Enhanced Luminescence Of Y2MoO6:Eu3+and Y2(W,Mo) O6:Eu3+ By Incorporation Of Li+ Ion

In recent years, scientists were interesting in tungstate, molybdate, aluminate or silicate as host materials for LED applications. Among these hosts materials for phosphors, tungstate or molybdate had excellent luminescence properties, chemical stability and wide applicability. Tungstate or molybdate could be effectively excited under ultraviolet (UV) and show high luminescence intensities, and their excitation spectra contained broad and strong charge transfer bands. Doped Eu3+ ions obtained strongly red light under near UV excitation.With incorporating Mo6+ions into Y2WO6:Eu3+, the structure had not changed significantly due to the similar radii of Mo6+ and W6+. In the excitation spectra of Y2(W,Mo)O6:Eu3+, the edge of the charge-transfer absorption band was broadened from 370 nm to 430 nm. The excitation spectra exhibited two broad absorption bands centered at 275 nm and 365 nm respectively, and several sharp peaks at 395 nm and 465 nm which due to the f-f transitions of Eu3+ ions. The emission spectra of Y2(W,Mo)O6:Eu3+ showed the emission peaks at 611 nm (5D0â†'7F2),581 nm (5D0â†'7F0) and 591 nm (5D0â†'7Fr). The 5D0â†'7F2 transition of Eu3+ was dominated, which indicates that Eu3+ occupies an inversion symmetry site in Y2(W,Mo)06.With codoped Li+into Y2(W,Mo)O6:Eu3+ or Y2MoO6:Eu3+, the excitation and emission intensities were enhanced significantly. Morphology of the powder particles was examined with a scanning electron microscope. The incorporation of Li+ had increased the particle grain size. The hexagonal crystalline of Y2(W,Mo)O6:Eu3+,Li+or Y2MoO6:Eu3+,Li+ powder had a preferred growth orientation. It was speculated that the Li+ions may serves as a self-promoter for better crystallization or as a lubricant for the complete incorporation of the Eu3+ ions into the Y2(W,Mo)06 and Y2MOO6 hosts. It resulted the improvement of the luminescence intensity of Y2(W,Mo)O6:Eu3+ or Y2MoO6:Eu3+by incorporated with Li+ ions. Thus, this study showed that the red phosphor, Y2(W,Mo)O6:Eu3+ or Y2MoO6:Eu3+ incorporated with Li+ ions was advantageous for LEDs applications.