Carbon nanotubes/nanocoils: Synthesis, mechanical properties and electromechanical devices

本文主要是針對奈米碳管以及碳螺旋線圈的成長，機械性質的量測與機電方面的應用做相關的研究與討論。奈米碳管由於具有獨特的結構、電性和機械性質，吸引眾多研究人員的目光，奈米碳管如同分子般大小的一維材料，不但提供了一個理想的基礎研究平台，也可以被用在許多極具潛力的應用，例如：奈米電子元件、感測器、超強複合材料、超平面顯示器、燃料電池…等等。然而，對於製作奈米碳管元件而言，如何控制奈米碳管的方向性以及位置是一個極大的挑戰，本文利用化學與物理方式分別製作不同形態的催化劑，以化學氣相沉積法，從這些催化劑中，成長大面積平行排列單/多層奈米碳管，催化劑種類對於成長方向性排列的奈米碳管之影響將在本文中討論。米碳管除了以筆直的形態呈現外，也可以三維立體的螺旋狀來表現，本文改良以往的成長技術，成功地在低價的不?鋼上成長大量的碳螺旋線圈，碳螺旋線圈佔所有碳產物之比例高達80%，本研究發現在不?鋼表面添加錫奈米粒子，同時配合適當的退火溫度，能有效地提升碳螺旋線圈的產率，本研究之結果未來可用於大量生產碳螺旋線圈。米碳管的機械性質已有相當多研究進行相關的討論，也有許多量測方法相繼被開發出來，目前最為準確的方法是利用共振的原理來量測奈米碳管的彈性模數，本研究將提出一套更為精確的共振偏移法來量測奈米碳管彈性模數，本研究發現一般傳統共振法量測奈米碳管強度時會有20％的誤差，利用共振偏移法則能有效去除這項誤差。至於碳螺旋線圈的機械性質，本文是發展出一項利用側向力顯微鏡的技術對碳螺旋線圈進行壓縮與伸長測試，比較傳統的量測方法，本方法能在常溫常壓下進行，而且能精確控制碳螺旋線圈變形量小到10 奈米大到數十微米。所量出來的碳螺旋線圈機械強度也會在本文中討論。理論與實驗可知奈米碳管的應變規因子可高達數百以上，本文利用成長方向性排列之單層奈米碳管技術，製作出釐米長的懸空單層奈米碳管結構，再將其轉移到具有溝槽結構的可撓性基板上，製作出來的可撓性電子元件，其應變靈敏度達0.004％，應變規因子高達269，本方法所製作出來的可撓性應變感測電子元件不但具有高靈敏度、高應變規因子，還適合大量生產。螺旋線圈的機電性質目前還不是很清楚，本研究首先利用介電泳動法將碳螺旋線圈平行排列在可撓性基板上，在介電泳動法中，分別調整操作電壓以及可撓性基板上的電極間距，藉此得到最佳平行排列碳螺旋線圈的條件，接下來，在機電性質量測結果中，發現碳螺旋線圈的應變規因子約在20?50之間，其數值與多層奈米碳管相當，隨著碳螺旋線圈平行排列的數量愈多，其應變規因子也愈低，其中的原因與機制將在本文中討論。This dissertation reports on the synthesis of carbon nanotubes/nanocoils, the measurement of their mechanical properties and some of their electromechanical applications. Carbon nanotubes have attracted considerable attention because of their remarkable structural, electrical and mechanical properties. They not only offer an ideal arena for fundamental research but also have great potential for various applications, including nanoelectronic devices, sensors, high-strength composite materials, flat-panel displays, hydrogen fuel cells, and others. However, for applications in nanoelectronics, controlling the locations and orientations of carbon nanotubes is extremely challenging. This work prepared several catalysts via chemical and physical methods. Large-scale aligned carbon nanotubes were synthesized using chemical vapor deposition. The effect of the catalysts on the growth of directional aligned carbon nanotubes was also discussed.arbon nanotubes are generally grown in straight wire-like structure. However, under specific growth conditions, carbon nanotubes can be also grown in 3D helical/spiral structures. This work demonstrates high-yield growth of carbon nanocoils on stainless steel by chemical vapor deposition. The stainless steel substrate was coated with tin acetate as the catalyst. The effects of the tin and preparative oxidation pretreatment on the morphologies of the carbon nanocoils were investigated. Tin was found to be crucial in the formation of the carbon nanocoils. A preparative oxidation temperature of 800 centigrade degree yields 80% nanocoil growth in carbon products. This synthetic approach is scalable for the mass production of carbon nanocoils.he mechanical properties of carbon nanotubes have been extensively discussed in the literature, and various measurement methods have also been developed. The most accurate method for estimating the elastic modulus of carbon nanotubes is considered to be the resonance method. This study demonstrates a resonance shift method that is more accurate than the resonance method. It is found that the estimation of the elastic modulus of carbon nanotubes by the traditional resonance method could yield a 20% deviation, compared with the value estimated from the resonance shift method.heoretical and experimental studies have shown that carbon nanotubes have a gauge factor of above several hundreds. This work demonstrates an approach for fabricating high-sensitivity flexible strain sensors at room temperature. At first, the well-aligned mm-long single-walled carbon nanotube (SWCNT) was chemical vapor deposition grown on silicon. The SWCNT was then transferred from the silicon substrate to the flexible substrate and cross the pre-fabricated trench between two electrodes. To prevent shipping, the most of the mm-long SWCNT was in well contact with the electrodes to provide strong adhesion. Therefore, during the bending experiments, the suspended SWCNT exhibits effectively strained, inducing piezo-resistivity change. Experimental results reveal that the sensor achieves a high strain resolution of 0.004%. The measured piezoresistive gauge factor of the flexible sensor is 269. The demonstrated technique for fabricating flexible sensors provides the advantage of high sensitivity and high quality and is suitable for mass production.he electromechanical properties of carbon nanocoils have not yet been properly studied. In this work, carbon nanocoils were aligned and positioned using dielectrophoresis techniques. The applied voltage and the gap between the electrodes were controlled to optimize conditions to align the carbon nanocoils between the electrodes. The electromechanical measurements indicate that the gauge factor of the carbon nanocoils was in the range 20 to 50, which is close to that of multi-walled carbon nanotubes. The gauge factor declines as the number of aligned carbon nanocoils between the electrodes increases. The mechanism was also discussed.摘要 ibstract iii錄 vi目錄 ix目錄 xvi1章 緒論 1.1 奈米碳管之介紹 1.2 碳螺旋線圈之介紹 5.3 關於本論文 72章 奈米碳管的成長與方向性控制 10.1奈米碳管成長之介紹 10.1.1奈米碳管成長方法 10.1.2奈米碳管成長的機制 14.1.3水平方向性奈米碳管之成長 16.2以化學氣相沉積法成長單層奈米碳管 20.2.1實驗設計與實驗架構 20.2.2成長單層奈米碳管之結果與討論 28.2.3成長單層奈米碳管之結論 40.3以氣流控制水平方向性排列之奈米碳管 42.3.1實驗設計與流程 42.3.2方向性排列奈米碳管之結果與討論 44.4材料分析 54.4.1 TEM之分析 54.4.2拉曼光譜之分析 57.2.3特殊珠狀結構之奈米碳管 59.5奈米碳管探針之快速組裝技術 61.5.1實驗設計與流程 62.5.2實驗結果與討論 633章 金屬基板上成長碳螺旋線圈 69.1成長碳螺旋線圈之介紹 69.2實驗設計與流程 70.3碳螺旋線圈之成長結果與討論 72.4碳螺旋線圈之外型與尺寸分析 85.5碳螺旋線圈之TEM分析 89.6碳螺旋線圈頂部催化劑之EDS分析 914章 共振偏移法量測奈米碳管之機械性質 94.1介紹 94.2實驗流程與實驗方法 96.3實驗結果與討論 104.3.1以介電泳動法排列奈米碳管 104.3.2奈米碳管共振及共振偏移量測 105.3.3奈米碳管之奈米操控技術 110.3.4奈米碳管之TEM結果圖 115.3.5奈米碳管之共振偏移分析結果 1195章 以側向力顯微鏡技術量測碳螺旋線圈之機械性質 122.1介紹 122.2實驗方法與設備 123.2.1成長碳螺旋線圈 123.2.2 AFM側向力技術校正 123.2.3量測碳螺旋線圈之方法 124.3實驗結果與討論 128.3.1成長碳螺旋線圈之結果 128.3.2側向力校正之結果 130.3.3量測碳螺旋線圈之結果與分析 1316章 奈米碳管/碳螺旋線圈之機電元件的開發 138.1 介紹 138.2 製作高靈敏度之可撓性奈米碳管應變感測元件 139.2.1實驗流程與設備 141.2.2實驗結果與討論 148.3 方向性排列碳螺旋線圈之機電性質量測 155.3.1實驗設計與流程 156.3.2實驗結果與討論 1587章 結論與未來展望 169.1結論 169.2未來展望 171考文獻 173人簡歷 191人著作 19