Achieving fast oxygen diffusion in perovskites by cation ordering

TL;DR

This study demonstrates that inducing cation ordering in perovskite oxides significantly enhances oxygen diffusivity by creating channels that facilitate ion movement, offering a promising approach for designing better ionic conductors.

Contribution

It introduces a method to improve oxygen diffusion in perovskites through cation ordering, transforming the structure to reduce bonding strength and enhance ion mobility.

Findings

Oxygen diffusivity increased by orders of magnitude with cation ordering.

Layered structure GdBaMn_2O_{5+x} enables efficient oxygen ion transport.

Cation ordering reduces oxygen bonding strength, facilitating diffusion.

Abstract

The oxygen-exchange behavior has been studied in half-doped manganese and cobalt perovskite oxides. We have found that the oxygen diffusivity in Gd_{0.5}Ba_{0.5}MnO_{3-\delta} can be enhanced by orders of magnitude by inducing crystallographic ordering among lanthanide and alkali-earth ions in the A-site sublattice. Transformation of a simple cubic perovskite, with randomly occupied A-sites, into a layered crystal GdBaMn_2O_{5+x} (or isostructural GdBaCo_2O_{5+x} for cobalt oxide) with alternating lanthanide and alkali-earth planes reduces the oxygen bonding strength and provides disorder-free channels for ion motion, pointing to an efficient way to design new ionic conductors.