NaLaMgWO6:Pr3+: A novel blue-light excitable red-emitting phosphor for white light-emitting diodes

A series of Pr3+-doped double perovskite tungstate NaLaMgWO6 with composition NaLa1−xMgWO6:xPr3+ (x = 0.01-0.15) were synthesized by a conventional solid-state reaction technique at high temperature. The crystal structure, microstructure, photoluminescence properties as well as decay curves are investigated systematically. The excitation spectrum consists of a host-related excitation band (250-350 nm) and some f-f transition bands of Pr3+ (440-500 nm), in which the latter ones can match well with the commercially available blue-emitting LED chip. Upon excitation with UV (~ 268 nm) and blue light (~ 451 nm), the as-prepared phosphors exhibit red emission originating in the transitions from 3P0 state of Pr3+, in which the transition of 3P0 → 3F2 (~ 654 nm) is dominant. The optimal concentration of Pr3+ is confirmed to be 7%, beyond which the d-d interaction plays an important role in the concentration quenching phenomenon of Pr3+. Furthermore, the luminescence decay lifetime for 3P0 → 3F2 transition of Pr3+ is of microsecond level and decreases with the increase in Pr3+ ion concentration. Finally, a white LED device is fabricated with the combination of phosphors (YAG:Ce3++NaLaMgWO6:Pr3+) and commercial blue-emitting LED chip to explore preliminarily the potential application of NaLaMgWO6:Pr3+ red phosphor in solid state lighting field.