Doping induced morphology, crystal structure, and upconversion luminescence evolution: from Na 3 ScF 6 :Yb/Er/Y to NaYF 4 :Yb/Er/Sc nanocrystals

Abstract Impurity doping not only provides a fundamental approach to impart unique electronic, magnetic and optical properties to target nanomaterials, but also has critical influence on nucleation and growth of many functional nanocrystals. In the current study, Y 3+ and Sc 3+ were adopted to tune the shape, size, and upconversion luminescence properties of Na 3 ScF 6 :Yb/Er and NaYF 4 :Yb/Er samples, respectively. When Y 3+ doping concentration was lower than 10 mol%, the size and shape of Na 3 ScF 6 :Yb/Er (18/2) nanoparticles gradually changed from ~ 18 nm rhombus to 36 nm spheres. Subsequently, the co‐existence of Na 3 ScF 6 :Yb/Er and NaYF 4 :Yb/Er nanoparticles was observed during 20 mol%–50 mol% Y 3+ doping, and finally NaYF 4 :Yb/Er nanoparticles became the only product at > 60 mol% Y 3+ doping where the role of Sc 3+ turned into dopant and the size of nanocrystals decreased from ~ 30 to 20 nm gradually. Both Y 3+ and Sc 3+ ions doping could enhance the upconversion luminescence intensity of Na 3 ScF 6 :Yb/Er and NaYF 4 :Yb/Er samples, for which possible mechanism was proposed from the perspective of crystal structure. Finally, the upconversion luminescence details were disclosed.