Tunable bluish green to yellowish green Ca2(1-x)Sr2xAl2SiO7:Eu2+ phosphors for potential LED application

A series of solid solutions with a general formula of Ca2(1-x)Sr2xAl2SiO7:Eu2+ were synthesized by a high temperature solid state reaction. The structure, diffuse reflection spectra, photoluminescence spectra, color-coordinate parameters and lifetimes of phosphors were investigated. XRD results show that Ca2Al2SiO7 is totally miscible with Sr2Al2SiO7. These solid solution phosphors show a broad excitation band of 350–450 nm that matches well with the output lights of near-UV LEDs and tunable emission from bluish green to yellowish green. These optical properties originate from the 4f7–4f65d transition of Eu2+ ions. The crystal field strength was considered to be tailed by controlling the host composition, which leads to the shift of absorption band and emission band, and the varying of color coordinates.