Enhanced transport properties of Sn‐substituted proton‐conducting BaZr_0.8Sc_0.2O_3–δ ceramic materials

Abstract

High-temperature proton conductors based on acceptor-doped barium zirconate exhibit excellent chemical stability in atmospheres containing CO 2 or H 2 O. However, due to their refractory nature, these conductors have a low grain growth rate, which negatively affects the overall electrical conductivity. A possible strategy for increasing the ionic conductivity of zirconates lies in the partial substitution of Zr-ions with other isovalent dopants. In this work, we carried out systematic studies of the crystal structure, microstructure, hydration capacity, transport, and thermal properties of BaZr 0.8-x Sn x Sc 0.2 O 3-δ (x = 0, 0.1, and 0.2).According to X-ray powder diffraction and scanning electron microscopy data, all studied ceramic samples have a cubic perovskite structure, whose average grain size decreases with tin doping. It is found that the composition with x = 0.1 exhibits the highest values in terms of total, ionic, grain, and grain-boundary conductivities. The complex analysis of the obtained data shows that a low-level substitution of Zr 4+ -with Sn 4+ -ions is a competent approach for designing new proton-conducting electrolytes attractive for high-temperature applications.

High-temperature transport properties of BaSn1−xScxO3−δ ceramic materials as promising electrolytes for protonic ceramic fuel cells

“…Similar effects were observed when tin was introduced into barium zirconate in Ref. [26]. Therefore, a direct concentration dependence of the hydration degree on the tin amount was observed, reaching 97% of the theoretical value even at 20 at% tin in the Zr sublattice.…”

“…For instance, despite a slight decrease in ionic conductivity, doping with tin increases the chemical stability of BaCeO 3 -based electrolyte materials when they are exposed to carbon dioxide and water vapor atmospheres [25]. An isovalent substitution with tin in the barium zirconate system also produces positive effects, e.g., an increase in both hydration and proton conductivity, as confirmed by several studies [26][27][28]. Based on the favorable changes observed in the properties of both cerates and zirconates from tin doping, it is also of interest to carry out a detailed study into the use of barium stannate materials as proton-conducting electrolytes.…”

Harnessing High‐Throughput Computational Methods to Accelerate the Discovery of Optimal Proton Conductors for High‐Performance and Durable Protonic Ceramic Electrochemical Cells

“…To this end, we have deliberately introduced only a single H 2 O or CO 2 molecule onto the surface in our models to simulate the low concentration/non‐saturated environment, thereby allowing us to more precisely isolate and evaluate the impact of the doping elements. While Sn‐substituted barium zirconates have been previously investigated, [ 19 ] our high‐throughput computational results highlight the distinct properties of Sn‐incorporated barium cerates (Figure 1), underscoring the need for a comprehensive investigation. Additionally, there is a dearth of systematic comparisons between Sn‐ and conventionally Zr‐incorporated materials, impeding a profound comprehension and broader utilization of this family of proton conductor.…”

Insight into Grain and Grain‐Boundary Transport of Proton‐Conducting Ceramics: A Case Report of BaSn0.8Y0.2O3−δ

“…[53]), and BaZr 0.8 Sc 0.2 O 3−δ (see Figure 5a in ref. [54]). However, in most of these cases, the σ = f (pO 2 ) measurements were carried out in a closed reactor, starting with an air atmosphere containing a certain pH 2 O level.…”