In situ hydration study of the novel ionic conductor Ba7MoNb4O20

Oxide-ion and proton-conducting materials attract considerable interest thanks to their application as electrolytes in solid-oxide fuel cells (SOFCs). We have recently identified remarkable oxide ion and proton conductivity in Ba7MoNb4O20, a 7H hexagonal perovskite derivative. Ba7MoNb4O20 presents a complex structure, with positional oxygen disorder along palmierite-like layers leading to mixed coordination of the Mo/Nb cations. Via neutron diffraction measurements under controlled temperature and atmosphere, we aim to investigate in more detail the structural features of Ba7MoNb4O20 and study the hydration process in situ, in order to locate the possible proton sites and the ionic migration pathways within the crystal lattice. This study will help to understand the mechanism of oxide-ion and proton diffusion in this fascinating novel conductor.

氧离子与质子传导材料因其作为固体氧化物燃料电池（SOFCs）的电解质而受到广泛关注。本课题组近期在一种7H型六方钙钛矿衍生物Ba7MoNb4O20中，观测到优异的氧离子与质子传导性能。Ba7MoNb4O20具有复杂的晶体结构，沿类棕榈石结构层存在氧原子位置无序现象，使得Mo/Nb阳离子呈现混合配位模式。本研究旨在通过控温与控气氛条件下的中子衍射（Neutron Diffraction）测试，深入探究Ba7MoNb4O20的结构特征，并原位（in situ）研究其水合过程，以确定晶格中潜在的质子位点与离子迁移路径。本研究将有助于阐明这类极具潜力的新型导体中的氧离子与质子扩散机制。