abstract
The influence of elevated oxygen pressure (from 1 to 50 bar) on phase separation in Ba0.5Sr0.5Co0.8Fe0.2O3-delta(BSCF) cubic perovskite was investigated in the range of 300to 1300 K. X-ray diffraction and thermogravimetric analysis revealed two separation processes occurring in the high temperature (HT), 1043 K, and low temperature (LT), 713 K, ranges. Increasing oxygen pressure shifts slightly the LT phase separation to lower temperature, but has a rather minor effect on the volume fraction growth of the secondary phase. Phase transformation in the HT range is a slow process and the degree of decomposition is strongly influenced by the cooling rate from higher temperatures. On the contrary, the LT separation is relatively fast and is essentially independent of the cooling rate. The BSCF ceramics thermally treated at p(O-2)=50 bar was analyzed by different electron microscopy techniques. The structures of separation products were identified as trigonal Ba3Co10O17-like lamellae and 2H-hex-agonal Ba-0.5 (+/-) Sr-x(0.5) (+/-) xCoO3-delta perovskite, respectively. (C) 2016 Elsevier B.V. All rights reserved.
keywords
OXIDE FUEL-CELLS; SITU NEUTRON-DIFFRACTION; BA0.5SR0.5CO0.8FE0.2O3-DELTA PEROVSKITE; STRUCTURAL STABILITY; ELECTRON-MICROSCOPY; MEMBRANES; PERMEATION; SRCO0.8FE0.2O3-DELTA; NONSTOICHIOMETRY; PERFORMANCE
subject category
Engineering; Polymer Science
authors
Ravkina, O; Yaremchenko, A; Feldhoff, A
our authors
Aleksey Yaremchenko
Principal ResearcherProjects
acknowledgements
O.R. and A.F. acknowledge financial support by the Deutsche Forschungs-gemeinschaft (DFG) under grant FE928/7-1. We also acknowledge Frank Steinbach for his support during TEM investigations and fruitful discussions. A.Y. would like to acknowledge support from the FCT, Portugal (project 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 and when applicable co-financed by FEDER under the PT2020 Partnership Agreement).