發(fā)布時(shí)間：2018-02-08 17:23

  本文關(guān)鍵詞： K納米團(tuán)簇 K(110)表面 BOLS 能量釘扎 芯能級(jí)偏移　出處：《湘潭大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：在塊體材料表面和納米材料的一系列研究中,人們致力于開拓并透徹了解這兩者所具有的新穎的物理特性。在研究與低維材料系統(tǒng)有關(guān)的現(xiàn)象時(shí),因?yàn)檫B續(xù)介質(zhì)力學(xué)和近代量子理論等經(jīng)典理論方法都遇到了一些難以突破的瓶頸,致使相關(guān)的實(shí)驗(yàn)測(cè)量?jī)?yōu)先于理論研究,且很少將低維材料與材料表面用低配原子這一概念聯(lián)系在一起。通過(guò)構(gòu)筑低配位原子間相互作用關(guān)系的理論模型,我們揭示了低維材料和塊體材料表面部分不同于孤立原子和理想塊體材料內(nèi)部原子的相關(guān)物理機(jī)制。通過(guò)結(jié)合鍵序-鍵長(zhǎng)-鍵強(qiáng)理論、緊束縛近似方法、密度泛函理論計(jì)算、X-射線光電子能譜測(cè)量、以及區(qū)域選擇光電子譜,我們獲得了與原子配位數(shù)相關(guān)的K(110)表面和K納米團(tuán)簇的局域晶格應(yīng)變、3p芯能級(jí)偏移等定量信息,總結(jié)如下:1.經(jīng)計(jì)算得到,K孤立原子相應(yīng)的3p軌道芯能級(jí)為15.595±0.003 eV,標(biāo)準(zhǔn)差為0.003,K塊體對(duì)應(yīng)的3p軌道芯能級(jí)為18.353 eV,因此可知,鉀塊體相對(duì)于孤立原子能級(jí)的能級(jí)偏移量為2.758 eV。2.我們認(rèn)為,孤立原子和理想塊體內(nèi)部的有效原子配位數(shù)分別為0和12,而我們測(cè)量的K(110)表面第二層和第一層的有效原子配位數(shù)分別為5.81和3.93,且表面最外層所產(chǎn)生的晶格應(yīng)變、結(jié)合能相對(duì)密度變化、以及原子內(nèi)聚能相對(duì)變化分別為2.76%、72.67%、和-62.46%。3.通過(guò)以上數(shù)據(jù)我們可以知道,K納米團(tuán)簇尺寸的減小會(huì)引起原子有效配位數(shù)的減少,并且進(jìn)一步增加了表面原子的相對(duì)數(shù)目,增大了表面電子的貢獻(xiàn)。結(jié)果表明:K(110)表面和K納米團(tuán)簇3p軌道芯能級(jí)的偏移來(lái)源于原子低配位引發(fā)的電荷致密化和量子釘扎對(duì)哈密頓量的微擾。理論與實(shí)驗(yàn)的一致性表明了體材料表面和原子團(tuán)簇中低配位原子的鍵變短變強(qiáng),相應(yīng)原子的芯能級(jí)隨著配位數(shù)的變化會(huì)發(fā)生有規(guī)律的改變。通過(guò)實(shí)驗(yàn)結(jié)果和計(jì)算以及理論預(yù)測(cè)得到局域晶格應(yīng)變、能量密度、原子內(nèi)聚能、以及它們低配關(guān)聯(lián)的偏移量等定量信息,對(duì)滿足特定結(jié)構(gòu)和物理性能要求的納米晶體的設(shè)計(jì)是非常有幫助的。
[Abstract]:In a series of studies on the surface of bulk materials and nanomaterials, efforts have been made to develop and understand thoroughly the novel physical properties of these two materials. Because the classical theoretical methods such as continuum mechanics and modern quantum theory have encountered some bottlenecks which are difficult to break through, the relative experimental measurement has priority over the theoretical research. The concept of low ligand atom is rarely associated with the low dimensional material and material surface. By constructing a theoretical model of the interaction between low coordination atoms, We reveal the physical mechanisms of the surface parts of low dimensional materials and bulk materials which are different from those of isolated atoms and internal atoms of ideal bulk materials. By combining the theory of bond order, bond length and bond strength, the tight-binding approximation method is proposed. The density functional theory (DFT) is used to calculate the X-ray photoelectron spectroscopy (XPS) measurements and the region-selective photoelectron spectra. We obtain the quantitative information such as the local lattice strain and 3p core energy level migration on the surface of K ~ (10) and K nanoclusters, which are related to the atomic coordination number. The results are as follows: 1.The corresponding 3p orbital core energy level of K solitary atom is 15.595 鹵0.003 EV, and the standard deviation of 3p orbital core energy level corresponding to 0.003 K block is 18.353 EV. Therefore, the energy level deviation of potassium block relative to the isolated atomic level is 2.758 eV.2. we think, The effective atomic coordination numbers of isolated atoms and ideal blocks are 0 and 12, respectively, while the effective atomic coordination numbers of the second layer and the first layer are 5.81 and 3.93, respectively, and the lattice strain produced by the outermost layer of the surface is obtained. The relative density of binding energy and the relative change of cohesive energy in atoms are 2.76 ~ 72.67 and -62.46.3. from the above data, we can see that the reduction of the size of K nanoclusters will lead to the reduction of the effective coordination number of atoms. And further increase the relative number of atoms on the surface, The results show that the shift of the energy levels of the 3p orbital core on the surface and K nanoclusters originates from the charge densification induced by the low coordination of atoms and the perturbation of Hamiltonian by quantum pinning. The results show that the bond between the low coordination atoms on the surface of the bulk materials and the atomic clusters becomes shorter and stronger. The core energy levels of the corresponding atoms change regularly with the change of the coordination number. The local lattice strain, energy density and atomic cohesive energy are obtained by experimental results and calculations, as well as theoretical prediction. The quantitative information such as their low correlation offset is very helpful for the design of nanocrystalline which can meet the requirements of specific structure and physical properties.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：O614.113;TB383.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 吳凱;迷人的表面科學(xué)[J];科學(xué)中國(guó)人;2003年08期

2 余春江,駱仲泱,張文楠,方夢(mèng)祥,周勁松,岑可法;堿金屬及相關(guān)無(wú)機(jī)元素在生物質(zhì)熱解中的轉(zhuǎn)化析出[J];燃料化學(xué)學(xué)報(bào);2000年05期

相關(guān)博士學(xué)位論文 前1條

1 曹先凡;帶隙材料與特定性能材料設(shè)計(jì)[D];大連理工大學(xué);2007年

，

本文編號(hào)：1495965