Comparing the Pressure-Induced Structural Behavior of CuCr₂O₄ and CuCr₂Se₄ Spinels

Journal Article · 12 July 2017 · Journal of Physical Chemistry. C

DOI: https://doi.org/10.1021/acs.jpcc.7b04657 · OSTI ID:1375342

Efthimiopoulos, I.  ^[1]; Tsurkan, V. ^[2]; Loidl, A. ^[3]; Zhang, Dongzhou ^[4]; Wang, Y.  ^[5]

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1. Oakland Univ, Rochester, MI (United States); Deutsches GeoForschungsZentrum (GFZ), Potsdam (Germany)
2. Academy of Sciences of Moldova, Chisinau, (Republic of Moldova); Univ. of Augsburg (Germany)
3. Univ. of Augsburg (Germany)
4. Univ. of Hawaii at Manoa, Honolulu, HI (United States)
5. Oakland Univ, Rochester, MI (United States)

We have conducted high-pressure measurements on the CuCr₂O₄ and CuCr₂Se₄ spinels to unravel the structural systematics of these materials under compression. Our studies have revealed diverse structural behavior in these two compounds. In particular, CuCr₂O₄ retains its ambient-pressure I4₁/amd structure up to 50 GPa. Close inspection of the lattice and interatomic parameters reveals a compressibility change near 23 GPa, which is accompanied by an expansion of the apical Cr–O bond distances. We speculate that an outer Cr³⁺ 3d orbital reorientation might be at play in this system, manifesting as the change in compressibility at that pressure point. On the other hand, CuCr₂Se₄ undergoes a structural transformation from the starting Fd3¯m phase toward a monoclinic structure initiated at ~8 GPa and completed at ~20 GPa. Furthermore, this high-pressure behavior resembles that of ZnCr₂Se₄, and it appears that, unlike similar chalcogenide Cr spinels, steric effects take a leading role in this pressure-induced Fd3¯m → monoclinic transition. Close comparison of our results with the reported literature yields significant insights behind the pressure-induced structural systematics of this important family of materials, thus both allowing for the careful manipulation of the structural/physical properties of these systems by strain and promoting our understanding of similar pressure-induced effects in relevant systems.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
• Grant/Contract Number: AC02-06CH11357; NA0001974; FG02-94ER14466; EAR 11-57758; EAR-1128799
• OSTI ID: 1375342
• Journal Information: Journal of Physical Chemistry. C, Vol. 121, Issue 30; ISSN 1932-7447
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: ENGLISH