resumo
The applicability of perovskite-type SrVO3-delta 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 SrVO3-SrTiO3 system. Increasing titanium content in SrV1-yTiyO3-delta (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 approximate to 10(-15) bar at 900 degrees C for undoped SrVO3-delta to approximate 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 SrV0.7Ti0.3O3-delta and SrV0.5Ti0.5O3-delta at 900 degrees 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 SrV0.5Ti0.5O3-delta ceramics under inert gas conditions and a nearly reversible behavior after exposure to an inert atmosphere at elevated temperatures. Substitution by titanium in the SrV1-yTiyO3-delta 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 SrV1-yTiyO3-delta series are discussed in combination with the simulated defect chemistry of solid solutions.
palavras-chave
SULFUR-TOLERANT ANODE; Y-DOPED SRTIO3; THERMAL-EXPANSION; THERMOCHEMICAL EXPANSION; HYDROGEN ELECTRODE; DEFECT CHEMISTRY; VANADIUM-OXIDES; PEROVSKITE; CONDUCTIVITY; SRVO3
categoria
Chemistry; Science & Technology - Other Topics
autores
Macias, J; Yaremchenko, AA; Rodriguez-Castellon, E; Starykevich, M; Frade, JR
nossos autores
Aleksey Yaremchenko
Investigador Principal
Javier Macias Montiel
Estudante de doutoramento
Jorge Ribeiro Frade
Professor(a) Jubilado(a)
Maksim Starykevich
Investigador JúniorProjectos
agradecimentos
This work was done within the scope of projects SFRH/BD/91675/2012, IF/01072/2013/CP1162/CT0001, and project CICECO-Aveiro Institute of Materials POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC (Portugal) and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. E.R.C. would like to acknowledge funding within the project CTQ2015-68951-C3-3-R (MINECO, Spain) and FEDER funds.