Structure, energy transfer and tunable photoluminescence of Sr 7 Zr(PO 4 ) 6 :Tb 3+ , Eu 3+ phosphors for near-UV white LEDs

Abstract

Abstract A series of Sr7Zr(PO4)6:Tb3+, Eu3+ phosphors of eulytite-type structure have been synthesized via a high temperature solid-state reaction. The crystal structure and luminescence property of the samples was systematically investigated by XRD Rietveld refinement, excitation and photoluminescence, respectively. For Tb3+ and Eu3+ ions single doped phosphor, the characteristic emission from f-f transitions of Tb3+ at 544 nm and Eu3+ at 613 nm was observed, while for Tb3+ and Eu3+ co-doped phosphor Sr7Zr(PO4)6:Tb3+, xEu3+, various emission color from green to red can be achieved by trimming the relative ratio of Eu3+ to Tb3+ in Sr7Zr(PO4)6 host. Moreover, a warm white light emission of single phased with CIE coordinates at (0.359, 0.327) and correlated color temperature (CCT) at 4264 K was realized under 374 nm excitation. The energy transfer process from Tb3+ to Eu3+ in Sr7Zr(PO4)6 was verified by fluorescence spectra and decay time, where a resonant type via a dipole-dipole mechanism was demonstrated. In addition, the Sr7Zr(PO4)6:Tb3+, Eu3+ phosphors exhibited an excellent thermal quenching luminescence property owing to the structural stability. These results indicate that Sr7Zr(PO4)6:Tb3+, Eu3+ could be anticipated as color-tunable and direct white-light-emitting phosphor for near-UV-pumped w-LEDs application.