發(fā)布時間：2018-01-27 06:26

  本文關(guān)鍵詞： 透射電子顯微鏡 原位透射電鏡 環(huán)境透射電鏡 表面結(jié)構(gòu) 表面動態(tài)行為　出處：《浙江大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：研究材料表面原子結(jié)構(gòu)及電子結(jié)構(gòu)對于理解其催化、電學(xué)、光學(xué)、超導(dǎo)等性能具有極其重要的意義;隨尺寸減小,材料表面原子比例大幅增加,表面對其性能具有更加決定性的影響。過去幾十年里,以掃描隧道顯微鏡(STM)為代表的傳統(tǒng)表面研究手段在確定微米級晶體的表面原子結(jié)構(gòu)方面取得了巨大成功,但也在研究納米材料的表面結(jié)構(gòu)、表面應(yīng)力應(yīng)變、表面動態(tài)行為、表面成分及價態(tài)分析等方面遇到了巨大困難。本論文利用浙大電鏡中心國際先進的環(huán)境透射電子顯微鏡(ETEM)、球差校正透射電鏡、原位樣品桿等設(shè)備,發(fā)展出一套利用原位透射電鏡在外場環(huán)境中研究納米材料表面行為的方法。以被最廣泛研究的TiO2等體系為突破口,實現(xiàn)了對納米晶表面原子結(jié)構(gòu)的確定、少數(shù)晶面及棱角處的原子結(jié)構(gòu)研究、外場環(huán)境原子尺度觀察表面動態(tài)行為、結(jié)構(gòu)演變及表面催化反應(yīng)。透射電鏡在這些傳統(tǒng)表面研究手段難以適用的方面所取得的成功展示了其在表面科學(xué)領(lǐng)域中的巨大應(yīng)用潛力,具體成果如下:(1)通過原位透射電鏡,我們首次從側(cè)視視角確定了 TiO2(1×4)-(001)重構(gòu)表面原子排布,給出了 ADM表面重構(gòu)模型最直接的實驗證據(jù)。結(jié)束了關(guān)于這一重構(gòu)表面原子結(jié)構(gòu)長達十多年的爭議。(2)首次在實驗中揭示了 TiO2(102)、(103)、(301)等少數(shù)晶面的原子結(jié)構(gòu)及不同晶面之間棱角處原子結(jié)構(gòu)。(3)首次在氧氣環(huán)境下原子尺度觀察了 TiO2(001)表面(1×4)重構(gòu)的形成過程,并觀察到“1×3”、“1×5”、“1×4”等表面結(jié)構(gòu)之間的動態(tài)演變;結(jié)合理論計算,我們揭示了應(yīng)力驅(qū)動的(1×4)表面重構(gòu)機理。(4)利用球差校正掃描透射電鏡(STEM),我們原子尺度原位研究了銳鈦礦TiO2(101)、(100)、(001)、(102)等不同表面的穩(wěn)定性;發(fā)現(xiàn)TiO2不同晶面在高溫下能夠通過表面重構(gòu)、結(jié)構(gòu)演變等行為降低體系能量;首次從表面結(jié)構(gòu)的視角闡述了 TiO2的穩(wěn)定性問題,解釋了銳鈦礦TiO2納米晶相變溫度高于理論值的原因。(5)以石墨烯包裹的Pt納米顆粒作為反應(yīng)平臺,首次實現(xiàn)了原子尺度在同一實驗中實時對比Pt不同表面的催化活性,證明了 Pt(100)及(110)表面相比Pt(111)表面具有更好的催化石墨烯氧化性能。(6)氧氣條件下原位原子尺度觀察了 MoO2納米棒的動態(tài)結(jié)構(gòu)演變;揭示了其頂端表面周期性振蕩蕩分解和側(cè)壁表面的逐層生長現(xiàn)象;結(jié)合DFT理論計算發(fā)現(xiàn),電子束輻照引起的頂端晶面氧流失導(dǎo)致了優(yōu)先生長晶面的改變及形貌的重構(gòu)。
[Abstract]:It is very important to study the surface atomic structure and electronic structure of materials for understanding their catalytic, electrical, optical and superconducting properties. As the size decreases, the atomic ratio on the surface of the material increases significantly, and the surface has a more decisive effect on its properties. Scanning tunneling microscope (STM) as the representative of the traditional surface research methods in the determination of the surface atomic structure of micron crystals has achieved great success, but also in the study of the surface structure of nanomaterials. Great difficulties have been encountered in the analysis of surface stress and strain, surface dynamic behavior, surface composition and valence state. In this paper, ETEM, an international advanced environmental transmission electron microscope (ETEM), is used in the electron microscope center of Zhejiang University. Spherical aberration correction transmission electron microscope, in situ sample rod and other equipment. A method for studying the surface behavior of nanocrystalline materials using in situ transmission electron microscopy (TEM) was developed. The atomic structure of nanocrystalline surface was determined by using the most widely studied systems such as TiO2 as the breakthrough point. The atomic structure of a few crystal planes and corners is studied, and the surface dynamic behavior is observed at the atomic scale in the external field. The structural evolution and surface catalytic reaction. The success of transmission electron microscopy in the application of these traditional surface research methods shows its great application potential in the field of surface science. The results are as follows: (1) by in situ transmission electron microscopy, we have for the first time determined the surface atomic arrangement of TiO2(1 脳 4 ~ 4 ~ (-0 ~ (001)) from a side-view angle. The most direct experimental evidence of the ADM surface reconstruction model is given. The conclusion of the controversy over the atomic structure of the reconstructed surface for more than a decade is given. ). The atomic structure of a few crystal planes and the atomic structure at the angles between different crystal faces are observed for the first time on the atomic scale of TiO2O001) in oxygen environment. The forming process of reconstruction. The dynamic evolution of surface structures such as "1 脳 3", "1 脳 5" and "1 脳 4" was observed. Combined with theoretical calculations, we reveal the stress-driven surface reconstruction mechanism of 1 脳 4) using spherical aberration corrected scanning transmission electron microscope (STEMM). We have studied in situ the stability of different surfaces such as anatase TiO2O101O101O1001O102at atomic scale. It is found that the energy of TiO2 can be reduced by surface reconstruction and structural evolution at high temperature. The stability of TiO2 is discussed for the first time from the point of view of surface structure. The reason why the phase transition temperature of anatase TiO2 nanocrystalline is higher than the theoretical value is explained. It is the first time that the catalytic activity of Pt on different surfaces can be compared in the same experiment at atomic scale for the first time. It has been proved that the catalytic graphene oxidation performance on the surface of Ptn100) and Pt110) is better than that of PtC111). The dynamic structure evolution of MoO2 nanorods was observed in situ at atomic scale under oxygen condition. The periodic oscillatory oscillation decomposition of the top surface and the growth of the lateral surface layer by layer are revealed. Based on the DFT theory, it is found that oxygen loss in the apical plane induced by electron beam irradiation leads to the change of the preferential growth plane and the reconstruction of the morphology.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TB383.1;TN16

【參考文獻】

相關(guān)期刊論文 前1條

1 Chunhai Jiang;Jinsong Zhang;;Nanoengineering Titania for High Rate Lithium Storage: A Review[J];Journal of Materials Science & Technology;2013年02期

相關(guān)碩士學(xué)位論文 前1條

1 李恒博;氣體環(huán)境下金屬與金屬氧化物催化劑納米顆粒表面形貌研究[D];浙江大學(xué);2016年

，

本文編號：1467820