Cubic KLu3F10 nanocrystals: Mn2+ dopant-controlled synthesis and upconversion luminescence

Cubic KLu3F10 nanocrystals have been fabricated by doping Mn2+ ions via a liquid–solid solution (LSS) hydrothermal method. With an increase in the Mn2+ level, a phase transformation from orthorhombic KLu2F7 to cubic KLu3F10 associated with evolution of the particle morphologies and sizes is evident. The phase transformation mechanism based on doping with Mn2+ ions was studied via a series of time-controlled experiments and the enhancement of the intensity of upconversion luminescence (UCL) via doping with Mn2+ ions is discussed in detail. In addition, under 980 nm excitation, the UCL properties of Er3+/Tm3+/Ho3+-doped KLu3F10:Yb3+ upconversion nanoparticles (UCNPs) have been investigated and a possible UCL mechanism has been discussed. It has been demonstrated that cubic KLu3F10 is an excellent host for upconversion luminescence.