resumo
We explore three different potential mechanisms to introduce 4 mol% ZnO sintering additive to the promising yttrium-doped barium zirconate (Ba(Zr,Y)O3-delta, BZY) proton conductor. The mechanisms involve Zn substitution for Y, Zr, or B-site cation excess. The addition of ZnO promotes high densification levels (up to 98% of the theoretical value) at 1300 degrees C, irrespective of the mechanism. However, scanning electron microscopy shows that the B-site cation excess mechanism leads to an impaired grain growth compared to the other mechanisms. Rietveld refinement of the lattice-parameters and scanning transmission electron microscopy-energy dispersive X-ray spectroscopy indicates that Zn resides in both grains and grain boundaries in all cases. Determination of partial conductivities demonstrates that the Zr substitution mechanism provides slightly higher values of bulk protonic conductivity, as well as a higher hydration enthalpy. In contrast, the B-site excess mechanism provides the highest specific grain-boundary conductivity, as a result of greater Zn segregation to the grain boundary. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
palavras-chave
DOPED BARIUM ZIRCONATE; TEMPERATURE; ELECTROLYTE; BAZRO3; BAZR0.9Y0.1O3-DELTA; FABRICATION; BEHAVIOR; CERATE; CELLS
categoria
Chemistry, Physical; Electrochemistry; Energy & Fuels
autores
Soares, HS; Antunes, I; Loureiro, FJA; Perez-Coll, D; Willinger, MG; Brandao, AD; Mather, GC; Fagg, DP
nossos autores
Ana Daniela Isidoro Brandão
Estudante de doutoramento
Francisco José Almeida Loureiro
Bolseiro de investigação
Isabel Alexandra Gonçalves Antunes
Investigador Júnioragradecimentos
The authors acknowledge the projects, UID/EMS/00481/2019FCT, PTDC/CTMCTM/2156/2020, PTDC/QUIELT/3681/2020, POCI010247FEDER039926, POCI010145FEDER032241, UIDB/00481/2020 and UIDP/00481/2020 and CENTRO010145FEDER022083Centro Portugal Regional Operational Programme (Centro2020) , under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) and MICINN, Spain (RTI2018095088BI00) .