Tunable luminescence and efficient energy transfer investigation of a borosilicate phosphor KBSiO: Bi, Eu with hypersensitive thermal quenching.

Energy transfer between Bi and Eu has undergone substantial research but Bi and Eu co-doped luminescent materials with high energy transfer efficiency for temperature sensing are rarely investigated until now. Herein, Eu and Bi co-doped KBSiO phosphors were successfully synthesized by solid-state reaction method. The phase purity structure as well as the element distribution were carefully investigated through X-ray diffraction structural refinement and energy dispersive spectrometer analysis. The characteristic luminescence property and luminescence kinetics of KBSiO: Bi, Eu were investigated. By the large spectra overlap between the emission spectrum of Bi and excitation spectrum of Eu, the energy transfer from Bi to Eu can be inferred. The corresponding decrease of the emission intensity and decay time of Bi in KBSiO: Bi, Eu provided direct evidence for the effective energy transfer from Bi to Eu. The interaction and energy transfer mechanism between Bi and Eu ions were also studied. By increasing the Eu concentration in KBSiO: Bi, Eu, the color-tunable emission from blue to red can be realized. KBSiO: Bi, Eu shows hypersensitive thermal quenching behavior and the maximum absolute sensitivity (S) and relative sensitivity (S) are determined to be 1.87 %K and 2.895 %K, respectively. All of the above results imply that KBSiO: Bi, Eu phosphor can be a color-tunable phosphor for optical temperature sensing.