本文選題：第一性原理 + 類石墨烯��； 參考：《山東大學(xué)》2017年博士論文

【摘要】：低維材料是當(dāng)前凝聚態(tài)物理和材料科學(xué)領(lǐng)域的研究熱點(diǎn),石墨烯和碳納米管的制備和性能研究推動(dòng)了該領(lǐng)域的發(fā)展。石墨烯材料具有一系列獨(dú)特的物理性質(zhì),例如:零帶隙半導(dǎo)體,高載流子遷移率,最薄的晶體,超高的剛性和彈性,極高的電導(dǎo)率等優(yōu)異的性能具有廣泛的應(yīng)用前景。碳納米管可以看成由石墨烯卷曲而成的一維結(jié)構(gòu)。根據(jù)手性、直徑、堆疊方式的不同展現(xiàn)出規(guī)律可調(diào)的電學(xué),熱學(xué)和機(jī)械性質(zhì),例如比金剛石還要高的熱導(dǎo)率,超強(qiáng)的機(jī)械性能,扶手椅狀納米管規(guī)律性變化的帶隙等,碳納米管被認(rèn)為是下一代電子元器件的理想材料。石墨烯的應(yīng)用還是會(huì)受到很多限制,例如其零帶隙的半導(dǎo)體性質(zhì)必須通過(guò)化學(xué)修飾等方式打開(kāi)帶隙,才能應(yīng)用于邏輯電路等電子元器件中,石墨烯的自旋軌道耦合效應(yīng)特別弱,無(wú)法在實(shí)驗(yàn)上實(shí)現(xiàn)量子自旋霍爾效應(yīng),石墨烯不存在自旋極化等等。碳納米管在可控合成方面也面臨很多困難。這些問(wèn)題都限制了石墨烯和納米管的實(shí)際應(yīng)用范圍�；诖�,一種被稱為"類石墨烯"的材料應(yīng)運(yùn)而生,這些類石墨烯及納米管材料具有石墨烯的部分奇特性質(zhì),比如硅稀和鍺烯是零帶隙半導(dǎo)體的性質(zhì);某些特性甚至優(yōu)于石墨烯,例如具有自旋極化零帶隙半導(dǎo)體性質(zhì)的氮化碳納米材料。隨著理論和實(shí)驗(yàn)工作的研究進(jìn)展,類石墨烯納米材料在未來(lái)的電子技術(shù),通訊技術(shù),機(jī)械制造,環(huán)境保護(hù),能源動(dòng)力等各個(gè)方面擁有廣泛的應(yīng)用前景。本論文通過(guò)基于密度泛函理論的第一性原理研究方法,設(shè)計(jì)研究了幾種具有新奇特性的類石墨烯納米材料。鍺化硅(SiGe)納米單層是具有零帶隙半導(dǎo)體性質(zhì)的類石墨烯單原子層化合物,二維氧化碳氮材料(g-C_2NO)的自旋極化零帶隙半導(dǎo)體性質(zhì)拓展了類石墨烯氮化碳材料的研究范圍,新型超硬材料bct-C8來(lái)源于冷壓T型石墨烯。一氧化碳(CO)納米管束結(jié)構(gòu)代表了固體一氧化碳低壓下穩(wěn)定的新結(jié)構(gòu),二氧化硅(SiO_2)納米片層和納米管在生物制藥,催化劑載體等領(lǐng)域具有潛在的應(yīng)用前景。上述材料的研究結(jié)果對(duì)于類石墨烯納米材料的實(shí)驗(yàn)合成及應(yīng)用提供了重要的理論依據(jù)。論文的第一章主要討論研究背景和選題意義,第二章討論基于密度泛函理論的第一性原理研究方法,結(jié)構(gòu)設(shè)計(jì)方法以及在論文中所使用到的軟件包,第三章至第六章詳細(xì)的介紹了攻讀博士學(xué)位期間的主要研究工作和研究成果。主要研究?jī)?nèi)容和結(jié)果如下所示:1)提出了由硅原子(Si)和鍺原子(Ge)交替排列形成的穩(wěn)定的鍺化硅(SiGe)單層化合物,該材料是具有狄拉克錐能帶的類石墨烯化合物。由于硅元素和鍺元素的電負(fù)性相差很小,費(fèi)米面附近錐帶的來(lái)源是兩種原子的pz軌道,自旋耦合效應(yīng)很弱,但是區(qū)別于單質(zhì)石墨烯,SiGe單層具有選擇吸附性,能夠首先在硅原子上完成氫化作用,合成具有自旋極化性質(zhì)的半導(dǎo)體HSiGe。該半導(dǎo)體具有鍺原子貢獻(xiàn)的1μB每原胞的磁性,鐵磁態(tài)最穩(wěn)定,根據(jù)伊辛模型進(jìn)行蒙特卡洛模擬證明在溫度低于110K時(shí)HSiGe保持鐵磁態(tài)性質(zhì)。另外在能量上優(yōu)于鍺烯,因此更有利于實(shí)驗(yàn)合成。2)提出了由三嗪和碳氧環(huán)組成的類石墨烯氧化碳氮材料g-C_2NO,聲子譜和分子動(dòng)力學(xué)模擬均驗(yàn)證了該材料的穩(wěn)定性。g-C_2NO具有自旋極化的零帶隙半導(dǎo)體性質(zhì),每個(gè)原胞具有1μB的磁矩,在費(fèi)米面上下,兩條不同曲率的能帶相切,使得電子和空穴兩種載流子有效質(zhì)量相差很大,有助于自旋注入和自旋過(guò)濾。與純g-C_6N_6相比,氧原子的加入,使g-C_2NO費(fèi)米面升高,g-C_6N_6中pz軌道貢獻(xiàn)的導(dǎo)帶,在g-C_2NO中成為費(fèi)米面附近的兩條相切能帶,從而產(chǎn)生自旋極化的零帶隙半導(dǎo)體性質(zhì)。作為不含金屬的有機(jī)二維材料,g-C_2NO具有環(huán)境友好的特點(diǎn),在自旋電子器件領(lǐng)域具有應(yīng)用潛力。3)在冷壓T型石墨烯的基礎(chǔ)上設(shè)計(jì)出一種新型的高對(duì)稱性超硬材料bct-C8。在能量上,bct-C8比T型石墨烯更穩(wěn)定,其聲子譜沒(méi)有虛頻。盡管相對(duì)于其它超硬材料bct-C8有較大直徑的8元碳環(huán)構(gòu)成,但仍表現(xiàn)出較好的力學(xué)特性,在同密度材料中,它的硬度是最強(qiáng)的,在相同硬度的范圍內(nèi),bct-C8的密度是最小的。能帶結(jié)構(gòu)顯示,該材料為寬帶隙半導(dǎo)體。作為碳元素家族的一個(gè)新成員,bct-C8的研究將對(duì)超硬材料的設(shè)計(jì)提供新的思路。4)研究了Ⅳ族硅(碳)氧化物的低維結(jié)構(gòu),提出了 Si02類石墨烯結(jié)構(gòu),即由Si-O六邊形組成的雙層結(jié)構(gòu),層間由Si-O-Si鍵連接。證明該類石墨烯結(jié)構(gòu)比其它納米結(jié)構(gòu)更穩(wěn)定。由該結(jié)構(gòu)出發(fā)通過(guò)AB堆垛可以形成穩(wěn)定的多層結(jié)構(gòu)。由SiO_2準(zhǔn)二維材料卷曲得到的納米管最小直徑約為12A。類石墨烯SiO_2納米材料的結(jié)構(gòu)孔徑為5.23A,相較于僅有2.48A的石墨烯結(jié)構(gòu),類石墨烯SiO_2納米材料在分子篩選,催化反應(yīng),緩釋微膠囊等領(lǐng)域有著獨(dú)特的發(fā)展?jié)摿ΑＡ硗?從理論上預(yù)言了一氧化碳(CO)一個(gè)新的低壓相,納米管束(bnudles)結(jié)構(gòu)。焓變分析和聲子譜分析均證明了該結(jié)構(gòu)的穩(wěn)定性。這種新結(jié)構(gòu)為一氧化碳晶體結(jié)構(gòu)的多樣性及一氧化碳的貯存等提供了新思路。
[Abstract]:Low dimensional materials are the hot spots in the field of condensed matter physics and material science. The preparation and properties of graphene and carbon nanotubes have promoted the development of this field. The graphene materials have a series of unique physical properties, such as zero band gap semiconductors, high carrier mobility, the thinnest crystals, ultra high rigidity and elasticity. Excellent properties, such as conductivity, have wide application prospects. Carbon nanotubes can be seen as a one-dimensional structure made of graphene. According to the chirality, diameter, and stacking mode, the electrical, thermal and mechanical properties, such as the higher thermal conductivity, the super mechanical properties, the armchair nanotube gauge, are higher than the diamond. Carbon nanotubes are considered to be ideal materials for the next generation of electronic components. The application of graphene will be limited by many limitations. For example, its zero band gap semiconductor properties must be opened by chemical modification to be applied to the electronic components such as logical circuits, and the spin orbit coupling effect of graphene. It should be especially weak, the quantum spin Holzer effect can not be realized in the experiment, the spin polarization does not exist in graphene and so on. The carbon nanotubes are also faced with many difficulties in the controllable synthesis. These problems restrict the practical application of graphene and nanotubes. Based on this, a kind of material called "graphene like" has come into being, these kinds of graphite. Alkene and nanotube materials have some peculiar properties of graphene, such as silicon thin and germanium are zero band gap semiconductors; some properties are even better than graphene, such as carbon nitride nanomaterials with spin polarized zero band gap semiconductors. With the progress of theoretical and experimental research, the future electricity of graphene nano materials is in the future Sub technology, communication technology, mechanical manufacturing, environmental protection, energy power and other aspects have wide application prospects. In this paper, several novel graphene like nanomaterials with novel properties are designed and studied by the first principle research method based on density functional theory. The SiGe nano monolayer is with zero band gap semiconductor properties. A qualitative graphene like single atomic layer compound, the spin polarized zero band gap semiconductor properties of two dimensional carbon and nitrogen oxides (g-C_2NO) expand the scope of the study of graphene carbon nitride materials. The new superhard material bct-C8 is derived from the cold pressed T type graphene. The carbon monoxide (CO) nanotube structure represents the new stability of the solid carbon monoxide under low pressure. Structure, silica (SiO_2) nanoscale and nanotube have potential applications in the fields of biopharmaceuticals, catalyst carriers and other fields. The research results of these materials provide important theoretical basis for the experimental synthesis and application of graphene like nanomaterials. The first chapter of the paper mainly discusses the research background and the significance of the topic, second chapters The first principle research method based on density functional theory, structure design method and software package used in the paper, third chapters to sixth chapters are introduced in detail to introduce the main research work and research results during the period of studying the doctorate. The main research contents and results are as follows: 1) the silicon atoms (Si) and germanium are proposed. A stable single layer of germanium (SiGe) compound formed by the alternating arrangement of Ge. The material is a graphene like compound with a Dirac cone. Because the electronegativity of the silicon and germanium elements is very small, the source of the cone in the vicinity of the Fermi surface is the PZ orbit of the two atoms. The self spin coupling effect is very weak, but it is distinguished from the single graphene, SiGe The monolayer has the choice of adsorbability. It can first complete the hydrogenation of the silicon atom and synthesize the semiconductor HSiGe. with spin polarization properties. The semiconductor has 1 u B of germanium atom contribution, and the ferromagnetic state is the most stable. According to the isin model, the Monte Carlo simulation shows that HSiGe maintains the ferromagnetic properties when the temperature is below 110K. In addition, the energy is superior to germanium, so it is more beneficial to the experimental synthesis of.2). A graphene like carbon and nitrogen oxide material composed of three azinazine and carbon oxygen ring is proposed. G-C_2NO, phonon spectrum and molecular dynamics simulation all verify that the stability of the material has the properties of spin polarized zero band gap half conductor, and the magnetic moment of each primary cell with 1 mu B, at the expense of.G-C_2NO. In the upper and lower sides of the rice, two bands of different curvature of the energy are tangent, which makes the two carrier mass of the electron and hole very different, and helps to spin and spin. Compared with the pure g-C_6N_6, the oxygen atom is added, the g-C_2NO Fermi surface is raised, the guide band of the PZ orbit in g-C_6N_6 is the two tangent energy near the Fermi surface in g-C_2NO. Band, thus producing spin polarized zero band gap semiconductor properties. As a non metallic organic two-dimensional material, g-C_2NO has environmental friendly characteristics and has potential application potential in the field of spintronic devices. A new type of high symmetry superhard material, bct-C8., is designed on the basis of cold pressed T graphene, bct-C8. in energy, bct-C8 than T stone. It is more stable and its phonon spectrum has no imaginary frequency. Although it is made up of 8 yuan carbon ring with larger diameter than other superhard material bct-C8, it still exhibits better mechanical properties. In the same density material, its hardness is the strongest and the density of bct-C8 is the smallest in the range of same hardness. The band structure shows that the material is half gap half. Conductor. As a new member of the family of carbon elements, the research of bct-C8 will provide a new idea for the design of super hard materials (.4). The low dimensional structure of Si (carbon) oxide is studied. The structure of Si02 class graphene is proposed, which is a double layer structure composed of Si-O hexagons and the interlayer is connected by the Si-O-Si bond. It is proved that the structure of this kind of graphene is more than the others. The structure is more stable. A stable multilayer structure can be formed by the structure of the AB stacking. The minimum diameter of the nanotube obtained by the SiO_2 quasi two-dimensional material is about 5.23A of the structure of the 12A. class graphene SiO_2 nanomaterials. Compared with the graphene structure with only 2.48A, the graphene SiO_2 nanomaterials are screened and catalyzed by molecules. In addition, a new low pressure phase, nano tube bundle (bnudles) structure of carbon monoxide (CO) was predicted theoretically. Both enthalpy and phonon spectrum analysis proved the stability of the structure. This new structure is the diversity of the crystalline structure of the mono oxygenated carbon and the storage of carbon monoxide. A new way of thinking is provided.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：O613.71;TB383.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 Jinying Wang;Shibin Deng;Zhongfan Liu;Zhirong Liu;;The rare two-dimensional materials with Dirac cones[J];National Science Review;2015年01期

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本文編號(hào)：2087424