Large enhancement of red upconversion luminescence in beta Ba2Sc0.67Yb0.3Er0.03AlO5 phosphor via Mn2+ ions doping for thermometry

Abstract

Here, this study reports single-band red upconversion emission in β-Ba₂ScAlO₅: Yb³⁺/Er³⁺ phosphor by doping Mn²⁺. The optimum concentration of Mn²⁺ ions in β-Ba₂ScAlO₅: Yb³⁺/Er³⁺ phosphor was 0.20. The intensity of red and green emissions is increased by 27.4 and 19.3 times, respectively. Compared with the samples without Mn²⁺ ions, the red-green integral strength ratio of β-Ba₂ScAlO₅: Yb³⁺/Er³⁺/Mn²⁺ sample was significantly increased by 28.4 times, reaching 110.9. The UCL mechanism was explored by analyzing the down-conversion luminescence spectra, absorption spectra, UCL spectra, and upconversion fluorescence lifetime decay curves of Yb³⁺/Er³⁺/Mn²⁺ co-doped β-Ba₂ScAlO₅. The enhancement of upconversion red light is achieved through energy transfer between defect bands and Er³⁺ ions, as well as energy transfer between Mn²⁺ ions and Er³⁺ ions. In addition, the Mn²⁺ doped β-Ba₂ScAlO₅: Yb³⁺/Er³⁺ red UCL phosphors have great potential for ambient temperature sensing in the 298-523 K temperature range. The maximum sensitivity of β-Ba₂ScAlO₅: Yb³⁺/Er³⁺/Mn²⁺ phosphor as a temperature sensor at 523 K is 0.0247 K^-1.

Keywords: Mn2+ doping; Optical thermometry; Single red emission; Upconversion luminescence.