Protons in Al doped BaZrO3 escape dopant traps to access long range proton conduction highways
abstract Article history:Received 17 January 2013Received in revised form 18 May 2013Accepted 21 May 2013Available online 13 June 2013Keywords:Proton conductionAluminumYttriumDopantPerovskiteLong range pathways A combination of electronic structure methods, graph theory, and kinetic Monte Carlo (KMC) shows thatdoping BaZrO 3 with aluminum instead of yttrium at the Zr site changes the long range proton conductionpathways by altering local geometry. When the zirconium ion is replaced by the smaller aluminum ion,there is a small contraction which decreases the degree of octahedral tilting possible. The decreased octahe-dral tilting results in a greater contrast in energies close to the dopant and farther from it. The greater con-trast leads to such high barriers to escape the dopant region that the most probable long range protonconduction pathways avoid the dopant region. KMC trajectories show long periods of proton trapping nearthe dopant followed by rare excursions away from it during which the proton accesses the high probabilitylong range proton conducting pathways enabling long range conduction. In contrast, in yttrium dopedsystems where the barrier to get away from the dopant is lower, earlier work has shown that the probablelong range proton conducting pathways include sections near the dopant.© 2013 Elsevier B.V. All rights reserved.