Effect of Mn(2+) on Upconversion Emission, Thermal Sensing and Optical Heater Behavior of Yb(3+) - Er(3+) Codoped NaGdF(4) Nanophosphors

In thiswork, we investigate the influence of Mn(2+) on the emission color, thermal sensing and optical heater behavior of NaGdF(4): 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(2+) dopant contents in NaGdF(4): Yb/Er system. Moreover, an enhancement in overall UCL spectra of Mn(2+) doped UCNPs for NaGdF(4) host compared to the UCNPs is observed, which results from a closed back-energy transfer between Er(3+) and Mn(2+) ions ((4)S(3/2) (Er(3+)) → (4)T(1) (Mn(2+)) → (4)F(9/2) (Er(3+))). The temperature sensitivity of NaGdF(4):Yb(3+)/Er(3+) doping with Mn(2+) based on thermally coupled levels ((2)H(11/2) and (4)S(3/2)) of Er(3+) is similar to that particles without Mn(2+) in the 303–548 K range. And the maximum sensitivity is 0.0043 K(−1) at 523 K for NaGdF(4):Yb(3+)/Er(3+)/Mn(2+). Interestingly, the NaGdF(4):Yb(3+)/Er(3+)/Mn(2+) shows preferable optical heating behavior, which is reaching a large value of 50 K. These results indicate that inducing of Mn(2+) ions in NaGdF(4):Yb(3+)/Er(3+) nanophosphors has potential in colorful display, temperature sensor.