Synthesis, upconversion luminescence and optical heating of hexagonal NaGdF4:Yb3+,Er3+

An optical heater based on hexagonal NaGdF 4 :Yb 3+ /Er 3+ is reported. XRD , SEM and EDS characterization results show that F − /Ln 3+ can not only control the phase composition , particle size and morphology, but also affect the effective doping concentration of Yb 3+ and Er 3+ . When F − /Ln 3+ is 12/1, the strongest upconversion luminescence is obtained. Based on the luminescent temperature sensing behavior of Er 3+ , the photo-thermal conversion performance was investigated. The results indicate that the temperature of irradiation spot is linearly dependent on the power density, and the photo-thermal responsivity is determined to be 3.3 K·cm 2 /W. Also, it is found that the photo-thermal conversion efficiency can be regulated by changing the Yb 3+ doping concentration. Compared with the nano-gold, copper sulfide and carbon nanotubes , the NaGdF 4 :Yb 3+ /Er 3+ has the triple functions of upconversion luminescence, temperature sensing, and photo-thermal conversion, and may therefore be a promising optical heater for photo-thermal therapy of tumors.