Keyword(s):  
Fine Structure ◽  
Rock Salt ◽  
Growth Temperature ◽  
Local Structure ◽  
Structure Study ◽  
Rock Salt Structure ◽  
X Ray ◽  
Local Structures ◽  
Salt Structure ◽  
X Ray Absorption

For understanding the luminescence of Er atoms in III–V semiconductors, OMVPE-grown InP doped with Er has been investigated by fluorescence EXAFS (extended X-ray absorption fine structure) in order to study the local structure around Er atoms. The local structures around the Er atoms doped in InP, with doping as dilute as 3 × 1012 Er atoms in a 1.5 mm × 1.0 mm spot, were successfully measured by fluorescence EXAFS. The EXAFS analysis revealed that the Er atoms doped in InP above 853 K (which showed low luminescence) formed the rock-salt-structure ErP, while the Er atoms doped in InP below 823 K (which showed high luminescence) substituted on the In site of InP. The dependence of the local structure on growth temperature was observed for the samples doped with 3 × 1012 atoms and 1.2 × 1013 atoms of Er.

Effects of annealing on the local structure of Fe and Co in CoFeB/MgO/CoFeB tunnel junctions: An extended x-ray-absorption fine structure study

2010 ◽  
Vol 96 (11) ◽  
pp. 112502 ◽  
Author(s):  
Abdul K. Rumaiz ◽  
J. C. Woicik ◽  
W. G. Wang ◽  
Jean Jordan-Sweet ◽  
G. H. Jaffari ◽  
...  
Keyword(s):  
Fine Structure ◽  
Local Structure ◽  
Tunnel Junctions ◽  
Structure Study ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption
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