Abstract: The relation between the content of YF₃ and oxygen in the host lattice and luminescence change of Eu²⁺ in BaF_2-xYF₃ has been studied. The energy transfer frotn BaF_2-xYF₃ to Tb³⁺ in Ti-doped BaYF₃ was observed. The emission strength of Eu²⁺ was found to be reduced greatly and the decay time of the luminescence of the luminescence of Eu²⁺ was shortened due to the energy transfer from Eu²⁺ to Tb³⁺.

Key words: barrum flouride, yttriun1 fluoride, luminescence change, europium(Ⅰ), energytranster