Energy transfer and white light emission of KGdF4 polycrystalline co-doped with Tb3+/Sm3+ ions

KGdF4:Tb3+, KGdF4:Sm3+ and KGdF4:Tb3+,Sm3+ polycrystalline were synthesized under hydrothermal conditions. The XRD and TEM patterns as well as excitation, luminescence spectra and luminescence decay curves of Sm3+, Tb3+ and Gd3+ have been measured at room temperature. For KGdF4:Tb3+(Sm3+), energy transfer processes from Gd3+ ions to Tb3+ (or Sm3+) ions are related to energy migration through Gd3+ ions and energy trapping by Tb3+ (or Sm3+) ions. The energy trapping rate strongly depends on the nature of RE3+ (Tb3+ or Sm3+) ions and it influences to the luminescence efficiency of RE3+ ion. For KGdF4 :Tb3+,Sm3+, the characteristic emission bands of Tb3+ ion (blue and green) and Sm3+ ion (orange-red) are obtained simultaneously upon excitation by 375 nm. The chromaticity coordinates and correlated color temperature (CCT) are used to estimate the emission feature of prepared material. The quenching of the luminescence and lifetime of D-5(4) (Tb3+) level are relate to the energy transfer process from Tb3+ to Sm3+ ions. It is shown that, by fitting the decay curves of D-5(4) (Tb3+) to the Inokuti and Hirayama model, the dominant interaction mechanism between Tb3+ and Sm3+ is dipole-quadrupole interaction. The probability (W ET ) and the efficiency (W-ET) of energy transfer from Tb3+ ions to Sm3+ ions increase with the increase of Sm3+ concentration.