Strong red upconversion luminescence and optical thermometry of Yb3+/Er3+ Co-doped β-Ba2ScAlO5 phosphor

•Yb3+/Er3+ co-doped β-Ba2ScAlO5 phosphor with strong red upconversion fluorescence was prepared for the first time.•The overall emission profile with strong red luminescence is insensitive to the dopant concentration and pump power.•Red-green integral intensity ratio of β-Ba2ScAlO5:Yb3+, Er3+ can reach 82.5.•The obtained samples can be operated as thermometers with a wide linear temperature sensing range from 298 to 523 K•The max sensitivity value of 0.021 K−1 was achieved at 523 K. 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.