本論文主要為利用晶種還原法(seed-mediate growth method)製備銀奈米結構粒子。製備方式主要分為兩個主要步驟，第一步先製備3~5 nm之銀奈米粒子作為晶種，第二步再將晶種加入成長液中當作聚集點反應成長。晶種製備主要用含包覆劑(AOT)與銀離子(AgNO3)之溶液，加入強還原劑NaBH4還原形成銀奈米顆粒；成長液則包含銀離子、弱還原劑(L-ascorbic acid)與界面活性劑(CTAB)，最後加入NaOH調整溶液酸鹼值。研究中主要以紫外-可見光光譜與掃描式電子顯微鏡探討分析改變反應參數對產物的影響。研究結果發，晶種還原法所得產物的形貌大小分佈不均勻，主要產物為三角形、六角形奈米平板與部分奈米棒(依實驗條件不同則比例不同)。晶種添加量的減少會使得光譜呈現紅位移且產物中出現較多且長寬比(aspect ratio)較大之銀奈米棒；反應溫度的升高也會使得產物奈米棒的長寬比變小；NaOH的添加量則存在兩個臨界值，第一是趨動成長反應的臨界值，第二則是形成奈米棒與奈米線的臨界值；成長液中CTAB濃度則在晶種添加量較少時會有較明顯之影響，CTAB濃度過低，則會形成不規則形狀之奈米顆粒，而結果中也看到某些低濃度CTAB條件下(約低於20 mM)會有少數微米大小之立方體的形成。另外，我們也探討了利用加熱過之晶種做成長反應，結果發現會成長出尺度相當大之奈米平板。

In this study, silver nanoparticles were synthesized by seed-mediated growth method, following the procedures described by Jana et al. In seed-mediated growth method, it starts with the synthesis of silver nano-seeds using chemical reduction of a silver salt with a strong reducing agent such as sodium borohydride in the presence of AOT as a capping agent to prevent particle growth. The synthesized silver nano-seeds are 3~5 nm in diameter and served as the seeds to grow more anisotropic nanostructures. These silver nano-seeds were added in the growth solution containing more silver salt, ascorbic acid (weak reducing agent) and cetyltrimethylammonium bromide (CTAB). The effects of various processing parameters on the morphology and uniformity of silver nanoparticles were investigated by UV-Vis spectroscopy and scanning electron microscopy. Preparation of silver nanoparticles by seed-mediated methods generally yielded a wide range of sizes and morphologies. At lower nano-seed concentration, longer silver nanorods can be produced. Increase the reaction temperature led to a decrease of aspect ratio of nanorods. When the pH of solution was increased by adding NaOH, the reducing power of ascorbic acid was increased. The high pH of the reaction solution caused short nanorods to form and the low pH might induce the formation of longer nanowires. But if the pH is too low, silver ions will not be reduced. The concentration of CTAB also has significant effect for low seed concentration cases. When the concentration of CTAB was vary law (a few mM), small irregular silver nanoparticles would be synthesized. Few cubic particles of micron size were synthesized at CTAB concentrations around 20 mM. On the other hand, nano-seeds annealed at higher temperature were also used and quite large silver nanoplates were synthesized.

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