Strong Red Upconversion Luminescence and Optical Thermometry of Yb3+/Er3+ Co-doped β-Ba2ScAlO5 Phosphor

Abstract Near infrared-to-red upconversion phosphors of Yb3+/Er3+ co-doped β-Ba2ScAlO5 through equivalent substitution strategy has been prepared. They emit strong red emission at 662 nm under 980 nm NIR laser irradiation. Their red-green integrated intensity ratio can reach up to 82.5. The excitation mechanism of red emission mainly arises from energy transfer that promotes Er3+ from 4I13/2 to 4F9/2 level. The overall emission profile of upconversion luminescence is insensitive to the dopant concentration and pump power. The doping concentrations of Yb3+ and Er3+ in β-Ba2ScAlO5 have been optimized based on the steady state upconversion luminescence and lifetime decay studies. The integrated intensity of the upconverted red emission of β-Ba2ScAlO5:Yb3+, Er3+ displays a linear relationship with the temperature in the wide temperature range from 298 to 523 K, which has promising application in optical thermometry.