Tin-(IV) dopant-controlled synthesis of Yb3+/Er3+:NaGdF4 nanocrystals: Morphology transformation and intensified upconversion performance

Abstract Hexagonal Yb3+/Er3+:NaGdF4 nanocrystals codoped with Sn4+ ions were produced via an adjustive solvothermal approach. Simultaneous morphology regulation and intensified upconversion (UC) luminescence of Yb3+/Er3+:NaGdF4 nanocrystals were achieved through Sn4+ ions doping. Upon introducing Sn4+ ions into the NaGdF4 host, a part of the nanocrystals were converted to nanocubes. By optimizing the Sn4+ ions doping content to 40 mol%, UC luminescence intensity of the green and red emissions were intensified by 21 and 31 times, respectively. Moreover, the possible mechanisms for morphology transformation and UC luminescence enhancement of Sn4+-doped Yb3+/Er3+:NaGdF4 nanocrystals were discussed elaborately. Additionally, in contrast to the sample fabricated by co-precipitation method, the result indicated that the UC luminescence intensity with 40 mol% Sn4+ ions doping was about 2.5 times higher than the former one. This research could be helpful for designing high-performance UC materials and fulfilling their practical applications.