Structural Evolution of Atomically Dispersed Fe Species in Fe–N/C Catalysts Probed by X-ray Absorption and 57Fe Mössbauer Spectroscopies

Author(s):  
Jinwoo Woo ◽  
Hyunkyung Choi ◽  
Young Jin Sa ◽  
Ho Young Kim ◽  
Taejung Lim ◽  
...  
Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 800
Author(s):  
Vladimír Girman ◽  
Maksym Lisnichuk ◽  
Daria Yudina ◽  
Miloš Matvija ◽  
Pavol Sovák ◽  
...  

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.


Soft Matter ◽  
2021 ◽  
Author(s):  
Ana Guilherme Buzanich ◽  
Anicó Kulow ◽  
Anke Kabelitz ◽  
Christian Grunewald ◽  
Robert Seidel ◽  
...  

The present study investigates structural evolution of early ZIF-8 crystallization up to 5 minutes post mixing of precursor solutions using Dispersive X-ray Absorption Spectroscopy (DXAS).


2007 ◽  
Vol 561-565 ◽  
pp. 2099-2102 ◽  
Author(s):  
Chung Kwei Lin ◽  
Chin Yi Chen ◽  
Pee Yew Lee ◽  
Chih Chieh Chan

In the present study, pure elemental powders of Fe and S were mixed to give the desired compositions of Fe50S50. A SPEX 8000D high-energy ball mill was used to synthesize iron sulfide powders under an Ar-filled atmosphere. The prepared powders were examined by conventional X-ray diffractometry and synchrotron X-ray absorption spectroscopy. The experimental results revealed that mechanochemical reactions occurred during the ball milling process for all the compositions. The Fe50S50 phase was obtained after ball milling for 20 h. Extended X-ray absorption fine structure (EXAFS) results revealed that the nearest neighbor bond lengths of the radial distribution function (RDF) for iron decreased when iron sulfides formed. X-ray absorption near edge structure (XANES) of S K-edges distinguished better the structural evolution of these iron sulfides.


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