Atomic-Scale Picture of the Ion Conduction Mechanism in a Tetrahedral Network of Lanthanum Barium Gallate

Combined experimental study of impedance spectroscopy, neutron powder diffraction, and quasielastic neutron scattering was performed to shed light onto the atomic-scale ion migration processes of protons and oxide ions in La(0.8)Ba(1.2)Gao(3.9). This material consists of tetrahedral GaO(4)units, which are rather flexible, and rocking motion of these units promotes the ionic migration process. The oxide ion (vacancy) conduction takes place on channels along the c axis, involving a single elementary step, which occurs between adjacent tetrahedra (intertetrahedra jump). The proton conduction mechanism consists of intratetrahedron and intertetrahedra elementary processes. The intratetrahedron proton transport along the c axis is the rate-limiting process, with activation energy of 0.44 eV. The intertetrahedra proton transport has the activation energy of 0.068 eV.