In:
Scientific Reports, Springer Science and Business Media LLC, Vol. 7, No. 1 ( 2017-06-16)
Abstract:
The pressure-response of the Co-O bond lengths and the spin state of Co ions in a hybrid 3d-5d solid-state oxide Sr 2 Co 0.5 Ir 0.5 O 4 with a layered K 2 NiF 4 -type structure was studied by using hard X-ray absorption and emission spectroscopies. The Co- K and the Ir- L 3 X-ray absorption spectra demonstrate that the Ir 5+ and the Co 3+ valence states at ambient conditions are not affected by pressure. The Co Kβ emission spectra, on the other hand, revealed a gradual spin state transition of Co 3+ ions from a high-spin (S = 2) state at ambient pressure to a complete low-spin state (S = 0) at 40 GPa without crossing the intermediate spin state (S = 1). This can be well understood from our calculated phase diagram in which we consider the energies of the low spin, intermediate spin and high spin states of Co 3+ ions as a function of the anisotropic distortion of the octahedral local coordination in the layered oxide. We infer that a short in-plane Co-O bond length ( 〈 1.90 Å) as well as a very large ratio of Co-O apex /Co-O in-plane is needed to stabilize the IS Co 3+ , a situation which is rarely met in reality.
Type of Medium:
Online Resource
ISSN:
2045-2322
DOI:
10.1038/s41598-017-03950-z
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2017
detail.hit.zdb_id:
2615211-3
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