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Compromising Between Phase Stability and Electrical Performance: SrVO 3 –SrTiO 3 Solid Solutions as Solid Oxide Fuel Cell Anode Components
Author(s) -
Macías Javier,
Yaremchenko Aleksey A.,
RodríguezCastellón Enrique,
Starykevich Maksim,
Frade Jorge R.
Publication year - 2019
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201801727
Subject(s) - materials science , perovskite (structure) , oxidizing agent , oxide , solid solution , thermogravimetric analysis , phase (matter) , analytical chemistry (journal) , titanium , oxygen , electrical resistivity and conductivity , electrochemistry , chemical engineering , chemistry , crystallography , electrode , metallurgy , electrical engineering , organic chemistry , chromatography , engineering
The applicability of perovskite‐type SrVO 3− δ in high‐temperature electrochemical energy conversion technology is hampered by the limited stability domain of the perovskite phase. The aim of the present work was to find a compromise between the phase stability and electrical performance by designing solid solutions in the SrVO 3 –SrTiO 3 system. Increasing titanium content in SrV 1− y Ti y O 3− δ ( y =0–0.9) perovskites is demonstrated to result in a gradual shift of the upper‐ p (O 2 ) phase stability boundary toward oxidizing conditions: from ≈10 −15 bar at 900 °C for undoped SrVO 3− δ to ≈10 −11 –10 −5 bar for y= 0.3–0.5. Although the improvement in the phase stability is accompanied by a decrease in electrical conductivity, the conductivities of SrV 0.7 Ti 0.3 O 3− δ and SrV 0.5 Ti 0.5 O 3− δ at 900 °C remain as high as 80 and 20 S cm −1 , respectively, and is essentially independent of p (O 2 ) within the phase‐stability domain. Combined XRD, thermogravimetric analysis, and electrical studies revealed very sluggish kinetics of oxidation of SrV 0.5 Ti 0.5 O 3− δ ceramics under inert gas conditions and a nearly reversible behavior after exposure to an inert atmosphere at elevated temperatures. Substitution by titanium in the SrV 1− y Ti y O 3− δ system results also in a decrease of oxygen deficiency in perovskite lattice and a favorable suppression of thermochemical expansion. Variations of oxygen nonstoichiometry and electrical properties in the SrV 1− y Ti y O 3− δ series are discussed in combination with the simulated defect chemistry of solid solutions.