Blue-green emitting ZnS_0.75O_0.25:Ce³⁺,x%Tb³⁺ phosphor with tunable fluorescence lifetime

A series of ZnS_0.75O_0.25:0.1%Ce³⁺,x%Tb³⁺ phosphors were prepared by high temperature solid state reaction method. These phosphors exhibited two mixed phases consisting of hexagonal phase ZnS and hexagonal phase ZnO with the average particle size of 13.83 μm and emitted blue-green light. The luminescence mechanism consisted of Zn vacancy defects, the 5d₁ → ²F_5/2 radiative transitions of Ce³⁺, the ⁵D₄ → ⁷F₅ and ⁵D₄ → ⁷F₆ radiative transition of Tb³⁺ induced by the energy transfer of Ce³⁺ → Tb³⁺. An equation for the variation of the fluorescence lifetime of ZnS_0.75O_0.25:0.1%Ce³⁺,x%Tb³⁺ phosphors with concentration of Tb³⁺ fraction was obtained by exponential fitting. The short fluorescence lifetime could be tuned within the range of 113 μs to 550 μs with the increase of Tb³⁺ concentration, and the color was tunable from blue to blue-green, which is of important application in the field of high-energy particle detection.