Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5150483 | Solid State Ionics | 2017 | 9 Pages |
Abstract
The replacement of Co by Nb in the La1 â xBaxCo1 â yNbyO3 â δ (0.6 â¤Â x â¤Â 1.0) system and its effects on phase stability and high temperature properties of the cubic perovskite phase were investigated by X-ray diffraction, dilatometry, electrical conductivity, oxygen permeation and electrochemical impedance spectroscopy. The incorporation of Nb in the B site stabilizes the cubic perovskite in the as prepared samples. The Nb solubility increases from y = 0.1, for the sample with Ba content x = 0.6, to y = 0.4 for 0.8 â¤Â x â¤Â 1.0. However, after a heat treatment at 750 °C during 10 days small amounts of secondary phases were detected for samples with x = 0.9 and 1.0. The linear expansion of the cubic phases decreases with the Nb content as well as with the Ba content. The minimum value, α = 12.9 Ã 10â 6 Kâ 1, was obtained for La0.2Ba0.8Co0.6Nb0.4O3 â δ. The behavior of electrical conductivity and oxygen permeation data with Nb content is explained from variations in the oxygen vacancy concentration, which is controlled by Nb5 + and Ba2 + contents. The minimum polarization resistance value, Rp = 0.08 Ω cm2, was obtained at 600 °C for La0.2Ba0.8Co0.9Nb0.1O3 â δ. The low Rp value of this compound and the crystal structure stability of various compositions in the system La1 â xBaxCo1 â yNbyO3 â δ with x â¥Â 0.7 and y â¥Â 0.1 make these materials of interest as mixed conductors.
Related Topics
Physical Sciences and Engineering
Chemistry
Electrochemistry
Authors
C. Setevich, L. Toscani, S. Larrondo, F. Prado, A. Caneiro,