Proton transport in doped yttrium oxide. Monte-Carlo simulation

The Monte-Carlo technique is used to calculate the dependences of the tracer diffusion coefficient D* and conductivity ?? of protons on the temperature and content x of the acceptor dopant in oxides with the structure of distorted fluorite (??bixbyite?? structure). Analysis is carried out for the calcium doped Y₂O₃ oxide as an example. The effect of dopant-generated traps (different energy states for protons) and also the effect of site blocking due to interaction of protons between themselves and with oxygen vacancies are considered. It is shown that mobility of protons decreases significantly as a result of doping already at low x ?? 1 mol %. The behavior of conductivity noticeably depends on the distribution of dopant ions over nonequivalent cation sites in the lattice. The predominant dopant distribution over the sites of the same type accounts for the appearance of a maximum in the dependence of ??(x) when correlations are taken into account.