The influence of the local structure on proton transport in a solid oxide proton conductor La_0.8Ba_1.2GaO_3.9

The local structure around the mobile ions influences their dynamics. The knowledge about the relationship between these properties is of fundamental importance and may lead the way for development of improved solid state ionic conductors. In this study, we use inelastic neutron scattering and ab initio modeling to study a representative proton conductor, La_0.8Ba_1.2GaO_3.9, where different local structures are possible for the same stoichiometry. The intrinsic correlations between the local bonding environment and the dynamical behavior of protons are presented. In particular, we identify how the local Ba/La concentration affects the proton vibrational frequencies, hydrogen bond strength, O-H rotations and in turn long-range proton mobility. Further, possible mechanism for proton transport, through the inter-tetrahedral bond switching, O-H rotations and tetrahedral reorientation is anticipated.