Computational investigation of interstitial neon diffusion in pure hematite

International audienceMulti-scale simulations were used to investigate the neon diffusivity in hematite for thermochronometry applications. Analyses of the magnetic, electronic, and structural properties of antiferromagnetic α-Fe2O3 are reported. At the microscopic scale, Ne insertion and atomic jumps in hematite are studied by means of the spin polarized Density Functional Theory + U, and the Transition State Theory. The minimum path energy of Ne migration between interstitial sites, and its position at the transition state, are determined by the climbing image-Nudged Elastic Band method (CI-NEB). Finally, these microscopic output data are used as inputs to a homemade code, based on Kinetic Monte Carlo (KMC) algorithms, in order to calculate the effective activation enthalpy and the diffusivity at infinite temperature for Ne in hematite. The Ne diffusion coefficient in pure hematite is calculated according to: D=9.78×10−3(cm2/s)exp(−2.42eVkBT) This formula shows very high retentivity of hematite relative to Ne at surface temperatures, and opens new geological dating fields