LnBSb₂O₈ (Ln = Sm, Eu, Gd, Tb): A Series of Lanthanide Boroantimonates with Unusual 3D Anionic Structures

A series of lanthanide boroantimonates, namely, LnBSb₂O₈ (Ln = Sm 1, Eu 2, Gd 3, and Tb 4) have been successfully synthesized by high temperature solid-state reactions for the first time. They are isostructural and feature novel three-dimensional (3D) frameworks composed of 2D [Sb₃O₁₂]^9– layers interconnected by 1D [SbBO₇]^6– chains with remaining BO₃ groups hanging on the walls of the 1D 6-membered-ring (MR) tunnels along the a-axis, and the lanthanide ions filled in the voids of the anionic structure. They exhibit high thermal stability (up to 900 °C). Luminescent studies suggest that compounds 1, 2, and 4 have potential application as orange, red, and green light luminescent materials, respectively. Magnetic measurements reveal ferromagnetic coupling interactions in compound 3 and antiferromagnetic coupling interactions between magnetic centers in compounds 1, 2, and 4.