NSUF 20-4164: Probing the mobility of radiation induced defects in Nickel/Oxide systems through in-situ TEM irradiation
This investigation aims at probing the radiation induced defects in Nickel/Oxide systems. The mobility and transport of defects by in-situ transmission electron microscopy allows to follow the micro-stuctural evolution of the irradiation induced defects in real time for experiments conducted at a wide range of temperatures. In addition to high temperatures, the investigation of the oxide at cryogenic temperatures allows the study of the amorphization behavior of the oxide. In this proposed work, cross-sectional TEM specimens of Ni/NiO and (Ni-18%Cr)/NiO multilayers prepared by FIB lift-out technique will be irradiated in-situ in the microscope at the IVEM of ANL at temperatures from 20 to 773K using 1 MeV Kr2+ ions to 10 dpa similar to previous Fe-based samples irradiation conditions. The large range of temperatures is meant to provide information on the range of mobility of irradiation induced defects as a function of temperature. In addition, the cryogenic temperature will allow the study of the amorphization behavior of the oxide. The microstructure evolution under irradiation will thus be followed and characterized at successive doses, using bright field and (g, 3g) weak beam dark field TEM imaging methods. Diffraction patterns will also be acquired at each irradiation condition. Furthermore, videos will be recorded throughout irradiation for subsequent frame-by-frame analysis (15 frames/s). The study of the mobility of the defects focuses on the identification of dislocation loop Burgers vectors, nature (interstitial vs. vacancy) and density as a function of dose. Special attention will be put on the characterization of the type of defect (faulted vs unfaulted loops and Burgers vector). Due to the time-consuming nature of this involved technique requiring the imaging of the same loops under several different diffraction conditions, this analysis will be conducted ex-situ at NCSU after the experiments are complete. In relation to the amorphization of the oxide, the formation of amorphous rings in the diffraction patterns as well as the loss of diffraction contrast in the bright field images will be investigated. The ex-situ microchemistry analysis will be carried out at the NCSU using ChemiSTEM to evidence diffusion behavior under irradiation. Elemental mapping using the ChemiSTEM method will be carried out at interfaces of metal/oxide multilayers. In addition to the ex-situ ChemiSTEM mapping, high resolution TEM and high resolution STEM electron energy loss spectroscopy (EELS) will be utilized to characterize the valence state of Nickel and Chromium before and after irradiation at the interface between the metal and the metal oxide. Capturing any change in the valence state at the interface between the metal and the metal oxide will provide evidence of any oxygen diffusion across the interface due to an influx of point defects to this feature.
Additional Info
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| Abstract | This investigation aims at probing the radiation induced defects in Nickel/Oxide systems. The mobility and transport of defects by in-situ transmission electron microscopy allows to follow the micro-stuctural evolution of the irradiation induced defects in real time for experiments conducted at a wide range of temperatures. In addition to high temperatures, the investigation of the oxide at cryogenic temperatures allows the study of the amorphization behavior of the oxide. In this proposed work, cross-sectional TEM specimens of Ni/NiO and (Ni-18%Cr)/NiO multilayers prepared by FIB lift-out technique will be irradiated in-situ in the microscope at the IVEM of ANL at temperatures from 20 to 773K using 1 MeV Kr2+ ions to 10 dpa similar to previous Fe-based samples irradiation conditions. The large range of temperatures is meant to provide information on the range of mobility of irradiation induced defects as a function of temperature. In addition, the cryogenic temperature will allow the study of the amorphization behavior of the oxide. The microstructure evolution under irradiation will thus be followed and characterized at successive doses, using bright field and (g, 3g) weak beam dark field TEM imaging methods. Diffraction patterns will also be acquired at each irradiation condition. Furthermore, videos will be recorded throughout irradiation for subsequent frame-by-frame analysis (15 frames/s). The study of the mobility of the defects focuses on the identification of dislocation loop Burgers vectors, nature (interstitial vs. vacancy) and density as a function of dose. Special attention will be put on the characterization of the type of defect (faulted vs unfaulted loops and Burgers vector). Due to the time-consuming nature of this involved technique requiring the imaging of the same loops under several different diffraction conditions, this analysis will be conducted ex-situ at NCSU after the experiments are complete. In relation to the amorphization of the oxide, the formation of amorphous rings in the diffraction patterns as well as the loss of diffraction contrast in the bright field images will be investigated. The ex-situ microchemistry analysis will be carried out at the NCSU using ChemiSTEM to evidence diffusion behavior under irradiation. Elemental mapping using the ChemiSTEM method will be carried out at interfaces of metal/oxide multilayers. In addition to the ex-situ ChemiSTEM mapping, high resolution TEM and high resolution STEM electron energy loss spectroscopy (EELS) will be utilized to characterize the valence state of Nickel and Chromium before and after irradiation at the interface between the metal and the metal oxide. Capturing any change in the valence state at the interface between the metal and the metal oxide will provide evidence of any oxygen diffusion across the interface due to an influx of point defects to this feature. |
| Award Announced Date | 2020-07-14T14:11:15.333 |
| Awarded Institution | Idaho National Laboratory |
| Facility | Advanced Test Reactor |
| Facility Tech Lead | Alina Zackrone, Wei-Ying Chen |
| Irradiation Facility | Intermediate Voltage Electron Microscopy (IVEM)-Tandem Facility |
| PI | Martin Owusu-Mensah |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 4164 |