NSUF 19-1752: A study using stoichiometry to control structural disorder and subsequent radiation tolerance of rare-earth based zirconates and titanates
NSUF RTE Argonne National Labs IVEM – Tandem facility. March 2019 Investigators: Nestor Zaluzec (PI) Robert D. Aughterson Gregory R. Lumpkin Technical Abstract: Objectives Two systems of ceramics; rare-earth zirconates and rare-earth titanates have been synthesised and characterised with a focus on creating materials suitable for use as inert-matrix-fuels (IMF) and waste-form matrices. One of the major desirable properties of IMF and waste-form materials is that of radiation tolerance. The objective of monitoring the test materials’ response to irradiating ions is to attain a quantifiable characteristic; the critical dose of irradiating ions required to facilitate a transition from a crystalline to amorphous state. This provides a means of comparing the radiation tolerance between the materials of interest. Ion-irradiation response is also to be monitored over a range of temperatures. By measuring the critical dose of amorphisation at various temperatures and plotting the response we attain a second quantity; the critical temperature of crystallinity (the temperature above which the rate of crystalline structure recovery is greater than the rate of defect accumulation). This gives us another means of comparing material response to ion-irradiation along with testing at temperatures applicable to nuclear-based application environments. Methods The ceramic oxides are exposed to high energy ions (Kr 1 MeV, and/or He 20 keV) whilst being monitored in-situ using the transmission electron microscope (TEM) (IVEM-tandem facility). Collection of bright field images (BF) and electron diffraction patterns (SADP) are used to monitor crystalline to amorphous phase transition. The TEM specimens consist of finely ground ceramic oxide particles dispersed on holey carbon film supported on TEM specimen grids. TEM characterisation involves the collection of BF and SADPs of 5 grains. After collection of images the sample is irradiated to a certain dose. Selected ion doses followed by BF and SADP collection are continued until there are no observable Bragg diffraction spots left in the SADP. This approach is used to measure the irradiating ion dose required to cause amorphisation. The critical dose of amorphisation gives a quantitative approach for comparing radiation tolerance between different test materials. This same experimental approach is repeated for the test material whilst holding it at a range of temperatures. The duration of each critical dose measurement is dependent on both the dose of ions required to render the sample amorphous and the time it takes to cool or heat the sample. Potential Impact to state-of-the Knowledge The proposed test materials have pyrochlore / fluorite structure types, structures associated with flexibility in radionuclide incorporation along with radiation tolerance. The proposed test materials consist of novel compounds that may lend to improvement in these properties. The proposed radiation response study will have considerable impact on the decision making process for down-selection of the best candidates for further development as inert- matrix fuels, and waste forms. Period of performance On average 1 critical dose measurement takes approximately 2 hours. 3 to 5 specimens are tested per day. There are 9 samples proposed requiring approximately 1 day per sample. This proposal is requesting the maximum 10 days.
Additional Info
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| Abstract | NSUF RTE Argonne National Labs IVEM – Tandem facility. March 2019 Investigators: Nestor Zaluzec (PI) Robert D. Aughterson Gregory R. Lumpkin Technical Abstract: Objectives Two systems of ceramics; rare-earth zirconates and rare-earth titanates have been synthesised and characterised with a focus on creating materials suitable for use as inert-matrix-fuels (IMF) and waste-form matrices. One of the major desirable properties of IMF and waste-form materials is that of radiation tolerance. The objective of monitoring the test materials’ response to irradiating ions is to attain a quantifiable characteristic; the critical dose of irradiating ions required to facilitate a transition from a crystalline to amorphous state. This provides a means of comparing the radiation tolerance between the materials of interest. Ion-irradiation response is also to be monitored over a range of temperatures. By measuring the critical dose of amorphisation at various temperatures and plotting the response we attain a second quantity; the critical temperature of crystallinity (the temperature above which the rate of crystalline structure recovery is greater than the rate of defect accumulation). This gives us another means of comparing material response to ion-irradiation along with testing at temperatures applicable to nuclear-based application environments. Methods The ceramic oxides are exposed to high energy ions (Kr 1 MeV, and/or He 20 keV) whilst being monitored in-situ using the transmission electron microscope (TEM) (IVEM-tandem facility). Collection of bright field images (BF) and electron diffraction patterns (SADP) are used to monitor crystalline to amorphous phase transition. The TEM specimens consist of finely ground ceramic oxide particles dispersed on holey carbon film supported on TEM specimen grids. TEM characterisation involves the collection of BF and SADPs of 5 grains. After collection of images the sample is irradiated to a certain dose. Selected ion doses followed by BF and SADP collection are continued until there are no observable Bragg diffraction spots left in the SADP. This approach is used to measure the irradiating ion dose required to cause amorphisation. The critical dose of amorphisation gives a quantitative approach for comparing radiation tolerance between different test materials. This same experimental approach is repeated for the test material whilst holding it at a range of temperatures. The duration of each critical dose measurement is dependent on both the dose of ions required to render the sample amorphous and the time it takes to cool or heat the sample. Potential Impact to state-of-the Knowledge The proposed test materials have pyrochlore / fluorite structure types, structures associated with flexibility in radionuclide incorporation along with radiation tolerance. The proposed test materials consist of novel compounds that may lend to improvement in these properties. The proposed radiation response study will have considerable impact on the decision making process for down-selection of the best candidates for further development as inert- matrix fuels, and waste forms. Period of performance On average 1 critical dose measurement takes approximately 2 hours. 3 to 5 specimens are tested per day. There are 9 samples proposed requiring approximately 1 day per sample. This proposal is requesting the maximum 10 days. |
| Award Announced Date | 2019-05-14T15:57:51.597 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Wei-Ying Chen |
| Irradiation Facility | Intermediate Voltage Electron Microscopy (IVEM)-Tandem Facility |
| PI | Nestor Zaluzec |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1752 |