利用瞬時過程製作奈米微粒之研究

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题名:	利用瞬時過程製作奈米微粒之研究
其它题名:	The Research on the Production of Nanoparticles by Flash Process
作者:	單郁翔 SHAN, YU-XIANG
贡献者:	王昌仁 WANG, CHANG-REN 應用物理學系
关键词:	奈米微粒;蒸鍍;析出;脈衝雷射;噴霧;鈦;鉭;氯化鈉;磷酸二氫鉀;瞬間過程 nanoparticles;deposition;precipitation;pulsed laser;spray;titanium;tantalum;sodium chloride;potassium dihydrogen phosphate;flash process
日期:	2019
上传时间:	2019-12-16T07:03:07Z (UTC)
摘要:	利用蒸發或析出等物理過程製作奈米顆粒時，準確地掌握停止材料成長的時機一直都是其中的關鍵。本論文將探索兩個奈米微粒的製程，其特點都是利用瞬時凝結或析出的過程來製作奈米微粒。一為雷射剝蝕法：利用脈衝雷射瞬時製造出金屬蒸氣生成奈米顆粒時，並於氣相或液相環境裡形成奈米微粒，其特點是可以用於製作各種金屬奈米微粒；二是噴霧液相析出法：利用化合物在不同溶劑中明顯地溶解度差異，讓微液滴中的溶質可以瞬時析出成長為固體奈米顆粒。　　本研究中，首先利用PLD製備Ti與Ta的奈米微粒，利用改變靶距，施加外加磁場於靶材等條件製作金屬微粒，再利用TEM觀察微粒形貌及結構，以研究這些條件對生成微粒尺寸的影響。結果顯示，無論靶距或外加磁場等條件對這些微粒樣品的尺寸雖有影響，但影響程度相較於傳統的熱蒸鍍法並不那麼明顯而且微粒尺寸均很小（通常是小於5 nm）。其原因可能與雷射剝鍍形成的羽輝型態與傳統的熱蒸法蒸氣團型態上有所差異所致。而施加外加磁場於靶材的效應與增加靶距類似。值得注意的是Ta奈米微粒形成在純元素金屬中很少見的非晶態型態。而在辛烷中製作的奈米微粒平均尺寸則均較氣相沉積的樣品稍大且呈現明顯的單晶。　　利用噴霧液相析出法製作奈米顆粒，有別於常見的噴霧乾燥法是讓材料藉由溶劑的蒸發而析出，本研究液相析出是利用溶質在不同溶劑中有明顯的溶解度差異，但所使用的溶劑卻能彼此互溶的特性，當微液滴進入不同溶劑時因相異的溶劑彼此快速互溶的過程溶質瞬間析出的方式，使溶質形成奈米微粒。原本預期產生的奈米微粒尺寸會隨溶液濃度改變而變化。但實際產生的微粒尺寸遠小於原本的估計值，推測是這個方法溶質析出的速度極快，使液滴周圍多處同時成核所導致。 Exactly stopping growth of materials is fundamental method for the fabrication of nanoparticles with physical process that like vaporization or precipitation. In this report, the nanoparticles were fabricated with two process, those method make materials freezing or precipitating in a flash process. First method, the metal bulks was ablated to make metal vapor with pulsed laser in gas or liquid ambience, metal vapor is solidified and turn into nanoparticles. Second method, the microdrops was sprayed into different solvent, and the nanoparticles was precipitated because solubility of solute drastically down in a flash. In this research, the first part, titanium and tantalum nanoparticles are fabricated with pulsed laser deposition. Both parameters that were the distance between target and substrate and the applied magnetic field were controlled to produce nanoparticles. The morphology and structure of samples was observed with transmission electron microscopy. Both parameters can effect particle size of samples, but the effects in PLD method are less significant than in traditional vaporization method. The particle sizes of Ti and Ta nanoparticles by PLD method are generally smaller than 5 nm. The applied magnetic field on target has a similar effect as increasing the distance between target and substrate. Specially, the Ta nanoparticles of samples are amorphous by PLD method. Usually, the pure metal elements is hard to be amorphous. This imply that the cooling rate is very high in PLD method. All of the Ti and Ta nanoparticles fabricated in octane by PLD are single crystal with larger particle size than those were fabricate in gas by PLD. The second part, the nanoparticles were fabricated with spray precipitation in liquid. It is different from general spray heating method. In this report, we chose two types of solvents those solubility are different for the solute, but they are miscible. When microdrops of solution drop into the other solvent that can’t dissolve the solute, the solute will precipitate and form nanoparticles quickly because solvents mutually dissolve and solubility for the solute rapidly down. We expected that the nanoparticle sizes of samples should be controlled by concentration of solution and the volume of drop. In this report, the particle sizes of samples are generally much smaller than predicted value. The possible reason is that nucleation rate is too fast in the microdrops.
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