Conductivity measurements at intermediate temperatures and phase studies were

carried out in the compositions Ba xCe1−yGd yO3−δ (x = 0.8 to 1.1, y = 0 to 0.3) and

BaxCe0.8Ln0.2O3−δ (x = 0.975, 1.0; Ln = Nd, Sm, Gd, Dy, Yb). In BaxCe0.8Ln0.2O3−δ,

the Ba-deficient compositions (x = 0.975) showed higher conductivity than the

stoichiometric ones (x = 1.0) for all of the Ln. The total (bulk) conductivities had a

maximum (σ = 5.5 x 10−4S/cm at 250C) for Ln = Gd and x = 0.975. The σ value

was nearly two times higher than that of the known stoichiometric

BaCe0.8Gd0.2O3−δ electrolyte and the best of those of known oxide ion conductors at

intermediate temperatures. The Ba-deficient Ba0.975Ce0.8Gd0.2O3−δ composition was

a single phase of the monoclinic perovskite-related phase (I2/m). The high ionic

conductivity was attributed to the fact that the Gd-doped composition had the

largest cell volume in the Ln-doped Ba0.975Ce0.8Ln0.2O3−δ series.

Ionic Conductivity in Lanthanoid Ion-Doped BaCeLnO3 Electrolytes. J.Kikuchi,

S.Koga, K.Kishi, M.Saito, J.Kuwano: Solid State Ionics, 2008, 179[27-32], 1413-6