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Published April 1, 2022 | Published + Supplemental Material
Journal Article Open

Systematic structural study in praseodymium compressed in a neon pressure medium up to 185 GPa


Angle-dispersive x-ray powder diffraction experiments have been performed on praseodymium metal compressed in a soft pressure-transmitting medium at ambient temperature up to 185 GPa. We observe the previously reported high-pressure structural transition sequence up to 20 GPa and the coexistence of body-centered orthorhombic (bco) Pr and α-U Pr from ∼20 up to ∼38 GPa. The α-U structure of Pr is stable from 20 to 185 GPa, and no evidence of the proposed transition to a primitive orthorhombic phase > 147 GPa was observed. With density functional theory (DFT), we calculated the lattice parameters and y coordinate for α-U Pr and found good agreement between our calculations and experimental measurements. The obtained DFT energies of the proposed primitive orthorhombic (P2₁2₁2₁) and the α-uranium phases at ∼150 GPa show that the α-uranium phase is lower in energy. Hence, neither our experimental data nor our DFT results support the transition to a primitive orthorhombic phase > 150 GPa. DFT suggests, however, that Pr may transform to the P2₁2₁2₁ phase above ∼220 GPa. We also compare the axial ratios and lattice parameters of praseodymium to α-uranium structured Nd, Ce, and U.

Additional Information

© 2022 American Physical Society. (Received 24 January 2022; revised 18 March 2022; accepted 5 April 2022; published 25 April 2022) We thank S. Finnegan and M. McMahon for providing the lattice parameters for α-U structured Nd from their recent publication (Ref. [8]). E.F.O. thanks I. Cube for helpful discussions. This paper was performed under the auspices of the U.S. Department of Energy (DOE) by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344. O.S.P. acknowledges the support of DOE National Nuclear Security Administration (NNSA) Stewardship Science Graduate Fellowship (DE-NA0003960). Portions of this paper were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operations are supported by DOE-NNSA's Office of Experimental Sciences. The APS is a DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Attached Files

Published - PhysRevB.105.144107.pdf

Supplemental Material - Static_Pr_Supplement_R1_2022-4-6_new.pdf


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August 20, 2023
September 8, 2023