Thermodynamics of radiation induced amorphization and thermal annealing of Dy2Sn2O7 pyrochlore

Chung, Cheng-Kai; Lang, Maik; Xu, Hongwu; Navrotsky, Alexandra

doi:10.1016/j.actamat.2018.06.003

Title: Thermodynamics of radiation induced amorphization and thermal annealing of Dy₂Sn₂O₇ pyrochlore

Abstract

Thermodynamics and annealing behavior of swift heavy ion amorphized Dy₂Sn₂O₇ pyrochlore were studied. Its amorphization enthalpy, defined as the total energetic difference between the irradiation amorphized and undamaged Dy₂Sn₂O₇ 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 Dy₂Ti₂O₇. A second pronounced heat event beginning at ~1148 K, which results from local structural rearrangement, is clearly decoupled from the first event for irradiated Dy₂Sn₂O₇. Both the heat releases measured by DSC on heating to 1023 and 1473 K, and the excess enthalpies of the annealed samples indicatemore »« less

Authors:

Chung, Cheng-Kai ^[1]; Lang, Maik ^[2]; Xu, Hongwu ^[3];

^[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); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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:: Thu Jun 14 00:00:00 EDT 2018

Research Org.:: Energy Frontier Research Centers (EFRC) (United States). Materials Science of Actinides (MSA); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES); LANL Laboratory Directed Research and Development (LDRD) Program

OSTI Identifier:: 1457279

Alternate Identifier(s):: OSTI ID: 1564297

Report Number(s):: LA-UR-18-22912
Journal ID: ISSN 1359-6454; TRN: US1901348

Grant/Contract Number:: AC52-06NA25396; SC0001089; 20180007

Resource Type:: Accepted Manuscript

Journal Name:: Acta Materialia

Additional Journal Information:: Journal Volume: 155; Journal ID: ISSN 1359-6454

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; pyrochlore; irradiation effect; amorphization; annealing; calorimetry

Citation Formats


                    Chung, Cheng-Kai, Lang, Maik, Xu, Hongwu, and Navrotsky, Alexandra. Thermodynamics of radiation induced amorphization and thermal annealing of Dy2Sn2O7 pyrochlore.  United States: N. p., 2018. 
Web.  doi:10.1016/j.actamat.2018.06.003.

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                    Chung, Cheng-Kai, Lang, Maik, Xu, Hongwu, & Navrotsky, Alexandra. Thermodynamics of radiation induced amorphization and thermal annealing of Dy2Sn2O7 pyrochlore.  United States.  https://doi.org/10.1016/j.actamat.2018.06.003

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                    Chung, Cheng-Kai, Lang, Maik, Xu, Hongwu, and Navrotsky, Alexandra. Thu .  
"Thermodynamics of radiation induced amorphization and thermal annealing of Dy2Sn2O7 pyrochlore".  United States.  https://doi.org/10.1016/j.actamat.2018.06.003.  https://www.osti.gov/servlets/purl/1457279.

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@article{osti_1457279,

  title        = {Thermodynamics of radiation induced amorphization and thermal annealing of Dy2Sn2O7 pyrochlore},

  author       = {Chung, Cheng-Kai and Lang, Maik and Xu, Hongwu and Navrotsky, Alexandra},

  abstractNote = {Thermodynamics and annealing behavior of swift heavy ion amorphized Dy2Sn2O7 pyrochlore were studied. Its amorphization enthalpy, defined as the total energetic difference between the irradiation amorphized and undamaged Dy2Sn2O7 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 rA/rB-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 Dy2Ti2O7. A second pronounced heat event beginning at ~1148 K, which results from local structural rearrangement, is clearly decoupled from the first event for irradiated Dy2Sn2O7. Both the heat releases measured by DSC on heating 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 Dy2Sn2O7 may provide insights into the general mechanisms of radiation damage and recovery of pyrochlores relevant to their nuclear applications.},

  doi          = {10.1016/j.actamat.2018.06.003},

  journal      = {Acta Materialia},

  number       = ,

  volume       = 155,

  place        = {United States},

  year         = {Thu Jun 14 00:00:00 EDT 2018},

  month        = {Thu Jun 14 00:00:00 EDT 2018}

}

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https://doi.org/10.1016/j.actamat.2018.06.003

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Cited by: 12 works

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Figures / Tables:

Fig. 1: XRD patterns of Dy₂Sn₂O₇pyrochlore (a) before (black) and after (red) irradiation with 2.2 GeV Au ions. The dashed curve denotes the “baseline” to emphasize diffuse scattering in the irradiated sample. (b) Stacked XRD patterns of Dy₂Sn₂O₇: undamaged (black), after irradiation and annealing to 1023 K (red), andmore »

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Title: Thermodynamics of radiation induced amorphization and thermal annealing of Dy2Sn2O7 pyrochlore

Abstract

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Title: Thermodynamics of radiation induced amorphization and thermal annealing of Dy₂Sn₂O₇ pyrochlore