Enhanced green upconversion luminescence properties of Er3+/Yb3+ co-doped strontium gadolinium silicate oxyapatite phosphor.

Upconversion Sr 2 (Gd .98- x Er .02 Yb x ) 8 Si 6 O 26 (SGSO:2Er 3+ / x Yb 3+ ) phosphor materials were synthesized using a citrate sol-gel process. X-ray diffraction patterns confirmed their hexagonal structure. Field emission scanning electron microscopy images of SGSO:2Er 3+ / x Yb 3+ phosphors depicted submicron particles. The enhanced upconversion luminescence properties of SGSO:2Er 3+ / x Yb 3+ phosphors were analysed as a function of Yb 3+ ion concentration and laser power. The energy transfer induced enhanced emission of the Er 3+ / Yb 3+ ions co-doped SGSO phosphors was ascribed to multi-phonon relaxation. The calculated chromaticity coordinates of the SGSO:2Er 3+ / x Yb 3+ phosphors showed emissions could be tuned by changing Yb 3+ ion concentration. Optimized sample exhibited the chromaticity coordinate values near to the ultra-high definition television standard green emission coordinates. [ABSTRACT FROM AUTHOR]