The replacement of Fe by Al in perovskite-type La0.3Sr0.7Fe1-xAlxO3-δ (x = 0 to 0.4) decreased the unit-cell volume, and the partial O ionic and electronic conductivities. At O partial pressures of 10-10 to 0.5atm, the total conductivity was predominantly p-type electronic. The O-ion transference numbers of La0.3Sr0.7Fe1-xAlxO3-δ (x = 0.2 to 0.4) in air, as determined from Faradaic efficiency measurements, varied from 7 x 10-4 to 10-2 at 1023 to 1223K; increasing with temperature and Al content. Reduction of the O pressure to below 10-10atm resulted in predominant ionic and n-type electronic contributions to the total conductivity. The activation energy for ionic transport in La0.3Sr0.7(Fe,Al)O3-δ (95 to 102kJ/mol) was essentially independent of the cation composition and the O chemical potential. The ionic conductivity could increase slightly upon reducing PO2. The level of O-ionic conduction in Al-containing ferrites was lower than that in Ga-substituted analogues.

Oxygen Ionic and Electronic Conductivity of La0.3Sr0.7Fe(Al)O3-δ Perovskites. A.A.Yaremchenko, M.V.Patrakeev, V.V.Kharton, F.M.B.Marques, I.A.Leonidov, V.L.Kozhevnikov: Solid State Sciences, 2004, 6[4], 357-66