UV and X-ray excited luminescence of Tb3+-doped ZnGa2O4 phosphors

Terbium-doped zinc gallates with nominal formulae of Zn(1−x)Ga2O4:xTb, ZnGa2O4:xTb and ZnGa(2−x)O4:xTb were prepared by solid-state reaction method, respectively. Only intrinsic UV emission of ZnGa2O4 host is observed in the photoluminescence spectra of Zn(1−x)Ga2O4:xTb samples, while both ZnGa2O4 emission band and Tb3+ characteristic emission lines (5D4-7FJ) are observed in the emission spectra of ZnGa2O4:xTb and ZnGa(2−x)O4:xTb samples. The different luminescent properties of the three types of phosphors are attributed to their different energy transfer rates from the host to the activators. The X-ray excited luminescence of ZnGa(2−x)O4:xTb exhibits much more intensive emission of Tb3+ and completely suppressed emission of ZnGa2O4, showing an efficient energy transfer from the host lattice to the activator under the X-ray excitation.