The electrical transport properties of La0.95Sr0.05Ga0.9Mg0.1O3–δ crystals with a <001>p direction, grown using the Czochralski method, were investigated by using mainly alternating-current measurements. The crystal comprised twin structures composed of different domain states. Only the highest-frequency semicircle was observed in impedance spectroscopy. However, 2 dielectric relaxation peaks existed in the loss tangent. These results indicated that the equivalent circuit of the twin structures was a parallel R-C circuit, because they exhibited 2 parallel diffusion paths for O2– ions. One path was within the domains, and the other was along the domain walls. Based upon the migration energies of O2– in the domains and along the domain walls, as estimated from dielectric relaxation processes, the resistances to ionic conduction were assessed separately. This revealed that a low resistance to O ionic conduction along the domain walls considerably reduced the resultant resistance of the crystal, and O vacancies segregated preferentially in domain-wall zones. A comparison between these results, and those for the polycrystalline ceramic, suggested that the twin structures within the grains in were one of the main reasons for the high ionic conductivity.

Correlation between High Ionic Conductivity and Twin Structure of La0.95Sr0.05Ga0.9Mg0.1O3– δ. M.Kurumada, E.Iguchi, D.I.Savytskii: Journal of Applied Physics, 2006, 100[1], 014107 (9pp)