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The phenomenon of frequency upconversion (UC) is observed in Er3+:Yb3+:SrAl2O4 powders prepared by combustion synthesis. Strong UC emission at the green (bands peaked at 521, 538, 547, and 562 nm) and weak UC emission at the red (bands peaked at 659 and 682 nm) corresponding to 4f–4f transitions of Er3+ were observed when the samples were irradiated with near-infrared laser excitation at ∼980 nm. Saturation of UC emission is observed for concentrations of 1.5 wt.% of Er3+ and 1.5 wt.% of Yb3+. The green-to-red intensity ratio, on the other hand, increases linearly with Er3+ concentration (Er3+ concentration varying from 0.5 to 1.5 wt.%) while keeping Yb3+ concentration fixed (at 1.5 wt.%). The green UC decay time was measured and Er3+–Er3+ interaction was suggested as a possible mechanism to explain the luminescence quenching effect observed. [ABSTRACT FROM AUTHOR]

The phenomenon of frequency upconversion (UC) is observed in Er3+:Yb3+:SrAl2O4 powders prepared by combustion synthesis. Strong UC emission at the green (bands peaked at 521, 538, 547, and 562 nm) and weak UC emission at the red (bands peaked at 659 and 682 nm) corresponding to 4f–4f transitions of Er3+ were observed when the samples were irradiated with near-infrared laser excitation at ∼980 nm. Saturation of UC emission is observed for concentrations of 1.5 wt.% of Er3+ and 1.5 wt.% of Yb3+. The green-to-red intensity ratio, on the other hand, increases linearly with Er3+ concentration (Er3+ concentration varying from 0.5 to 1.5 wt.%) while keeping Yb3+ concentration fixed (at 1.5 wt.%). The green UC decay time was measured and Er3+–Er3+ interaction was suggested as a possible mechanism to explain the luminescence quenching effect observed. [ABSTRACT FROM AUTHOR]