Simultaneous phase and morphology control of Ba2YbF7: Er3+ upconversion nanocrystals through La3+ doping

Lanthanide doped upconversion nanocrystals are widely applied in biological imaging, photonics, photovoltaics and therapeutics. Highly monodispersed and uniform products with controllable optical modulation of upconversion fluorescence really matters their promising applications. Here, Er 3+ doped Ba 2 YbF 7 nanocrystals with phase transformation, controllable morphology and tunable upconversion emission color is investigated via varying the concentration of La 3+ . Accompanied with tetragonal Ba 2 YbF 7 transformed to be cubic phase, nanocubes appear instead of nanorods, and a distinct upconversion color changing from yellow to green is obtained. Crystal structure management of Ba 2 YbF 7 contributing to a suppressive back energy transfer process, which facilitates a controllable upconversion color in monodispersed nanocrystals with a uniform morphology, is demonstrated.