Electric conductions in La0.9Sr0.1Ga1−xMgxO3−δ (x = 0 and 0.1) were elucidated by ac and dc methods as a function of temperature. Using complex-plane impedance analyses and dielectric relaxation processes along with dc results, activation energy for electric conduction, migration energy of O2− ions (EM), and energy required to create a free mobile O vacancy which assists O2− migration (EO) within intragrains and in boundaries were obtained separately. Dielectric dispersion due to a distribution of relaxation times in boundaries was observed. The activation energy for each electric conduction was nearly equal to sum of EM and EO. Lattice distortion due to a large difference in ionic radii of Mg2+ and Ga3+ brings about high migration energy within intragrains in x = 0.1 specimen compared with that of x = 0. Such high migration energy had an adverse effect on improvement of ionic conductivities but excess O vacancies compensate this adverse effect. In boundaries, disturbances in coulombic potential fields due to disordered ionic arrangements discourage ionic conductions.

Electric Conduction in La0.9Sr0.1GaO3−δ and La0.9Sr0.1Ga0.9Mg0.1O3−δ. M.Kurumada, H.Hara, F.Munakata, E.Iguchi: Solid State Ionics, 2005, 176[3-4], 245-51