Molecular Dynamics Simulation of Primary Damage in β-Li2TiO3

Abstract Displacement cascades were conducted on β-Li2TiO3 to determine threshold displacement energies and understand primary damage. Two different PKA energies and three different crystallographic directions were used for the study. Ti seemed to have the lowest threshold displacement energy. The evolution of the damage showed an oscillating behavior suggesting that subcascades form even for the low PKA energies considered in this work. This observation suggested that, either high angle scattering or short range channeling occurs during radiation damage. The primary damage was found to consist mainly of Li Frenkel pairs, OLi and LiO antisites. Almost all the defects showed a strong, identical dependence on the PKA direction, independent of the PKA energy. In particular, PKA directions of [100] produced maximum defects, while [001] the lowest. LiTi and TiLi showed directional dependence only for high energy cascades. The primary damage state had significant fractions of Lii close to O atoms, and Oi close to Li atoms. This observation suggests that Li atoms are trapped by O atoms due to Coulombic interactions. Such a trapping behavior may also be observed for positively charged T, thus reducing T yield. For the PKA energies and the time scales examined in this work, no clusters were found to occur.

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