skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Order-disorder phase transformation in ion-irradiated rare earth sesquioxides

Abstract

An order-to-disorder (OD) transformation induced by ion irradiation in rare earth (RE) sesquioxides, Dy{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, and Lu{sub 2}O{sub 3}, was studied using grazing incidence x-ray diffraction and transmission electron microscopy. These sesquioxides are characterized by a cubic C-type RE structure known as bixbyite. They were irradiated with heavy Kr{sup ++} ions (300 keV) and light Ne{sup +} ions (150 keV) at cryogenic temperature ({approx}120 K). In each oxide, following a relatively low ion irradiation dose of {approx}2.5 displacements per atom, the ordered bixbyite structure was transformed to a disordered, anion-deficient fluorite structure. This OD transformation was found in all three RE sesquioxides (RE=Dy, Er, and Lu) regardless of the ion type used in the irradiation. The authors discuss the irradiation-induced OD transformation process in terms of anion disordering, i.e., destruction of the oxygen order associated with the bixbyite structure.

Authors:
; ; ;  [1];  [2]
  1. Materials Science and Technology Division, Mail Stop G755, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20960207
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 15; Other Information: DOI: 10.1063/1.2720716; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANIONS; ATOMIC DISPLACEMENTS; CUBIC LATTICES; DYSPROSIUM OXIDES; ERBIUM OXIDES; ION BEAMS; IRRADIATION; KEV RANGE 100-1000; KRYPTON IONS; LUTETIUM OXIDES; NEON IONS; ORDER-DISORDER TRANSFORMATIONS; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0065-0273 K; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION

Citation Formats

Tang, M., Valdez, J. A., Sickafus, K. E., Lu, P., and Department of Materials and Metallurgical Engineering, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801. Order-disorder phase transformation in ion-irradiated rare earth sesquioxides. United States: N. p., 2007. Web. doi:10.1063/1.2720716.
Tang, M., Valdez, J. A., Sickafus, K. E., Lu, P., & Department of Materials and Metallurgical Engineering, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801. Order-disorder phase transformation in ion-irradiated rare earth sesquioxides. United States. doi:10.1063/1.2720716.
Tang, M., Valdez, J. A., Sickafus, K. E., Lu, P., and Department of Materials and Metallurgical Engineering, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801. Mon . "Order-disorder phase transformation in ion-irradiated rare earth sesquioxides". United States. doi:10.1063/1.2720716.
@article{osti_20960207,
title = {Order-disorder phase transformation in ion-irradiated rare earth sesquioxides},
author = {Tang, M. and Valdez, J. A. and Sickafus, K. E. and Lu, P. and Department of Materials and Metallurgical Engineering, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801},
abstractNote = {An order-to-disorder (OD) transformation induced by ion irradiation in rare earth (RE) sesquioxides, Dy{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, and Lu{sub 2}O{sub 3}, was studied using grazing incidence x-ray diffraction and transmission electron microscopy. These sesquioxides are characterized by a cubic C-type RE structure known as bixbyite. They were irradiated with heavy Kr{sup ++} ions (300 keV) and light Ne{sup +} ions (150 keV) at cryogenic temperature ({approx}120 K). In each oxide, following a relatively low ion irradiation dose of {approx}2.5 displacements per atom, the ordered bixbyite structure was transformed to a disordered, anion-deficient fluorite structure. This OD transformation was found in all three RE sesquioxides (RE=Dy, Er, and Lu) regardless of the ion type used in the irradiation. The authors discuss the irradiation-induced OD transformation process in terms of anion disordering, i.e., destruction of the oxygen order associated with the bixbyite structure.},
doi = {10.1063/1.2720716},
journal = {Applied Physics Letters},
number = 15,
volume = 90,
place = {United States},
year = {Mon Apr 09 00:00:00 EDT 2007},
month = {Mon Apr 09 00:00:00 EDT 2007}
}
  • Polycrystalline pellets of cubic C-type rare earth structure (Ia3) Dy{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, and Lu{sub 2}O{sub 3} were irradiated at cryogenic temperature (120 K) with 300 keV Kr{sup ++} ions to a maximum fluence of 1x10{sup 20} Kr/m{sup 2}. Irradiated specimens were examined using grazing incidence x-ray diffraction and transmission electron microscopy. Ion irradiation leads to different radiation effects in these three materials. First, Dy{sub 2}O{sub 3} begins to transform to a monoclinic B-type rare earth structure (C2/m) at a peak dose of {approx}5 displacements per atom (dpa) (corresponding to a fluence of 2x10{sup 19} Kr/m{sup 2}). Thismore » transformation is nearly complete at a peak dose of 25 dpa (a fluence of 1x10{sup 20} Kr/m{sup 2}). Er{sub 2}O{sub 3} also transforms to the B-type structure, but the transformation starts at a higher irradiation dose of about 15-20 dpa [a fluence of about (6-8)x10{sup 19} Kr/m{sup 2}]. Lu{sub 2}O{sub 3} was found to maintain the C-type structure even at the highest irradiation dose of 25 dpa (a fluence of 1x10{sup 20} Kr/m{sup 2}). No C-to-B transformation was observed in Lu{sub 2}O{sub 3}. The irradiation dose dependence of the C-to-B phase transformation observed in Dy{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, and Lu{sub 2}O{sub 3} is closely related to the temperature dependence of the C-to-B phase transformation found in phase diagrams for these three materials.« less
  • 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 highestmore » 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.« less
  • High-temperature order-disorder transformations in R{sub 2}T{sub 17} and R{sub 2}T{sub 17}-M-C intermetallics with R = Pr, Sm, Dy, Tb; T = Co, Fe; and M = Zr, Nb were studied utilizing time-resolved synchrotron x-ray diffraction at the Advanced Photon Source (APS) at the U.S. Department of Energy's Argonne National Laboratory (Argonne, IL). High-energy synchrotron radiation provides intense, highly penetrating x-rays, which are ideal for in situ studies of phase transformations. Alloying additions are used to stabilize formation of metastable phases; their influence on order recovery was investigated. The experimental setup utilized Debye-Scherrer geometry; specimens were heated at a rate ofmore » 10 K/min. Full-profile diffraction patterns collected every 10 s were refined in sequence using the Rietveld method to track changes of lattice parameters and phase assemblages during heating. Sharp changes observed in the evolution of temperature-dependent lattice parameters suggested formation of ordered structure via nucleation and growth. Both 2-17 polymorphs co-existed in light and heavy rare-earth systems at high temperatures. The presence of alloying additions in the solid solution greatly influenced long-range order formation.« less