A QUANTUM MOLECULAR-DYNAMICS STUDY OF PROTON CONDUCTION PHENOMENA IN BACEO3

Acceptor doped barium cerate dissolves significant amounts of water th us forming protonic defects. High proton mobility is generally conside red to depend strongly on the dynamics of the proton environment. In t his paper numerical results using quantum molecular dynamics simulatio ns are presented to study the dynamics of the BaCeO3 host lattice. At elevated temperatures O-Ce-O bending modes mainly determine the oxygen separation coordinate Q which is considered to be responsible for mod ulating the proton transfer potential. It is also anticipated that thi s frequency coincides with the attempt frequency for proton conduction . For low proton excitations the dynamics of the proton is found to be part of a hydroxide ion rotating around the oxygen atom in the plane perpendicular to the Ce-O-Ce axis.