Bright orange upconversion in a ZnO–TiO2 composite containing Er3+ and Yb3+

Abstract

ZnO–TiO2 composite system containing Er3+ and Yb3+ were prepared by solid state reaction method and its upconversion (UC) luminescence excited by 980nm laser was studied for the first time. The effects of firing temperature, ZnO/TiO2 composition and Er3+, Yb3+ concentrations on the UC emission behavior were examined. The ZnO–TiO2 composite product sintered at 1200°C contained Zn2TiO4, TiO2 and RE2Ti2O7 (RE=Er3+ and Yb3+) phases and exhibited strong green and red emissions arising due to the 2H11/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions for Er3+ ion, respectively. Bright orange color by the mixing of green and red colors was observed in the 1ZnO–1TiO2 product doped with 2at.% Er3+ and 6at.% Yb3+. The ZnO–TiO2:Er3+, Yb3+ phosphor was compared to the brightest available phosphor, Y2O3:Er3+, Yb3+ and found to be 3-fold brighter than it. It suggests that ZnO–TiO2:Er3+, Yb3+ is a potential material for the orange upconversion phosphor.