Carbyne链力学性能的热依赖性

文章通过第一性原理计算和基于Tersoff-Brenner势的理论研究,阐明了热效应对carbyne链力学性能的影响。从单键和三键的原子特性得到了carbyne链的力学强度和热学特性。研究发现热波动影响下的单键和三键对carbyne链的热容和热膨胀系数起着至关重要的作用,并得到了室温下的热膨胀系数为+6.85×10^(-5)K^(-1)。此外,文章还对carbyne链的弹性性质和持续长度的温度依赖性进行了研究,结果表明carbyne链在整个三维空间内膨胀,并且其以4个碳原子为基本单位形成carbyne链。计算结果与模拟和实验测量一致,表明利用该方法研究carbyne链力学和热性能可行。

一维carbyne链原子键性质应变调控的第一性原理研究

基于密度泛函理论和广义梯度近似的第一原理方法,系统研究了应变对一维carbyne(卡拜)链原子键性质的调控机理.结果表明,轴向压缩应变的增加将导致carbyne链中碳-碳单键和碳-碳三键之间的键长差值越来越小,最终变为零.通过分析能带结构和差分电荷密度,发现当压缩应变为16%时,carbyne链由半导体转变为金属.当应变为17%时,声子谱出现虚频.在可研究范围内,应变对carbyne链的热容量有增强作用.而且,carbyne链的刚度远大于石墨烯和碳纳米管.

Raman spectroscopy of isolated carbyne chains confined in carbon nanotubes:Progress and prospects

Carbyne is an infinitely long linear chain of carbon atoms with sp1hybridization and the truly one-dimensional allotrope of carbon.While obtaining freestanding carbyne is still an open challenge,the study of confined carbyne,linear chains of carbon encapsulated in carbon nanotubes,provides a pathway to explore carbyne and its remarkable properties in a well-defined environment.In this review,we discuss the basics and recent advances in studying single confined carbyne chains by Raman spectroscopy,which is their primary spectroscopic characterization method.We highlight where single carbyne chain studies are needed to advance our understanding of confined carbyne as a material system and provide an overview of the open questions that need to be addressed and of those aspects currently under debate.

On-surface synthesis of one-dimensional carbyne-like nanostructures with sp-carbon

Carbyne is an infinite one-dimensional carbon chain comprising of sp-hybridized carbons.Due to its high chemical reactivity and extreme instability,the synthesis and structural diversity of carbyne have been much less investigated in the past decades compared to carbon allotropes built with sp^(2)hybridized carbons,such as fullerenes,carbon nanotubes,and graphene.The emerging on-surface synthesis strategy provides an extremely promising approach for the fabrication of novel carbyne-like nanostructures with atomic precision.Herein,we summarize recent exciting progress in the synthesis of carbyne-like nanostructures with one-dimensional sp-carbon on surfaces,including polyynes,cumulenes,and organometallic polyynes.We also point out the scientific challenges and prospects,encouraging scientists to explore the fabrication and characterization of single strands of carbyne in this young and promising research field.

Extraordinary mechanical performance in charged carbyne

Carbyne,the linear chain of carbon,promises the strongest and toughest material but possesses a Peierls instability(alternating single-bonds and triple-bonds)that reduces its strength and toughness.Herein,we computationally found that the gravimetric strength,strain-to-failure,and gravimetric toughness can be improved from 74 GPa·g^(-1)·cm^(3),18%,and 9.4 k J·g^(-1)for pristine carbyne to the highest values of 106 GPa·g^(-1)·cm^(3),26%,and 19.0 k J·g^(-1)for carbyne upon hole injection of+0.07 e/atom,indicating the charged carbyne with record-breaking mechanical performance.Based on the analyses of the atomic and electronic structures,the underlying mechanism behind the record-breaking mechanical performance was revealed as the suppressed and even eliminated bond alternation of carbyne upon charge injection.

Superinjection from Oriented Carbyne as the Result of Landau Quantization in Giant Pseudo-Magnetic Field

The qualitative explanation of the earlier published experimental data was obtained within new energetic model of oriented carbyne. The conductivity spectrum and the superinjection effect feature Landau quantization in a giant pseudomagnetic field. The relativistic dispersion of carriers and non-dissipative character of their motion cause the effect of superinjection where carriers go upwards on an energetic ladder. Raman-spectra and other data point out to the fact that the plane of carriers’ motion is close to the carbyne-insulator interface. Quantum effects and on-surface conductivity allow considering oriented carbyne as an analogue of topological insulator.

Time-of-Flight Mass Spectrometry of Highly Ordered Carbyne

Matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry was applied to a non-conven-tional object–highly ordered carbyne films. Mass spectra of both positive and negative ions were recorded in all tests. The spectra had a rather high number of hydrogen atom peaks and specific features indicative of hydrogen acting as a requisite stabilizer in the crystalline carbyne structure. A new model based on interchain dihydrogen bonds was proposed.

Prospects of Carbyne Applications in Microelectronics

We design carbyne transistor which is integrable into the existing silicon technology and can be scaled up in a rather broad range -- starting from that prepared by us (by 0.5-mkm technology) up to the monomolecular one because the key mechanism here is the inter-chain charge transfer.

A robust synthesis route of confined carbyne

The unique mechanical,optical,and electrical properties of carbyne,a one-dimensional allotrope of carbon,make it a highly promising material for various applications.It has been demonstrated that carbon nanotubes(CNTs)can serve as an ideal host for the formation of confined carbyne(CC),with the yield being influenced by the quality of the carbon nanotubes for confinement and the carbon source for carbyne growth.In this study,a robust synthesis route of CC within CNTs is proposed.C70 was utilized as a precursor to provide an additional carbon source,based on its ability to supply more carbon atoms than C60 at the same filling ratio.Multi-step transformation processes,including defect creation,were designed to enhance the yield of CC.As a result,the yield of CC was significantly increased for the C70 encapsulated single-walled CNTs by more than an order of magnitude than the empty counterparts,which also surpasses that of the double-walled CNTs,making it the most effective route for synthesizing CC.These findings highlight the importance of the additional carbon source and the optimal pathway for CC formation,offering valuable insights for the application of materials with high yield.

Forging Three Single Bonds on One Carbon via Metal Carbynes or Carbyne Equivalents

Metal carbyne(M≡C)complexes have been discovered for nearly half a century,however,they gained far less study in comparison with metal-carbon single bond(M—C)and metal carbene(M=C)species in synthetic chemistry.Up to three sigma bonds are possibly forged on a single carbon through metal carbynes or carbyne equivalents,which holds great potentials in organic synthesis but also requires high efficiency of bond formation and precise control of reactivity and selectivity.Along this line,two systems based on stoi-chiometric transformations of manganese carbynes and ruthenium/rhodium-catalyzed reactions of diazo hypervalent iodine reagents,carbyne equivalents,have emerged recently,which will be highlighted herein.Future potentials and challenges in this intriguing area are also briefly discussed.

Pulsed laser ablation in liquid of sp-carbon chains:Status and recent advances

This review provides a discussion of the current state of research on sp-carbon chains synthesized by pulsed laser ablation in liquid.In recent years,pulsed laser ablation in liquid(PLAL)has been widely employed for polyynes synthesis thanks to its flexibility with varying laser parameters,solvents,and targets.This allows the control of sp-carbon chains properties as yield,length,termination and stability.Although many reviews related to PLAL have been published,a comprehensive work reporting the current status and advances related to the synthesis of sp-carbon chains by PLAL is still missing.Here we first review the principle of PLAL and the mechanisms of formation of sp-carbon chains.Then we discuss the role of laser fluence(i.e.energy density),solvent,and target for sp-carbon chains synthesis.Lastly,we report the progress related to the prolonged stability of sp-carbon chains by PLAL encapsulated in polymeric matrices.This review will be a helpful guide for researchers interested in synthesizing sp-carbon chains by PLAL.

Enigmatic Glass-Like Carbon from the Alpine Foreland, Southeast Germany: A Natural Carbonization Process

Unusual carbonaceous matter, termed here chiemite, composed of more than 90% C from the Alpine Foreland at Lake Chiemsee in Bavaria, southeastern Germany has been investigated using optical and atomic force microscopy, X-ray fluorescence spectroscopy, scanning and transmission electron microscopy, high-resolution Raman spectroscopy, X-ray diffraction and differential thermal analysis, as well as by δ13 C and 14 C radiocarbon isotopic data analysis. In the pumice-like fragments, poorly ordered carbon matter co-exists with high-ordering monocrystalline α-carbyne, and contains submicrometersized inclusions of complex composition. Diamond and carbyne add to the peculiar mix of matter. The required very high temperatures and pressures for carbyne formation point to a shock event probably from the recently proposed Holocene Chiemgau meteorite impact. The carbon material is suggested to have largely formed from heavily shocked coal, vegetation like wood, and peat from the impact target area. The carbonization/coalification high PT process may be attributed to a strong shock that instantaneously caused the complete evaporation and loss of volatile matter and water, which nevertheless preserved the original cellular structure seen fossilized in many fragments. Relatively fresh wood encapsulated in the purported strongly shocked matter point to quenched carbon melt components possibly important for the discussion of survival of organic matter in meteorite impacts, implying an astrobiological relationship.

First-principles study on the mechanics, optical, and phonon properties of carbon chains

Besides graphite,diamond,graphene,carbon nanotubes,and fullerenes,there is another allotrope of carbon,carbyne,existing in the form of a one-dimensional chain of carbon atoms.It has been theoretically predicted that carbyne would be stronger,stiffer,and more exotic than other materials that have been synthesized before.In this article,two kinds of carbyne,i.e.,cumulene and polyyne are investigated by the first principles,where the mechanical properties,electronic structure,optical and phonon properties of the carbynes are calculated.The results on the crystal binding energy and the formation energy show that though both are difficult to be synthesized from diamond or graphite,polyyne is more stable and harder than cummulene.The tensile stiffness,bond stiffness,and Young's modulus of cumulene are 94.669 eV/Å,90.334 GPa,and 60.62 GPa,respectively,while the corresponding values of polyyne are 94.939 eV/Å,101.42 GPa,and60.06 GPa.The supercell calculation shows that carbyne is most stable at N=5,where N is the supercell number,which indicates that the carbon chain with 10 atoms is most stable.The calculation on the electronic band structure shows that cumulene is a conductor and polyyne is a semiconductor with a band gap of 0.37 eV.The dielectric function of carbynes varies along different directions,consistent with the one-dimensional nature of the carbon chains.In the phonon dispersion of cumulene,there are imaginary frequencies with the lowest value down to-3.817 THz,which indicates that cumulene could be unstable at room temperature and normal pressure.

A review of arc-discharge method towards large-scale preparation of long linear carbon chains

Linear carbon chains as new one-dimensional(1D)nanomaterials attract attention for the predicted outstanding properties.However,the high reactivity of linear carbon chains hampers further experimental research.To date,different methods have been developed to synthesize new materials containing linear carbon chains.Among them,the arc-discharge method is a practical way to prepare both finite and infinite linear carbon chains.This review provides a brief discussion of the recent progress in the techniques to prepare carbon chain-based materials and then focuses on the arc-discharge method.The configuration of apparatus,optimal conditions,and the corresponding mechanism of arc-discharge method to prepare long linear carbon chain inside multi-walled carbon nanotubes are summarized in detail.The characterization techniques are introduced to evaluate the quality of products.Moreover,remaining challenges and perspectives are presented for further investigation of long linear carbon chains.

One-dimensional sp carbon:Synthesis,properties,and modifications

Carbyne,as the truly one-dimensional carbon allotrope with sp-hybridization,has attracted significant interest in recent years,showing potential applications in next-generation molecular devices due to its ultimate one-atom thinness.Various excellent properties of carbyne have been predicted,however,free-standing carbyne sample is extremely unstable and the corresponding experimental researches and modifications are under-developed compared to other known carbon allotropes.The synthesis of carbyne has been slowly developed for the past decades.Recently,there have been several breakthroughs in in-situ synthesis and measurement of carbyne related materials,as well as the preparation of ultra-long carbon chains toward infinite carbyne.These progresses have aroused widespread discussion in the academic community.In this review,the latest approaches in the synthesis of sp carbon are summarized.We then discuss its extraordinary properties,including mechanical,electronic,magnetic,and optical properties,especially focusing on the regulations of these properties.Finally,we provide a perspective on the development of carbyne.

A Simplified Approach to the Problems of Room-Temperature Superconductivity

An attempt to simplify the approach to the problems of room-temperature superconductors was done. The key factor has been highlighted—a giant spin-orbit interaction as a result of specific geometry of crystal. Considering oriented carbyne as an example, it was shown that maximal value of SOC was attained in low-dimensional systems. A qualitative model of superconductivity in the localized phase with “pseudo-magnetic field” and “Rashba effective field” as parameters was presented. Their correlation was shown via geometry of electric microfields of crystal. Oriented carbyne was presented as localized phase of room-temperature superconductor and the recipe of its transformation to macroscopic superconductivity was given.

Synthesis and Characterization of Osmium Polycyclic Aromatic Complexes via Nucleophilic Reactions of Osmapentalyne

Treatment of osmapentalyne [Os { ≡C-C（COOMe）=CH-C =CH-C（PPh3） =CH-}Cl（PPh3）2]＋ BF4-with arylamines in the presence of Cs2CO3 produced osmium-bridged polycyclic aromatic complexes.In this reaction,metal carbyne of osmapentalyne was first attacked by nucleophiles,followed by a C-H oxidative addition.The UV-Vis spectra of these osmium-bridged polycyclic aromatic complexes were measured.The result shows that these osmium-bridged polycyclic aromatic complexes have broad absorption in the UV-Vis region up to 650 nm.

A review of linear carbon chains

Linear carbon chains(LCCs)are a one-dimensional sp1-hybridized allo trope of ca rbon.LCCs are extre mely unstable:The longer the LCCs,the less stable the materials.Thus,it is a big challenge to synthesize long LCCs.Although the research on the short LCCs,e.g.,polyynes,can be traced back to the 18th,LCCs are still not well-known compared to other allotropes of carbon,e.g.,fullerenes,carbon nanotubes and graphene.Therefore,introducing recent progress on LCCs is of great significance to draw more attention in the community of nanocarbons as well as nanomaterials in general.Theoretically,various excellent properties have been predicted.Experimentally,LCCs with different length in many kinds of forms have been successfully synthesized.In this review,we summarized recent studies of polyynic LCCs from both theoretical and experimental aspects.Also,perspectives are highlighted to point out the further investigations of the materials.