A novel Cr3+-activated far-red titanate phosphor: synthesis,luminescence enhancement and application prospect

Plant factory, a new agricultural planting technology, has emerged and rapidly grown in recent years, with phosphor conversion light emitting diodes (pc-LEDs) considered as the first choice of source light for the plant factory. In this study, a new type of Cr³⁺-activated Li₂MgTi₃O₈ phosphor (LMT: Cr³⁺) was synthesized by high temperature solid state method. X-Ray diffraction patterns showed that there was no detectable impurity in these samples. The photoluminescence spectra revealed that this phosphor can emit far-red light with the peak at 740 nm excited by ultraviolet and blue light, overlapped well with the P_FR. After introducing Zn²⁺ ions (LMT: Cr³⁺, Zn²⁺), the luminescence intensity increases by 46% mainly due to the increase of lattice distortion, and internal quantum yield was improved from 25.4% to 41.3% under 365 nm excitation. Finally, the pc-LED devices, consisting of 470 nm chip coated with the optimal phosphor, exhibited good luminescence and overlapping with P_FR. These results indicate that the LMT: Cr³⁺, Zn²⁺ phosphor has the potential application in modern agriculture.