Atomistic simulation of amorphization thermokinetics in lanthanum pyrozirconate

摘要

The kinetics of amorphization in La_2Zr_2O_7 pyrochlore is investigated using molecular dynamics simulations. Irradiation damage is simulated by continuous accumulation of cation Frenkel pairs at various temperatures. As observed experimentally, La_2Zr_2O_7 first transitions to the fluorite structure, independent of the temperature, and amorphization occurs at low temperatures. A model fit of the simulated dose-temperature curve reproduces experimental results in the literature, with a low temperature amorphization dose D_0 = 1.1 displacement per cation and an activation energy E_(act) = 0.036 eV. Present simulations indicate that point defect recombination can control the temperature dependence of amorphization driven by point defect accumulation.