Tb ³⁺ to Cr ³⁺ energy transfer in a co-doped Y ₃ Al ₅ O ₁₂ host

Strong absorption and high quantum efficiency are the key features for any phosphor. Chromium and terbium co-doped yttrium aluminum garnets (YAGs) are perfect candidates for luminescence. All samples of singly doped and co-doped YAG were prepared by the aqueous sol-gel route, which is advantageous and useful to obtain single phase garnets. Samples were annealed at 1500 °C in order to minimize crystal lattice defects and to obtain better luminescence properties. An efficient energy transfer from Ce ³⁺ to Tb ³⁺ ion was observed in the co-doped YAG phosphors. It was found that optimal Tb ³⁺ doping concentration in YAG:x%Tb ³⁺ was x = 1%, with external quantum efficiency (EQE) of nearly 71%. Optimal Tb ³⁺ co-doping concentration in YAG:1%Cr ³⁺ ,x%Tb ³⁺ was x = 15%, with EQE of more than 98% (excited at 273 nm). All series of samples of YAG:Tb ³⁺ and YAG:Cr ³⁺ ,Tb ³⁺ were characterized by X-ray diffraction (XRD) analysis, steady state and kinetic luminescence measurements.