Comparison of the high-pressure behavior of the cerium oxides and
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of Washington, Seattle, WA (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States)
The high pressure behavior of Ce2O3 was studied 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. A theoretically predicted phase instability for 30 GPa is not observed. The isothermal bulk modulus and its pressure derivative for the quasi-hydrostatic case are B0 = 111 ± 2 GPa, B0’ = 4.7 ± 0.3 and for the case without pressure transmitting medium B0 = 104 ± 4 GPa, B0’ = 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 (2.57 μB 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. No change of the respective lineshape was observed, 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:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Carnegie Inst. of Science, Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC52-07NA27344; FG02- 09ER16106; SC0008580; AC52- 07NA27344; FG02-09ER16106; AC02-06CH11357; NA0001974; NA0002006
- OSTI ID:
- 1240965
- Alternate ID(s):
- OSTI ID: 1237507; OSTI ID: 1379168
- Report Number(s):
- LLNL-JRNL-675872; PRBMDO
- Journal Information:
- Physical Review B, Vol. 93, Issue 6; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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