材料科學進展張奇

1、張奇材料發(fā)展電卡材料多孔膜石墨烯“有些事不懂，就先放下，不急，假以時日，像是枝頭的葡萄，自然會熟，落下來，嘗了，就懂了。”材料發(fā)展歷史材料革命材料研究進展材料分類智能材料鋁（金屬材料）混凝土（復合材料）天然橡膠（高分子材料）皮革（生物材料）人類文明的發(fā)展水平很大程度上取決于該文明所處時期的材料的特征和功能人造粘土制品、天然金屬玻璃、陶瓷、青銅、鐵鋼、合金、聚合物有機化學的發(fā)展 1825年， 德國化學家維勒制備了尿素 1856年， 英國化學家博金合成染料 馬尾紫 19世紀90年代稱為“紫紅色十年”， 這期間誕生了有機化學的另一分支 聚合物化學， 這一領(lǐng)域?qū)π虏牧系陌l(fā)展產(chǎn)生了巨大的影響新材料的發(fā)現(xiàn)

2、 1865年， 英國發(fā)明家亞歷山大 帕克斯，硝酸纖維素 1900年， 美國化學家貝蘭德， 酚醛塑料20世紀20-30年代許多聚合物新材料的發(fā)明和商品化，包括：脲醛塑料、聚氯乙烯、聚苯乙烯、尼龍、聚甲基丙烯酸甲酯、聚乙烯、密胺塑料等。新金屬的發(fā)展 鐵碳合金熟鐵鑄鐵碳鋼英國冶金學家 - 亨利 貝莫西現(xiàn)代煉鋼法：向熔化的鐵水中吹入熱空氣，可得到含碳比例適當?shù)匿撹F與各種金屬的合金 1868年，蘇格蘭冶金學家馬歇特在貝莫西鋼中加入少量鎢， 使其硬度更大，韌性更好，使用壽命更長。 1819年，鉻合金鋼 1912年， 不銹鋼 1905，鎳鉻鐵合金 （美國工程師瑪希發(fā)明，熱電絲）其它非鐵合金 鋁銅鎂錳合金 硬

3、鋁，1908年，德國工程師維爾姆發(fā)明。之后Al-Cu-Mg合金系、Al-Zn-Mg-(Cu)合金系、Al-Li合金系相繼發(fā)明。 鎳鉻合金 鎳鈦合金 銅合金 鎂合金新型材料師法自然的材料復合材料生物材料人工合成材料智能材料光學材料納米材料 材料研究目前最具有發(fā)展前景的領(lǐng)域是納米材料?？茖W家將采用自下而上的順序從分子和原子層次來合成新物質(zhì)。納米技術(shù)不僅能夠?qū)ΜF(xiàn)有材料進行變革，同時還能夠為新的化合物的設(shè)計和制造提供新的方式。材料分類化學狀態(tài)物理性質(zhì)用途組成物理效應(yīng)狀態(tài)材料金屬材料非金屬材料陶瓷材料高分子材料有機材料無機物材料高強度耐高溫超硬導電絕緣磁性透光半導體導電橡膠不銹鋼鋁箔復合材料螺母單晶硅透

4、光混凝土鐵氧體環(huán)氧樹脂材料單晶多晶非晶態(tài)準晶態(tài)材料壓電熱電鐵電光電電光聲光磁光激光材料單組分復合材料研究制備技術(shù)計算機輔助設(shè)計檢測工藝應(yīng)用研究實驗室實際應(yīng)用改進壽命定義能感知外界的變化后以某種形式對其作出反應(yīng)，從而改變自己的行為的材料種類 壓電和電致伸縮材料、磁致伸縮材料、現(xiàn)狀記憶合金、電流變液和磁流變液材料、光致變色或熱致變色材料現(xiàn)狀記憶合金 有記憶功能的合金材料是1963年美國海軍軍悈實驗室的研究人員發(fā)現(xiàn)的具有現(xiàn)狀記憶功能的合金一般都具有馬氏體相變，將合金加熱到相變溫度時，就能從馬氏體結(jié)構(gòu)轉(zhuǎn)變?yōu)閵W氏體結(jié)構(gòu)，完全恢復原來的形狀。加熱會變直的勺子鎳系合金：Ni-Ti，Ni-Ti-Pd，Ni-T

5、i-Fe銅系合金：Cu-Zn-Al，Cu-Al-Ni鐵系合金：Fe-Pt，F(xiàn)e-Cr-Ni，F(xiàn)e-Mn-Si形狀記憶合金的應(yīng)用形狀記憶合金被廣泛地應(yīng)用于衛(wèi)星、航空、生物工程、醫(yī)藥、能源和自動化等方面。如：“阿波羅”11號登月艙攜帶的天線。先在相變溫度以上把天線做好，然后在相變溫度以下把它壓縮成一團，塞進登月艙，到登月艙進入軌道后，加熱天線到相變溫度以上，天線完全打開。壓電和電致伸縮材料 壓電效應(yīng)是1880年杰克斯 、居里倆兄弟首先發(fā)現(xiàn)的。 壓電效應(yīng)：某些電介質(zhì)在沿一定方向上受到外力的作用而變形時，其內(nèi)部會產(chǎn)生極化現(xiàn)象，同時在它的兩個相對表面上出現(xiàn)正負相反的電荷。當外力去掉后，它又會恢復到不帶電

6、的狀態(tài)，這種現(xiàn)象稱為正壓電效應(yīng)。當作用力的方向改變時，電荷的極性也隨之改變。相反，當在電介質(zhì)的極化方向上施加電場，這些電介質(zhì)也會發(fā)生變形，電場去掉后，電介質(zhì)的變形隨之消失，這種現(xiàn)象稱為逆壓電效應(yīng)。 逆壓電效應(yīng)屬于一種典型的電致伸縮效應(yīng)壓電材料壓電效應(yīng) 壓電效應(yīng)是某些材料的特性（尤其是某些晶體和特定的陶瓷，包括骨髓），即加載機械應(yīng)力時能夠產(chǎn)生出電勢 （正壓電效應(yīng)）。這樣電荷在晶格上可能表現(xiàn)為是分開的。如果材料不短路，被作用的電荷使得材料產(chǎn)生出電壓。 壓電效應(yīng)是可逆的，在那些存在直接壓電效應(yīng)（即當施加壓力時產(chǎn)生電）的材料中，同樣也存在相反的壓電效應(yīng)（即施加電場時產(chǎn)生出壓力和/或張力）（逆壓電效應(yīng)）

7、。正壓電效應(yīng) 當對壓電材料施以物理壓力時，材料體內(nèi)之電偶極矩會因壓縮而變短，此時壓電材料為抵抗這變化會在材料相對的表面上產(chǎn)生等量正負電荷，以保持原狀。這種由于形變而產(chǎn)生電極化的現(xiàn)象稱為“正壓電效應(yīng)”。正壓電效應(yīng)實質(zhì)上是機械能轉(zhuǎn)化為電能的過程。P= d其中，P為晶體的電極化率，單位是C/m2， d為壓電常數(shù)，單位是C/N， 為應(yīng)力，單位是N/m2。逆壓電效應(yīng) 當在壓電材料表面施加電場（電壓），因電場作用時電偶極矩會被拉長，壓電材料為抵抗變化，會沿電場方向伸長。這種通過電場作用而產(chǎn)生機械形變的過程稱為“逆壓電效應(yīng)”。逆壓電效應(yīng)實質(zhì)上是電能轉(zhuǎn)化為機械能的過程。S = dt E其中，S為晶體的楊氏模量

8、， dt為壓電常數(shù)，單位是m/V，E為電場強度，單位是V/m。 壓電晶體目前用于很多途徑，其中一種是致動器： 由于晶體的寬度只要稍微有一點微小的變化就會相應(yīng)的出現(xiàn)極高的電壓，這個寬度的變化比千分尺還要精確，使得壓電晶體成為用來極其準確的定位物體的最重要的工具這就是他們在致動器中的用途。 揚聲器：電壓轉(zhuǎn)換為壓電高分子膜的機械運動。 壓電馬達：壓電元件用定向力驅(qū)動一個軸，使之旋轉(zhuǎn)。由于是非常小的距離，壓電馬達做為高精度馬達從而取代步進電機。 原子力顯微鏡和掃描隧道顯微鏡采用逆壓電保持傳感針靠近探針。 噴墨打印機：在某些噴墨打印機，特別是那些愛普生生產(chǎn)的，壓電晶體是用來控制從噴墨頭到紙張上墨水的流量

9、。柴油發(fā)動機：高性能的共軌柴油發(fā)動機使用壓電噴油器，最先由羅伯特博世有限公司研發(fā)的，替代了更常見的電磁閥裝置。壓電材料的研究發(fā)展方向 馳豫型鐵電單晶 壓電復合材料 主要用于水聽器，理論未完全建立，開發(fā)未充分發(fā)掘 高居里溫度復合材料 必須在高溫下具有壓電性能 三元及多元系壓電材料 壓電薄膜 滿足器件的小型化需求 細晶粒壓電陶瓷壓電材料的研究發(fā)展方向 無鉛壓電材料目前所用的壓電材料絕大部分為鉛基壓電陶瓷，對人和環(huán)境有污染。無鉛壓電材料的性能還遠遠落后于鉛基壓電陶瓷材料，要達到鉛基壓電材料的性能還需要做大量的研究工作。日本在無鉛壓電材料研究開發(fā)上的論文和專利最多。鐵電材料的主要特征值鐵電體自發(fā)極化電

10、疇電滯回線居里溫度介電反常自發(fā)極化在沒有外施電場的情況下，晶體的正、負電荷中心也不重合而呈現(xiàn)電偶極矩這種現(xiàn)象稱為自發(fā)極化。凡是呈現(xiàn)自發(fā)極化，并且自發(fā)極化的方向能因施加外場而改變的晶體稱為鐵電體(ferroelectrics)。 電疇 具有自發(fā)極化的晶體中存在一些自發(fā)極化取向一致的微小區(qū)域，稱為電疇。兩疇之間的界壁稱為疇壁。若兩個電疇的自發(fā)極化方向互成90，則其疇壁叫90疇壁。此外，還有180疇壁等。18090電滯回線鐵電體的基本特征是在外電場的作用下，晶體的自發(fā)極化強度能隨外電場而轉(zhuǎn)向。從電疇的角度出發(fā)，在無外場時，各小電疇在晶體中的分布是無規(guī)律的，晶體呈電中性，也即從宏觀的整體來說，晶體是不

11、極化的。但當有外電場加于晶體時，由于電場同方向的電疇增長，逆電場方向的電疇逐漸消失，以及由于其他方向分布的電疇轉(zhuǎn)向電場方向等原因，使極化矢量P隨電場E的增大而增加，且它們之間的關(guān)系曲線完全相似于鐵磁性物質(zhì)的HB曲線，這種曲線叫做電滯回線。 居里溫度 居里溫度是指材料從鐵電性轉(zhuǎn)變成非鐵電性的溫度。TTc介電反常BaTiO3鐵電體的研究歷史與現(xiàn)狀 1920年，法國人瓦拉賽克 （Valasek）發(fā)現(xiàn)羅息鹽（酒石酸甲納），具有鐵電性。 第一階段：1920-1939, 發(fā)現(xiàn)了兩種鐵電結(jié)構(gòu)， 即羅息鹽和KH2PO4系列。 第二階段：1940-1958，鐵電熱力學理論。 第三階段：1959-1970年代，鈣

12、態(tài)礦時期-鐵電軟模理論出現(xiàn)。 第四階段：1980年代-今，鐵電薄膜及器件時期-小型化。壓電體熱釋電體鐵電體介電體熱釋電效應(yīng) （pyroelectric effect)在某些絕緣物質(zhì)中，由于溫度的變化引起極狀態(tài)改變的現(xiàn)象稱為熱釋電效應(yīng)。Ps =TPs為自發(fā)式極化強度變化量；T為溫度變化；為熱釋電系數(shù)。熱釋電系數(shù) = Ps/T=dPs/dTPTTcVIZT1T2T1T1T1T2熱釋電材料 LiTaO3單晶 PZT陶瓷 硫酸三甘鈦電卡效應(yīng)是在極性材料中因外電場的改變從而導致極化狀態(tài)的改變而產(chǎn)生的絕熱溫度或等溫熵的改變。When an electric field is applied to or r

13、emoved from a dielectric material, under adiabatic conditions, it will induce a change in the polarization and consequently a change in the entropy and temperature in the material. Such an electric field-induced temperature and entropy change in a dielectric material is known as the electrocaloric e

14、ffect (ECE). -3-好心情T1 (= Room T), S1 E1 (=0) T2 (= T1 + T), S1E2 = EmaxT1, S2 ( S1)S0S = 0S = 0S(E1,T1) = S(E2,T2)S(E2,T1) = S(E1,T3)All solid-state cooling devicesOn-chip devices Refrigerationfridges, air-conditioners (more environmentally friendly)heaterKapton filmECE film+-IR sensor電卡測試裝置cccSTQHH

15、hSTQA-B Adiabatic polarizationB-C Heat transferC-D Adiabatic depolarizationD-A Entropy transferhcgenSSSgenhcchSTSTTW)(WQCOPcchcCRTTTCOPCRCOPCOP)(11chcgenhTTSSTcchhchSTSTQQWNet Electrical Energy:Coefficient of Performance (COP): For ideal reversible cycle:hcSSFor real cycle:Why ECE Based Cooling Devi

16、ces Are Interesting?Energy and Environment Refrigeration, air-conditioning, and cooling overall consume more than 20 % of electricity in the developed countries Air conditioning is a key driver of peak electricity demand The mechanical Vapor Compression Cycle cooling (VCC) devices have COP 2 to 4 (

17、70% of Carnot efficient) Environmental concerns: the refrigerant gases (HFC) in the mechanical VCC cooling devices are strong greenhouse gases. They contribute to about 25% of total greenhouse gases!In bulk ceramics, it was found that- T a few Kelvin (2.5 K in Pb0.99Nb0.02(Zr0.75Sn0.20Ti0.05)O3), -

18、A small change of heat 0.2 kJ kg-1 and - A small breakdown field 50 kVcm-1.All of these are too small to be of practical use.Electrocaloric properties of PZT thin filmsassociated with the FE-PE phase transitionA.S. Mischenko，Q. Zhang, et al. Science 311, 1270 (2006)Hysteresis losses 4%211EEEdETPCTTJ

19、oule heating 10-3 K220CCostEnvironment ImpactEfficiency/PowerCostEnvironment Impact)(11chcgenhTTSST21EEpdESHigh Breakdown Field(Thin films)High pyroelectric coefficient(Phase transition)21EEpdECTT-40-2002040P (C cm-2)-1000 -5000500 1000E (kV cm-1)21C-40-2002040P (C cm-2)-1000 -5000500 1000E (kV cm-1

20、)9C-40-2002040P (C cm-2)-1000 -5000500 1000E (kV cm-1)59C-40-2002040P (C cm-2)-1000 -5000500 1000E (kV cm-1)80C(Partially-ordered)T. M. Correia, et al. J. of Phys. D: Appl. Phys. 44, 165407 (2011).(Partially-ordered)32282420161284P (C cm-2)120100806040200T (C)201296583774392E (kV cm-1) FC FH Cubic-s

21、pline fitDeviation from ideal reversible Carnot cycleMaterial irreversible processes Thermal hysteresis (first-order phase transitions, glassy state in relaxors,) Electrical hysteresisThermodynamic Cycle Losses during heat exchange-11-10-9-8-7-6-5-4-3-2-10S (K kg-1K-1)45403530252015105T (C) FC FH723

22、509434360723285210E (kV cm-1)509434360285210a)-11-10-9-8-7-6-5-4-3-2-10T (K)45403530252015105T (C)723509434360723285210E (kV cm-1)509434360285210b)Relaxor 0.93PbMg1/3Nb2/3O3-0.07PbTiO3 Thin FilmNon-ergodic phaseThermal HysteresisRelaxor 0.93PbMg1/3Nb2/3O3-0.07PbTiO3 Thin Film-20-1001020P (C cm-2)-75

23、0 -3750375750E (kV cm-1)70C-20-1001020P (C cm-2)-750 -3750375750E (kV cm-1)30C-20-1001020P (C cm-2)-750 -3750375750E (kV cm-1)18C-20-1001020P (C cm-2)-750 -3750375750E (kV cm-1) FC FH5C)(chcTTSRCFWHMSSdTRCmTThcCostEnvironment ImpactEfficiency/PowerRaw MaterialsThin Film growthOperationInexpensiveSol

24、-Gel method: Cost-effective techniqueLow-cost operating device (no need for expensive magnets like magnetocaloric refrigerants)CostEnvironment ImpactEfficiency/Power(Lead is a toxic element for which special facilities are required during handling in order to minimize risk to health and to the envir

25、onment.)Electrocaloric refrigeration do not involve harmful gasesLead-based electrocaloric thin filmsTitleIntroduction Why capture CO2 ? Sources of CO2 emission? CO2 separation technologiesGas separation technologies Basic concepts MembranesvMechanism of membrane separation processesvSelection of Me

26、mbranesvPermeabilityvSelectivityvPolymeric MembranesvInorganic MembranesvOther membranes ConclusionsRealize the CO2 separation mechanism by membranes.What are the advantages of the use of membranes for CO2 separation?Realize current development of polymeric and inorganic membranes.Realize the future

27、 development direction of membranes. 85% of the worlds trade energy needs is provided by mineral fuels that are largely responsible for the increase in CO2 emissions. Climate change is one of the most significant factors faced by humanity and society as a whole. With the current structure of global

28、power, there are no viable alternative energy sources to mineral fuels, capable to fully replace them.Why capture carbon?A rapid change of energy sources of non mineral origin would result in a major disruption to the infrastructure of energy supply, with significant consequences for the global econ

29、omy. The CO2 capture and storage (CCS) is seen as a fundamental and indispensable measure to reduce the environmental impacts associated with this potentially catastrophic phenomenon. Commercial CO2 capture technology that exists today is very expensive and energy intensive. It is necessary to devel

30、op technologies that will allow us to utilize the fossil fuels while reducing the emission of green house gases.This lecture presents a summary of membrance technology of capture/separation of CO2.Currently the largest single point sources of CO2 emission are power plants that produce streams of flu

31、e gas, exhausted combustion smoke, with CO2 concentrations of ca. 15% at 1 atm.Sources of CO2 emissionFossil fuel （化石燃料） Natural gas(power plant)Mixed gases reusetransportseparationCO2StorageIntroduction -CO2 Emission SourcesNatural gas generationMixed gasesCO2, CH4, H2, etc separationCO2Cryogenic d

32、istillationSorbent absorption （吸附劑吸附）Membrane Adsorption is the adhesion of atoms, ions, biomolecules or molecules of gas, liquid, or dissolved solids to a surface.Absorption in chemistry, is a physical or chemical phenomenon or a process in which atoms, molecules, or ions enter some bulk phase-gas,

33、 liquid or solid material.Adsorbent is a substance, usually porous in nature and with a high surface area that can adsorb substances onto its surface by intermolecular forces.Adsorbate the molecules or atoms being accumulated on the surface of the adsorbent. Surface energy the excess energy at the s

34、urface of a material compared to the bulk.Physisorption also called physical adsorption, is a process in which the electronic structure of the atom or molecule is barely perturbed upon adsorption.Chemisorption is a sub-class of adsorption, driven by a chemical occurring at the exposed surface. A new

35、 chemical species is generated at the adsorbent surface (e.g. corrosion, metallic oxidation). The strong interaction between the adsorbate and the substrate surface creates new types of electronic bonds ionic or covalent, depending on the reactive chemical species involved.Van der Waals force is the

36、 sum of the attractive or repulsive forces between molecules (or between parts of the same molecule) other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral molecules. Micropores, of dimensions below 2 nm, Mesopores, between 2 and 50 nm, an

37、d Macropores, 50 nm.86 Gas separation membranes allow one component in a gas stream to pass through faster than the others. There are many different types of gas separation membrane, including porous inorganic membranes, palladium membranes, polymeric membranes and zeolites. MembranesMembranes canno

38、t usually achieve high degrees of separation, so multiple stages and/or recycle of one of the streams is necessary. This leads to increased complexity, energy consumption and costs.89The transport of chemical species through a membrane occurs when there is a driving force acting on it.In general, ch

39、emical potential gradient is the driving force.Chemical potential gradient can be expressed in terms of pressure gradient and concentration gradient.A successful membrane allows the desired gas molecule to adsorb to the surface on one side, often at higher pressure (solubility). The molecule then ab

40、sorbs into the membrane interior, eventually reaching the other side of the membrane (mobility) where it can desorb under different conditions, such as low pressure.Solution-diffusion mechanismo the separation of permeates due to two factorsv Solubility (thermodynamic factor)v mobility of the permea

41、tes into the membrane matrix diffusion (kinetic factor)SolubilityMobilityIntegral CompositeisotropicAnisotropicdCDJJ : the specific gas flowD: diffusion coefficient (m2 s-1)C: gas concentration in material (mol m-3)d: film thicknessThe permeability per unit thickness:PtAQtyPJdSDdPegas1The selectivit

42、y of a membrane 2222/NCONCOdPedPeySelectivitNCO22Select the most suitable material for separating gas mixtures, leading to better selectivity and permeability ratio.Study the yield and purity of the product. This means that the permeability and selectivity for the transport of gas should be high.The

43、 anisotropic membrane with appropriate morphology for gas separation must present a coating, free from defects, favouring the transport solution by diffusion.In order to obtain efficiency, a reduced coating thickness should be used, which provides higher permeate flux.Porous sub layer with low resis

44、tance to the transport of permeate. This sub layer must operate only as a porous support, providing mechanic strength to finish.The challenge for polymer chemists is to develop polymers with much higher permeability, whilst retaining adequate selectivity and meeting other requirements, such as proce

45、ssability and long-term stability. Many polymers have been investigated as gas separation membrane materials, but up to now only a handful have found commercial success. These includeq Rubbery polymers v Poly(dimethylsiloxane)q Glassy polymersv Polysulfonev Cellulose acetatev Polyimidev Poly(phenyle

46、ne oxide)Glassy polymer contains micropores (2 nm) high selectivity good mechanic strengthPlot of selectivity vs permeabilitySolid line 1991Dashed Line 2008 PTMSP; polyacetylene 2e; Teflon AF2400; + poly(trimethylsilyl norbornene) PIM-1; PIM-1 after methanol treatment 6FDA-DMN polyimide PIM-PI-8Perf

47、ormance of polymeric membranes separating CO2/N2(Powell and Qiao, 2006)Porous aluminaPolymer precursor solutionCarbonized under vacuum or high T The CO2 affinity of a typical carbon membrane was enhanced to improve the separation performance of the membrane based on the concept of Scheme I. Zeolites

48、 are crystalline aluminosilicates with a uniform pore structure and a minimum channel diameter range of 0.3 to 1.0 nm. Selectively adsorb molecules by size and polarity.Separation occurs in zeolite membranes by both molecular sieving and surface diffusion mechanisms.Zeolite membranesIncorporation of

49、 molecular sieves within a polymer membrane possibly provides both the processibility of polymers and selectivity of molecular sieves.The permeability of a gas through a zeolite-filled polymeric membrane depends on the intrinsic properties of the zeolite and polymer.Examples: polyimide-carbon molecu

50、lar sieve; polyimide-silica; etc.Mixed-matrix membranesA porous inorganic support material is surface-modified with chemicals which have good affinity with CO2.This helps CO2 separation in two ways: porous inorganic materials allow large flux while the chemical provides selectivity.Examples: Trichlo

51、rosilane-alumina; tetrapropylammonium-silica, etc.Hybrid membranesPolymeric membranesRelatively easy to manufacture and well-suited for low temperature applications.By carbonizing these polymeric materials it is possible to obtain a molecular sieve capability.Inorganic membranesMuch greater thermal

52、and chemical stability.Fossil fuel continues to be the primary energy source, at least for this century. There are many technical options for separation and /or capture of CO2 from combustion flue gas and other industrial effluents. Membrane separation processes provide several advantages over other

53、 conventional separation techniques; A membrane combining high flux, high selectivity and high stability is required, but is not realistic at this stage. Mixed-matrix membranes provide hopes. Membrane process as energy-saving, space saving, easy to scale-up, could be the future technology for CO2 se

54、paration.Basic definitionsCarbonIntroductionOccurrence and productionPropertiesPotential applicationsExamplesConclusionGraphene a one-atom-thick plannar sheet of carbon atoms that are densely packed in a honeycomb crystal lattice.Graphite many graphene sheets stack together2D crystal a single atomic

55、 plane is a 2D crystal, whereas 100 layers should be considered as a thin film of a 3D material. Composite the material is made of two or more different parts; one or more discontinuous phases distributed in one continuous phase.STM image of graphite surface atomsSide view of layer stackingGraphite

56、has a layered, planar structure. In each layer, the carbon atoms are arranged in a hexagonal lattice with separation of 0.142 nm, and the distance between planes is 0.335 nm.Graphite is an electrical conductor, a semimetal.Graphite is the most stable form of carbon under standard conditions (273 C,

57、0.986 atm. by IUPAC).IUPAC International Union of Pure and Applied ChemistryGraphite can conduct electricity due to the vast electron delocalization within the carbon layers. These valence electrons are free to move, so are able to conduct electricity. However, the electricity is only conducted with

58、in the plane of the layers. face-centered cubic crystal structure less stable than graphite strong covalent bonding between its atoms the highest hardness and thermal conductivity of any bulk materialDiamond （鉆石）Graphite（石墨）Graphene or graphite rolls and forms carbon nanotubes, the former single wal

59、l and the later multi-walls. 碳納米管The hexagonal grid structure of graphene Monolayer graphene was first obtained as a transferable material in 2004. This development has recently culminated in the award of the 2010 Nobel Prize to Andre Geim and Konstantin Novoselov of the University of Manchester, UK

60、, for “groundbreaking experiments regarding the two-dimensional material graphene.” Graphene can be wrapped up into 0D fullerences, rolled into 1D nanotubes or stacked into 3D graphite. Nature, 2007,6, 183.石墨碳納米管石墨烯足球烯In 2004, the researchers in the University of Manchester, obtained graphene by mec