abstract
Ln-substituted SrTiO3 is a promising material for energy conversion technologies such as. thermoelectric generators and solid oxide fuel/electrolysis cells. In this study, formation of local structures enabling accommodation of excess oxygen in perovskite matrix of SrTiO3 and related redox behavior were assessed employing static lattice simulations in combination with experimental methods (XRD, SEM/EDS, XPS, TGA, and electrical measurements) using Sr(0.90-x)Ln(0.10)TiO(3 +/-delta) (Ln = Ce, Pr; x = 0-0.10) as model systems. Although strontium-vacancy formation is found to be a preferable mechanism for donor compensation in oxidized Sr(Ln)TiO3, oxygen excess still can be accommodated by extended defects quenched from high temperatures. Linear Ln(Sr)(3+)center dot center dot center dot O-i(2-) defect clusters and SrO shear planes characteristic of Ruddlesden Popper phases are found to be the most probable extended defects enabling the accommodation of excess oxygen in oxidized titanates with Sr(1-x)Ln(x)TiO(3+delta) cation stoichiometry. The presence of oxygen-rich local structures is shown to be strongly correlated with the faster redox kinetics and higher electrical conductivity critical for practical applications. Easy oxidation of reduced Sr(1-x)Ln(x)TiO(3+delta) (with electronic donor compensation) provide further evidence in favor of Ln(Sr)(3+)center dot center dot center dot O-i(2-) defect clusters as mechanism of excess oxygen accommodation.
keywords
LA-DOPED SRTIO3; OXIDE FUEL-CELLS; TEMPERATURE STEAM ELECTROLYSIS; ANODE MATERIALS; THERMOELECTRIC PERFORMANCE; ELECTRICAL-PROPERTIES; DEFECT CHEMISTRY; CERIUM DIOXIDE; SINGLE-CRYSTAL; SOFC ANODES
subject category
Chemistry
authors
Yaremchenko, AA; Naumovich, EN; Patricio, SG; Merkulov, OV; Patrakeev, MV; Frade, JR
our authors
Aleksey Yaremchenko
Principal Researcher
Jorge Ribeiro Frade
Retired Professor
Sónia Gonçalves Patrício
Assistant ResearcherGroups
G3 - Electrochemical Materials, Interfaces and Coatings
G5 - Biomimetic, Biological and Living Materials
acknowledgements
This work was done within the scope of Projects IF/01072/2013/CP1162/CT0001, BPD/75943/2011, and Project CICE-CO-Aveiro Institute of Materials POCI-01-0145-FEDER-007679 (FCT ref UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement.