Phases, structures, and electrical properties of Li-doped LaNbO${}_4$ materials

Acceptor-doped LaNbO${}_4$ is well documented to be a promising proton conductor. However, the relatively low proton conductivity limits its widely application, although many dopants are applied to overcome this shortcoming. Herein, a series of Li-doped La${}_{1-x}$Li${}_x$NbO${}_{4-x}$ materials are prepared via a traditional solid-state reaction method, with their phases, structures, and electrical properties being studied thoroughly. The results reveal an extremely low solubility for Li at the La site, which can be rationalized by the high endothermic solution energy of ≈7.57 eV calculated by the atomistic-static-lattice simulation method. Thus, all the prepared single-phase samples (0 ≤ x ≤ 0.3) show similar chemical compositions, crystal structures, and electrical properties. (© 2022 Wiley‐VCH GmbH)