Evolution of the Nanostructure of Giant Magnetoresistance Heterogeneous Alloys CoxAg1-x Upon Annealing

1995 ◽  
Vol 400 ◽  
Author(s):  
J. R. Regnard ◽  
C. Revenant-Brizard ◽  
B. Dieny ◽  
B. Mevel ◽  
J. Mimault
Keyword(s):  
Giant Magnetoresistance ◽  
Annealing Temperature ◽  
Liquid Nitrogen Temperature ◽  
Waller Factor ◽  
Total Electron Yield ◽  
Total Electron ◽  
X Ray ◽  
Debye Waller Factor ◽  
X Ray Absorption ◽  
Heterogeneous Alloys

AbstractHeterogeneous alloys CoxAg1-x with atomic concentrations x=0.20 and 0.35, presenting giant magnetoresistance properties, have been studied by Total Electron Yield X-ray absorption spectroscopy at liquid nitrogen temperature at the Co K edge after annealings at various temperatures. For both sample concentrations, the Co atoms are mainly in small filament agglomerates for the as-deposited and low temperature annealed samples (T<150°C). In this temperature range, the local Co atomic environment is very stable and disordered. A structural change has been detected by XANES and EXAFS analysis between the 250 and 400°C annealings. After a 400°C annealing during 10 min, the nanostructures evolve towards larger, more compact and well ordered granules. The Co-Co distance varies from 0.246 to 0.248 nm as the annealing temperature increases indicating that the small filament-shaped agglomerates are under strain in the Ag matrix. The Debye-Waller factor of the Co0.35Ag0.65 samples decreases continously as the annealing temperature increases, as this factor drops suddenly after a 250°C annealing for the Co0.20Ag0.80 sample. The Co agglomeration is steadily larger for the Co0.35Ag0.65 sample than for the Co0.20Ag0.80 one. The Co-Ag contribution is negligible for the Co0.35Ag0.65 sample, as it represents approximately one third of the nearest neighbors for the Co0.20Ag0.80 sample from the as-deposit up to a 250°C annealing stage.

Study on Effects of Heavy Ion Irradiation on CeO2 by Using Synchrotron Radiation X-Ray Absorption Spectroscopy -as a Simulation Study for Radiation Damage in High-Burnup Light Water Reactor Fuels-

2007 ◽  
Vol 1043 ◽  
Author(s):  
Hirotaka Ohno ◽  
Daiju Matsumura ◽  
Yasuo Nishihata ◽  
Jun'ichiro Mizuki ◽  
Norito Ishikawa ◽  
...  
Keyword(s):  
Thin Films ◽  
Synchrotron Radiation ◽  
Ion Irradiation ◽  
Heavy Ion ◽  
Waller Factor ◽  
X Ray ◽  
Debye Waller Factor ◽  
Atomic Distance ◽  
Exafs Measurement ◽  
X Ray Absorption

AbstractCeO2 thin films were irradiated with 200MeV Xe ions. Effects of the irradiation were studied by using Extended X-ray Absorption Fine Structure (EXAFS) measurement at SPring8 synchrotron radiation facility. EXAFS spectra for the irradiated thin films near the Ce K-edge show that the coordination number for oxygen atoms around Ce atom decreases and that the Ce-O Debye-Waller factor increases by the irradiation. The atomic distance between oxygen atom and Ce atom does not vary within the accuracy of EXAFS measurement. The effect of high density electronic excitation on the structure of CeO2 is discussed.

Short Range Order Structure Around Oxygen Atoms in the Superconductor Y-Ba-Cu-O

1987 ◽  
Vol 99 ◽  
Author(s):  
S. C. Woronick ◽  
W. Ng ◽  
A. Krol ◽  
B. X. Yang ◽  
Y. H. Kao ◽  
...  
Keyword(s):  
Short Range ◽  
Short Range Order ◽  
Local Environment ◽  
Order Structure ◽  
Total Electron Yield ◽  
Total Electron ◽  
X Ray ◽  
Superconducting Compound ◽  
X Ray Absorption ◽  
Oxygen Atoms

ABSTRACTSpectra of the oxygen K-edge extended x-ray absorption fine structure (EXAFS) of the superconducting compound Y-Ba-Cu-O were obtained by measuring the total electron yield as a function of incident x-ray energy at temperatures between 77K and 300K. This technique affords a convenient way for probing the local environment around the oxygen atoms and soft modes in the lattice.

VUV- and Soft X-Ray-Induced Optical Luminescence and X-Ray Absorption Fine Structures of Porous Silicon

1992 ◽  
Vol 281 ◽  
Author(s):  
T. K. Sham ◽  
D. T. Jiang ◽  
I. Coulthard ◽  
J. W. Lorimer ◽  
X. H. Feng ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Total Electron Yield ◽  
Total Electron ◽  
X Ray ◽  
Absorption Fine ◽  
Electron Yield ◽  
Optical Luminescence ◽  
Fine Structures ◽  
X Ray Absorption ◽  
Uv Excitation

ABSTRACTOptical luminescence in porous silicon induced by soft X-ray and vacuum UV excitation with energies in the vicinity of the Si K-edge (1838 eV) and the Si L-edge (99 eV) has been observed. The luminescence has been used, together with total electron yield, to record X-ray absorption fine structure (XAFS) in the near-edge region of both Si edges. The near- edge spectra recorded simultaneously with either luminescence or total electron yield were compared, and the implications of these measurements for the structure of porous silicon are discussed.

ISOTOPIC EFFECT IN DEBYE–WALLER FACTOR OF CRYSTALLINE GERMANIUM

2013 ◽  
Vol 27 (26) ◽  
pp. 1350191
Author(s):  
HO KHAC HIEU ◽  
VU VAN HUNG
Keyword(s):  
Lattice Dynamics ◽  
Mass Difference ◽  
Relative Displacement ◽  
Waller Factor ◽  
Isotopic Effect ◽  
Mean Square ◽  
X Ray ◽  
Debye Waller Factor ◽  
X Ray Absorption ◽  
Crystalline Germanium

The statistical moment method has been used to study the effect of isotopic mass difference on extended X-ray absorption fine structure (EXAFS) Debye–Waller factor of crystalline germanium. The effects on the parallel mean-square relative displacement and the atomic mean square displacements have been considered. This research also exposed that isotopic effect is noticeable where the correlated atomic motion is concerned. Numerical calculations have been performed for two isotopes 70 Ge and 76 Ge in range of temperature from 0 K to 600 K. Our results are compared with available experimental EXAFS data [J. Purans et al., Phys. Rev. Lett.100 (2008) 055901] as well as with lattice dynamics calculations [A. Sanson, Solid State Sci.12 (2010) 1988] and the good agreements are found.

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