Interionic cross relaxation and tunable color luminescence in KY3F10:Tb3+ nano/microcrystals synthesized by hydrothermal approach

Abstract Color tunable phosphors of KY 3(1− x ) Tb 3 x F 10 (KY 3 F 10 : x Tb 3+ ) were synthesized by the hydrothermal (HT) approach. The luminescence consists of a group of blue and green emission lines originating from 5 D 3 → 7 F J and 5 D 4 → 7 F J transitions of Tb 3+ , respectively. The emitting color tunes from blue to green by gradually increasing Tb 3+ concentrations, which is attributed to the enhanced 5 D 3 – 5 D 4 cross-relaxation (CR) between two Tb 3+ ions, as described by ( 5 D 3 , 7 F 6 )–( 5 D 4 , 7 F 0 ). The CR process is analyzed based on Inokuti–Hirayama model and ascribed to the electric dipole–dipole interaction. The energy transfer critical distance and critical concentration between Tb 3+ ions are evaluated to be 8.03 A and 4.61 × 10 20  cm −3 , respectively. Moreover, the initial transfer rate on acceptor concentration is also presented with an averaged CR coefficient.