White light generation in Eu- and Mn-codoped Ca7Mg2P6O24 phosphor for white light-emitting diodes

Polycrystalline Ca7Mg2P6O24:Eu2+,Mn2+ phosphors were prepared by a solid-state reaction under a weak reductive atmosphere. The phosphors have been characterized by X-ray diffraction and fluorescence measurements. The results show that the obtained phosphors are of single-phase rhombohedral Ca7Mg2P6O24. Upon excitation of 355 nm ultraviolet (UV) light, two intense broad bands have clearly been observed due to the allowed 5d–4f transition of Eu2+ and the forbidden 4T1–6A1 transition of Mn2+, respectively. A white light has been obtained from Ca7Mg2P6O24:0.035Eu2+,0.5Mn2+ phosphor with CIE chromaticity coordinates of (x = 0.32, y = 0.29) and color temperature of 6175 K. These results suggest that Ca7Mg2P6O24:Eu2+,Mn2+ phosphors could be a promising candidate for UV-converting white light-emitting diodes (LEDs).