Synthesis,upconversion luminescence and optical heating of hexagonal NaGdF_4:Yb^(3+),Er^(3+)

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-cm2/W. Also, it is found that the photo-thermal conversion efficiency can be regulated by changing the Yb3~ doping concentration. Compared with the nano-gold, copper sulfide and carbon nanotubes, the NaGdF4：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.