本文選題：手性碳納米管　切入點：核結(jié)構(gòu)　出處：《新疆師范大學(xué)》2017年碩士論文

【摘要】：碳納米管(CNTs)在生物工程、醫(yī)學(xué)載體、儲氫材料等方面具有潛在的應(yīng)用價值,在原子尺度范圍內(nèi),其結(jié)構(gòu)的變化改變著它的電子特性。為了研究手性碳納米管的結(jié)構(gòu)特征和電子特性,我們通過建立了“一端開口,一端閉口”的生長模型,采用第一性原理密度泛函理論(DFT),模擬計算了手性碳納米管核的形貌,研究其衍生過程和電子特性,其中包括單壁(SWCNTs)、雙壁(DWCNTs)以及三壁碳納米管(TWCNTs)。主要研究內(nèi)容及結(jié)論如下:1、微觀結(jié)構(gòu)衍生過程解釋了如何獲得手性碳納米管,即可以通過逐層吸附d′個碳原子(Cd')。密立根電子轉(zhuǎn)移解釋了碳納米管的生長點位于碳納米管的開口端,其中,多壁碳納米管還遵循 由外向里‖的微觀結(jié)構(gòu)衍生規(guī)律。2、通過結(jié)構(gòu)的穩(wěn)定性分析說明了隨著管徑,管間距或管壁的增加,這些開口端,處于亞穩(wěn)定狀態(tài)的碳原子占所有碳原子的比例逐漸減小。因此,隨著管徑,管間距或管壁的增加,碳管狀團簇的平均結(jié)合能Eb(l)的增長趨勢越加不明顯。3、通過周期性邊界條件(PBC)模擬計算,結(jié)果顯示了獲得的無限長碳納米管依賴于其對應(yīng)的核結(jié)構(gòu)。能帶結(jié)構(gòu)的分析說明了能隙是由碳管壁的曲率造成的,并且能隙隨管徑的增大顯著地減小。(1)當(dāng)滿足n m≠3q時(對于整數(shù)q,n㧐m),SWCNTs呈現(xiàn)半導(dǎo)體性質(zhì);當(dāng)滿足n m=3q時,單壁碳納米管呈現(xiàn)導(dǎo)體性質(zhì);(2)對于(n1,m1)@(n2,m2)型雙壁碳納米管,當(dāng)滿足n1 m1≠3q@n2 m2≠3q嵌套或者n1 m1=3q@n2 m2=3q嵌套時,手性DWCNTs呈現(xiàn)導(dǎo)體性質(zhì);當(dāng)滿足n1 m1≠3q@n2 m2=3q嵌套時,手性雙壁碳納米管呈現(xiàn)半導(dǎo)體性質(zhì);(3)對于(n1,m1)@(n2,m2)@(n3,m3)型手性TWCNTs,當(dāng)滿足n1 m1≠3q@n2 m2≠3q@n3 m3=3q嵌套或者n1 m1=3q@n2 m2=3q@n3 m3=3q嵌套時,手性三壁碳納米管就呈現(xiàn)導(dǎo)體性質(zhì)。我們模擬計算的碳納米管核結(jié)構(gòu)和微觀結(jié)構(gòu)衍生過程更好的闡述了在實驗上手性碳納米管可能的生長機制,并且在工業(yè)水平上為手性碳納米管結(jié)構(gòu)均一可控生產(chǎn)提供有益指導(dǎo)。
[Abstract]:Carbon nanotubes (CNTs) have potential applications in bioengineering, medical carriers, hydrogen storage materials and so on. In the atomic scale, the structural changes of CNTshave changed its electronic properties.In order to study the structural and electronic characteristics of chiral carbon nanotubes, we have established a growth model of "one end open, one end closed". The morphology of chiral carbon nanotubes has been simulated and calculated by first principle density functional theory (DFT).The derivation process and electronic properties were studied, including single-walled SWCNTsO, double-walled DWCNTsand three-walled carbon nanotubes (TWCNTsN).The main research contents and conclusions are as follows: 1. The microstructural derivation process explains how to obtain chiral carbon nanotubes, that is, they can be adsorbed by layer by layer.Millikan electron transfer explained that the growth point of carbon nanotubes was located at the open end of carbon nanotubes, in which multi-walled carbon nanotubes also followed the law of microstructural derivation from extroverted tubes.With the increase of tube spacing or tube wall, the proportion of the carbon atoms in the metastable state to all the carbon atoms decreases gradually.Therefore, with the increase of pipe diameter, tube spacing or tube wall, the increasing trend of the average binding energy of carbon tubular clusters is less obvious, and calculated by PBC (periodic boundary condition).The results show that the obtained infinite carbon nanotubes are dependent on their corresponding nuclear structures.The analysis of the band structure shows that the energy gap is caused by the curvature of the carbon tube wall, and the energy gap decreases significantly with the increase of the diameter of the tube.鍗曞紕崇撼綾崇鍛堢幇瀵間綋鎬ц川;(2)瀵逛簬(n1,m1)@(n2,m2)鍨嬪弻澹佺⒊綰崇背綆，

本文編號：1705452