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A common characteristic of many “overdoped” cuprates prepared with high-pressure oxygen isTcvalues ≥ 50 K that often exceed that of optimally doped parent compounds, despite O stoichiometries that place the materials at the edge or outside of the conventional boundary between superconducting and normal Fermi liquid states. X-ray absorption fine-structure (XAFS) measurements at 52 K on samples of high-pressure oxygen (HPO) YSr2Cu2.75Mo0.25O7.54,Tc= 84 K show that the Mo is in the (VI) valence in an unusually undistorted octahedral geometry with predominantly Mo neighbors that is consistent with its assigned substitution for Cu in the chain sites of the structure. Perturbations of the Cu environments are minimal, although the Cu X-ray absorption near-edge structure (XANES) differs from that in other cuprates. The primary deviation from the crystal structure is therefore nanophase separation into Mo- and Cu-enriched domains. There are, however, indications that the dynamical attributes of the structure are altered relative to YBa2Cu3O7, including a shift of the Cu-apical O two-site distribution from the chain to the plane Cu sites. Another effect that would influenceTcis the possibility of multiple bands at the Fermi surface caused by the presence of the second phase and the lowering of the Fermi level.
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This content will become publicly available on August 28, 2025
Cu site differentiation in tetracopper( i ) sulfide clusters enables biomimetic N 2 O reduction
Resonant X-ray diffraction measurements were used to examine Cu site differentiation within a Cu4S cluster that distorts its geometry to activate N2O, thus mimicking the behavior of the biological CuZactive site.
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- Award ID(s):
- 1834750
- PAR ID:
- 10578061
- Publisher / Repository:
- The Royal Society of Chemistry
- Date Published:
- Journal Name:
- Chemical Science
- Volume:
- 15
- Issue:
- 34
- ISSN:
- 2041-6520
- Page Range / eLocation ID:
- 13668 to 13675
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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