Enhanced luminescence by tunable coupling of Eu3+ and Tb3+ in ZnAl2O4:Eu3+:Tb3+ phosphor synthesized by solution combustion method

ZnAl2O4:Eu3+ or Tb3+ (1 mol%) and ZnAl2O4:Eu3+/Tb3+ with varied concentrations of Eu3+ and Tb3+ were prepared by solution combustion method. The photoluminescence spectra of synthesized compounds shows that simultaneous doping of Tb3+ and Eu3+ causes enhancement in Eu3+ luminescence intensity. This indicates some energy transfer from Tb3+ to Eu3+. This phenomenon of Tb3+ → Eu3+ energy transfer, accomplishing enhanced intensity of Eu3+ ions, is attributed to the cross relaxation phenomenon, which is favored by overlap between the donor and acceptor transition. The energy is transferred to Eu3+ cascade rapidly via non-radiative transitions to 5D0 state. The synthesized compounds were characterized by XRD, SEM for their structural and morphological characteristics respectively.