abstract
Samples of Gd-doped ceria (GDC, Ce0.9Gd0.1O1.95) with eutectic mixtures of Na2CO3 and Li2CO3 (NLC), or K2CO3, Na2CO3 and Li2CO3 (KNLC) as sintering aids (5 mol%) were studied against pure GDC and cobalt doped GDC. The former electrolytes reached densifications in excess of 95% when sintered at 1100 degrees C, values comparable to pure GDC sintered at 1500 degrees C, and more than 20% higher than for GDC sintered at 1100 degrees C. X-ray diffraction powder patterns showed only typical GDC peaks without any noticeable lattice modification and microstructural analysis suggested a homogeneous distribution of residual amounts of sintering aids. The electrical properties of all materials were studied by impedance spectroscopy in air from 200 to 750 degrees C. Materials with NLC and KNLC showed a total ionic conductivity matching pure GDC at 600 degrees C. Hebb-Wagner polarization measurements, used to assess the impact of sintering aids on the n and p-type electronic conductivity of GDC (600-750 degrees C) showed that NLC and KNLC additions lower the p-type conductivity of GDC while Co additions have the opposite effect. The efficacy of alkali metal salts to produce ceria-based electrolytes with competitive ionic and electronic transport properties is exposed. (C) 2019 Elsevier Ltd. All rights reserved.
keywords
GRAIN-BOUNDARY CONDUCTIVITY; TRANSITION-METAL OXIDE; ELECTRICAL-PROPERTIES; ELECTROCHEMICAL PROPERTIES; COMPOSITE ELECTROLYTES; TRANSPORT-PROPERTIES; SOLID ELECTROLYTES; IONIC-CONDUCTIVITY; SINTERING AIDS; LITHIUM-OXIDE
subject category
Electrochemistry
authors
Grilo, JPF; Macedo, DA; Nascimento, RM; Marques, FMB
our authors
Fernando Manuel Bico Marques
Full professor
João Grilo
Junior ResearcherProjects
acknowledgements
This work was funded by projects CO2ZERO (POCI-01-0145-FEDER-016654 - PTDC/CTM-CER/6732/2014), MOCO3 - (M-ERA.NET2 2016 - MOCO3-0009/2016), and CICECO-Aveiro Institute of Materials (FCT Ref. UID/CTM/50011/2019), financed by national (Portugal) funds through the FCT/MCTES, and when applicable co-financed by FEDER under the COMPETE 2020 Program. This work was also developed with funding from CNPq (Program Ciencia sem Fronteiras, Brazil).