Comparison of the high-pressure behavior of the cerium oxides and
Journal Article
·
· Physical Review B
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of Washington, Seattle, WA (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States)
We studied the high-pressure behavior of Ce2O3 using angle-dispersive x-ray diffraction to 70 GPa and compared with that of CeO2. Up to the highest pressure Ce2O3 remains in the hexagonal phase (space group 164, P ¯32/m1) typical for the lanthanide sesquioxides. We did not observe a theoretically predicted phase instability for 30 GPa. The isothermal bulk modulus and its pressure derivative for the quasihydrostatic case are B0 = 111 ± 2 GPa, B'0 = 4.7 ± 0.3, and for the case without pressure-transmitting medium B0 = 104 ±4 GPa, B'0 = 6.5 ± 0.4. Starting from ambient-pressure magnetic susceptibility measurements for both oxides in highly purified form,we find that the Ce atom in Ce2O3 behaves like a trivalent Ce3+ ion (2.57μB per Ce atom) in contrast to previously published data. Since x-ray emission spectroscopy of the Lγ (4d3/2 → 2p1/2) transition is sensitive to the 4f -electron occupancy, we also followed the high-pressure dependence of this line for both oxides up to 50 GPa. We observed no change of the respective line shape, indicating that the 4f -electron configuration is stable for both materials. We posit from this data that the 4f electrons do not drive the volume collapse of CeO2 from the high-symmetry, low-pressure fluorite structure to the lower-symmetry orthorhombic phase.
- Research Organization:
- Carnegie Inst. of Washington, Argonne, IL (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- AC02-06CH11357; AC52-07NA27344; NA0001974; NA0002006; SC0002194; SC0008580
- OSTI ID:
- 1240965
- Alternate ID(s):
- OSTI ID: 1237507
OSTI ID: 1238280
OSTI ID: 1379168
- Report Number(s):
- LLNL-JRNL--675872
- Journal Information:
- Physical Review B, Journal Name: Physical Review B Journal Issue: 6 Vol. 93; ISSN 2469-9950; ISSN PRBMDO
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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