Data analysis method to achieve sub-10 pm spatial resolution using extended X-ray absorption fine-structure spectroscopy

Abstract

Obtaining sub-10 pm spatial resolution by extended X-ray absorption fine structure (EXAFS) spectroscopy is required in many important fields of research, such as lattice distortion studies in colossal magnetic resistance materials, high-temperature superconductivity materials etc. However, based on the existing EXAFS data analysis methods, EXAFS has a spatial resolution limit of π/2Δk which is larger than 0.1 Å. In this paper a new data analysis method which can easily achieve sub-10 pm resolution is introduced. Theoretically, the resolution limit of the method is three times better than that normally available. The method is examined by numerical simulation and experimental data. As a demonstration, the LaFe1-xCrxO3 system (x = 0, 1/3, 2/3) is studied and the structural information of FeO6 octahedral distortion as a function of Cr doping is resolved directly from EXAFS, where a resolution better than 0.074 Å is achieved.

Cobalt Boron Imidazolate Framework Derived Cobalt Nanoparticles Encapsulated in B/N Codoped Nanocarbon as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

“…In order to further gain more accurate structural information about the coordination model and the oxidation state of cobalt atoms in the Co/NBC hybrid. The X‐ray absorption fine structure (X‐ray absorption near edge structure, XANES) and extended X‐ray absorption fine structure (EXAFS) spectroscopy were performed on the Co/NBC hybrid (Figure f; Figure S7, Supporting Information) . For comparison, three cobalt‐based samples, including Co foil, CoOOH, and Co 3 O 4 , were also investigated.…”

Superexchange Effects on Oxygen Reduction Activity of Edge‐Sharing [CoxMn1−xO6] Octahedra in Spinel Oxide

“…Information on site occupation can be extracted from the Fourier transform (FT) of EXAFS spectra (Figure b,c and Figure S3b, Supporting Information), where the bond distances between the absorbing metal atom and backscattering atom are revealed . The first peak around ≈1.5 Å represents the distance to the nearest neighbor oxygen from the absorbing metal (TMO bond distance) . The second and third peaks at ≈2.5 Å (TM Oh –TM Oh ) and ≈3.0 Å (e.g., TM Td –TM Td or TM Td –TM Oh ), respectively, are interatomic metal–metal distances from the absorbing metal atom to the second nearest neighbor metal atoms at the octahedral or tetrahedral site.…”

“…The second and third peaks at ≈2.5 Å (TM Oh –TM Oh ) and ≈3.0 Å (e.g., TM Td –TM Td or TM Td –TM Oh ), respectively, are interatomic metal–metal distances from the absorbing metal atom to the second nearest neighbor metal atoms at the octahedral or tetrahedral site. [23b] The FT of the Zn EXAFS spectra (Figure S3b, Supporting Information) indicates that Zn is preferentially fixed at the tetrahedral A‐sites because there is only one metal–metal distance (at ≈3.0 Å, Zn Td –Zn Td and Zn Td –Zn Oh ). [23b] Literature reports also indicate that the tetrahedral site is preferred by Zn 2+ in various spinel oxides, such as ZnMn 2 O 4 and ZnCo 2 O 4 .…”

“…[23b] The FT of the Zn EXAFS spectra (Figure S3b, Supporting Information) indicates that Zn is preferentially fixed at the tetrahedral A‐sites because there is only one metal–metal distance (at ≈3.0 Å, Zn Td –Zn Td and Zn Td –Zn Oh ). [23b] Literature reports also indicate that the tetrahedral site is preferred by Zn 2+ in various spinel oxides, such as ZnMn 2 O 4 and ZnCo 2 O 4 . [15,23b] The FT spectra of Mn and Co (Figure b,c) look similar to that of either octahedral‐Co in ZnCo 2 O 4 or octahedral‐Mn in ZnMn 2 O 4 , confirming the unchanged coordination environment of Mn and Co on substitution.…”

“…[23b] Literature reports also indicate that the tetrahedral site is preferred by Zn 2+ in various spinel oxides, such as ZnMn 2 O 4 and ZnCo 2 O 4 . [15,23b] The FT spectra of Mn and Co (Figure b,c) look similar to that of either octahedral‐Co in ZnCo 2 O 4 or octahedral‐Mn in ZnMn 2 O 4 , confirming the unchanged coordination environment of Mn and Co on substitution. Thus, the Mn and Co cations are occupying the octahedral sites in all the spinel ZnCo x Mn 2− x O 4 ( x = 0.0–2.0) oxides synthesized here.…”