P 45 Perovskite-like system (Sr, La)(Fe, Ga)O3-delta: structure and ionic transport under oxidizing conditions [] / V. V. Kharton, A. L. Shaulo, A. P. Viskup, M. Avdeev, A. A. Yaremchenko, M. V. Patrakeev, A. I. Kurbakov, E. N. Naumovich, F. M. B. Marques // Solid State Ionics. - 2002. - V. 150, N 3-4. - С. 229-243. - Bibliogr.: p. 243 (50 ref.) . - ISSN 0167-2738 Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): ПЕРОВСКИТЫ -- СМЕШАННЫЕ ПРОВОДНИКИ -- ПРОВОДНИКИ СМЕШАННЫЕ -- ОКИСЛЕНИЕ -- ИОННАЯ ПРОВОДИМОСТЬ -- ПРОВОДИМОСТЬ ИОННАЯ -- КРИСТАЛЛИЧЕСКАЯ СТРУКТУРА -- СТРУКТУРА КРИСТАЛЛИЧЕСКАЯ -- ИОННАЯ ПРОВОДИМОСТЬ -- ПРОВОДИМОСТЬ ИОННАЯ -- Ga -- ГАЛЛИЙ -- Sr -- СТРОНЦИЙ -- ПЕРЕНОС ИОННЫЙ -- ИОННЫЙ ПЕРЕНОС Аннотация: The maximum solid solubility of gallium in the perovskite-type La1-xSrxFe1-yGayO3-delta (x = 0.40 - 0.80; y = 0-0.60) was found to vary in the approximate range y = 0.25-0.45, decreasing when x increases. Crystal lattice of the perovskite phases, formed in atmospheric air, was studied by X-ray diffraction (XRD) and neutron diffraction and identified as cubic. Doping with Ga results in increasing unit cell volume, while the thermal expansion and total conductivity of (La, Sr)(Fe, Ga)O3-delta in air decrease with gallium additions. The average thermal expansion coefficients (TECs) are in the range (11.7-16.0) x 10(-6)K(-1) at 300-800 K and (19.3-26.7) x 10(-6)K(-1) at 800-1100 K. At oxygen partial pressures close to atmospheric air, the oxygen permeation fluxes through La1-xSrxFe1-yGayO3-delta (x = 0.7-0.8; y = 0.2-0.4) membranes are determined by the bulk ambipolar conductivity; the limiting effect of the oxygen surface exchange was found negligible. Decreasing strontium and g allium concentrations leads to a greater role of the exchange processes. As for many other perovskite systems, the oxygen ionic conductivity of La1-xSrxFe1-yGayO3-delta increases with strontium content up to x = 0.70 and decreases on further doping, probably due to association of oxygen vacancies. Incorporation of moderate amounts of gallium into the B sublattice results in increasing structural disorder, higher ionic conductivity at temperature below 1170 K, and lower activation energy for the ionic transport |