828 nm近红外光激发下Ho3+掺杂NaYF4的上转换发光性质

采用水热法合成了NaYF4:Ho3+上转换发光材料，用XRD、红外光谱、能谱及荧光光谱等对其进行表征，探讨了掺杂浓度、退火温度对上转换发光特性及晶型的影响. 结果表明，在828 nm近红外光激发下，在Ho含量0.7%(mol)、退火温度900℃时，样品的上转换发光效果最好，退火前样品发射蓝、黄光，700℃退火后，除发射蓝、黄光外，出现绿光的尖锐强峰，且温度越高其发光强度越高；退火温度为400℃时样品为a相和b相的混合相，随温度升高晶型转变为纯b相；Ho3+的上转换发光机制为能级跃迁，绿光、黄光、蓝光分别对应5F4,5S2?5I8, 5I5?5G6和3K8,5F3?5I8跃迁.

Upconversion Luminescence of Ho3+ Doped NaYF4 Powder at 828 nm Laser Excitation

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.