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Title: Thermodynamics of radiation induced amorphization and thermal annealing of Dy 2Sn 2O 7 pyrochlore

Thermodynamics and annealing behavior of swift heavy ion amorphized Dy 2Sn 2O 7 pyrochlore were studied. Its amorphization enthalpy, defined as the total energetic difference between the irradiation amorphized and undamaged Dy 2Sn 2O 7 states, was determined to be 283.6 ± 6.5 kJ/mol by high temperature oxide melt drop solution calorimetry. It has been an enigma that stannate and some other pyrochlores do not follow the general r A/r B-radiation resistance relation seen in most pyrochlore systems. In this paper, we use the amorphization enthalpy, which reflects all the complex chemical and structural characteristics, as a more effective parameter to correlate the radiation damage resistance of pyrochlores with their compositions. It successfully explains the superior radiation damage resistance of the stannate pyrochlores compared with titanate pyrochlores. Differential scanning calorimetry (DSC) reveals a strong exothermic event starting at 978 K, which is attributed to long-range recrystallization based on X-ray diffraction (XRD) analysis, similar to the effect previously observed in Dy 2Ti 2O 7. A second pronounced heat event beginning at ~1148 K, which results from local structural rearrangement, is clearly decoupled from the first event for irradiated Dy 2Sn 2O 7. Both the heat releases measured by DSC on heatingmore » to 1023 and 1473 K, and the excess enthalpies of the annealed samples indicate that the recovery to the original, ordered state was not fully achieved up to even 1473 K, despite XRD showing the apparent restoration of crystalline pyrochlore structure. The remaining metastability may be attributed to local disorder in the form of weberite-like short-range domains in the recrystallized material. Intriguingly, the second event for different pyrochlores generally starts at similar temperatures while the onset of the long range recrystallization is compositionally dependent. Finally, the amorphization and thermal annealing behavior observed in irradiated Dy 2Sn 2O 7 may provide insights into the general mechanisms of radiation damage and recovery of pyrochlores relevant to their nuclear applications.« less
 [1] ;  [2] ;  [3] ; ORCiD logo [4]
  1. Univ. of California, Davis, CA (United States). Peter A. Rock Thermochemistry Lab. Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Univ. of California, Davis, CA (United States). Peter A. Rock Thermochemistry Lab. Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU)
Publication Date:
Report Number(s):
Journal ID: ISSN 1359-6454
Grant/Contract Number:
AC52-06NA25396; SC0001089
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 155; Journal ID: ISSN 1359-6454
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of California, Davis, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); LANL Laboratory Directed Research and Development (LDRD) Program
Country of Publication:
United States
36 MATERIALS SCIENCE; pyrochlore; irradiation effect; amorphization; annealing; calorimetry
OSTI Identifier: