Solid oxide fuel cells (SOFCs) are among the most efficient energy conversion devices, but their widespread application is limited by high operating temperatures (typically 800-1000 degrees C). Proton-conducting oxides have emerged as promising electrolytes for intermediate and low temperature SOFCs (pSOFCs), enabling reduced operating temperatures and improved compatibility at the electrolyte/electrode interface [1,2]. In this context, density functional theory (DFT) and high-throughput computational screening have become powerful tools to identify candidate compositions prior to experimental synthesis, accelerating materials discovery [3]. Translating such predictions into real materials, however, remains a critical step: most screened compositions including SrZrO3 based perovskites identified by Szaro et al as promising proton-conducting electrolytes have not yet been reported experimentally.
Motivated by these computational predictions, this work presents the initial experimental realization of a set of SrZrO3 based perovskite compositions proposed by Szaro et al. Compositions were selected based on the general formula Sr1-yAyZr1-xBxO3, involving partial A-site substitution of Sr2+ by A = Ca, Ba, or Zn, or partial B-site substitution of Zr4+ by transition metals (B = Mn, Ti). Although not an alkaline-earth cation, Zn2+ was included both as a composition predicted by Szaro et al. and as a well-established sintering aid in zirconate ceramics, potentially contributing to improved densification. A-site substitutions were chosen to tune lattice parameters and proton incorporation sites, while B-site substitutions can modify local bonding and promote oxygen vacancy formation, both being key factors for proton uptake and transport in perovskite oxides. All samples were prepared by the Pechini method, a wet-chemical route that ensures stoichiometric control and compositional homogeneity. The resulting powders were shaped by uniaxial pressing followed by cold isostatic pressing, and the compacts were then sintered at 1500 degrees C for 1 h in ambient atmosphere to promote densification. Preliminary structural characterization was performed by X-ray diffraction (XRD), and qualitative analysis of the diffraction patterns indicates the formation of the cubic perovskite structure as the main phase for all synthesized compositions, suggesting the effective incorporation of the dopants into the SrZrO3 matrix.
These preliminary results support the Pechini route as a viable approach to access this family of compositions and provide a baseline for further optimization of the synthesis parameters. Ongoing and future work includes adjustment of the sintering conditions, quantitative structural refinement, microstructural analysis, and electrical characterization by impedance spectroscopy under controlled atmospheres (dry and humid) and temperatures representative of pSOFC operation, aiming to assess the proton conductivity of these materials.
References
1. Zhang, W. & Hu, Y. H. Progress in proton-conducting oxides as electrolytes for low-temperature solid oxide fuel cells: From materials to devices. Energy Sci. Eng. 9, 984-1011 (2021).
2. Priya, P. & Aluru, N. R. Accelerated design and discovery of perovskites with high conductivity for energy applications through machine learning. npj Comput. Mater. 7, 1-12 (2021).
3. Szaro, N. A., Ammal, S. C., Chen, F. & Heyden, A. First principles material screening and trend discovery for the development of perovskite electrolytes for proton-conducting solid oxide fuel cells. J. Power Sources 603, 234411 (2024).
Comissão Organizadora
Pedro Alves da Silva Autreto
Comissão Científica
Ferramenta completa de submissão, avaliação e publicação de anais para eventos científicos.
