Mn, Cr-co-doped MgAl2O4 phosphors for white LEDs

The Mn-, Cr-doped and Mn, Cr-co-doped MgAl2O4 powders have been synthesized via a gel–solid reaction method. Energy transfer from Mn2+ to Cr3+ has been observed for the first time in the co-doped MgAl2O4 phosphors. When excited with blue light with a wavelength of 450 nm at room temperature, both green emission from Mn2+ around 520 nm and red emission from Cr3+ around 675and 693 nm were generated. Moreover, the color of the emission can be modified by controlling the doping concentrations of Mn2+ and Cr3+. Therefore, MgAl2O4: Mn2+, Cr3+ could be used as a single-phased phosphor for white LED with a blue LED chip. The energy transfer in terms of Mn2+ to Cr3+ is determined by means of radiation and reabsorption.