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Enhanced Oxide Ion Diffusion by Lanthanum Substitution in the Palmierite Sr3–3xLa2xV2O8via Increased Tetrahedral Distortion and Cation Vacancies

Lookup NU author(s): Dr Ying Zhou, Oscar Ballantyne, Dr James DawsonORCiD

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Abstract

© 2025 The Authors. Published by American Chemical SocietyPromising ionic conductivity has previously been reported in the palmierite oxide Sr3V2O8. Oxide-ion diffusion within this system occurs via the “cog-wheel” mechanism where rotation of VO4and oxygen deficient VO3units result in the formation of V2O7dimers which continuously break and reform. During this process an oxide ion from a VO4tetrahedra can move to the vacant site of the VO3group, facilitating the movement of oxide-ions throughout the structure. Here, we report the electrical and structural properties of the series Sr3–3xLa2xV2O8(x = 0.00–0.25). Combined neutron diffraction and atomistic simulations reveal that substituting Sr2+with La3+results in ordered cation vacancies, an elongation of the apical V–O1 bond and an increase in the distortion of the VO4tetrahedra, which together enhances the cog-wheel-like rotational dynamics of the VO4tetrahedra that mediate oxide ion transport. Molecular dynamics simulations further indicate that La-substitution facilitates the formation of a continuous diffusion network, leading to improved oxide ion conductivity so that Sr2.55La0.3V2O8(x = 0.15) exhibits the highest bulk conductivity of 7.64 × 10–4S cm–1at 700 °C, an order of magnitude higher than Sr3V2O8. The results demonstrate that palmierites are highly flexible to doping strategies for improving the oxide ion conductivity.

Publication metadata

Author(s): Watson V, Zhou Y, Smith RI, Fop S, Sun Y, Shao Z, Jiang SP, Ballantyne OJB, Dawson JA, Mclaughlin AC

Publication type: Article

Publication status: Published

Journal: Chemistry of Materials

Year: 2025

Volume: 37

Issue: 19

Pages: 7987-7995

Print publication date: 14/10/2025

Online publication date: 19/09/2025

Acceptance date: 11/09/2025

Date deposited: 28/10/2025

ISSN (print): 0897-4756

ISSN (electronic): 1520-5002

Publisher: American Chemical Society

URL: https://doi.org/10.1021/acs.chemmater.5c01856

DOI: 10.1021/acs.chemmater.5c01856

Data Access Statement: Data is available here: 10.5286/ISIS.E.RB2410130-1.

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