Green, room-temperature, fast route for NH4Yb2F7:Tm3+ nanoparticles and their blue upconversion luminescence properties

Abstract A pure ammonium fluorolanthanate NH4Yb2F7 matrix and its derivative doped Tm3+ were successfully synthesized by an ultra-fast solution route at room temperature. The as-prepared nanoparticles (NPs) were about 70 nm in diameter with the uniform size. In addition, NH4Yb2F7:Tm NPs demonstrated a bright blue upconversion luminescence feature, which can be observed with the naked eye. There are five emission bands in the range of 400–800 nm and the primary blue and red bands derived from the transitions of 1D2→3F4 and 1G4→3F4, respectively. The blue emission was populated via a three-photon process based on the relationship between emission intensity and excitation pump power. Our ultra-fast synthesis route presents a green and one-step strategy for the large-scale production. Moreover, the excellent blue upconversion will arouse extensive interest in upconversion studies in ammonium fluorolanthanate based hosts and pave the way for further development of upconversion material family.