Dear all,
I know there is a software called SRIM, which can calculate the dose depth profile. Also, the pre-irradiation and post-irradiation properties can be compared and evaluated by many experimental techniques such as nano-indentation, in situ X ray micro-diffraction, Tof-SIMS, SEM and TEM. In addition, first-principles simulation and kMC can be used to simulate the bulk and grain boundary diffusion of some fission products like Ag, Cs, Sr and Eu. What I would like to ask is, however, the kinetic process regarding the nuclear materials, for example the diffusion under irradiation. Does someone have relevant research experiences or can you recommend some references for me?
Any suggestions are appreciated.
Thanks in advance!
Hi Cheng,
Determining radiation effects on materials, their properties and their overall performance is a multi-scale problem. The simulation approach often depends on the material properties you seek to evaluate. It also depends on the type of radiation being used and the energy of the radiation particles. For example, gamma rays interact with the electrons whereas neutrons interact directly with the nucleus. Furthermore, the radiation dose is also something you may want to take into consideration.
Without knowing the details about your problem, I will attempt to answer your question assuming there is significant radiation damage due to energetic particles impinging on the material of interest.
In your case, one approach I would recommend is to you start out with DFT calculation of the crystalline structure with arbitrary defects in the structure to mimic radiation damage. These defects may include vacancies or interstitials placed at random in your simulation cell. Then you can use the nudged elastic band approach (after determining the stable binding sites) to find the energy barriers and the frequency for the atom of the species of interest hopping between the different sites. You can then use your results in a kinetic Monte Carlo simulation to determine the diffusion coefficient which can ultimately be used in the diffusion equation to evaluate the effect of radiation on the evolution of the concentration profile in your material.
Another, perhaps simpler approach is to use Molecular Dynamics simulations to calculate the diffusion coefficient. Here, you will again build a simulation cell with defects to mimic radiation damage effects, but you can then use the simulation cell immediately in an MD simulation and determine the diffusion coefficient. You can then still use the diffusion equation as before to evaluate radiation effects on the evolution of the concentration profile. If you decide to use an MD simulation (and LAMMPS is a great option for that and is an open source code), then using SRIM can help you determine the size of the cell to use in your simulation depending on the type and energy of the irradiation particles.
I hope this helps.
Hi Adib Samin,
Thanks for your elaborate answer. It is really helpful.
Regards.
With MD, the defects configuration of cascade debris generated by one neutron could be obtained. In the kinetic Monte Carlo model, the neutron irradiation effects are simulated by inserting the defects configuration of cascade debris (containing vacancies and dumbbells) into the simulation box with certain frequency.
The following link may help.
Article Introducing chemistry in atomistic kinetic Monte Carlo simul...
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