Dopant and proton incorporation in perovskite-type zirconates

Atomistic simulation techniques are used to investigate the energetics of d efect and dopants, of oxygen migration and of proton incorporation in AZrO( 3) (A = Ca, Sr). In agreement with recent EXAFS studies, small lanthanide d opants are predicted to substitute on the Zr-site (with oxygen vacancy comp ensation necessary for proton incorporation), while larger lanthanide dopan ts substitute on the A-site. Proton incorporation in AZrO(3) is found to be exothermic, with increasing acceptor dopant levels causing an energetic st abilisation of the protonic defect. Our results suggest that trends in prot on conductivity can be rationalised in terms of effective oxygen vacancy cr eation arising from dopant site selectivity, relative values of water incor poration energies, and possible proton-dopant association. (C) 1999 Elsevie r Science BN. All rights reserved.