Energy transfer among three luminescent centers in full-color emitting ZnGa2O4:Mn2+, Cr3+ phosphors

The ZnGa2O4:Mn2+, Cr3+ phosphors show three colors; the blue band of 380 nm from the charge transfer between Ga–O, the green band of 505 nm from Mn2+ and the red band of 705 nm from Cr3+. As a variation of Mn2+ or Cr3+ concentrations in ZnGa2O4:Mn2+, Cr3+, the relative emission intensity can be tuned. This phenomenon is explained in terms of the energy transfer based on four factors: the spectral overlap between the energy donors (Ga–O) and the energy accepters of Mn2+ or Cr3+, the absorption cross section of the energy accepters, the distance between them, and the decay time of the energy donors. ZnGa2O4:0.0025Mn2+, 0.010Cr3+ shows the CIE coordinates of x=0.4014, y=0.3368, which is a pure white light. The single-phased full-color emitting ZnGa2O4:Mn2+, Cr3+ phosphors can be applied to illumination devices.