Effect of Nb5 + content on the high temperature properties of the mixed conductors system La1 − xBaxCo1 − yNbyO3 − δ with 0.6 ≤ x ≤ 1.0 and 0 ≤ y ≤ 0.4
The replacement of Co by Nb in the La1 − xBaxCo1 − yNbyO3 − δ (0.6 ≤ x ≤ 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 im...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2017 |
| País: | Argentina |
| Institución: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/44191 |
| Acceso en línea: | http://hdl.handle.net/11336/44191 |
| Access Level: | acceso abierto |
| Palabra clave: | Cobaltites Crystal Structure Stability Nb-Doping Oxide Mixed Conductors Perovskites Thermal Expansion, Impedance Spectroscopy https://purl.org/becyt/ford/2.5 https://purl.org/becyt/ford/2 |
| Sumario: | The replacement of Co by Nb in the La1 − xBaxCo1 − yNbyO3 − δ (0.6 ≤ x ≤ 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 ≤ x ≤ 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 × 10− 6 K− 1, was obtained for La0.2Ba0.8Co0.6Nb0.4O3 − 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 − δ. The low Rp value of this compound and the crystal structure stability of various compositions in the system La1 − xBaxCo1 − yNbyO3 − δ with x ≥ 0.7 and y ≥ 0.1 make these materials of interest as mixed conductors. |
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