Protonic Transport in Layered Perovskites BaLanInnO3n+1 (n = 1, 2) with Ruddlesden-Popper Structure

Abstract

The work focused on the layered perovskite-related materials as the potential electrolytic components of such devices as proton conducting solid oxide fuel cells for the area of clean energy. The two-layered perovskite BaLa2In2O7 with the Ruddlesden–Popper structure was investigated as a protonic conductor for the first time. The role of increasing the amount of perovskite blocks in the layered structure on the ionic transport was investigated. It was shown that layered perovskites BaLanInnO3n+1 (n = 1, 2) demonstrate nearly pure protonic conductivity below 350 °C.

Oxide Ion Conduction, Defect Chemistry, and the Conducting Mechanism in Ruddlesden–Popper La2–xMxBaIn2O7–0.5x (M = Ca, Sr, Ba)

“…As reported in Tarasova et al’s work, , protonic conduction was evidenced for the parent La 2 BaIn 2 O 7 material under 400 °C. In the present work, to study the proton conduction properties of these acceptor-doped La 2 BaIn 2 O 7 materials, the electrical conductivities of the selected composition of La 1.7 Ba 1.3 In 2 O 6.85 were also recorded under the wet condition at high oxygen partial pressures, and the results are provided in Figure S3a–d.…”

“…Then, numerous studies applying a doping strategy to further improve its oxide ion conductivity have been carried out by different research groups. − As to the La 2 BaIn 2 O 7 material, the La 3+ and Ba 2+ cations also have ordered distributions in the rock salt layer and the perovskite layer, respectively, as shown in Figure d, due to the large ionic radius difference between La 3+ (1.216 Å) and Ba 2+ (1.47 Å) for CN = 9, and this material was reported even more early than NdBaInO 4 . However, until more recently, the protonic conduction was reported for the parent (La/Nd) 2 BaIn 2 O 7 materials by Tarasova et al , They claimed that the (La/Nd) 2 BaIn 2 O 7 materials demonstrated nearly pure protonic conductivity below 350 °C, and no obvious oxide ion conductions were observed.…”

Phosphorus-doped protonic conductors based on BaLanInnO3n+1 (n = 1, 2): applying oxyanion doping strategy to the layered perovskite structure

“…We can assume that such increasing electrical conductivity is due to two factors. Firstly, an increase in the lattice parameters for the layered perovskites of BaLanInnO3n+1 results in a higher conductivity due to facilitating ionic transport [50]. Secondly, the phosphorous-doping can be considered as a donor doping (P 5+ → In 3+ ) that causes the appearance of interstitial ("additional") oxygen in the structure.…”

“…The air humudification leads to an increase in the conductivity values at low temperatures (450 °C). Because layered perovskites BaLaInO4 and BaLa2In2O7 are capable for the dissociative absorption of water from the gas phase [50], the reason of better conductivity is the appearance of proton contribution of conductivity. It can be concluded that the oxyanion doping strategy can be applied for layered perovskites for improving their transport properties.…”

“…They belong to the newly opened class of proton-conducting solid oxide materials [38−49]. It was proved that they are nearly pure (~95-98 %) protonic conductors under wet air below 350-400 °C [50]. Different ways of cationic (iso-and heterovalent) doping lead to increasing the protonic conductivity up to ~1.5 orders of magnitude (from 2•10 -7 S cm -1 for BaLaInO4 to 8•10 -6 S cm -1 for Ba1.1LaInO3.95 at 400 °C) [51−56].…”