Photoluminescence properties of Bi3+-doped YInGe2O7 phosphors under an ultraviolet irradiation

Yttrium indium germanate (YInGe2O7) doped with different concentrations of Bi3+ ion was synthesized using a vibrating milled solid-sate reaction. The compound was characterized and its optical properties were investigated. The precursor powders were heated at 1300 °C for 10 h to obtain good crystallinity with better luminescence. The XRD results show that all peaks can be attributed to the monoclinic YInGe2O7 phase when the Bi3+ ion concentration is increased up to 5 mol%. Furthermore, the 0.5 mol% of Bi3+ ion doping lead to obvious improvements in the surface morphology of the YInGe2O7 powder, because the Bi2O3 also acts as a flux reagent. In the PL studies, excitation under an ultraviolet (302 nm) irradiation shows that the (Y1−xBix)InGe2O7 phosphors display luminescence belonging to the 3P1 → 1S0 transition from 457 to 496 nm, and the CIE color coordinates changed from a blue to blueish region as the Bi3+ ion concentration increased from 0.2 mol% to 5 mol%. The time-resolved of the 3P1 → 1S0 transition presents a non-single exponential decay behavior, and the decay time decreases from 8 ms to 1 ms.

► The CIE color coordinates change from a blue to blueish region as Bi3+ concentration increasing.
► The decay time for the 3P1 → 1S0 transition decreases from 8 ms to 1 ms.
► The concentration quenching effect occurs for (Y1−xBix)InGe2O7 when x > 0.005.