Upconversion Luminescence of Ho3+ Doped NaYF4 Powder at 828 nm Laser Excitation
828nm近红外光激发下Ho3+掺杂NaYF4的上转换发光性质

Trivalent Ho3+-doped NaYF4 up-conversion luminescence powder was synthesized.The effects of heat treatment temperature and concentration of Ho3+ on its structure,morphology and luminescent behavior were examined by XRD,FT-IR,EDX and upconversion luminescence.Characters are studied on the synthesis temperature and concentration.The strongest emission was obtained under the excitation of 828 nm laser when annealing temperature was 900℃ and Ho3+ concentration 0.7%(mol).Upconversion luminescence of yellow and blue light emissions was obtained under the excitation of 828 nm diode in NaYF4:Ho3+ before annealing,strong green was obtained after annealing at 700℃.The mixed crystals of phases α and β appeared after annealing at 400℃,and the pure phase β appeared after annealing at high temperature.The upconversion mechanisms are green,yellow and blue emissions corresponding to the transitions of 5F4,5S2-5I8,5I5-5G6 and 3K8,5F3-5I8,respectively.