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  • 學位論文

以分子動力學模擬單壁奈米碳管在定溫定管徑下表面能對氬原子吸附之研究

Molecular Dynamic Simulation on Surface Energy Effects in SWNTs Argon Release Phenomena

指導教授 : 王金樹 林水泉
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摘要


本研究的目的爲了探討單壁奈米碳管(SWNT)內氬原子非平衡態之釋放行為。其利用分子動力模擬(Molecular Dynamics Simulation)的技巧,從微觀粒子間之運動行為了解其微觀的釋放行為並探討釋放原子之凝結液滴現象。爲能建立一個精確控制液滴的機制,需將氬原子高壓填充進奈米碳管中,考慮氬原子彼此及其與碳原子間的雷諾瓊斯勢能式(Lennard-Jones Potential),再以修正過的布列尼爾勢能(Brenner Tersoff Potential)建立單壁奈米碳管模型,用以模擬碳原子在不同表面能下管內氣體的運動行為。期間可發覺到氣體原子的流動行為將明顯受到碳原子的表面能影響。再藉由改變表面力使得系統產生不同的釋放現象及液滴大小之探討。 本研究根據其釋放原子數量的速率分別在各釋放階段建立釋放指標(α),結果顯示,表面能較小時,氬原子以較小的角度向外快速釋放,當αExplosion>40時,氬原子在空間中形成明顯的液滴;當表面能變大時,由於表面效應使得原子在出口時受到碳管表面影響,以扇形形狀釋放出管外,並且會有在外壁凝聚的現象;5>αBackflow>5時管口附近之氬原子互向聚集成氬液滴,並受到氬原子與氬原子間作用力與碳原子與氬原子間作用力合力的影響,回流區所釋放之氬原子在管口外分別與管外氬液滴凝結與回流回碳管內,產生一類似頸而斷離成液滴的釋放行為。 研究結果顯示經由表面能改變可得到在E2 Case(ε*=0.71)時,碳管管內氬原子之間作用力與碳對氬的作用力下產生直徑38Å最大之氬原子液滴。

並列摘要


The purpose of this paper is in order to research a Non-equilibrium released action of argon atom in single canbon nanotube(SWNT). Using Molecular Dynamic Simulation(MD) finds out the microscopic released action from the active process between microscopic particle and probes into the phenomenon of producing Argon droplet. In order to set up a mechanism, which can control accurately the droplet, we have to put high pressure Argon atom into Carbon nanotube and consider Lennard-Jones Potential among Argon atom and Carbon atom. Then we use the revised Brenner Tersoff Potential to build SWNT model for simulating the active process of gas in SWNT, in which Carbon atom is under different surface energy. We can discover that the moving behaviors of gas atom will be affected obviously by the surface energy of Carbon atom. This article discusses that system will produce different released phenomenon and droplet size by varying the surface energy. This research will set up a released index(α) in each released stage individually, according to the rate, which to release the quantity of Argon. The result reveals when the degrees of surface energy are different; it will cause different released behavior for the Argon atom in Single wall carbon nanotube. When the surface energy is lower, Argon atom will be released speedily toward outside in smaller angle and the quantity of Argon atom, which are released is much more. WhenαExplosion is >40, Argon atom will form obvious droplets; but when the surface energy become higher, due to the surface effect makes Argon atom to be effected by the surface of Carbon tube at the exit. It will be released out of the tube in sector shape and will produce the phenomenon of agglomerate at outside wall. When ﹣5>αExplosion >5, the Argon atom near the opening of tube will gather into Argon droplet and it will be effected by the co-force combined by the force between Argon atom and Argon atom and the force between Carbon atom and Argon atom. The Argon atoms, which are released at backflow area, will condense with Argon droplets at outside of tube and flow back to Carbon tube. It will cause the stagnancy for total released quantity and produce a released behavior, which is similar to “neck”. The result of research shows that through the change of surface energy, we can get that in E2 Case(ε*=0.71), the force among Argon atoms and the force between Carbon atoms and Argon atoms inside Carbon tube will produce maximum Argon droplet, which diameter is 38Å.

參考文獻


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被引用紀錄


李健仁(2008)。以分子動力學模擬二氧化碳在石墨片與鉑邊界之吸附現象〔碩士論文,國立臺北科技大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0006-3001200801301600

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