A continuum theory describing the behavior of dielectric materials containing

mobile, electrically charged vacancies was formulated. The theory was

implemented to simulate diffusion, at the nanometer scale, of oxygen vacancies in

acceptor-doped barium strontium titanate thin films in the paraelectric state. In the

simulations, charged vacancies coalesce into boundary layers of large

concentration at potential-free interfaces, with increases in the local electric field

intensity emerging near such boundaries. Upon relating this increase to a reduction

in the energy barrier for charge transmission from film to electrode at the interface,

and accepting an inverse relationship between the concentrations of doping

elements and mobile oxygen vacancies, the model showed agreement with

observed trends of decreasing current losses with increased doping.

Continuum Modeling of Charged Vacancy Migration in Elastic Dielectric Solids,

with Application to Perovskite Thin Films. J.D.Clayton, P.W.Chung, M.A.Grinfeld,

W.D.Nothwang: Mechanics Research Communications, 2008, 35[1-2], 57-64