Ag-Cu离子注入玻璃后不同气氛退火的光吸收研究

Optical absorption of nanoclusters by sequentially implanting into SiO_2 glass and subsequently annealing in a selected atmosphere

采用MEVVA源 (metalvaporvacuumarcionsource)引出的强束流脉冲Ag,Cu离子先后注入到SiO2 玻璃 ,x射线光电子能谱仪 (XPS)分析显示Ag ,Cu大多仍为金属态 ,有部分氧化态Cu存在 .透射电镜观察分析和光学吸收谱都表明在衬底中形成了纳米合金颗粒 .结合有效媒质理论 ,得到模拟的光学吸收谱 ,与实验结果基本符合 ,较好地验证了以上结论 .样品退火后颗粒发生分解 ,分解的颗粒在氧化气氛下被氧化 ,且有部分向样品表面蒸发 ;在还原气氛下氧化态元素被还原并成核生长 .

Ag and Cu ions were implanted sequentially into SiO 2 glass by using a metal vapor vacuum arc (MEVVA) source in the room temperature. Both of the doses were 5×10 16 ions/cm 2 The accelerated voltage for Ag was 43kV and for Cu 30kV with the ion flux density ～2mA/cm 2 The valence states of composite samples were observed in details by x ray photoelectron spectroscopy (XPS). The results showed that there were metallic Ag and Cu and CuO in the sample. The formation of alloy nanoclusters have been evidenced by selected area electron diffraction (SAED), energy dispersive x ray spectra (EDS) and optical absorption spectra which fit the result of theoretical simulation well. After annealed at different temperatures for 1h in either oxidizing (air) or reducing(70%N 2+30%H 2 gas mixture, gas pressure 20Pa) atmosphere, the absorption peaks shifted to blue and appeared a new peak during annealing in reducing atmosphere. Applying the free electron model of metal particles, we have calculated the average size of nanoclusters annealed at different temperatures, the results showed that the size of nanoclusters increased gradually with the enhancement of temperature. Ag Cu alloy nanoclusters were decomposed after annealing in oxidizing atmosphere. Cu atoms migrated to the surface of the sample and are oxidized; Ag nanoclusters were formed due to low oxygen silver interaction. For the sample annealed in reducing atmosphere, the alloy decomposed to Ag and Cu nanoclusters.