Speaker
Description
Energetic particle irradiation creates a multitude of metastable defects through atomic displacements in lattice structure and/or excitations/ionizations in electronic configurations of a material. These defects are then responsible for the microstructural evolution and property changes of the material, which often come down to a balance of kinetic processes that determine whether the material will recover or whether larger-scale extended defect aggregates such as voids and loops will form. Critically, the defects most responsible for this evolution – the fastest moving defects – disappear quickly once the radiation source is removed. Thus, post-mortem examination can only provide indirect evidence of their presence and is unable to characterize neither the nature nor properties of these defects.
To better understand the transient behavior associated with fast moving radiation-induced defects, we have developed an in-situ positron annihilation spectroscopy beamline and an in-situ electrochemical impedance spectroscopy system at LANL’s Ion Beam Materials Laboratory that allow us to measure the vacancy-type defects and conductivity of the material as it is being irradiated. These capabilities can provide unprecedented insight into the kinetic nature of defects, both as the material approaches a steady-state defect concentration under irradiation and as it recovers once the irradiation source is removed. In this talk, I will discuss the status of these capabilities, their preliminary applications, and challenges.
*This work is supported by Center for Fundamental Understanding of Transport Under Reactor Extremes (FUTURE), DOE Office of Science Energy Frontier Research Center (EFRC) at Los Alamos National Laboratory, and Center for Integrated Nanotechnologies (CINT), a DOE of Office of Science Nanoscale Science Research Center jointly operated by Los Alamos and Sandia National Laboratories.
