A molecular dynamics study of displacement cascades and radiation induced amorphization in Li2TiO3

DR Sahoo and P Chaudhuri and N Swaminathan, COMPUTATIONAL MATERIALS SCIENCE, 200, 110783 (2021).

DOI: 10.1016/j.commatsci.2021.110783

Molecular dynamics simulations are conducted on beta-Li2TiO3 to evaluate several radiation damage related properties. Firstly, including the polarization of the O atom through a core-shell potential while modeling cascades was found to predict a qualitatively acceptable level of primary damage. The primary damage was dominated by Li Frenkel pairs followed by O and Ti Frenkel pairs. Except for LiTi and TiLi, antisites had negligible contribution. Computational samples were amorphized by explicitly moving atoms and relaxing the structure. The dose to amorphization was around 0.5dpa (displacement per atom), but required displacement of Ti and O atoms to cause the peaks of pair correlation functions to disappear, indicating a collapse of the crystalline structure. Displacing Li atoms alone did not cause any noticeable change to the structure even for high doses. Propensity of tritium trapping was studied by examining the number of Lii (Oi) in O (Li) voronoi cells. Nearly 41% of Lii (48% of Oi) were found to be in the voronoi cells containing an O (Li) atoms, indicating that primary damage can increase tritium inventory within the material by formation of hydroxyl groups.

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