Journal ArticleDOI
Depth dependence for extended x-ray-absorption fine-structure spectroscopy detected via electron yield in He and in vacuum
TLDR
X-ray absorption spectra have been measured using electron detection with both vacuum and helium gas surrounding the samples, and the extended x-ray-absorption fine-structure (EXAFS) amplitudes agree with transmission measurements to better than 3%.Abstract:
X-ray absorption spectra have been measured using electron detection with both vacuum and helium gas surrounding the samples. The samples consisted of thin iron films covered with various thicknesses of aluminum to determine the contribution versus depth. The height of the iron K--absorption-edge jump decreases exponentially with aluminum covering thickness, with a 1/e depth of 1600 A. The addition of helium gas forms an ionization detector for the electrons, which have an average energy of about 2500 eV. The effects of electrode geometry and bias voltage are evaluated. When operated in a linear-response region, the signal-to-noise ratio for this method is excellent and the extended x-ray-absorption fine-structure (EXAFS) amplitudes agree with transmission measurements to better than 3%.read more
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Structural Changes of Cobalt-Based Perovskites upon Water Oxidation Investigated by EXAFS
Marcel Risch,Alexis Grimaud,Kevin J. May,Kelsey A. Stoerzinger,Tina J. Chen,Azzam N. Mansour,Yang Shao-Horn +6 more
TL;DR: In this paper, the local structure changes of perovskites LaCoO3, Ba0.5Sr 0.5Co 0.2O3-δ, and SrCo0.8Fe 0.
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On the formation of nanocrystals in the soft magnetic alloy Fe73.5Nb3Cu1Si13.5B9
TL;DR: In this article, the role of the Cu clusters as catalyzing nucleation of the DO3 crystallites by providing a low energy interface upon which the activation energy for DO3 phase is lowered.
Journal ArticleDOI
Large zinc cation occupancy of octahedral sites in mechanically activated zinc ferrite powders
TL;DR: In this article, the cation site occupancy of a mechanically activated nanocrystalline zinc ferrite powder was determined as (Zn0.552+Fe0.183+)tet[Zr0.452+Fe1.823+]octO4 through analysis of extended x-ray absorption fine structure measurements.
Journal ArticleDOI
Oxygen Evolution Activity and Stability of Ba6Mn5O16, Sr4Mn2CoO9, and Sr6Co5O15: The Influence of Transition Metal Coordination
Alexis Grimaud,Christopher E. Carlton,Marcel Risch,Wesley T. Hong,Kevin J. May,Yang Shao-Horn +5 more
TL;DR: The influence of cobalt and manganese coordination on the oxygen evolution reaction (OER) activity and oxide stability in alkaline solution was studied in this article, where high-resolution transmission electron microscopy (HRTEM) and X-ray absorption spectroscopy (XAS) were combined to confirm the presence of coordination environments such as Co2+ in disordered prisms and Co4+/Mn4+ in face shared octahedra.
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Determination of the valence of Pr, Gd, and Ho in YBa2Cu3O7 by x-ray absorption spectroscopy.
TL;DR: The most intense edge resonances were at the same energy position and nearly the same in appearance as the trivalent Pr reference compounds but with unique, extra features attributable to Pr, and were tentatively identified as substitution of Pr into the Cu site.