Strong red upconversion luminescence of NaYF₄: Yb³⁺, Er³⁺ through Sc³⁺ ions doping for temperature sensing

The Sc³⁺ ions doped NaYF₄: Yb³⁺, Er³⁺ upconversion (UC) nanoparticles are synthesized by thermal decomposition method. We successfully obtained the upconversion luminescence (UCL) nanoparticles from green emission to red emission through doping Sc³⁺ ions with different concentrations. Based on the XRD, the phase change process of Sc³⁺ ions doped NaYF₄ nanocrystalline phase were demonstrated. More importantly, through the analysis of UC spectrum data, the change in the phase of the NaY/ScF₄: Yb³⁺, Er³⁺ nanocrystalline corresponds to the change in its luminous properties. It determines that the change of crystal field will lead to the change of luminescence, and then modulate the luminescence. NaScF₄: Yb³⁺, Er³⁺ UC nanoparticles exhibit strong red light emission. In addition, the temperature-sensitive properties of the optimal doping concentration of Sc³⁺ ion were tested. The sensitivity of NaYF₄: Yb³⁺, Er³⁺ nanoparticles doped with Sc³⁺ ion reached the maximum value of 0.024 K^− 1 at 498 K. The nanocrystalline has great application value in the fields of optical temperature measurement, biomedicine, bioprobes and colorful display.