980nmLD激发下YAG：Yb^3＋,Ho^3＋纳米晶粉体的上转换发光

以稀土氧化物、硝酸铝为原料,采用溶胶-凝胶法合成了钇铝石榴石（Y3Al5O12,YAG）纳米晶粉体。采用X射线衍射（XRD）确定了1200℃煅烧后的晶体粉为纯YAG结构,无杂质相,晶体尺寸约为90 nm;该粉体在波长为980 nm的半导体激光器激发下发射出中心波长为547 mm的绿色上转换荧光,对应于Ho离子的^5F4→^5I8的跃迁。发光强度和激发功率关系的研究揭示其为双光子过程,能量传递和激发态吸收是上转换发光的主要机制。

Up-conversion Luminescence in YAG:Yb~(3+),Ho~(3+) Nano-crystalline Powders Excited by a 980nm Laser Diode

Yttrium aluminum garnet （Y3A15 O12, YAG） nano-erystalline powders were synthesized by a sol-gel process from a mixed solution containing aluminum nitrates and rare-earth oxide. XRD technique was used to characterize structures of sample and precursor. It was found that Mono-phase YAG crystallites were formed at 1200 ℃ without formation of any intermediate phase. The up-conversion spectroscopic properties of the powders were investigated under the excitation of a 980 nm continuous wave diode laser. Strong green up-conversion emissions which centered at 547 nm respectively was observed. The green emission was assigned to the transition of energy levels of ions. The dependence of the intensity of up-conversion emission upon the excitation power of diode laser suggested that two-photon absorption processes are involved in the green up-conversion luminescence.