Effect of Mn on Upconversion Emission, Thermal Sensing and Optical Heater Behavior of Yb - Er Codoped NaGdF Nanophosphors.

In thiswork, we investigate the influence of Mn on the emission color, thermal sensing and optical heater behavior of NaGdF: Yb/Er nanophosphors, which the nanoparticles were synthesized by a hydrothermal method using oleic acid as both a stabilizing and a chelating agent. The morphology and crystal size of upconversion nano particles (UCNPs) can be effectively controlled through the addition of Mn dopant contents in NaGdF: Yb/Er system. Moreover, an enhancement in overall UCL spectra of Mn doped UCNPs for NaGdF host compared to the UCNPs is observed, which results from a closed back-energy transfer between Er and Mn ions (S (Er) → T (Mn) → F (Er)). The temperature sensitivity of NaGdF:Yb/Er doping with Mn based on thermally coupled levels (H and S) of Er is similar to that particles without Mn in the 303-548 K range. And the maximum sensitivity is 0.0043 K at 523 K for NaGdF:Yb/Er/Mn. Interestingly, the NaGdF:Yb/Er/Mn shows preferable optical heating behavior, which is reaching a large value of 50 K. These results indicate that inducing of Mn ions in NaGdF:Yb/Er nanophosphors has potential in colorful display, temperature sensor.