Luminescence properties of triple phosphate Ca8MgGd(PO4)7:Eu2+ for white light-emitting diodes

A novel Eu2+ ion doped triple phosphate Ca8MgGd( PO4)(7) was synthesized by a general high-temperature solid-state reaction in a reductive atmosphere. X-ray powder diffraction analysis confirmed the formation of single phase Ca8MgGd(PO4)(7). Scanning electron microscopy indicated that the microstructure of the phosphor consisted of irregular fine grains with a size of about 1-2 mu m. Photoluminescence excitation spectrum measurements show that the phosphor can be efficiently excited by UV-visible light from 250 to 480 nm to realize emission in the visible range. The emission spectrum showed a broad and asymmetric profile from 410 to 750 nm, which corresponds to the allowed f-d transition from three kinds of Eu2+ ions. The characteristics indicated that this phosphor is a candidate for application in the white light-emitting diodes. The luminescence mechanism and three site occupancies of Eu2+ ions in Ca8MgGd( PO4)(7) lattices are briefly discussed.