Anionic Condensation-Guided Synthesis of LaSi ₂ N ₃ O: A “Missing” Structure in the Ln–Si–N–O Series of Oxonitridosilicate Phosphor Materials

The development of innovative luminescent materials for lighting and display applications is an important research field. In this work, we have employed an anionic condensation approach to discover a novel oxonitridosilicate synthesized via Li metal flux. LaSi2N3O crystallizes in the orthorhombic space group Pna21 (a = 7.82609(6), b = 18.24908(15), and c = 4.86567(5) Å) with a structure consisting of [Si6N12O2] ribbons cross-linked by [SiN3O] tetrahedra. This follows previously reported structural rules for a series of condensed rare-earth oxonitridosilicates, and discovery of this relatively simple composition verifies the design principles. Ce3+-doped LaSi2N3O is a highly efficient blue phosphor with peak emission at 450 nm under 390 nm excitation and a quantum yield of 72.0% and demonstrates strong potential for near-UV phosphor applications.