Order-to-disorder phase transformation in ion irradiated uranium-bearing delta-phase oxides RE{sub 6}U{sub 1}O{sub 12} (RE=Y, Gd, Ho, Yb, and Lu)

Journal Article · Thu Apr 15 00:00:00 EDT 2010 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2010.01.020· OSTI ID:21372561

Tang, M ^[1]; Holliday, K S ^[2]; Jiang, C; Valdez, J A; Uberuaga, B P; Dickerson, P O; Dickerson, R M; Wang, Y ^[1]; Czerwinski, K R ^[2]; Sickafus, K E ^[1]

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1. Materials Science and Technology Division, Mail-Stop G755, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2. Radiochemistry Group, University of Nevada, Las Vegas, NV 89154 (United States)

Polycrystalline uranium-bearing compounds Y{sub 6}U{sub 1}O{sub 12}, Gd{sub 6}U{sub 1}O{sub 12}, Ho{sub 6}U{sub 1}O{sub 12}, Yb{sub 6}U{sub 1}O{sub 12}, and Lu{sub 6}U{sub 1}O{sub 12} samples were irradiated with various ions species (300 keV Kr{sup ++}, 400 keV Ne{sup ++}, and 100 keV He{sup +}) at cryogenic temperature ({approx}100 K), and the microstructures were examined following irradiation using grazing incidence X-ray diffraction and transmission electron microscopy. The pristine samples are characterized by an ordered, fluorite derivative structure, known as the delta phase. This structure possesses rhombohedral symmetry. Amorphization was not observed in any of the irradiated samples, even at the highest dose {approx}65 dpa (displacement per atom). On the other hand, some of these compounds experienced an order-to-disorder (O-D) phase transformation, from an ordered rhombohedral to a disordered fluorite structure, at ion doses between 2.5 and 65 dpa, depending on ion irradiation species. Factors influencing the irradiation-induced O-D transformation tendencies of these compounds are discussed in terms of density functional theory calculations of the O-D transformation energies. - Graphical abstract: The different order-to-disorder (O-D) phase transformation tendencies in irradiated uranium-bearing delta-phase RE{sub 6}U{sub 1}O{sub 12} compounds (Y{sub 6}U{sub 1}O{sub 12}, Gd{sub 6}U{sub 1}O{sub 12}, Ho{sub 6}U{sub 1}O{sub 12}, Yb{sub 6}U{sub 1}O{sub 12}, and Lu{sub 6}U{sub 1}O{sub 12}) are revealed by grazing incidence X-ray diffraction and transmission electron microscopy measurements, and theoretical simulations of the O-D transformation energies, performed using DFT, also support our experimental results.

• OSTI ID: 21372561
• Journal Information: Journal of Solid State Chemistry, Vol. 183, Issue 4; Other Information: DOI: 10.1016/j.jssc.2010.01.020; PII: S0022-4596(10)00034-4; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
ATOMIC DISPLACEMENTS
DENSITY FUNCTIONAL METHOD
GADOLINIUM COMPOUNDS
HELIUM IONS
HOLMIUM COMPOUNDS
IRRADIATION
KEV RANGE 100-1000
KRYPTON IONS
LUTETIUM COMPOUNDS
MICROSTRUCTURE
NEON IONS
ORDER-DISORDER TRANSFORMATIONS
OXIDES
POLYCRYSTALS
RADIATION DOSES
SIMULATION
TRANSMISSION ELECTRON MICROSCOPY
TRIGONAL LATTICES
URANIUM COMPOUNDS
X-RAY DIFFRACTION
YTTERBIUM COMPOUNDS
ACTINIDE COMPOUNDS
CALCULATION METHODS
CHALCOGENIDES
CHARGED PARTICLES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DIFFRACTION
DOSES
ELECTRON MICROSCOPY
ENERGY RANGE
IONS
KEV RANGE
MICROSCOPY
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS
RARE EARTH COMPOUNDS
SCATTERING
VARIATIONAL METHODS