Preparation of Sr8Mg1-mZnmY(PO4)(7):Eu2+ solid solutions and their luminescence properties

A series of orthophosphate solid solutions with a general formula of Sr8Mg1-mZnmY(PO4)(7): Eu2+ (0 <= m <= 1) were synthesized by the combustion-assisted synthesis technique. The XRD patterns confirm the formation of a solid solution of Sr8Mg1-mZnmY(PO4)(7) and lattice parameters of the solid solutions are linearly dependent on m. The excitation spectra of these phosphors show broad band excitation and absorption in the 250-470 nm near ultraviolet (UV) region, which is ascribed to the 4f(7)-4f(6)5d(1) transitions of Eu2+. With an increase in m, the emission color shifts from yellow to green under near-UV excitation, which is rationalized in terms of two competing factors of the crystal filed strength and bond covalence. All the results indicate that the solid solution Sr8Mg1-mZnmY(PO4)(7): Eu2+ can be a good candidate of phosphor applicable to near-UV LEDs for solid-state lighting.