本文選題：浸潤(rùn)性 + 接觸角��； 參考：《中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院物理研究所)》2017年碩士論文

【摘要】：二維(2D)范德華(vdW)層狀材料與環(huán)境之間的相互作用已經(jīng)受到了巨大的研究關(guān)注。研究該類層狀材料浸潤(rùn)性所面臨的一個(gè)關(guān)鍵挑戰(zhàn)是如何在原子層面上獲得良好定義并且完全清潔的表面,這是在宏觀實(shí)驗(yàn)中難以實(shí)現(xiàn)的�；谙惹暗膶�(shí)驗(yàn)報(bào)道,范德華層狀材料,諸如石墨烯、h-BN和MoS2的浸潤(rùn)性質(zhì)都是存在著較大的爭(zhēng)論。雖然已經(jīng)發(fā)現(xiàn)范德華層狀材料的浸潤(rùn)性能在很大程度上取決于其厚度、缺陷、襯底的作用、來(lái)自大氣環(huán)境的污染和轉(zhuǎn)移方法等。但是,關(guān)于范德華層狀材料浸潤(rùn)性的清晰的物理圖像仍然是缺乏的。另一方面,如何定量地表征范德華層狀材料的表面形貌也是非常重要的。常規(guī)的方式是利用原子力顯微鏡的掃描來(lái)獲得其表面的均方根粗糙度,這在實(shí)際的工業(yè)領(lǐng)域中是非常緩慢、不準(zhǔn)確和不切實(shí)際的。但是,如果我們可以清楚地理解該類材料表面的浸潤(rùn)性原理,那么我們便可以使用浸潤(rùn)性作為指標(biāo),簡(jiǎn)單快速地表征vdW層狀材料的表面形貌。在本論文中,我們利用分子束外延(MBE)合成具有清潔和明確定義表面的Bi_2Se_3薄膜,作為研究vdW層狀材料浸潤(rùn)原理的具體實(shí)例。我們發(fā)現(xiàn)水浸潤(rùn)性與Bi_2Se_3薄膜相對(duì)表面粗糙度之間存在著線性關(guān)系,這也意味著這種廣義的Wenzel模型能夠適用于廣泛的vdW層狀材料。這種廣義的Wenzel模型也第一次提供了vdW層狀材料浸潤(rùn)性清晰和準(zhǔn)確的物理圖像。此外,根據(jù)上述線性關(guān)系外推獲得的水接觸角(CA約為98.4°)顯示理想的Bi_2Se_3表面具有意想不到的高疏水性,但粗糙的Bi_2Se_3表面上梯田小島的邊緣卻具有非常強(qiáng)的親水性。根據(jù)第一性原理計(jì)算的結(jié)果,我們發(fā)現(xiàn)這種不尋常的疏水/親水轉(zhuǎn)變與其特定的原子和電子結(jié)構(gòu)有直接聯(lián)系。高質(zhì)量Bi_2Se_3薄膜表面的疏水性質(zhì)使得其很有可能成為無(wú)需封、低成本、自清潔的納米電子學(xué)和自旋電子學(xué)器件。
[Abstract]:The interaction between layered materials and environment has attracted much attention. One of the key challenges in studying the wettability of this kind of layered materials is how to obtain a well-defined and completely clean surface at the atomic level, which is difficult to achieve in macroscopic experiments. Based on previous experimental reports, the wetting properties of Van der Waals layered materials, such as graphene h-BN and MoS2, are controversial. Although it has been found that the wettability of Van der Waals layered material depends to a great extent on its thickness, defects, the effect of substrate, pollution from atmospheric environment and transfer methods, etc. However, clear physical images of the wettability of Van der Waals laminated materials are still lacking. On the other hand, how to quantitatively characterize the surface morphology of Van der Waals layered materials is also very important. The conventional method is to obtain the root-mean-square roughness of the surface by scanning the atomic force microscope, which is very slow, inaccurate and impractical in the practical industrial field. However, if we can clearly understand the principle of surface wettability of this kind of materials, we can use wettability as an indicator to characterize the surface morphology of vdW layered materials simply and quickly. In this thesis, Bi_2Se_3 thin films with clean and clearly defined surfaces have been synthesized by molecular beam epitaxy (MBE) as an example to study the wetting principle of vdW layered materials. It is found that there is a linear relationship between the water wettability and the relative surface roughness of Bi_2Se_3 films, which means that the generalized Wenzel model can be applied to a wide range of vdW layered materials. This generalized Wenzel model also provides clear and accurate physical images of the wettability of vdW layered materials for the first time. In addition, the water contact angle (CA) obtained from the extrapolation of the above linear relation shows that the ideal Bi_2Se_3 surface has unexpected high hydrophobicity, but the edge of the terraced island on the rough Bi_2Se_3 surface is very hydrophilic. Based on the results of first-principles calculations, we find that this unusual hydrophobic / hydrophilic transition is directly related to its specific atomic and electronic structures. The hydrophobic properties of high quality Bi_2Se_3 films make it possible for them to become self-cleaning nano-electronics and spin electronics devices without sealing and low cost.
【學(xué)位授予單位】：中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院物理研究所)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB34
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本文編號(hào)：1933326