Efficient green and red upconversion emissions in Er3+/Yb3+ co-doped ZnAl2O4 phosphor obtained by combustion reaction

Thin ceramic powders of zinc aluminate ZnAl2O4 co-doped with Er3+ and Yb3+ were prepared by a combustion reaction and characterized from the spectroscopic point of view, with the aim of investigating the effect and mechanisms of upconversion emissions. The characteristic cubic spinel structure was predominantly formed for all doped samples, and intense upconversion emission was observed in the green and red spectral regions, under 980 nm diode laser excitation. The upconversion mechanism of both emissions was confirmed to involve two photon absorptions and it was found that the efficiencies of the emissions are considerably enhanced by increasing the Yb3+ concentration in relation to Er3+. The results indicate the potential of ZnAl2O4:Er3+, Yb3+ phosphor powders for applications in luminescent display panels and other photonic devices.