Luminescence characteristics of Bi3+/Tb3+/Mn2+-doped Sr3Y2Ge3O12 phosphors

Bi3+/Tb3+/Mn2+-doped Sr3Y2Ge3O12 phosphors were synthesized, and their luminescence performance was investigated. Upon excitation with UV/NUV, the Sr3Y2Ge3O12:Bi3+, Sr3Y2Ge3O12:Tb3+ and Sr3Y2Ge3O12:Mn2+ phosphors showed prominent cyan, green and red emissions, respectively. Energy transfer processes occur in Bi3+/Tb3+, Bi3+/Mn2+ and Bi3+/Tb3+/Mn2+-codoped Sr3Y2Ge3O12 phosphors, which leads to tunable luminescence. The calculated CIE coordinates on the basis of the emission spectra indicate that the tunability of the luminescence for the Bi3+/Tb3+-codoped Sr3Y2Ge3O12 phosphors is not conspicuous. Their light is mainly located in the cyan light region. However, for the Bi3+/Mn2+-codoped Sr3Y2Ge3O12 phosphors with a fixed Bi3+ concentration of 2 mol% and changing Mn2+ concentration, the emission shifts from the blue light region to the near white light region. After the doping of the Tb3+ ions in the Sr3Y2Ge3O12:2%Bi3+/5%Mn2+ phosphors, white light is generated. The CCTs of the light of the Bi3+/Tb3+/Mn2+-codoped Sr3Y2Ge3O12 phosphors decreased continuously with increasing Tb3+ concentration. Warm white light is generated by the Sr3Y2Ge3O12:2%Bi3+/5%Tb3+/5%Mn2+ phosphor.