Tuning the Anionic Configuration in ASc2(P2O7)2 (A = Ba, Pb) through A-Site Cationic Coordination Engineering

Rare-earth ions have garnered significant attention due to their large ionic radii and unique electronic configurations. In this study, two scandium-based pyrophosphates, ASc2(P2O7)2 (A = Ba, Pb), were successfully synthesized by using a high-temperature melting method. They are the first reported examples of divalent cations binding to scandium-based pyrophosphates. The anionic backbones in their structures are all based on Sc–P–O frameworks, and two distinct cluster configurations are observed: cyclic [ScP2O10] and linear [ScP2O11] clusters. A comprehensive comparison of Sc/Y-based pyrophosphates reveals a strong correlation between the Sc–P–O configurations and the A-site cationic coordination environments. This work also investigated the influence of cations on the P–O configuration of existing Sc/Y-based pyrophosphates, which also offers useful reference for the synthesis of novel scandium-based phosphates.