Abstract: A series of Tb³⁺ and/or Sm³⁺ doped KSrGd(WO₄)₃ phosphors were prepared by the high temperature solid-state reaction. The structure, morphology, luminescence properties and energy transfer mechanisms were also investigated. Under the excitation of 260 and 405 nm, KSrGd(WO₄)₃：Tb³⁺ and KSrGd(WO₄)₃：Sm³⁺ phosphors give rise to an intense green and orange red emission, respectively. And the optimal concentration of Tb³⁺ and Sm³⁺ in KSrGd(WO₄)₃ phosphors are 0.7 and 0.08, separately. After that, the luminescence intensity gradually decreases with increasing of doping concentration, due to the concentration quenching effect. In KSrGd(WO₄)₃：xTb³⁺ and KSrGd(WO₄)₃：ySm³⁺ samples, the types of energy transfer between activator ions are dipole-quadrupole and dipole-dipole interaction, respectively. When Sm³⁺ were co-doped in KSrGd(WO₄)₃：Tb³⁺ phosphors,the characteristic emissions of both Tb³⁺ and Sm³⁺ can be observed.Furthermore, as increasing concentration of Sm³⁺, the emission intensities of Tb³⁺ decreases, while those of Sm³⁺were enhanced. The experimental results show that there are not only energy transfer from WO^2-₄ to Tb³⁺ and Sm³⁺, but also energy transfer from Tb³⁺ to Sm³⁺, in Tb³⁺ and/or Sm³⁺ doped KSrGd(WO₄)₃ phosphors. The fluorescence lifetime analysis of Tb³⁺ further confirmed the energy transfer from Tb³⁺ to Sm³⁺. On the basis of CIE calculation, the color of phosphor can be adjusted by fixing the doping concentration of Tb³⁺ and changing the concentration of Sm³⁺ without changing the excitation wavelength. These above results confirm that the synthesized KSrGd (WO₄)₃： Tb³⁺, Sm³⁺phosphors may have potential application prospects for white light-emitting diodeds.

Key words: KSrGd(WO₄)₃, phosphor, high temperature solid-state reaction, concentration quenching effect, energy transfer