White light emission from Eu3+ co-activated Ca2Gd8Si6O26:Dy3+ nanophosphors by solvothermalsynthesis

Ca2Gd8(SiO4)6O2 (CGS) nanophosphors with different concentrations of single-doped Dy3+ ions and co-doped Dy3+/Eu3+ ions were prepared by a solvothermal synthesis. Very fine particles in the nanometer range could be achieved by this method, as evidenced by transmission electron microscope measurements. The hexagonal phase of the oxyapatite structure was confirmed by X-ray diffraction patterns. The energy transfer between Eu3+ and Dy3+ ions was investigated by photoluminescence excitation and emission properties. These phosphors had absorption bands in the UV and NUV region, which are suitable for the emission wavelength of UV or NUV light-emitting diodes (LEDs). With increasing the Eu3+ ion concentration, the emission peak intensity corresponding to the 5D0→7F2 transition increased and the yellow (4F9/2→6H13/2) emission intensity also increased compared to the blue (4F9/2→6H15/2) emission intensity due to the increased energy transfer between Dy3+ to Eu3+ ions. Thus, the Eu3+ ions compensated the red emission component of the Dy3+ doped CGS nanophosphors. Such phosphors are expected to have potential applications for NUV based white LEDs.