828nm近红外光激发下Ho^(3+)掺杂NaYF_4的上转换发光性质

Upconversion Luminescence of Ho^(3+) Doped NaYF_4 Powder at 828 nm Laser Excitation

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828nm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α相和β相的混合相,随温度升高晶型转变为纯β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.

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 u and 13 appeared after annealing at 400 ℃, and the pure phase 13 appeared after annealing at high temperature. The upconversion mechanisms are green, yellow and blue emissions corresponding to the transitions of 5F4,5S2→518, 5I5→5G6 and 3K8,5F3→518, respectively.