Red Emitting Ca2GeO4:Eu 31 Phosphors for Field Emission Displays

A novel red emitting phosphor, Eu3þ-doped Ca2GeO4 was prepared through the solid state reaction. We also replace Ca 2þ with Mg2þ and Ba2þ ions and add Liþ, Al3þ ions as charge compensators in the Ca2GeO4 host to improve the luminescence properties of Ca2GeO4:Eu 3þ phosphor. XRD, FE-SEM, photoluminescence and cathodoluminescence spectra were utilized to characterize the samples. XRD reveals that pure Ca2GeO4 phase can be obtained at 1250 C and all the above cation substitutions can be achieved in a certain concentration range except for Ba2þ ion. FE-SEM images indicate that the Ca1.99GeO4:0.01Eu 3þ sample and its substitutions consist of aggregated particles with size ranging from 0.5 to 2 lm, and Ba1.99GeO4:0.01Eu 3þ sample is composed of uniform and spindle-like structures with the size ranging from 300 to 500 nm. Under the excitation of ultraviolet light and low-voltage electron beams, the Ca2GeO4:Eu 3þ phosphor shows the characteristic emissions of Eu3þ (5D0– 7F2 at 613 nm, red). The op-timum concentration for the luminescence Eu3þ is determined to be 0.01 in Ca2xGeO4:xEu 3þ phosphor. The luminescent inten-sity can be improved by co-doping the Mg2þ ions and charge compensators (Liþ and Al3þ) to partially substitute of Ca2þ ions