Doping induced morphology,crystal structure,and upconversion luminescence evolution:from Na_(3)ScF_(6):Yb/Er/Y to NaYF_(4):Yb/Er/Sc nanocrystals

摘要

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 coexistence 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.