The effect of co-dopant addition on the properties of Ln sub(0.2Ce) sub(0).8O sub(2-[delta] (Ln = Gd, Sm, La) solid-state electrolyte)

• Published in: Journal of power sources 2008-07, Vol.181 (2), p.199-206
• Main Authors: Pikalova, EYu, Maragou, VI, Demina, AN, Demin, A K, Tsiakaras, P E
• Format: Article
• Language: English
• Subjects: Conductivity; Direct current; Electrical properties; Electrical resistivity; Electrolytes; Electrolytic cells; Partial pressure; Resistivity
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2008.02.003

The present work aims at the investigation of Ln sub(0.2Ce) sub(0).8O sub(2-[delta] (where Ln = Sm, La, Gd) structural and electrical properties when in the Ln sub-lattice, Ba[super]2+ and Sr[super]2+ with ionic radii 1.42 and 1.26 Aa, respectively, are introduced. The conductivity measurements were held both in air and in H) sub(2) + 3%H sub(2O atmosphere using the 4-probe dc technique at the temperature range of 600-900 [deg]C. Among all the samples, the highest value of electrical conductivity is obtained in the case of (Sm) sub(0).75Sr sub(0.2Ba) sub(0).05) sub(0.2Ce) sub(0).8O sub(2-[delta] , both in air and in hydrogen atmosphere. In the case of H) sub(2) + 3%H sub(2O the conductivity of the co-doped compounds increases in comparison with air. Moreover, the dependence of conductivity on the oxygen partial pressure, measured at the P) sub(O) sub(2 range of 0.21-10[super]-22 atm, showed that the electrolytic area of alkaline-earth metals doped Ln) sub(0).2Ce sub(0.8O) sub(2)-[delta] is considerably enhanced, as predicted by the theory. Finally, by comparing the thermal expansion coefficients of the different materials (TEC), the thermo-mechanical compatibility between the co-doped and the other cell components was also investigated.