Ce³⁺/Tb³⁺ co-doped KBaY(BO₃)₂: A color-tunable blue-green phosphor for near-UV white LEDs

Owing to the flexible composition, superior physicochemical properties and relative low synthesis temperature, rare-earth borates have attracted considerable attention as phosphor hosts. In this work, a series of Ce³⁺/Tb³⁺ co-doped KBaY(BO₃)₂ samples have been synthesized via a traditional high temperature solid-state reaction. The crystal structure and luminescence properties, especially the energy transfer behavior from Ce³⁺ to Tb³⁺, are discussed in detail. The energy transfer from Ce³⁺ to Tb³⁺ in the KBaY(BO₃)₂ host have been demonstrated to be resonant type via a dipole–dipole interaction mechanism and the critical distance of energy transfer was calculated to be 13.84 Å based on the concentration quenching theory. Tunable emission from blue to cyan, and eventually to green was realized by controlling the dopant content of the Ce³⁺/Tb³⁺ ions.