Synthesis and luminescence enhancement of white-emitting Ca9La(VO4)7:Dy3+ phosphors through Gd3+ and Al3+ codoping for white-light-emitting diodes

The single-component Ca9La(VO4)7:Dy3+, Gd3+ and Ca9La(VO4)7:Dy3+, Al3+ white-emitting phosphors were prepared through a solid-state method, and the Gd3+/Al3+ was introduced in the structure for photoluminescence enhancement. The XRD results verified that the structure of samples was consistent with the Ca9La(VO4)7 standard phase. The as-prepared Ca9La(VO4)7:Dy3+ exhibited a characteristic white emission consisting of a yellow peak (570 nm) and a blue peak (478 nm), which originated from the electron transitions 4F9/2→6H13/2 and 4F9/2→6H15/2 of Dy3+, respectively. Through the introduction of Gd3+/Al3+ into Ca9La(VO4)7:Dy3+, the luminescence intensity could be enhanced by 1.520 and 1.522 times, respectively, which are due to the crystal-field environmental effect. By combining the Ca9La0.79(VO4)7:0.18Dy3+, 0.03Gd3+ and Ca9La0.82(VO4)6.97:0.18Dy3+, 0.03Al3+ with a n-UV LED chip (λex = 365 nm), the warm w-LEDs with suitable CCT and CRI values were realized. In summary, the Gd3+/Al3+ introduced Ca9La(VO4)7:Dy3+ samples can serve as excellent white-emitting phosphors for white-light-emitting diode applications.