Monte Carlo simulation of segregation in ceramic thin films

Abstract

A Monte Carlo exchange technique is used to study segregation in thin ceramic films with application to MgO/MnO. The approach is not restricted to the dilute limit. Surface concentrations as a function of temperature and film composition are determined directly from the simulations. For all compositions studied (Mn_χMg_1−χO, 0 ≤ χ ≤ 1) the (001) surface is Mn²⁺ rich; the occupancy of sites by Mn²⁺ decreases rapidly with depth. The ratio of the number of Mn²⁺ to Mg²⁺ ions at the surface decreases as a function of temperature. The calculated enthalpies of segregation of Mn²⁺ for the thin film are strongly dependent on the total Mn²⁺ concentration at small Mn²⁺ concentrations, with the enthalpy of segregation varying by a factor of two with surface coverage.