High oxide-ion conductivity in acceptor-doped Bi-based perovskites at modest doping levels

A combination of impedance spectroscopy, time-of-flight secondary ion mass spectrometry and literature data are used to show that, (i) the bulk oxide ion conductivity of A-site, alkaline earth-doped BiFeO3 (BF) is independent of the ionic radius of the alkaline earth ion (Ca, Sr, Ba) and, (ii) despite very different A-site environments in (Na1/2Bi1/2)TiO3 and BF, similar high levels and optimisation of bulk oxide ion conductivity in these Bi-based tilted perovskites is achieved at modest acceptor doping levels of similar to 1-10%. These results clearly demonstrate that optimisation of oxide ion conductivity in these materials requires concepts beyond a simple crystallochemical approach based on matching the ionic radii of acceptor dopant and host lattice ions.

Automated summary

The research shows that optimization of oxide ion conductivity in materials like BiFeO3 requires considerations beyond a simple crystallochemical approach based on matching the ionic radii of acceptor dopant and host lattice ions.