Enhanced energy transfer in Nd3+/Cr3+ co-doped Ca3Ga2Ge3O12 phosphors with near-infrared and long-lasting luminescence properties

摘要

The phosphors of Ca3Ga2Ge3O12 (CGGG) co-doped with Nd3+ and Cr3+ ions were synthesized using conventional solid-state reaction techniques. Steady-state and time-resolved near-infrared (NIR) photoluminescence (PL) and long-lasting phosphorescence (LLP) properties are investigated in the Nd3+-doped CGGG samples. An increase in NIR luminescence traps can be realized in Nd3+/Cr3+ co-doped samples. Energy transfer from Cr3+ to Nd3+ with an efficiency of up to 57.5% is evident for Ca3-xNdxGa1.99Cr0.01Ge3O12 at x = 0.09. A cross relaxation scheme related to 4T2-4A2 of Cr3+ and 4I9/2-4F3/2 transitions of Nd3+ is discussed. We have presented the luminescence mechanism involving the competing processes of NIR PL and LLP, which is in accordance with our measurements. The results show that the NIR persistent luminescence of CGGG co-doped with Nd3+ and Cr3+ is more efficient compared to the single Nd3+ ion doped CGGG.