| 摘要: | 本研究成功將銀奈米粒子與銀離子在經過溶凝膠法（sol-gel）反應之後均勻嵌載氧化矽鋁的非晶結構表面及內部，其中鋁原子的導入扮演關鍵性的角色，為銀離子（Ag＋）均勻分佈在整體二氧化矽載體的主要原因。[AlO4]－四面體結構和Ag＋的交互作用導致Ag＋藉著庫倫靜電力散佈在主體結構，進而完整呈現Ag＋嵌載在 Al－O－Si 鍵結狀態的結構。首先，藉由一步驟（one-step）製成合成出表面幾乎無銀粒子覆蓋之氧化鋁矽奈米微球（AlxSi1-xO2@Ag），經過還原性氣體－H2 混N2 的氣氛下爐管退火將微球表面銀離子還原成銀原子。銀原子和銀離子在表面的比例隨著退火條件而改變，隨著退火溫度的增加，造成熱還原速度上升，銀原子會快速的堆疊成大顆的銀顆粒。但是由於小尺寸效應，奈米級的銀顆粒熔點可能低於200oC，所以造成一邊還原一邊熔化與離子化之情形，藉由特定退火條件的控制，還原於表面的銀原子能覆蓋於奈米微球表面形成核-殼之結構。為了更加深對於擴散之現象，製作了雙階段製程(two-steps)當做對照組，觀察 SiO2@Ag 結構受到溫度的上升，二氧化矽表面銀粒子的變化現象。本研究後續重要的實驗與測試主要使用 SEM、TEM 觀察奈米微球表面之形貌，UV-Visible 測量光學性質之改變，XPS、EDS 測量表面成份，最後針對 AlxSi1-xO2@Ag 和 SiO2@Ag 進行自組裝（Self -assemble），經由爐管退火後，比較、觀察其自組裝結構以及光學性質的差異，並利用拉曼光譜做分析，所得結果進行討論。
In this study, we have successfully prepared an ionic silver(Ag+) uniformly incorporated into amorphous silica/aluminum framework and silver nanoparticles was embedded on its surface by sol-gel process, which introduce controlled Al atoms to play a significant role in overall Silica matrix. It attributed that the premier reason for silver ions uniformly distribute in entity of silica carrier. The interaction between [AlO4]- tetrahedral structure and Ag+ result in uniform Ag+ distribution in matrix by electrostatic force, and then Ag+ embedded Al－O－Si structure is revealed.First of all, the non-silver nanoparticle covered silica/aluminum microspheres were synthesized by an one-step process. The product was then annealed in the H2/N2 atmosphere in order to make the silver ion reduce into silver atoms on the surface of the microspheres.
The proportion of silver atoms and silver ions changes with the condition of annealing on the surface. In principle, as the increase of annealing temperature, cause the thermal reduction speed up, which Ag particle size will grow bigger continuously.As well know, silver nanoparticles could be melted under relative low temperature owing to small size effect. The melting point of Ag nanoparticles decreases to below 200oC. Caused by reducing, melting and ionizing at the same time. Through the carefully –controlled annealing process, the silver nanoparticles can cover the surface of microspheres and formed a “core -shell structure”.In order to have more depth of diffusion phenomenon, I made a two-steps process as extra control group specimens. Observing its phenomenon silver nanoparticle of surface changes while the temperature rise.The morphology of the surface of the nano-microspheres were observed by SEM and TEM. The energy dispersive spectrometer（EDS） and XPS were used to analyze the chemical composition of the material “UV-Visible”was used to measure the changes of optical properties of the nanoparticles. Finally, we take AlxSi1-xO2@Ag and SiO2@Ag for self-assemble, then take into the furnace tube. The structure and optical properties after self-assemble was also be observed and the used of Raman Spectroscopy analysis. |
