Influence of alkali metal ions doping content on photoluminescence of (Y, Gd) BO3:Eu red phosphors under VUV excitation

The red-emitting Y_0.65−xGd_0.25M_xBO₃:0.10Eu³⁺ (M=Li, Na, K 0.00≤x≤0.10) phosphors were synthesized by solid-state reaction and their photoluminescence characteristics were studied under vacuum ultraviolet (VUV) excitation. The emission intensity is significantly improved by adding alkali metal ions dopants because they introduce some bounded electron−hole pairs, which act as an intermediator for the excitation energy transfer from the host lattice to the activator Eu³⁺. The chromaticity was improved due to the distorted surrounding of Eu³⁺. The emission intensity of the Y_0.65−xGd_0.25 M_xBO₃:0.10Eu³⁺ increased up to maximum with alkali metal ions doped to a certain concentration and then decreased with the increase in of alkali metal dopants.