Chessboard-like nanostructure evolution in Li0.48Nd0.5TiO2.99 perovskites and its effects on electrochemical properties

Abstract

Lithium neodymium titanate ABO3 perovskites have been synthesized by a solid-state synthesis route. All the samples sintered at 1250°C for 24 h followed by slow cooling at ∼ 10°C h−1 undergo an ordering−induced polymorphic transformation where the amount of ordering increases as the A site cation vacancy content increases. Li0.48Nd0.5TiO2.99 sintered at 1250°C for 24 h and then quenched to room temperature forms a Pnma orthorhombic phase. This phase is also observed after 100 charging and discharging cycles of the Li0.48Nd0.5TiO2.99 sample sintered at 1250°C and then slow-cooled. A chessboard-like nanostructure with a ∼7 nm × 7 nm domain size is observed in the sintered and slow-cooled Li0.48Nd0.5TiO2.99, forming along {001} or {010} interfaces of the pseudo-tetragonal crystal structure. In the slow-cooled sample, independent channels of Li-ions, Nd-ions, and mixed ions are observed in the [100] projection of this chessboard-like structure. The atom probe tomographic reconstruction of this phase clearly indicates phase separation, with a periodic variation of the Li, Nd, and Ti ions. Significantly, the electrochemical properties of this Li0.48Nd0.5TiO2.99 material are superior to those of sintered and quenched Li0.48Nd0.5TiO2.99 and those of sintered and slow-cooled Li0.36Nd0.5TiO2.93, neither of which exhibit a chessboard-like nanostructure. © 2025 The American Ceramic Society.