Beyond Lithium Lanthanum Titanate: Toward Metal-Stable Perovskite Electrolytes

According to Chambers et. al., the tetragonal I4/mcm LLTO is the ground-state polymorph.1 Thus, we retrieved the tetragonal I4/mcm SrTiO3 (mp-4651) from the materials project (MP) repository as a reference pristine perovskite structure.2 We chose SrTiO3 because its A-site ionic radius (Sr2+) is close to the ionic radius of La3+.3 At different stages of the study, two distinct working-ion concentration regimes were analyzed: a computationally efficient low concentration (lc) A’0.125A”0.625□0.25B1X3 (A’1A”5□2B8X24) for compositional screening with 38-atom unit cell and a high concentration (hc) A’0.3125A”0.5625□0.125B1X3 (A’5A”9□2B16X48) for the in-depth study stage with 78-atom unit cell. A’, A”, □, B, and X are the working-ion, large-ionic-radius cation, A-site vacancy, small-ionic-radius cation, and anion, respectively.