Photoluminescence, energy transfer and tunable color of Ce3+, Tb3+ and Eu2+ activated oxynitride phosphors with high brightness

New tuneable light-emitting Ca3Al8Si4O17N4:Ce3+/Tb3+/Eu2+ oxynitride phosphors with high brightness have been prepared. When doped with trivalent cerium or divalent europium they present blue luminescence under UV excitation. The energy transfer from Ce3+ to Tb3+ and Ce3+ to Eu2+ ions is deduced from the spectral overlap between Ce3+ emission and Tb3+/Eu2+ excitation spectra. The energy-transfer efficiencies and corresponding mechanisms are discussed in detail, and the mechanisms of energy transfer from the Ce3+ to Tb3+ and Ce3+ to Eu2+ ions are demonstrated to be a dipole-quadrupole and dipole-dipole mechanism, respectively, by the Inokuti-Hirayama model. The International Commission on Illumination value of color tuneable emission as well as luminescence quantum yield (23.8-80.6%) can be tuned by controlling the content of Ce3+, Tb3+ and Eu2+. All results suggest that they are suitable for UV light-emitting diode excitation.